Application of P37 polypeptide in preparation of product for improving learning and memory ability

Abstract

The invention relates to the technical field of biology, in particular to application of P37 polypeptide in preparation of a product for improving learning and memory ability. The invention provides new application of P37 in preparation of products for improving learning and memory ability, medicines for improving nerve injury, medicines for improving anxiety, medicines for treating neurodegenerative diseases and anti-aging. Results of the specific embodiment of the invention show that P37 not only can improve oxidative damage induced by D-gal, but also can obviously relieve anxiety-like behaviors, improve cognitive ability and memory function, improve nerve damage, and improve the curative effect of D-gal. The compound can be used for preparing a product for improving learning and memory ability, a medicine for improving nerve injury, a medicine for improving anxiety, a medicine for treating neurodegenerative diseases and an anti-aging product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biotechnology, in particular to the application of P37 polypeptide in the preparation of products for improving learning and memory ability. BACKGROUND

[0002] In recent years, domestic and foreign scholars have carried out extensive research on P37, and found that it has a variety of biological activities. P37 extract obtained by different means shows broad application prospects in the field of health food and functional food. Studies have shown that P37 extract has the effects of lowering blood sugar and blood lipids, anti-aging, antioxidant, anti-fatigue, anti-tumor, immune regulation and the like, and its components are polypeptide components. However, the current research on P37 is still not deep and systematic, especially the research on its material basis and mechanism of action is relatively less, which needs to be further explored.

[0003] The physiological function decline caused by aging is deeply affecting people's life. At the same time, various types of senile diseases induced by aging also pose a great challenge to families and society. Under this background, how to avoid or reduce the negative impact has become the focus of attention in today's society. Developing and reasonably using new natural anti-aging functional products can help improve the health level of the elderly, prolong their healthy life, and thus delay the aging process, which is of great significance to the development of human society. In fact, there are a large number of potential resources in animals, plants and microorganisms that can be used as natural anti-aging agents, which can be developed and transformed into functional active substances.

[0004] Hypoglycemic peptide P37 is a kind of polypeptide containing 37 amino acids found in legume seeds. In recent years, hypoglycemic peptide P37 has attracted widespread attention from the scientific and industrial communities due to its biological activity in regulating blood sugar and repairing pancreatic function. Current research on P37 is mainly focused on the field of diabetes treatment, and studies have shown that P37 has a significant hypoglycemic effect in the treatment of type 2 diabetes, so it is necessary to expand the new applications of P37. There is currently no research on the improvement of learning and memory ability, improvement of nerve damage, and improvement of anxiety of P37. SUMMARY

[0005] The purpose of the present application is to provide the application of P37 polypeptide in the preparation of products for improving learning and memory ability, in order to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] The present application provides the application of P37 polypeptide (referred to as P37) in the preparation of products for improving learning and memory ability, and the amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0008] Preferably, the amino acid sequence of the P37 polypeptide is shown as SEQ ID NO. 8; the product includes food or medicine.

[0009] The present application provides a product for improving learning and memory, which comprises a P37 polypeptide and excipient; the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0010] The present application provides a use of a P37 polypeptide in the preparation of a medicament for improving nerve injury, the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0011] Preferably, the amino acid sequence of the P37 polypeptide is shown as SEQ ID NO. 8.

[0012] The present application provides a medicament for improving nerve injury, which comprises a P37 polypeptide and excipient; the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0013] The present application provides a use of a P37 polypeptide in the preparation of a medicament for improving anxiety, the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0014] Preferably, the amino acid sequence of the P37 polypeptide is shown as SEQ ID NO. 8.

[0015] The present application provides a medicament for improving anxiety, which comprises a P37 polypeptide and excipient; the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0016] The present application provides a use of a P37 polypeptide in the preparation of a medicament for treating neurodegenerative diseases, the amino acid sequence of the P37 polypeptide is shown as any one of SEQ ID NO. 1-SEQ ID NO. 9.

[0017] The present application discloses the following technical effects:

[0018] The present application provides a new application of P37 in preparing products for improving learning and memory ability, drugs for improving nerve injury, drugs for improving anxiety, drugs for treating neurodegenerative diseases and anti-aging products. First, a D-gal-induced premature aging mouse model is established, and P37 is given by gavage intervention. The toxicity of P37 is evaluated by detecting the heart, liver, spleen, lung, kidney and other organs of the mice after treatment, and the effect of P37 on the learning and memory ability and aging of the mice is evaluated by open field, new object, water maze, hippocampal tissue section and serum detection. The results show that: P37 treatment does not cause obvious organ toxicity; compared with the model group, P37 intervention treatment can effectively alleviate the anxiety-like behavior induced by D-gal; the cognitive index of P37-intervened mice is significantly higher than that of the model group, indicating that P37 can effectively improve the recognition memory impairment induced by D-gal; D-gal-induced premature aging mice show significant decline in learning and memory ability, and P37 intervention can effectively improve the cognitive function of the mice and the spatial memory impairment caused by degenerative diseases, shorten the escape latency, increase the target quadrant residence time and increase the number of crossing the platform, and restore the normal target search trajectory; P37 can also improve the D-gal-induced aging-related nerve injury. At the same time, the specific embodiments of the present application use C. elegans as a model organism to evaluate the anti-aging effect of P37, and the results show that: P37 treatment can effectively delay the aging process of the worms, and its effect is concentration-dependent. Therefore, P37 can not only improve the oxidative damage induced by D-gal, but also significantly alleviate the anxiety-like behavior, improve the cognitive ability and memory function, improve the nerve injury, and can be used for preparing products for improving learning and memory ability, drugs for improving nerve injury, drugs for improving anxiety, drugs for treating neurodegenerative diseases and anti-aging products. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 Flow chart for modeling D-gal aging mice and P37 intervention and related behavior experiments;

[0021] Figure 2 Effect of P37 on body weight (A) and food intake (B) of aging mice;

[0022] Figure 3Effects of P37 on organ coefficients of aging mice; wherein, (A) is brain index; (B) is spleen and spleen index; (C) is heart and heart index; (D) is liver and liver index; (E) is kidney and kidney index;

[0023] Figure 4 Results of open field test; wherein, (A) is total distance of movement; (B) is average movement speed; (C) is residence time in central area of open field; (D) is residence time in edge area;

[0024] Figure 5 Results of novel object recognition (NOR) test (n = 5); wherein, (A) is total distance of movement; (B) is recognition index; (C) is action trajectory graph;

[0025] Figure 6 Results of Morris water maze (MWM) test (n = 5); wherein, (A) is latency time; (B) is number of crossing platform; (C) is residence time in target quadrant; (D) is motion trajectory graph;

[0026] Figure 7 Morphology of nerve cells in hippocampal CA1 region of mice;

[0027] Figure 8 Effects of P37 on antioxidant enzyme content in serum of aging mice; wherein, (A) is SOD activity investigation result; (B) is MDA level investigation result;

[0028] Figure 9 Effects of P37 on anti-aging of Caenorhabditis elegans. DETAILED DESCRIPTION

[0029] The various illustrative embodiments of the present application will now be described in detail in connection with the following figures. This description is made for the purpose of illustrating the general principles of the present application and is not meant to limit the present application in its application to such principles. Further, the description serves to provide full informing for those skilled in the art.

[0030] It should be understood that the terms used herein are for the purpose of describing particular embodiments and are not intended to limit the present application. In addition, for numerical ranges recited in the present application, it is contemplated that each and every value and sub-range encompassed therein can be specifically enumerated. Each of the smaller ranges that fall between the recited ranges can also be specifically enumerated. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0031] 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 application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference for the disclosure and

[0032] Many modifications and variations of the present application described in the specific embodiments of the application can be made by those skilled in the art without departing from the spirit or scope of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0033] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed materials and methods.

[0034] P37 polypeptide is mainly derived from leguminous plants, such as azuki bean, soybean, pea, mung bean, and astragalus mongholicus. P37 polypeptide sequence contains 37 amino acids, and contains 6 cysteines in the molecule, which are located at positions 3, 7, 15, 20, 22, and 32. The present application isolates and identifies 9 different sequences of cysteine-rich polypeptides from azuki bean, mung bean, pea, soybean, and astragalus mongholicus, respectively. The sequences are azuki bean leguin insulin: ADCNGACSPFEMPPCGSTDCRCVPIALVGGFCIHPTG, SEQ ID NO. 1; mung bean leguin insulin: ADCNGACSPFQMPPCGSTDCLCIPAGLLFGYCTYPSG, SEQ ID NO. 2; pea leguin insulin: ASCNGVCSPFEMPPCGSSACRCIPVGLVVGYCRHPSG, SEQ ID NO. 3; soybean leguin insulin: ADCNGACSPFEVPPCRSRDCRCVPIGLFVGFCIHPTG, SEQ ID NO. 4; soybean aglycin: ASCNGVCGPFEMPPCSSSACGCIPVRLVVGYCRHPSG, SEQ ID NO. 5; soybean iglycin: ISCNGVCGPFDIPPCSTPLCGCIPARLFVGKCRHPYG, SEQ ID NO. 6; soybean vglycin: VSCNGVCGPFDIPPCSTPLCGCIPARLFVGKCRHPYG, SEQ ID NO. 7; soybean glycin: GSCNGVCGPFDIPPCSTPLCGCIPARLFVGKCRHPYG, SEQ ID NO. 8; and astragalus mongholicus leguin insulin: ADCNGACSPFEMPPCGSTDCRCVPIALVGGFCIHPTG, SEQ ID NO. 9. 1: VSCNGVCGPFDIPPCSTPLCGCIPYRLFVGNCRHPYG, SEQ ID NO. 7; Glycine vglycin 2 : VSCNGVCGPFEMPPCSSSACGCIPYRLVVGNCRHPSG, SEQ ID NO. 8; Astragalus aM1: VDCSGACSPFEVPPCGSRDCRCIPIGLVVGFCIYPTG, SEQ ID NO. 9. Such polypeptides have the characteristics of acid resistance, alkali resistance, resistance to gastrointestinal digestive enzymes, and high temperature resistance, and thus can be orally taken.

[0035] Example 1

[0036] 1. Experimental animal grouping

[0037] This example uses 6-week-old male C57BL / 6 mice. After 7 days of acclimatization in a standardized feeding environment, they are divided into three experimental groups (n = 7) using a completely randomized grouping method, and are sequentially recorded as a control group (Control), a D-gal-induced sub-acute aging model group (Model), and an intervention group (Model + P37 (SEQ ID NO. 8) or Model + Vg).

[0038] The control group (Control or Con) is subcutaneously injected with physiological saline on the nape every day, with the injection volume being equal to that of the model group, and the continuous administration lasts for 49 days.

[0039] The model group (D-gal-induced sub-acute aging model group (Model)) receives a subcutaneous injection of a D-galactose (D-gal) solution with a dose of 300 mg / kg on the nape every day, and the continuous administration lasts for 42 days to construct an aging phenotype, and a daily equal-dose physiological saline gavage intervention is simultaneously implemented from the third day of the experiment, with a total period of 49 days. The present application utilizes the neurotoxic effect induced by D-galactose to process a mouse model having symptoms such as learning and memory decline, nerve damage, slow movement, sparse hair, and anxiety-like behavior.

[0040] The intervention group (Model + P37) is additionally given a P37 gavage treatment with a dose of 50 mg / kg / d on the basis of establishing a sub-aging state by subcutaneous injection of 200 mg / kg / d D-gal (for 42 days), and the anti-aging effect is evaluated through 49 days of drug intervention. Figure 1 ).

[0041] 2. Effect of P37 on body weight and food intake of aging mice

[0042] From the start of D-gal injection, the body weight and food intake of mice in each group are monitored every 7 days, and the results are as follows Figure 2The experimental results show that the body weight of the three groups of mice presents a slow growth trend throughout the experiment. However, on the 21st day, the body weight of the mice in the model group and the intervention group appears a short-term decline, but then quickly recovers to the normal level. After continuous injection of D-gal for 7 weeks, the body weight of the mice in each group does not differ significantly Figure 2 In addition, after monitoring the diet of the mice, it is found that after 10 days of administration, the food intake of the mice in the model group is reduced compared with the control group, and the food intake of the intervention group slightly rises on this basis Figure 2 It can be seen that the injection of D-gal for modeling and the P37 gavage intervention do not cause changes in the body weight and food intake of the mice, which indicates that the P37 intervention process does not cause serious toxic effects.

[0043] 3. Effect of P37 on the organ coefficients of aging mice

[0044] The change of organ coefficient can effectively reflect the toxic effect of chemical toxicants on each organ, and can be used as a key indicator for identifying the target organs of toxicants. In the case of excluding the influence of body weight change on organ coefficient, the abnormal change of organ coefficient can be used as an indirect evidence of histopathological change. After feeding for 63 days, the mice were euthanized, sampled, and the effect of P37 on the organ coefficients of aging mice was investigated. The effect of P37 on the organ coefficients of aging mice is shown in Figure 3 The brain tissue weight of the mice in each group is between 17 mg / g and 18 mg / g, and the difference between groups is not significant Figure 3 (A). The spleen of each group of mice is bright red and has a luster, and the organ coefficient is between 2.1 mg / g and 2.5 mg / g, and the difference between groups is also not statistically significant Figure 3 (B). In addition, the heart organ coefficient is between 3.6 mg / g and 4.9 mg / g, the liver organ coefficient is between 45 mg / g and 50 mg / g, and the kidney organ coefficient is between 11 mg / g and 13.5 mg / g. Compared with the Control group, the mice in the Model group only have significant changes in the heart Figure 3 (C), kidney Figure 3 (E) organ coefficients, while there is no significant difference in the brain Figure 3 (A), liver Figure 3 (D) and spleen Figure 3 (B) coefficients. After administration of P37, the decrease of organ coefficient indicates that P37 has a protective effect on the heart and kidney. The above results show that D-gal modeling can cause the decrease of heart and kidney indices of mice, and P37 treatment can alleviate the damage of D-gal-induced heart and kidney to a certain extent. At the same time, it also shows that P37 treatment does not cause obvious organ toxicity.

[0045] 4. Open field test and experimental results

[0046] D-gal-induced aging models are an important experimental paradigm for studying the pathological characteristics of aging. Related studies have found that this model not only induces age-related decline in physiological functions but also leads to neurobehavioral abnormalities, particularly elevated anxiety levels. Anxiety is an emotional response triggered by environmental stimuli, typically manifested as avoidance of open spaces, increased dependence on enclosed areas, and reduced exploratory behavior; these behaviors can be assessed using the open field test. In this embodiment, the open field test was used to detect changes in D-gal-induced anxiety-like behavior in mice and to explore whether p37 has a mitigating effect. The open field test assesses the anxiety levels of mice by measuring their movement trajectory, activity time, and dwell time in the central and peripheral areas of an open square area (open field).

[0047] Experimental results are as follows Figure 4 As shown, this embodiment measures the total movement distance of mice in different experimental groups. Figure 4 (A) and average moving speed ( Figure 4 In (B) of the study, it was found that the mice in the model group and the intervention group did not show significant differences compared with the control group in these two indicators (P>0.05). This indicates that D-gal treatment did not significantly affect the mice's motor ability, that is, the overall activity level of the mice was not inhibited, indicating that the mice in different groups had similar spontaneous activity abilities during the experiment. Therefore, the subsequent behavioral differences can be mainly attributed to the difference in anxiety level, rather than the influence of motor ability. Further analysis of the time the mice spent in the central area of ​​the open field ( Figure 4 (C) in the middle and the dwell time in the edge area ( Figure 4 The results showed that, compared with the control group, the model group mice spent significantly less time in the central region and significantly more time in the peripheral region. This indicates that D-gal-induced premature aging not only affects the physiological aging of mice but also leads to a significant increase in anxiety-like behavior. Generally, mice with higher anxiety levels exhibit avoidance behavior in open spaces, spending more time in the peripheral region near walls and less time in the central region. D-gal increases anxiety-like behavior by affecting the balance of oxidative stress, inflammatory response, and neurotransmitters in the brain. Notably, in the intervention group mice, the time spent in the central region was significantly prolonged, while the time spent in the peripheral region was significantly shortened, showing a clear improvement trend compared with the model group (P < 0.05), suggesting that P37 can effectively alleviate D-gal-induced anxiety-like behavior.

[0048] 5. Results of the Novel Object Recognition (NOR) experiment (n=5)

[0049] The Novel Object Recognition (NOR) test is a classic cognitive function test primarily used to assess the learning and memory abilities of mice, particularly their short-term recognition and memory performance. In this study, we analyzed the changes in cognitive abilities in a D-gal-induced premature aging model mouse using the NOR test and explored the potential ameliorative effect of p37. During the experiment, mice were first placed in an acclimatization box and then exposed to two identical objects during the training phase, allowing them to develop memory of the objects. Next, in the testing phase, one of the known objects was replaced with a new object. Because mice are naturally inclined to explore novelty, they normally pay more attention to the new object. However, if their cognitive abilities are impaired, they may not be able to effectively distinguish between new and old objects, exhibiting similar exploration times for both. Therefore, by measuring the exploration time of mice for new and old objects, a cognitive index can be calculated. This index represents the proportion of time spent exploring the new object to the total exploration time; a higher cognitive index reflects better recognition and memory abilities.

[0050] Experimental results are as follows Figure 5 As shown in (A), this embodiment first measured the total walking distance of mice to assess motor ability and spontaneous activity level. The results showed that the walking distance of the model group mice was slightly higher than that of the control group, but there was no significant difference between the two groups (P > 0.05), indicating that D-gal treatment did not significantly affect the motor ability of mice. However, after P37 intervention, the walking distance of the intervention group mice was significantly lower than that of the model group (P < 0.05), suggesting that P37 may have a certain regulatory effect on the behavioral patterns of mice, making their activities more stable. This phenomenon is related to the neuroprotective effect of P37; P37 reduces the nerve damage caused by D-gal, allowing the behavior of mice to recover to a level closer to normal. Furthermore, P37 can improve the neural excitability of mice by regulating neurotransmitter levels, causing them to exhibit more purposeful exploratory behavior rather than an increase in disordered activity. To further evaluate the short-term recognition memory ability of mice, this embodiment calculated the cognitive index of each group of mice (…). Figure 5 (B)). The trajectory plot results showed that, compared with the control group mice, the model group mice had no significant difference in the trajectories of new and old objects. Figure 5Cognitive index significantly decreased in (C). It suggested that D-gal-induced premature aging not only affected the physiological aging of mice, but also impaired their short-term recognition memory ability. This was related to the oxidative stress and inflammatory response caused by D-gal, which led to neuronal dysfunction, impaired synaptic plasticity, and decreased cognitive function in the hippocampus. Previous studies have shown that D-gal-induced oxidative damage can cause a decrease in synaptic-related proteins in the hippocampal CA1 region, affecting the structure and function of synapses, and leading to decreased memory storage and recall ability. In addition, D-gal can activate microglia cells and induce neuroinflammation, further exacerbating cognitive dysfunction. In the intervention group, the cognitive index of mice was significantly higher than that of the model group, indicating that P37 could effectively improve the recognition memory impairment induced by D-gal.

[0051] 6. Morris water maze (MWM) experiment results (n = 5)

[0052] The present application uses the classic Morris water maze (MWM) experiment to evaluate the effect of P37 on the learning and memory ability of D-gal-induced premature aging mice. Morris water maze is a widely used behavioral experiment for cognitive function research, which mainly reflects the spatial learning and memory ability of mice by measuring their performance in finding the hidden platform. In the experiment, mice were placed in an opaque circular pool filled with water, which was divided into four quadrants, and a hidden platform was placed in one of the quadrants. In the training stage, mice needed to rely on external visual cues to learn how to find the platform in the shortest time. In the test stage, the experimental platform was removed and the mice were allowed to swim freely in the pool. Researchers evaluated the spatial memory ability of mice by analyzing their movement trajectories, time spent in the target quadrant, and the number of times they crossed the original platform location. The experimental results are shown in Figure 6 (A) shows that the escape latency of mice in the training stage was first measured, i.e. the time required to find the hidden platform after entering the water. The research results showed that the escape latency of mice in the model group was significantly longer than that in the control group (P<0.05), which indicated that D-gal-induced aging impaired the spatial learning ability of mice, causing a significant delay in their response in finding the platform. This result is consistent with previous studies, however, under the intervention of P37, the escape latency of mice in the intervention group was significantly lower than that in the model group (P<0.05), indicating that P37 to some extent alleviated the cognitive impairment caused by D-gal and improved the learning ability of mice.

[0053] In addition, this embodiment further analyzes the time spent in the target quadrant and the number of times the platform is crossed. The time spent in the target quadrant refers to the proportion of time that mice spend in the quadrant where the hidden platform was originally located during the experiment, which is usually used to reflect the degree of memory of mice for the platform location. The study showed that the time spent in the target quadrant by mice in the model group was significantly lower than that in the control group (P<0.05), indicating that D-gal-induced aging impaired the memory ability of mice for the platform location. However, under the intervention of P37, the time spent in the target quadrant by mice in the intervention group was significantly higher than that in the model group (P<0.05), indicating that P37 could effectively improve the memory impairment of mice caused by D-gal. Figure 6Figure 6 shows the results of the spatial probe test. The model group showed significant spatial memory impairment, with a statistically significant decrease in the goal quadrant residence time compared to the control group. Notably, the intervention group showed a dose-dependent improvement, with the target area exploration time increasing to 35.6 ± 4.1 s, which was significantly different from the model group. This result suggests that P37 can effectively reverse the spatial memory impairment in model animals caused by neurodegenerative diseases by regulating hippocampus-dependent memory pathways.

[0054] In addition, the number of platform crossings reflects the mouse's willingness to search for the target area, i.e., the number of times the mouse crosses the original platform location during the experiment. The results are shown in Figure 6 (B). Figure 6 As shown in Figure 6 (B), the number of platform crossings in the model group was significantly lower than that in the control group, while the number of platform crossings in the intervention group was significantly higher than that in the model group (P < 0.05), further confirming the improvement of P37 on cognitive function. These data suggest that D-gal-induced cognitive impairment not only affects the learning ability of mice, but also damages their spatial memory ability, and the intervention of P37 can effectively improve these impairments, enabling mice to perform better in spatial memory tests.

[0055] To further visualize the movement patterns of mice, this embodiment plots the movement trajectories of mice in the pool (Figure 6 (D)). Figure 6 The movement trajectory of the control group mice showed a purposeful approach to the platform quadrant and concentrated search for the platform location, while the movement trajectory of the model group mice was more scattered, showing obvious random swimming behavior and difficulty in accurately positioning the target quadrant. This indicates that D-gal-induced aging impairment affects the spatial navigation ability of mice, making it difficult for them to form a stable target positioning strategy in the pool. However, the movement trajectory of the intervention group mice was obviously similar to that of the control group, with a more concentrated search path in the target quadrant and a higher directional search ability. This further supports the cognitive improvement effect of P37, i.e., P37 can restore the spatial learning and memory ability of mice by enhancing synaptic plasticity of neurons, increasing excitability of hippocampal neurons, or reducing oxidative stress damage to neurons, enabling them to more efficiently search for the target quadrant and platform location in the test phase.

[0056] In summary, the results of the Morris water maze experiment show that D-gal-induced premature aging mice exhibit significant decline in learning and memory ability, as evidenced by prolonged escape latency, reduced target quadrant residence time, decreased platform crossing frequency, and disordered movement trajectory. The intervention of P37 can effectively improve the cognitive function of mice, shorten the escape latency, increase the target quadrant residence time, increase the platform crossing frequency, and restore the normal target search trajectory.

[0057] 7. Morphology of nerve cells in the hippocampal CA1 region of mice

[0058] D-gal can trigger oxidative stress and inflammatory response, leading to neuronal dysfunction, impaired synaptic plasticity, and decreased cognitive function in the hippocampus. Previous studies have shown that D-gal-induced oxidative damage can cause a decrease in synaptic-related proteins in the hippocampal CA1 region, affecting the structure and function of synapses and leading to decreased memory storage and recall. In addition, D-gal can activate microglia and induce neuroinflammation, further exacerbating cognitive dysfunction. To evaluate the effects of D-gal-induced aging on the structure of the hippocampus in mice and further investigate whether P37 has a protective effect on D-gal-induced nerve damage, we performed HE staining on the hippocampal tissue of mice to observe the morphological changes of neurons in the hippocampus of different treatment groups. HE staining is a classic histological staining method, in which hematoxylin can specifically bind to DNA in the nucleus, making the nucleus appear dark blue or purple, and eosin can bind to proteins in the cytoplasm, making the cytoplasm appear pink or red, thus providing clear information on cell morphology and tissue structure.

[0059] After 63 days of feeding, the mice were euthanized, and samples were taken to investigate the effects of P37 on the morphology of nerve cells in the hippocampal CA1 region of mice. The effects of P37 on the morphology of nerve cells in the hippocampal CA1 region of mice are shown in Figure 7. Figure 7As shown in the hippocampal tissue of control mice, neurons were arranged in an orderly and compact structure, with round or oval nuclei. This indicates that the hippocampal tissue of control mice maintains normal histological characteristics, without obvious neuronal damage or abnormalities. However, significant pathological changes were observed in the CA1 region of the hippocampal tissue of D-gal-induced aging mice. Neurons were arranged in disarray, and some neurons showed obvious shrinkage, suggesting that the cells may have undergone oxidative stress or apoptosis. In addition, the cell staining of neurons in the D-gal group was significantly deepened, and the boundary between the nucleus and cytoplasm was unclear, which may indicate that the neurons were in a degenerative or dead state, which is closely related to D-gal-induced oxidative stress damage and neuroinflammation. D-gal can cause neuronal functional damage by increasing the level of reactive oxygen species (ROS), inducing mitochondrial dysfunction, and disrupting the normal metabolism of neurons, thereby affecting learning and memory ability. In the hippocampal tissue of mice treated with P37, significant protection was observed. Compared with the model group, the neurons in the CA1 region of the hippocampus of the intervention group were more complete in morphology, and the cells were arranged in a more regular manner, without obvious neuronal shrinkage, suggesting that P37 may have a certain alleviating effect on D-gal-induced neuronal damage. In addition, the degree of HE staining of cells in the P37 treatment group was lighter, and there was no significant deepening of staining, and the boundary between the nucleus and cytoplasm was clear, indicating that P37 may reduce D-gal-induced neuronal apoptosis or necrosis. P37 may exert neuroprotective effects by inhibiting oxidative stress, reducing the accumulation of ROS, maintaining mitochondrial function stability, and regulating antioxidant enzyme activity, thereby improving D-gal-induced aging-related neural damage.

[0060] 8. Effect of P37 on the content of antioxidant enzymes in the serum of aging mice

[0061] Oxidative stress is one of the characteristics of D-gal-induced aging. SOD is a class of metal enzymes (containing Cu / Zn, Mn or Fe) that is a core member of the antioxidant defense system. This enzyme converts two molecules of O 2- into H2O2 and O2, respectively. This biochemical process significantly reduces lipid peroxidation levels, inhibits protein carbonyl modification, and protects mitochondrial DNA integrity, thereby maintaining cellular redox homeostasis. When ROS is generated in excess, leading to oxidative stress, SOD acts as the first line of defense by scavenging O 2- maintain redox balance; but continuous high-intensity oxidative stress will consume SOD activity, exacerbate free radical accumulation and form a vicious cycle. MDA is the end product of lipid peroxidation reaction, mainly generated by β-cleavage of polyunsaturated fatty acids under ROS attack. At the same time, MDA itself has cytotoxicity and can cross-link with protein amino to form "lipofuscin", further damaging cell function. Clinically, SOD activity (antioxidant capacity) and MDA level (oxidative damage degree) are often detected together to assess the oxidative stress state.

[0062] After 63 days of feeding, samples were taken to investigate the effect of P37 on the content of antioxidant enzymes in the serum of aging mice. The effect of P37 on the content of antioxidant enzymes in the serum of aging mice is shown in Figure 8 It is shown that the SOD level of normal mice is 52 U / mg protein, the model group is reduced to 30 U / mg, and after P37 treatment, it is restored to 42 U / mg. Compared with the control group, the SOD activity in the serum of the model group mice was significantly reduced, and the MDA level was significantly increased. However, compared with the model group, the SOD activity in the intervention group was increased, and the MDA level was significantly reduced. The results show that P37 slows down the aging process by regulating redox homeostasis.

[0063] Example 2 Effect of P37 on the lifespan of Caenorhabditis elegans

[0064] Caenorhabditis elegans lifespan experiment as a key model for anti-aging research, through its short life cycle, highly conserved aging-related genes and easy operability, can quickly screen and verify the lifespan- extending effect of potential anti-aging compounds and reveal its molecular mechanism. In order to explore whether P37 has the effect of delaying aging, L4 (wild type Caenorhabditis elegans) was fed with two concentrations of P37 (0.2 mg / mL and 1 mg / mL) at 20°C for lifespan experiment.

[0065] As shown in Figure 9As shown, in the C. elegans lifespan experiment, there are Control, P37-Low (0.2 mg / mL) and P37-High (1 mg / mL) three experimental groups to evaluate the effect of P37 on the lifespan of nematodes at different concentrations. The experimental results show that the longest survival time of the Control group is 29 days, while the P37-Low and P37-High groups reach 33 days and 39 days, respectively, indicating that with the increase of P37 concentration, the lifespan of nematodes shows a trend of prolongation. In addition, the median survival time (i.e. the time when 50% of individuals die) also shows significant differences among the three groups. The median survival time of the Control group is 13 days, while that of the P37-Low and P37-High groups is 15 days and 27 days, respectively, especially the median survival time of the P37-High group is significantly prolonged, almost twice that of the Control group (Table 1). These data show that the treatment of P37 can effectively delay the aging process of nematodes, and its effect is concentration-dependent.

[0066] Table 1 Investigation results of C. elegans lifespan experiment

[0067] Treatment Longest survival (d) Survival (d) p-value (vs. Control) Control 29 13 P37-Low 33 15 >0.05 P37-High 39 27 <0.0001

[0068] The above-described embodiments are merely preferred modes of the present application, and do not limit the scope of the present application. Various modifications and improvements made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. The application of P37 peptide in the preparation of products that improve learning and memory abilities, characterized in that, The amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

2. The application according to claim 1, characterized in that, The amino acid sequence of the P37 polypeptide is shown in SEQ ID NO.8; the product includes food or medicine.

3. A product for improving learning and memory abilities, characterized in that, The product includes a P37 peptide and excipients; the amino acid sequence of the P37 peptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

4. The application of P37 polypeptide in the preparation of drugs to improve nerve damage, characterized in that, The amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

5. The application according to claim 4, characterized in that, The amino acid sequence of the P37 polypeptide is shown in SEQ ID NO.

8.

6. A drug for improving nerve damage, characterized in that, The drug comprises a P37 polypeptide and excipients; the amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

7. The application of P37 peptide in the preparation of drugs to improve anxiety, characterized in that, The amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

8. The application according to claim 7, characterized in that, The amino acid sequence of the P37 polypeptide is shown in SEQ ID NO.

8.

9. A drug for improving anxiety, characterized in that, The drug comprises a P37 polypeptide and excipients; the amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.

9.

10. The application of P37 polypeptide in the preparation of drugs for treating neurodegenerative diseases, characterized in that, The amino acid sequence of the P37 polypeptide is shown in any one of SEQ ID NO.1-SEQ ID NO.9.

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