Ameliorating agent for memory disorder

Abstract

To provide a novel ameliorating agent for memory disorder.SOLUTION: An ameliorating agent for memory disorder includes a PKCγ-activity inhibitor as an active ingredient.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an agent for improving memory impairment. [Background technology]

[0002] It is known that memory impairment is caused by irreversible neurodegeneration such as Alzheimer's disease. Memory impairment caused by irreversible neurodegeneration is basically not something that can be improved because the cause is irreversible, and the only way to deal with it is to slow down the progression.

[0003] However, memory impairment is also known to be caused by other factors, such as depression, trauma, stress, and brain fog.

[0004] For example, Non-Patent Document 1 describes that memory impairment is a neuropsychological symptom of depression, and that the brain function of depression recovers in accordance with clinical recovery. In addition, memory impairment is a symptom of brain fog, which is rapidly increasing as a sequelae of COVID-19, and Non-Patent Document 2 describes that brain fog often recovers gradually over time, and Non-Patent Document 3 describes that, although there are individual differences, more than half of the sequelae tend to feel improvement in symptoms within five months. Furthermore, Non-Patent Document 4 describes that the main symptoms of dissociative amnesia caused by trauma or stress are memory impairments that do not match normal forgetfulness, and that most patients regain their lost memories and amnesia is resolved. In other words, memory impairments caused by these other factors are fundamentally different from memory impairments caused by the above-mentioned irreversible neurodegeneration in that they are symptoms that can be expected to be recovered. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Yasumasa Okamoto, Brain basis of the pathology of depression, Journal of Psychiatry and Neurology, Vol. 111, No. 11 (2009), pp. 1330-1344 [Non-Patent Document 2] Kumiko Arai, What is brain fog, which is rapidly increasing as an aftereffect of COVID-19? How is it different from dementia and forgetfulness?, [online], 2023 / 2 / 13, [Retrieved April 12, 2023], Internet<URL:https: / / nishiharu-clinic.com / 2023 / 02 / 13 / korona-bureinfogu / > [Non-Patent Document 3] Eiichi Hatsumura What is "brain fog" after-effect of COVID-19?, [online], 2022 / 10 / 13, [Searched on April 12, 2023], Internet<URL:https: / / utu-yobo.com / column / brain-fog / > [Non-Patent Document 4] David Spiegel, MSD Manual Professional Edition 08. Mental Disorders / Dissociative Disorders / Dissociative Amnesia, [online], March 2021, Merck & Co., Inc., Rahway, NJ, USA, [Retrieved April 12, 2023], Internet <URL:https: / / www.msdmanuals.com / ja-jp / %E3%83%97%E3%83%AD%E3%83%95%E3%82%A7%E3%83%83%E3%82%B7%E3%83%A7%E3%83%8A%E3%83%AB / 08-%E7%B2%BE%E7%A5%9E%E9%9A%9C%E5%AE%B3 / %E8%A7%A3%E9%9B%A2%E7%97%87%E7%BE%A4 / %E8%A7%A3%E9%9B%A2%E6%80%A7%E5%81%A5%E5%BF%98> Summary of the Invention [Problem to be solved by the invention]

[0006] To improve memory disorders, treatment is generally performed to remove the causes of the disorder. In other words, to improve memory disorders caused by depression, trauma, or stress, treatment for the cause is necessary, and drugs used for these treatments must generally be applied carefully, taking into account the risk of side effects. In addition, there is no clear treatment for brain fog, an aftereffect of COVID-19, because the cause is not clearly known. Against this background, it is hoped that new ingredients that are effective against memory disorders based on a clear mechanism of action will be developed.

[0007] Therefore, an object of the present invention is to provide an agent for improving memory disorders, the mechanism of action of which is clear. [Means for solving the problem]

[0008] The present inventors used DGKβ knockout mice, which were found to show increased PKCγ phosphorylation in the brain (abnormal PKCγ activity), as a unique model of memory impairment, and found that administering a PKCγ activity inhibitor to the mice normalized PKCγ activity in the brain and improved memory impairment. The present invention was completed through further investigations based on this finding.

[0009] That is, the present invention provides the following aspects. Item 1. A memory impairment improving agent containing a PKCγ activity inhibitor as an active ingredient. Item 2. The memory impairment improving agent according to Item 1, wherein the PKCγ activity inhibitor is a flavonoid selected from the group consisting of scutellarin, baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof. Item 3. The memory impairment ameliorating agent according to Item 1 or 2, which is used to improve memory impairment not caused by accumulation of amyloid β. Item 4. The agent for improving memory impairment according to any one of Items 1 to 3, which is used for improving memory impairment not caused by exposure to general anesthesia. Item 5. The agent for improving memory impairment according to any one of Items 1 to 4, which is used for improving memory impairment not caused by cerebral infarction. Item 6. A food product comprising the memory impairment improving agent according to any one of Items 1 to 5. Effect of the Invention

[0010] According to the present invention, a new agent for improving memory impairment with a clear mechanism of action is provided. [Brief description of the drawings]

[0011] [Figure 1] 1 shows the results of a Y-maze test confirming the effect of orally administering a PKCγ activity inhibitor on improving memory impairment in mice. [Diagram 2] The results of confirming PKC activity in the cerebral cortex of mice administered a PKCγ activity inhibitor by Western blotting are shown. [Diagram 3] The figure shows the results of confirming PKC activity in the hippocampus of mice administered a PKCγ activity inhibitor, using Western blotting. [Figure 4] The results of confirming the PKCγ activity inhibitory effect of various flavonoids are shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1. Memory impairment improvement agent The agent for improving memory impairment of the present invention is characterized by comprising a PKCγ activity inhibitor as an active ingredient.

[0013] 1-1.Active ingredients The PKCγ activity inhibitor is not particularly limited as long as it is a compound that has an effect of inhibiting phosphorylation of PKCγ. Preferred PKCγ activity inhibitors used in the present invention include flavonoids such as scutellarin (formula (1) below), baicalin (formula (2) below), baicalein (formula (3) below), luteonin (formula (4) below), apigenin (formula (5) below), apigenin glucoside (formula (6) below), and salts thereof.

[0014] [ka]

[0015] [ka]

[0016] The salt is not particularly limited as long as it is pharma- ceutical or food-acceptable, and examples thereof include alkali metal salts such as sodium salts.

[0017] In the memory disorder improving agent of the present invention, among these PKCγ activity inhibitors, one kind may be contained alone, or a combination of a plurality of kinds may be contained.Among these PKCγ activity inhibitors, preferably, scutellarin, baicalin, luteolin, apigenin may be mentioned, more preferably, baicalin, luteolin may be mentioned, and even more preferably, baicalin may be mentioned.

[0018] The amount of PKCγ activity inhibitor contained in the memory impairment improving agent of the present invention is not particularly limited and can be appropriately set depending on the formulation form and specific use of the memory impairment improving agent, for example, 40 to 100% by weight, preferably 60 to 90% by weight.

[0019] 1-2.Other ingredients The memory disorder improving agent of the present invention may or may not further contain additives and / or bases according to the formulation form and use, as long as the effect of the present invention is not impaired, in addition to the above-mentioned active ingredients. Such additives and bases are not particularly limited as long as they are pharmacologic acceptable, and examples thereof include excipients, binders, disintegrants, lubricants, isotonicity agents, plasticizers, dispersants, emulsifiers, solubilizers, wetting agents, stabilizers, suspending agents, adhesives, gelling agents, coating agents, glossing agents, water, oils and fats, waxes, hydrocarbons, fatty acids, higher alcohols, esters, water-soluble polymers, surfactants, metal soaps, lower alcohols, polyhydric alcohols, pH adjusters, buffers, antioxidants, UV inhibitors, preservatives, flavorings, fragrances, powders, thickeners, colorants, chelating agents, sweeteners, etc. These additives may be used alone or in combination of two or more. The contents of these additives and bases are appropriately set depending on the types of additives and bases used, the dosage form and use of the memory impairment ameliorating agent of the present invention, and the like.

[0020] In addition, the memory disorder improving agent of the present invention may or may not contain other nutritional components or pharmacological components in the range that does not impair the effect of the present invention, in addition to the above-mentioned active ingredients. Such nutritional components and pharmacological components are not particularly limited as long as they are pharmacologic acceptable, and examples thereof include antacids, stomachic agents, digestive agents, intestinal regulators, antispasmodics, mucosal repair agents, anti-inflammatory agents, astringents, antiemetics, antitussives, expectorants, anti-inflammatory enzymes, sedatives, hypnotics, antihistamines, caffeine, cardiac diuretics, antibacterial agents, vasoconstrictors, vasodilators, local anesthetics, herbal extracts, vitamins, menthols, etc. These nutritional components and pharmacological components may be used alone or in combination of two or more. The content of these components is appropriately set according to the type of components used.

[0021] 1-3. Formulation The form and properties of the memory impairment improving agent of the present invention are not particularly limited, so long as it contains the above-mentioned active ingredient.

[0022] The administration form of the memory impairment improving agent of the present invention includes both oral and parenteral administration forms. Therefore, the memory impairment improving agent of the present invention can be prepared as an oral agent, an injection, a drip infusion, a nasal drop, etc. Among them, the memory impairment improving agent of the present invention is preferably an oral agent that is easy to administer (ingest) on a daily and / or continuous basis.

[0023] The memory impairment improving agent of the present invention may be in a liquid or solid form. Examples of liquids include liquids, beverages, emulsions, suspensions, spirits, syrups, elixirs, soft extracts, etc., and examples of solids include tablets, pills, powders, fine granules, granules, tablets, capsules (including hard capsules and soft capsules), lozenges, chewables, dry extracts, etc. When the memory impairment improving agent of the present invention is in a solid form, it may be in a sustained or sustained release form, or may be mixed with water or the like when administered (ingested).

[0024] The memory impairment improving agent of the present invention can also be used as an additive that adds value to foods, medicines, quasi-drugs, etc. Foods to which the memory impairment improving agent of the present invention is blended include general foods and beverages and health functional foods (including foods for specified health uses, foods with nutrient functions, and foods with functional claims, etc.). Among these, since the active ingredient of the memory impairment improving agent of the present invention contains flavonoids that can be ingested as food ingredients, it is preferable to blend it into a health functional food that can be easily ingested daily and / or continuously, and since the memory impairment improving agent of the present invention exerts an effect based on the action of reducing PKCγ phosphorylation (normalizing PKCγ activity), it is particularly preferable to blend it into a food for specified health uses or a food with functional claims.

[0025] 1-4. Manufacturing method The method for producing the memory impairment improving agent of the present invention may be carried out according to conventional formulation procedures using the above-mentioned active ingredient and other ingredients that are blended as necessary, depending on various forms and properties, and the purpose of use.

[0026] 1-5.Applications The memory impairment improving agent of the present invention is used for the purpose of improving memory impairment through normalization of PKCγ activity. The memory impairment is not particularly limited as long as it is caused by inhibition of PKCγ activity. For example, memory impairment caused by aging, depression, trauma, stress, and / or brain fog can be mentioned. In addition, in the memory impairment improving agent of the present invention, it is preferable that the memory impairment is not caused by either irreversible neurodegenerative disease or accumulation of amyloid β, not caused by exposure to general anesthesia (particularly, isoflurane), and not caused by cerebral infarction.

[0027] In addition, in memory disorders, the object of memory is not particularly limited, but preferably includes spatial memory (i.e., memory required for actions such as searching for an object, heading to a destination, and returning to an original location).

[0028] 1-6.Dose The dose of the memory impairment improving agent of the present invention, in terms of the dose for humans, is, in terms of the equivalent amount of a PKCγ activity inhibitor, for example, 0.1 g / day / 60 kg or more, preferably 0.3 g / day / 60 kg or more, more preferably 0.5 g / day / 60 kg or more, and even more preferably 1 g / day / 60 kg or more.

[0029] The method of administration (ingestion) of the memory impairment improving agent of the present invention is not particularly limited, but for example, it can be administered orally or parenterally once or multiple times a day, and preferably, it can be administered orally once or 2 to 3 times a day.

[0030] 2.PKCγ activity inhibitors Among the isoflavones used as the PKCγ activity inhibitor of the active ingredient in the memory disorder improving agent of the present invention, baicalin (above formula (2)), baicalein (above formula (3)), luteonin (above formula (4)), apigenin (above formula (5)), apigenin glucoside (above formula (6)), and salts thereof are not known to have an inhibitory effect on PKCγ activity. Therefore, the present invention further provides a PKCγ activity inhibitor containing as an active ingredient a compound selected from the group consisting of baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof. These PKCγ activity inhibitors can be used to improve any symptoms caused by abnormal PKCγ activity. EXAMPLES

[0031] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0032] [Test Example 1] (Memory impairment model mouse) DGKβ, one of the subtypes of diacylglycerol kinase (DGK), of which 10 subtypes have been found in mammals, is particularly abundant in the hippocampus, cerebral cortex, and striatum of the brain, and has been found by the present inventors to rapidly increase during the development of neural networks, and to be expressed neuron-specifically and promote neurite outgrowth. Mice in which this DGKβ was knocked out (DGKβKO mice) were generated as a memory impairment model. Note that this memory impairment model mouse is not a mouse showing intracerebral accumulation of Aβ, nor is it a model mouse of irreversible neurodegenerative disease, nor is it a mouse exposed to general anesthesia such as isoflurane, nor is it a cerebral infarction model mouse.

[0033] A PKCγ inhibitor, scutellarin, was orally administered to memory impairment model mice at a dose of 100 mg / mouse for 10 days. Separately, normal mice were also orally administered the PKCγ inhibitor, scutellarin, at a dose of 100 mg / mouse for 10 days.

[0034] (Memory impairment evaluation system) A Y-maze apparatus was used. The Y-maze is an apparatus with three arms of the same size connected radially at 120° intervals, and is used in the spontaneous alternation behavior test, which is one of the spatial memory evaluation tests. As an evaluation index of spatial memory, the number of times that a subject entered three consecutive different arms was divided by the total number of entries into the arms minus 1, and then multiplied by 100 (cross-reaction, alternations) was used. The lower the alternations, the greater the degree of memory impairment.

[0035] (result) The results are shown in Figure 1. In the figure, WT indicates the results for normal mice, KO indicates the results for memory-impaired model mice, - indicates the results without scutellarin administration, and + indicates the results with scutellarin administration. Furthermore, numbers written in the format "WT-: 5" etc. indicate the number of mice (the same applies to the following figures). As shown in Figure 1, the Alternations value was significantly lower in the memory-impaired mice (KO) group not administered scutellarin (-), revealing the occurrence of memory impairment. Furthermore, administration of scutellarin (+) significantly increased the Alternations value, demonstrating that the memory impairment in the memory-impaired mice (KO) group had improved to a level close to that of normal mice (WT).

[0036] The cerebral cortex and hippocampus of mice administered scutellarin were subjected to Western blotting to evaluate the activation of PKC. The results are shown in Figure 2 (cerebral cortex) and Figure 3 (hippocampus).

[0037] As shown in Figures 2 and 3, abnormal PKCγ activity was observed in the cerebral cortex and hippocampus in the memory impairment model mouse (KO) group without scutellarin administration (-), whereas PKCγ activity was observed to have improved to normal levels in the memory impairment model mouse (KO) group with scutellarin administration (+).

[0038] [Test Example 2] The inhibitory effect of various flavonoids on PKCγ activity was tested. Specifically, scutellarin (Scu), baicalin (Bai), luteolin (Lut), and apigenin (Api) were used as flavonoids. A plasmid encoding GFP-PKCγ was introduced into COS7 cells by electroporation, and the cells were cultured for 48 hours to express GFP-PKCγ. After treating the cells with TPA (12-O-Tetradecanoylphorbol-13-acetate, a PKCγ activator) and each flavonoid, the cells were ground and the proteins were subjected to SDS-PAGE. Western blotting was then performed for PKCγ and phosphorylated PKCγ (activated form).

[0039] The electrophoresis results (n=2) are shown in Figure 4. As shown in Figure 4, not only scutellarin (Scu), but also baicalin (Bai), luteolin (Lut), and apigenin (Api) were found to have an inhibitory effect on PKCγ activity. From these results, it can be reasonably inferred that similar memory impairment amelioration effects would be observed when baicalin (Bai), luteolin (Lut), and apigenin (Api) were administered to the memory impairment model mice of Test Example 1.

Claims

1. A memory impairment improving agent containing a PKCγ activity inhibitor as an active ingredient.

2. The memory impairment improving agent according to claim 1, wherein the PKCγ activity inhibitor is a flavonoid selected from the group consisting of scutellarin, baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof.

3. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by accumulation of amyloid beta.

4. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by exposure to general anesthesia.

5. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by cerebral infarction.

6. A food comprising the memory impairment improving agent according to claim 1.

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