Compounds and methods for treating central nervous system disorders

Abstract

Described herein are isolated peptides, compositions comprising the same, and methods of using such peptides or compositions in the treatment of central nervous system disorders.

Description

COMPOUNDS AND METHODS FOR TREATINGCENTRAL NERVOUS SYSTEM DISORDERSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to US Provisional Patent Application No. 63 / 536,009, filed on August 31, 2023, the entire content of which is incorporated by reference herein.FIELD

[0002] The present invention relates generally to the field of treatment of central nervous system disorders. More specifically, the present invention involves treatment with small peptides.SUMMARY

[0003] Provided herein in one aspect is an isolated peptide of Formula (I):or a pharmaceutically acceptable salt thereof, wherein:R1is Ci-Ce alkyl; andR2is each independently selected from the group consisting of H, polyethylene glycol, fatty acid, and half-life extending moiety.

[0004] Provided herein in another aspect is an isolated peptide comprising or consisting of the amino acid sequence LRP*, wherein P* is 2-methylproline.

[0005] Provided herein in another aspect is an isolated peptide comprising or consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0006] Provided herein in another aspect is an isolated peptide comprising or consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0007] In some embodiments, the peptide further comprises PEGylation, biotinylation, or one or more halogens, or a combination of two or more thereof. In some embodiments, the peptide further comprises N-terminal carboxylation, C-terminal amidation, C-terminal benzylation, or a combination of two or more thereof. In some embodiments, the peptide is cyclized.

[0008] Provided herein in another aspect is a pharmaceutical composition comprising a peptide described herein and at least one pharmaceutically acceptable excipient.

[0009] Provided herein in another aspect is a method of treating a central nervous system disorder in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide described herein or a composition described herein. In some embodiments, the central nervous system disorder is selected from autism spectrum disorders, bipolar disorder, catalepsy, depression, post-traumatic stress disorder (PTSD), encephalitis, epilepsy / seizures, locked-in syndrome, meningitis, migraine, multiple sclerosis, myelopathy, neurodegenerative disorders, schizophrenia, obsessive-compulsive disorder, tic disorders, and any combination thereof. In some embodiments, the central nervous system disorder is Alzheimer’s Disease.

[0010] Provided herein in another aspect is a method of treating Phelan-McDermid Syndrome in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide described herein or a composition described herein.

[0011] Provided herein in another aspect is a method of treating depression in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide described herein or a composition described herein.

[0012] Provided herein in another aspect is a method of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide described herein or a composition described herein.

[0013] Provided herein in another aspect is a method of treating a neurodevelopmental disorder in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide described herein or a composition described herein. In some embodiments, the neurodevelopmental disorder is selected from intellectual disability, autism spectrum disorders, motor disorders, tic disorders, traumatic brain injury, Down syndrome, attention deficit hyperactivity disorder, schizophrenia, schizotypal disorder, hypogonadotropic hypogonadal syndromes, fetal alcohol spectrum disorder, and Minamata disease caused by mercury, or any combination thereof. In some embodiments, the autism spectrum disorders are classical autism or Autistic Disorder; Asperger Syndrome; Childhood Disintegrative Disorder; Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS); Fragile X Syndrome; Rett Syndrome; Kanner’s Syndrome; or Phelan-McDermid Syndrome. In some embodiments, the motor disorders are developmental coordination disorder or stereotypic movement disorder.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 demonstrates Porsolt Forced Swim Test results using compound A (KKLRP (SEQ ID NO: 1)), compound B (AKKLRP (SEQ ID NO: 2)), or vehicle.

[0015] FIG. 2, FIG. 3, and FIG. 4 demonstrate potency changes in increasing intracellular calcium levels in vitro for compound A, compound B, and compound C (LRP*, wherein P* is 2-methylproline), respectively. Data was fit to a three-factor log agonist vs response dose response function and ECso values that were significantly different from zero at the P < .05 level were reported.

[0016] FIG. 5A demonstrates competition of varying concentrations of unlabeled control compound or compound C with labeled control compound (1 nM) for binding to recombinant IGF2R immobilized on a 96 well plate. N=4-7 wells per condition. IGF2R activity was measured in a hIGF2R expressing HEK via calcium activation with Fluo-8. Control compound = PKKLRP (SEQ ID NO: 3). FIG. 5B demonstrates IGF2R activity as measured in a hIGF2R expressing HEK via calcium activation with Fluo-8. * P < .05 student’s t-test, 2 tailed comparing control compound vs compound C at a fixed concentration.

[0017] FIGS. 6A, 6B, and 6C demonstrate in vivo rat electrophysiology testing results. Compound C (1 mg / kg PO; 1 hr post dosing) enhanced synaptic strength both postsynaptic(fEPSP) (FIG. 6A) and presynaptially (paired pulse) (FIG. 6B). Compound C also simultaneously enhanced qEEG alpha power (FIG. 6C).

[0018] FIGS. 7A and 7B demonstrate actigraphy and ultrasonic vocalizations in 24 hr home cage recording of pair housed adult male SD rats. N = 7-8 cages / pairs per group. FIG 7A: circadian amplitude was calculated by comparing the average activity 6 hrs before and after lights off, vehicle (Mean 20.5 ± SEM 3.4) and compound C (47.1 ± 2.3 change in % activity lights off - lights on). FIG. 7B: 24 hr aversive / total USVs call rate. * P < .05 vehicle vs control student’ s t-test.

[0019] FIGS. 8A and 8B demonstrate novel object recognition and Y-maze testing in mice. Adult Male Wild type and 5XFAD heterozygous animals were administered compound C (0.01 - 10 mg / kg PO; gastric gavage) or sterile saline vehicle (10 mg / ml) 1 hr before testing in the spontaneous alternating Y-maze and exposure to the familiar objects in the NOR test (retention test 24 hr post-dose) N= 6 mice per group. * P < .05 Dunnett’s post hoc test vs. veh 5XFAD.DETAILED DESCRIPTION

[0020] Various embodiments are described hereinafter. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment s).

[0021] As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term.

[0022] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in anysuitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0023] As used herein, the term “peptide” refers to a polymer of amino acid residues joined by amide linkages, which may optionally be chemically modified to achieve desired characteristics. The term “amino acid residue,” includes but is not limited to amino acid residues contained in the group consisting of alanine (Ala or A), cysteine (Cys or C), aspartic acid (Asp or D), glutamic acid (Glu or E), phenylalanine (Phe or F), glycine (Gly or G), histidine (His or H), isoleucine (He or I), lysine (Lys or K), leucine (Leu or L), methionine (Met or M), asparagine (Asn or N), proline (Pro or P), glutamine (Gin or Q), arginine (Arg or R), serine (Ser or S), threonine (Thr or T), valine (Vai or V), tryptophan (Trp or W), and tyrosine (Tyr or Y) residues. The term “amino acid residue” also may include unnatural amino acids or residues contained in the group consisting of homocysteine, 2-Aminoadipic acid, N-Ethyl-L- asparagine, 3 -Aminoadipic acid, Hydroxylysine, P-alanine, P-Amino-propionic acid, allo- Hydroxylysine acid, 2-Aminobutyric acid, 3-Hydroxyproline, 2-Methylproline, 4- Aminobutyric acid, 4-Hydroxyproline, Piperidine-3 -carboxylic acid, 6- Aminocaproic acid, Isodesmosine, 2-Aminoheptanoic acid, Alloisoleucine, 2-Aminoisobutyric acid, N- Methylglycine, 3-Aminoisobutyric acid, N-Methylisoleucine, 2-Aminopimelic acid, 6-N- Methyllysine, 2,4-Diaminobutyric acid, N-Methylvaline, Desmosine, Norvaline, 2,2'- Diaminopimelic acid, Norleucine, 2,3-Diaminopropionic acid, Ornithine, and N-Ethylglycine. Typically, the amide linkages of the peptides are formed from an amino group of the backbone of one amino acid and a carboxyl group of the backbone of another amino acid.

[0024] By “pharmaceutically acceptable” is meant a material that is not biologically or otherwise undesirable, e.g., the material may be incorporated into a pharmaceutical composition administered to a patient without causing any undesirable biological effects or interacting in a deleterious manner with any of the other components of the composition in which it is contained. When the term “pharmaceutically acceptable” is used to refer to a pharmaceutical carrier or excipient, it is implied that the carrier or excipient has met therequired standards of toxicological and manufacturing testing or that it is included on the Inactive Ingredient Guide prepared by the U.S. Food and Drug Administration.

[0025] As used herein, “subject” refers to an animal, such as a mammal (including a human), that has been or will be the object of treatment, observation or experiment. “Subject” and “patient” may be used interchangeably, unless otherwise indicated. Mammals include, but are not limited to, mice, rodents, rats, simians, humans, farm animals, dogs, cats, sport animals, and pets. The methods described herein may be useful in human therapy and / or veterinary applications. In some embodiments, the subject is a mammal. In some embodiments, the subject is a human.

[0026] The terms “therapeutically effective amount” and “effective amount” are used interchangeably and refer to an amount of a compound that is sufficient to effect treatment as defined below, when administered to a patient (e.g., a human) in need of such treatment in one or more doses. The therapeutically effective amount will vary depending upon the patient, the disease being treated, the weight and / or age of the patient, the severity of the disease, or the manner of administration as determined by a qualified prescriber or caregiver.

[0027] The term “treatment” or “treating” means administering a compound disclosed herein for the purpose of: (i) delaying the onset of a disease, that is, causing the clinical symptoms of the disease not to develop or delaying the development thereof; (ii) inhibiting the disease, that is, arresting the development of clinical symptoms; and / or (iii) relieving the disease, that is, causing the regression of clinical symptoms or the severity thereof.

[0028] A “half life extending moiety” as used herein refers to any moiety that prolongs the half life of the compound disclosed herein within a subject. Examples of half life extending moieties include, but are not limited to, polymers such as polyethylene glycol (PEG) moieties, fatty acids, polypeptides, glycosylates, starches such as hydroxyethyl starch, heparosans, isotope labels such as deuterium, and prodrug moieties.

[0029] “Fatty acid” as used herein refers to straight or branched saturated or unsaturated (including mono-, di- and poly- unsaturated) carboxylic acids or residues thereof having, for example 4 to 24 carbon atoms. Examples of fatty acids include, but are not limited to, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid,linoleic acid, linoelaidic acid, a-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, and docosahexaenoic acid.

[0030] The present disclosure also embraces isotopically labeled compounds of the disclosure which are identical to those recited herein, except that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into compounds of the present disclosure include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine and chlorine, such as2H,3H,13C,14C,15N,18O,17O,31P,32P,35S,18F, and36C1, respectively. For example, a compound of the disclosure may have one or more H atom replaced with deuterium.

[0031] "Prodrugs" refers to compounds, including derivatives of the compounds of the disclosure, which have cleavable groups and become by solvolysis or under physiological conditions the compounds of the invention which are pharmaceutically active in vivo. Such examples include, but are not limited to, choline ester derivatives and the like, N- alkylmorpholine esters and the like. Prodrugs also include acid derivatives such as, for example, esters prepared by reaction of the parent acid with a suitable alcohol, or amides prepared by reaction of the parent acid compound with a substituted or unsubstituted amine, or acid anhydrides, or mixed anhydrides.

[0032] When a range of values is listed, it is intended to encompass each value and sub-range within the range. For example, “Ci-Ce alkyl” is intended to encompass, Ci, C2, C3, C4, Cs, Ce, C1-C6 , C1-C5, C1-C4, C1-C3, C1-C2, C2-C6 , C2-C5, C2-C4, C2-C3, C3-C6 , C3-C5, C3-C4, C4-C6 , C4-C5, and C5-C6 alkyl.

[0033] The term “alkyl” as used herein refers to a saturated straight or branched hydrocarbon. Exemplary alkyl groups include, but are not limited to, straight or branched hydrocarbons of 1-6, 1-4, or 1-3 carbon atoms, referred to herein as Ci-Ce alkyl, C1-C4 alkyl, and C1-C3 alkyl, respectively. Exemplary alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, 2-methyl-l -butyl, 3-methyl-2-butyl, 2-methyl-l -pentyl, 3 -methyl- 1 -pentyl, 4- m ethyl- 1 -pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethyl-l- butyl, 3,3-dimethyl-l-butyl, 2-ethyl-l -butyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, and hexyl, etc.

[0034] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this present invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are described herein.

[0035] Central Nervous System Disorders

[0036] Central nervous system disorders are neurological disorders that affect the structure or function of the brain or spinal cord, which collectively form the central nervous system (CNS). CNS disorders include neurodegenerative disorders and neurodevelopmental disorders.

[0037] Neurodegenerative Disorders

[0038] Neurodegenerative diseases occur when nerve cells in the brain or peripheral nervous system lose function over time and ultimately die. Non-limiting examples of neurodegenerative disease include Alzheimer’s disease, ataxia, Huntington’s disease, Parkinson’s disease, motor neuron disease, multiple system atrophy, and progressive supranuclear palsy.

[0039] Neurodevelopmental Disorders

[0040] Neurodevelopmental disorders are disabilities associated primarily with the functioning of the neurological system and brain. Non-limiting examples include autism spectrum disorder.

[0041] One in 59 children in the U.S. are diagnosed with autism spectrum disorder (ASD). Phelan-McDermid Syndrome (PMS) is an etiologically-defined form of ASD caused by loss of function of the Shank3 gene and is estimated to account for up to 2% of ASD diagnoses. Currently, there are no disease-modifying treatments for ASD or for PMS. Diverse clinical and developmental symptoms of PMS and ASD are managed through a host of expensive interventions with varying degrees of success. Due to the immense etiological heterogeneity, development of therapeutics for ASD is extremely challenging. However, drug development for etiologically-defined subtypes of ASD, such as PMS, could be achievable, and could pave the way for treatment of other forms of autism.

[0042] With the high prevalence of ASD diagnoses among the general population, and with over 80% co-occurrence with other developmental, neurologic, genetic and psychiatric diagnoses, the economic and social burden of the disease is enormous. The annual costs for children with ASD in the U.S. have been estimated to be $11.5- $60.9B (Lavelle et al., Pediatrics, (2014), 133(3):e520-529; Buescher etal., JAMAPediatr., (2014), 168(8):721-728). Children and adolescents with ASD have median annual medical expenditures exceeding those of typically developing peers by a factor of 8.0-10. Ox.

[0043] Phelan-McDermid Syndrome is a rare and complex neurodevelopmental disorder characterized by global developmental delay, variable degrees of intellectual disability (ID), absent or delayed speech, ASD, epilepsy, sensory processing, attention and motor deficits, hypotonia, regression, brain abnormalities, mild dysmorphic features, feeding and gastrointestinal problems, and a range of other co-morbid clinical conditions (Drapeau et al., eNeuro, (2018), 5(3): ENEURO.0046- 18.2018; Harony-Nicolas et al., J. Child. Neurol., (2015), 30(14): 1861 - 1870; Kolevzon etal., Mol. Autism, (2014), 5(1):54). Indeed, PMS is one of the most frequent and penetrant monogenic causes of autism and ID, representing up to 2% of cases of ASD (Leblond et al., PLoS Genet., (2014), 10(9):el004580). Development of the first effective pharmacological treatment for PMS would thus have an impact for the management of PMS and, potentially, ASD.

[0044] Peptides

[0045] In one aspect, provided herein is an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0046] In another aspect, provided herein is an isolated peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0047] In another aspect, provided herein is an isolated peptide of Formula (I):or a pharmaceutically acceptable salt thereof, wherein:R1is Ci-Ce alkyl; andR2is each independently selected from the group consisting of H, polyethylene glycol, fatty acid, and half-life extending moiety.

[0048] In some embodiments, R1is C1-C4 alkyl. For example, R1is methyl.

[0049] In some embodiments, R2is H. In some embodiments, R2is selected from the group consisting of H, polyethylene glycol, and fatty acid.

[0050] In another aspect, provided herein is an isolated peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline. LRP* is also referred to herein as Leu- Arg-2 -Methyl-Pro-NH2 and has the chemical structure of:

[0051] In some embodiments, the peptide disclosed herein comprises D- and L-amino acids. In some embodiments, the peptide disclosed herein comprises only L-amino acids.

[0052] In some embodiments, the peptide disclosed herein is cyclized. In some embodiments, the peptide disclosed herein is not cyclized.

[0053] In some embodiments, the peptide disclosed herein further comprises modifications on the N-terminus, the C-terminus, or both. For example, in one embodiment, the peptide further comprises an acyl group (such as, but not limited to, an acetyl group) on the N-terminus. In another embodiment, the peptide further comprises an amido group on the C-terminus. In some embodiments, the peptide disclosed herein further comprises PEGylation, biotinylation, or one or more halogens, or a combination of two or more thereof. In some embodiments, the peptide disclosed herein further comprises N-terminal carboxylation, C-terminal amidation, C- terminal benzylation, or a combination of two or more thereof.

[0054] In some embodiments, the peptide disclosed herein includes any form of a peptide having substantial homology to SEQ ID NO: 1 or SEQ ID NO: 2. In some embodiments, a peptide which is “substantially homologous” is about 50% homologous, more preferably about 70% homologous, even more preferably about 80% homologous, more preferably about 90% homologous, even more preferably, about 95% homologous, and even more preferably about 99% homologous to SEQ ID NO: 1 or SEQ ID NO:2.

[0055] As known in the art the “similarity” between two peptides is determined by comparing the amino acid sequence and its conserved amino acid substitutes of one polypeptide to a sequence of a second polypeptide. Variants are defined to include peptide sequences different from the original sequence, preferably different from the original sequence in less than 40% of residues per segment of interest, more preferably different from the original sequence in less than 25% of residues per segment of interest, more preferably different by less than 10% of residues per segment of interest, most preferably different from the original protein sequence in just a few residues per segment of interest and at the same time sufficiently homologous to the original sequence to preserve the functionality of the original sequence and / or the ability to stimulate the differentiation of a stem cell into the osteoblast lineage. The present invention includes amino acid sequences that are at least 60%, 65%, 70%, 72%, 74%, 76%, 78%, 80%, 90%, or 95% similar or identical to the original amino acid sequence. The degree of identity between two peptides is determined using computer algorithms and methods that are widely known for the persons skilled in the art. The identity between two amino acid sequences is preferably determined by using the BLASTP algorithm [BLAST Manual, Altschul, S., et al., NCBI NLM NIH Bethesda, Md. 20894, Altschul, S., et al., J. Mol. Biol. 215: 403-410 (1990)].

[0056] In some embodiments, a peptide disclosed herein is a variant comprising one or more deletions relative to a reference amino acid sequence. A “deletion” refers to a change in the amino acid or nucleotide sequence that results in the absence of one or more amino acid residues or nucleotides relative to a reference sequence. A deletion removes at least 1 amino acid residue or nucleotide. A deletion may include an internal deletion or a terminal deletion (e.g., an N-terminal truncation or a C-terminal truncation of a reference polypeptide or a 5'- terminal or 3 '-terminal truncation of a reference polynucleotide).

[0057] In some embodiments, a peptide disclosed herein is a variant comprising a fragment of a reference amino acid sequence. A “fragment” is a portion of an amino acid sequence or a polynucleotide which is identical in sequence to but shorter in length than a reference sequence. A fragment may comprise up to the entire length of the reference sequence, minus at least one nucleotide / amino acid residue. For example, a fragment may comprise from 5 to 1000 contiguous nucleotides or contiguous amino acid residues of a reference polynucleotide or reference polypeptide, respectively. In some embodiments, a fragment may comprise at least 3 or 4 contiguous amino acid residues of a reference peptide, respectively. Fragments may be preferentially selected from certain regions of a molecule. The term “at least a fragment” encompasses the full length polynucleotide or full length polypeptide.

[0058] In some embodiments, a peptide disclosed herein is a variant comprising one or more insertions or additions relative to a reference sequence. The words “insertion” and “addition” refer to changes in an amino acid or sequence resulting in the addition of one or more amino acid residues. An insertion or addition may refer to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues.

[0059] The peptides disclosed herein may be variants comprising one or more unnatural amino acids formed by post-translational modification or by introducing one or more unnatural amino acids during translation or during chemical synthesis. A variety of approaches are available for introducing unnatural amino acids during protein translation.

[0060] The peptides disclosed herein may be variants comprising one or more selected from halogens, optional substitutions with C1-C3 alkyl (further optionally substituted with one or more halogen or amino (NH2) groups, or a combination thereof), optional substitutions with hydroxyl groups, optional substitutions with amino (NH2) groups, and optional deletions ofone or more of alkyl, hydroxyl, or amino groups. The variants comprising one or more halogens may include at least one radioactive isotopic halogen, such as 18-Fluorine. In some embodiments, the variant has proline replaced with 2-methylproline.

[0061] A peptide of the present invention may be synthesized by any technique known to those of skill in the art and by methods as disclosed herein. Methods for synthesizing the disclosed peptides may include chemical synthesis of proteins or peptides, the expression of peptides through standard molecular biological techniques, and / or the isolation of proteins or peptides from natural sources. The disclosed peptides thus synthesized may be subject to further chemical and / or enzymatic modification. Various methods for commercial preparations of peptides and polypeptides are known to those of skill in the art.

[0062] In a non-limiting example, LRP*, wherein P* is 2-methylproline, is prepared as shown in Scheme 1.Scheme 1.

[0063] A peptide of the present invention may alternatively be made by recombinant means or by cleavage from a longer polypeptide. The composition of a peptide may be confirmed by amino acid analysis or sequencing.

[0064] The peptides of the present invention can be post-translationally modified. For example, post-translational modifications that fall within the scope of the present invention include signal peptide cleavage, glycosylation, acetylation, isoprenylation, proteolysis, myristoylation, protein folding and proteolytic processing, etc. Some modifications or processing events require introduction of additional biological machinery. For example, processing events, such as signal peptide cleavage and core glycosylation, are examined by adding canine microsomal membranes or Xenopus egg extracts (U.S. Pat. No. 6,103,489) to a standard translation reaction.

[0065] The peptides disclosed herein may be modified to include non-amino acid moieties. Modifications may include but are not limited to carboxylation (e.g., N-terminal carboxylation via addition of a di-carboxylic acid having 4-7 straight-chain or branched carbon atoms, such as glutaric acid, succinic acid, adipic acid, and 4,4-dimethylglutaric acid), amidation (e.g., C- terminal amidation via addition of an amide or substituted amide such as alkylamide or dialkylamide), PEGylation (e.g., N-terminal or C-terminal PEGylation via additional of polyethylene glycol), acylation (e.g., O-acylation (esters), N-acylation (amides), S-acylation (thioesters)), acetylation (e.g., the addition of an acetyl group, either at the N-terminus of the protein or at lysine residues), formylation, biotinylation, lipoylation (e.g., attachment of a lipoate, a C8 functional group), myristoylation (e.g., attachment of myristate, a C14 saturated acid), palmitoylation (e.g., attachment of palmitate, a C16 saturated acid), alkylation (e.g., theaddition of an alkyl group, such as a methyl group at a lysine or arginine residue or a methyl group directly attached to the peptide backbone), isoprenylation or prenylation (e.g., the addition of an isoprenoid group such as farnesol or geranylgeraniol), amidation at C-terminus, glycosylation (e.g., the addition of a glycosyl group to either asparagine, hydroxylysine, serine, or threonine, resulting in a glycoprotein), and benzylation (e.g., replacement of a hydrogen atom with a benzyl group). In some embodiments, proline is replaced with 2-amino-thiophene- 3-carboxylate (Nadimpally et al., Chemistry Select, (2017), 3594-3596). In some embodiments, a benzene ring on select amino acid residue(s) is modified to include one or more fluorine atoms. In further embodiments, at least one of the fluorine atoms is 18-Fluorine.

[0066] Compositions

[0067] In some embodiments, a peptide described herein is formulated as a pharmaceutically acceptable composition when combined with at least one pharmaceutically acceptable carrier and / or excipient. Such pharmaceutically acceptable carrier(s) and / or excipient(s) are non-toxic and do not interfere with the efficacy of active ingredient (e.g., the peptides disclosed herein). The precise nature of the pharmaceutically acceptable carrier(s) and / or excipient(s) depends on the route of administration. The compositions can be formulated for any pharmaceutically acceptable route of administration, such as for example, by oral, parenteral, pulmonary, topical, rectal, nasal, vaginal administration, or via implanted reservoir. Parenteral or systemic administration includes, but is not limited to, subcutaneous, intravenous, intraperitoneally, intramuscular, intra-articular, intrasynovial, intrasternal, intrathecal, intralesional and intracranial injections. The compositions disclosed herein may be formulated into preparations in solid, semi-solid, liquid or gaseous forms, such as tablets, capsules, powders, granules, ointments, solutions, suppositories, injections, inhalants and aerosols.

[0068] In pharmaceutical dosage forms, the peptide disclosed herein may be administered in the form of its pharmaceutically acceptable salt (such as, but not limited to, an acetate salt) and / or as a pharmaceutically acceptable solvate of the salt thereof or of the free base form thereof, or the peptide may also be used alone or in appropriate association, as well as in combination, with other pharmaceutically active compounds. The following methods and excipients are merely exemplary and are in no way limiting.

[0069] For oral administration, liquid or solid dose formulations may be used. Some nonlimiting examples of oral dosage formulations include tablets, gelatin capsules, pills, troches, elixirs, suspensions, syrups, wafers, chewing gum and the like. The peptide can be mixed with a suitable pharmaceutical carrier (vehicle) or excipient as understood by practitioners in the art. Non-limiting examples of carriers and excipients include starch, milk, sugar, certain types of clay, gelatin, lactic acid, stearic acid or salts thereof, including magnesium or calcium stearate, talc, vegetable fats or oils, gums and glycols.

[0070] For systemic, intrathecal, topical, intranasal, subcutaneous, or transdermal administration, formulations of the peptides useful in the methods of the present invention may utilize conventional diluents, carriers, or excipients etc., such as are known in the art can be employed to deliver the peptides. For example, the formulations may comprise one or more of the following: a stabilizer, a surfactant (such as a nonionic, ionic, anionic, cationic, or zwitterionic surfactant), and optionally a salt and / or a buffering agent. The peptide may be delivered in the form of a solution or in a reconstituted lyophilized form.

[0071] In some embodiments, the stabilizer may, for example, be an amino acid, such as for instance, glycine or an oligosaccharide, such as for example, sucrose, tetralose, lactose or a dextran. Alternatively, the stabilizer may be a sugar alcohol, such as for instance, mannitol, sorbitol, xylitol, or a combination thereof. In some embodiments, the stabilizer or combination of stabilizers constitutes from about 0.1% to about 10% by weight of the formulation, or any percentage in between these two values.

[0072] In some embodiments, the surfactant is a nonionic surfactant, such as a polysorbate. Some examples of suitable surfactants include polysorbates (e.g.,Tween20, Tween80); a polyethylene glycol or a polyoxyethylene poly oxypropylene glycol, such as Pluronic F-68 at from about 0.001% (w / v) to about 10% (w / v), or any percentage in between these two values.

[0073] A salt or buffering agent may be any salt or buffering agent, such as for example, sodium chloride, or sodium / potassium phosphate, respectively. In certain embodiments, the buffering agent maintains the pH of the pharmaceutical composition in the range of about 5.5 to about 7.5, or any pH in between these two values. The salt and / or buffering agent is also useful to maintain the osmolality at a level suitable for administration to a human or an animal.In some embodiments, the salt or buffering agent is present at a roughly isotonic concentration of about 150 mM to about 300 mM.

[0074] The formulations of the peptides useful in the methods of the present invention may additionally comprise one or more conventional additives. Some non-limiting examples of such additives include a solubilizer such as, for example, glycerol; an antioxidant such as for example, benzalkonium chloride (a mixture of quaternary ammonium compounds, known as "quats"), benzyl alcohol, chloretone or chlorobutanol; anesthetic agent such as for example a morphine derivative; or an isotonic agent etc., such as described above. As a further precaution against oxidation or other spoilage, the pharmaceutical compositions may be stored under nitrogen gas in vials sealed with impermeable stoppers.

[0075] The amount of any individual excipient in the composition will vary depending on the role of the excipient, the dosage requirements of the active agent components, and particular needs of the composition. Generally, however, the excipient will be present in the composition in an amount of about 1% to about 99% by weight, from about 5% to about 98% by weight, or from about 15 to about 95% by weight of the excipient. In general, the amount of excipient present in a composition of the disclosure is selected from the following: at least about 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or even 95% by weight.

[0076] In another aspect, provided herein are formulations comprising, consisting essentially of, or consisting of a peptide disclosed herein and at least one pharmaceutically acceptable excipient for intravenous, intramuscular, subcutaneous, or intranasal administration. In some embodiments, the formulation is for intravenous administration. In some embodiments, the formulation is for intramuscular administration. In some embodiments, the formulation is for subcutaneous administration. In some embodiments, the formulation is for intranasal administration.

[0077] One or more additional active agents may be administered with a peptide disclosed herein, either sequentially or concomitantly. In some embodiments, the peptide disclosed herein and the one or more additional active agents are administered within a single composition. Non-limiting examples of additional active agents include sodium chloride and carboxymethyl cellulose.

[0078] In some embodiments, a peptide disclosed herein can be administered to a patient in an effective amount ranging from about 0.1 mg / kg to about 500 mg / kg per day. This includes 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 mg / kg.

[0079] Generally, a therapeutically effective amount of a peptide disclosed herein will range from a total daily dosage of about 0.1 mg / day to 500 mg / day, about 1-25 mg / day, about 3-15 mg / day, about 3-20 mg / day, about 30-720 mg / day, about 60-600 mg / day, or about 100-480 mg / day, or more. In some embodiments, a therapeutically effective amount of a peptide disclosed herein will range from about 1-240 mg / day, about 30-240 mg / day, about 30-200 mg / day, about 30-120 mg / day, about 1-120 mg / day, about 50-150 mg / day, about 60-150 mg / day, about 60-120 mg / day, or about 60-100 mg / day, administered as either a single dosage or as multiple dosages. In some embodiments, multiple dosages include two, three, or four doses per day.

[0080] In some embodiments, the therapeutically effective amount of a peptide disclosed herein is at least 0.1 mg / day, at least 0.5 mg / day, at least 1 mg / day, at least 5 mg / day, at least 10 mg / day, at least 15 mg / day, at least 20 mg / day, at least 30 mg / day, at least 40 mg / day, at least 50 mg / day, at least 60 mg / day, at least 70 mg / day, at least 80 mg / day, at least 90 mg / day, at least 100 mg / day, at least 110 mg / day, at least 120 mg / day, at least 130 mg / day, at least 140 mg / day, at least 150 mg / day, at least 160 mg / day, at least 170 mg / day, at least 180 mg / day, at least 190 mg / day, at least 200 mg / day, at least 225 mg / day, at least 250 mg / day, at least 275 mg / day, at least 300 mg / day, at least 325 mg / day, at least 350 mg / day, at least 375 mg / day, at least 400 mg / day, at least 425 mg / day, at least 450 mg / day, at least 475 mg / day, or at least 500 mg / day.

[0081] Of course, the dosage may be changed according to the patient's age, weight, susceptibility, symptom, or the efficacy of the compound.

[0082] The peptides and compositions disclosed herein may be used to prepare formulations and medicaments that treat depression, central nervous system disorders, or neurodevelopmental disorders. In some embodiments, the peptides and compositions disclosedherein are used to prepare formulations and medicaments that treat autism spectrum disorders. In some embodiments, the peptides and compositions disclosed herein are used to prepare formulations and medicaments that treat Phelan-McDermid Syndrome.

[0083] Methods

[0084] In another aspect, provided herein are methods of treating a central nervous system disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein. In some embodiments, the central nervous system disorder is selected from autism spectrum disorders, bipolar disorder, catalepsy, depression, post- traumatic stress disorder (PTSD), encephalitis, epilepsy / seizures, locked-in syndrome, meningitis, migraine, multiple sclerosis, myelopathy, neurodegenerative disorders, schizophrenia, obsessive-compulsive disorder, and tic disorders, or any combination thereof. In some embodiments, the central nervous system disorder is Alzheimer’s Disease.

[0085] In another aspect, provided herein are methods of treating a central nervous system disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0086] In another aspect, provided herein are methods of treating a central nervous system disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0087] In another aspect, provided herein are methods of treating central nervous system disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0088] In another aspect, provided herein are methods of treating central nervous system disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.

[0089] In another aspect, provided herein are methods of treating a neurodevelopmental disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein. In some embodiments, the neurodevelopmental disorder is selected from intellectual disability, autism spectrum disorders, motor disorders, tic disorders, traumatic brain injury, Down syndrome, attention deficit hyperactivity disorder, schizophrenia, schizotypal disorder, hypogonadotropic hypogonadal syndromes, fetal alcohol spectrum disorder, and Minamata disease caused by mercury, or any combination thereof.

[0090] In another aspect, provided herein are methods of treating a neurodevelopmental disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0091] In another aspect, provided herein are methods of treating a neurodevelopmental disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0092] In another aspect, provided herein are methods of treating a neurodevelopmental disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0093] In another aspect, provided herein are methods of treating a neurodevelopmental disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.

[0094] In some embodiments, the autism spectrum disorders are classical autism or Autistic Disorder; Asperger Syndrome; Childhood Disintegrative Disorder; Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS); Fragile X Syndrome; Rett Syndrome; Kanner’s Syndrome; or Phelan-McDermid Syndrome.

[0095] In some embodiments, the motor disorders are developmental coordination disorder or stereotypic movement disorder.

[0096] In another aspect, provided herein are methods of treating an autism spectrum disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein. In some embodiments, the autism spectrum disorder is classical autism or Autistic Disorder. In some embodiments, the autism spectrum disorder is Asperger Syndrome. In some embodiments, the autism spectrum disorder is Childhood Disintegrative Disorder. In some embodiments, the autism spectrum disorder is Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). In some embodiments, the autism spectrum disorder is Fragile X Syndrome. In some embodiments, the autism spectrum disorder is Rett Syndrome. In some embodiments, the autism spectrum disorder is Kanner’s Syndrome. In some embodiments, the autism spectrum disorder is Phelan-McDermid Syndrome.

[0097] In another aspect, provided herein are methods of treating an autism spectrum disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0098] In another aspect, provided herein are methods of treating an autism spectrum disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0099] In another aspect, provided herein are methods of treating an autism spectrum disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0100] In another aspect, provided herein are methods of treating an autism spectrum disorder in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.

[0101] In another aspect, provided herein are methods of treating Phelan-McDermid Syndrome in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein.

[0102] In another aspect, provided herein are methods of treating Phelan-McDermid Syndrome in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0103] In another aspect, provided herein are methods of treating Phelan-McDermid Syndrome in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0104] In another aspect, provided herein are methods of treating Phelan-McDermid Syndrome in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0105] In another aspect, provided herein are methods of treating Phelan-McDermid Syndrome in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.

[0106] In another aspect, provided herein are methods of treating depression in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein.

[0107] In another aspect, provided herein are methods of treating depression in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0108] In another aspect, provided herein are methods of treating depression in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administeringto the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0109] In another aspect, provided herein are methods of treating depression in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0110] In another aspect, provided herein are methods of treating depression in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.[OHl] In another aspect, provided herein are methods of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide or a composition disclosed herein.

[0112] In another aspect, provided herein are methods of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide of Formula (I), or a pharmaceutically acceptable salt thereof.

[0113] In another aspect, provided herein are methods of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of an isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

[0114] In another aspect, provided herein are methods of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, the methods comprising, consisting essentially of, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

[0115] In another aspect, provided herein are methods of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, the methods comprising, consisting essentiallyof, or consisting of administering to the subject a therapeutically effective amount of a peptide consisting of the amino acid sequence of LRP*, wherein P* is 2-methylproline.

[0116] The present invention, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present invention.EXAMPLES

[0117] Animals

[0118] Adult male (2-3 month old) Sprague-Dawley (SD) rats were purchased from Harlan (USA) for the Porsolt Forced Swim Test. Rats were housed in Lucite cages with aspen wood chip bedding, maintained on a 12: 12 light: dark cycle (lights on at 5 AM), and given ad libitum access to Purina lab chow (USA) and tap water throughout the study. All experiments were approved by the Sai Life Sciences (India) Animal Care and Use Committees.

[0119] Example 1. Porsolt Forced Swim Test

[0120] Porsolt forced swim testing was conducted as described in Burgdorf et al. (Neuropsychopharmacology, (2013), 38(5):729-742). Rats were dosed with compound A (KKLRP (SEQ ID NO: 1)), compound B (AKKLRP (SEQ ID NO: 2)), or 0.9% sterile saline vehicle (1 ml / kg, i.v.). Injections were made in the lateral tail vein and rats were tested 1 hour post-dosing. Animals were placed in a 46 cm tall x 20 cm in diameter clear glass tube filled to 30 cm with tap water (23 ± 1° C) for 15 min on the first day (habituation) and 5 min on the subsequent test day. Water was changed after every other animal. Animals were videotaped, and tapes were scored offline by a blind experimenter with high inter-rater reliability (Pearson’ s r > .9). Floating time (sec) was defined as the minimal amount of effort required to keep the animal’s head above and diving (number of incidences) was registered when the whole body of the animal was submersed and the animal’s head was facing towards the bottom of the tank.

[0121] As shown in FIG. 1, both compound A and compound B decreased floating time in the rat Porsolt test 1 hr after IV injection dosing [F (2, 9) = 46.72, P < .001; * Dunnett’s Multiple Comparison Test Vehicle vs. compound A P < .001 and Vehicle vs. compound B P < .001], N = 4 male 2-3 month old rats per group.

[0122] Example 2. Calcium Imaging Method.

[0123] Primary cortical cultures (El 8 rats) were plated onto 96 well plates and dendritic intracellular calcium (using Fluo-8 dye, Abeam) was measured at 21 DIV using high content confocal microscopy (ImageXpress, molecular devices). Measures were made immediately before dosing and again 1 hour after dosing, and the change scores were analyzed. Results were obtained for compound A (FIG. 2), compound B (FIG.3), and compound C (FIG. 4). In contrast, control compound (PKKLRP (SEQ ID NO: 3)) demonstrated ECso = 5 nM.

[0124] Example 3. IGF2R Binding Assay

[0125] Recombinant c-terminal HIS tagged IGF2R (R&D) systems were bound to clear copper coated 96 well plates (Thermo, USA). Various concentrations of unlabeled IGF2 or IGFBP2 (Thermo, USA) or compound C were co-incubated with Biotinylated control compound (PKKLRP (SEQ ID NO: 3)) (1 nM) for 30 min at room temperature on an orbital shaker. Non-specific binding was determined by co-incubation with 10 mM unlabeled control compound. The plates were then washed in sample buffer, tris HCL (10 mM) three times. Samples were then incubated with Streptavidin-HRP (1 : 1000, Sigma, USA), and after washing binding was visualized with TMB and stop solution (HCL) and absorbance quantified 440 nM using a plate reader (Molecular devices USA). Results are shown in FIG. 5A.

[0126] IGF2R activity assays were conducted exactly as described in Burgdorf et al. (Mol. Psychiatry, (2023) 28(3): 1101-1111, PMID: 36481930). In brief, a hIGF2-R expressing HEK cell line was treated with varying concentration of compound C and intercellular calcium was measured using fluo-8 using an ImageXpress (molecular devices) as measured by the calcium signal 1 hr post dose minus pre dose levels. Results are shown in FIG. 5B.

[0127] Replicates were averaged, and the data fit to a log(agonist) vs. response (three parameters) model (GraphPad Prism, USA).

[0128] Example 4. In vivo rat electrophysiology

[0129] Rats were anesthetized with isoflurane (5% induction and 2-3% maintenance; 15-20 min total duration) and implanted with skull screws to record cortical EEG (Pinnacle, USA), as well as intercranial medial prefrontal cortex (MPFC) and periaqueductal gray (PAG) recording and stimulating (bipolar) insulated stainless steel electrodes. Animals were given 7days to recover before the start of testing. EEG signals were captured via a tethered system (A- M systems, USA). Data were acquired at 10 kHz using an A-M systems (USA) amplifier with high (0.1 Hz)- and low-pass (100 kHz) filters and digitized using Data Wave ( A-M systems, USA) acquisition software. Data were analyzed using Brain Products Analyzer 2 software (Germany).

[0130] In vivo studies of excitatory synaptic strength (fEPSP S)’. For field potential studies, shock (10 pA, 70 ps, once every 30 seconds) induced field potentials simulated using a bipolar electrode in layer 2-3 of the MPFC and in layer 4 were recorded and the initial slope after the stimulation artifact was quantified. Excitatory field potential measures were made from single shock induced fEPSP. Paired pulse facilitation measures were made from two shock pairs separated by 50 ms, and paired pulse facilitation was calculated by the ratio of the second / first fEPSP. Normalized alpha power was calculated by FFT (Brain vision analyzer, Germany). Test results for compound C are shown in FIGS. 6A, 6B, and 6C.

[0131] Example 5. Home cage actigraphy and ultrasonic vocalization

[0132] Male 2-3 month old SD rats were dosed with compound C (1 mg / kg PO) or sterile saline vehicle (1 ml / kg PO) and home cage actigraphy and ultrasonic vocalization data was collected as described by Burgdorf et al. (Sleep, (2019), 42(10):zszl35). Circadian amplitude was calculated by comparing the average activity 6 hours before and after lights off, vehicle (Mean 20.5 ± SEM 3.4) and compound C (47.1 ± 2.3 change in % activity lights off - lights on) — see FIG. 7A. In addition 24 hour aversive / total US Vs call rate was calculated as a measure of negative affect (FIG. 7B).

[0133] Example 6. Novel object recognition (NOR) and Y-maze testing

[0134] Novel object recognition and Y-maze testing in 5XFAD mice (- / +) and wild type controls were conducted exactly as previously described in Burgdorf et al. (Mol. Psychiatry, (2023) 28(3): 1101-1111, PMID: 36481930). NOR test (working memory): briefly, mice were habituated to the empty NOR arena, as a group, for one hour, on each of three days prior to the acquisition trial. During the acquisition trial, the mice were allowed to explore two identical objects (e.g., Al and A2) for 10 min. This was followed by a 24 hour inter-trial interval, after which the mice were returned to the home cage. During the retention trial, the mice were allowed to explore the familiar object (A) from the acquisition trial and a novel object (e.g.,B). Y-maze (long-term memory): briefly, mice were placed in the Y-maze and allowed to enter any of the three arms for 7 min. The order of arm entries was recorded and analyzed for spontaneous alternation. An alternation was scored for each set of three consecutive choices when no repeated entries occurred. The discrimination index (DI) was calculated for both the Y-maze [(alternating entries — non alternating entries) / total entries] and NOR [(time spent exploring the novel object — time spent exploring the familiar object) / total exploration time] tests. Animals were dosed with compound C (0.01 - 10 mg / kg PO) or sterile saline vehicle (10 ml / kg PO) 1 hr before testing in the y-maze and training in the NOR test. The mean and SEM value for wild type (N=6), Vehicle 5XFAD (n=6) and compound C 5XFAD (n=6) mice were used for statistical analysis (Graphpad Prism, USA). Results are shown in FIG. 8A and FIG. 8B

[0135] While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the present invention in its broader aspects as defined in the following claims.

[0136] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed invention. Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed invention. The phrase “consisting of’ excludes any element not specified.

[0137] The present disclosure is not to be limited in terms of the particular embodiments described in this application. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of the disclosure, in addition to those enumeratedherein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, or compositions, which can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0138] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0139] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

[0140] All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[0141] Other embodiments are set forth in the following claims.

Claims

WHAT IS CLAIMED IS:

1. An isolated peptide of Formula (I):or a pharmaceutically acceptable salt thereof, whereinR1is Ci-Ce alkyl; andR2is each independently selected from the group consisting of H, polyethylene glycol, fatty acid, and half-life extending moiety.

2. An isolated peptide consisting of the amino acid sequence LRP*, wherein P* is 2- methylproline.

3. An isolated peptide consisting of the amino acid sequence of KKLRP (SEQ ID NO: 1).

4. An isolated peptide consisting of the amino acid sequence of AKKLRP (SEQ ID NO: 2).

5. The peptide of any one of claims 1-4, further comprising PEGylation, biotinylation, or one or more halogens, or a combination of two or more thereof.

6. The peptide of any one of claims 1-5, further comprising N-terminal carboxylation, C- terminal amidation, C-terminal benzylation, or a combination of two or more thereof.

7. The peptide of any one of claims 1-6, wherein the peptide is cyclized.

8. A pharmaceutical composition comprising a peptide of any one of claims 1-7 and at least one pharmaceutically acceptable excipient.

9. A method of treating a central nervous system disorder in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide of any one of claims 1-7 or a composition of claim 8.

10. The method of claim 9, wherein the central nervous system disorder is selected from autism spectrum disorders, bipolar disorder, catalepsy, depression, post-traumatic stress disorder (PTSD), encephalitis, epilepsy / seizures, locked-in syndrome, meningitis, migraine, multiple sclerosis, myelopathy, neurodegenerative disorders, schizophrenia, obsessive- compulsive disorder, tic disorders, and any combination thereof.

11. The method of claim 10, wherein the central nervous system disorder is Alzheimer’s Disease.

12. A method of treating Phelan-McDermid Syndrome in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide of any one of claims 1-7 or a composition of claim 8.

13. A method of treating depression in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide of any one of claims 1-7 or a composition of claim 8.

14. A method of treating post-traumatic stress disorder (PTSD) in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide of any one of claims 1-7 or a composition of claim 8.

15. A method of treating a neurodevelopmental disorder in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a peptide of any one of claims 1-7 or a composition of claim 8.

16. The method of claim 15, wherein the neurodevelopmental disorder is selected from intellectual disability, autism spectrum disorders, motor disorders, tic disorders, traumatic brain injury, Down syndrome, attention deficit hyperactivity disorder, schizophrenia, schizotypaldisorder, hypogonadotropic hypogonadal syndromes, fetal alcohol spectrum disorder, and Minamata disease caused by mercury, or any combination thereof.

17. The method of claim 16, wherein the autism spectrum disorders are classical autism or Autistic Disorder; Asperger Syndrome; Childhood Disintegrative Disorder; Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS); Fragile X Syndrome; Rett Syndrome; Kanner’s Syndrome; or Phelan-McDermid Syndrome.

18. The method of claim 16, wherein the motor disorders are developmental coordination disorder or stereotypic movement disorder.

Images