JP2011111440A - Neurocyte differentiation promoter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a neurocyte differentiation promotor which has differentiation promoting activity for neurocyte and is excellent in safety. <P>SOLUTION: The neurocyte differentiation promotor includes as an effective component a peptide expressed by Gly-Pro-Ala or salt thereof. The neurocyte differentiation promotor has high neurocyte differentiation promoting activity and also has high safety because the peptide (Gly-Pro-Ala) of an effective component is such a derivative of a living body as collagen. The neurocyte differentiation promotor can be used as a remedy for such an intracerebral neuropathy in a human or non-human animal as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, dementia, and melancholia. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an agent for promoting differentiation of nerve cells, which is highly safe and easy to continuously take.

  There is still no fundamental treatment for neurodegenerative diseases of the brain such as Alzheimer's disease and Parkinson's disease. Even if the progression of the disease can be delayed, the disease itself cannot be cured, and the side effects of drugs are also a problem. As a result, in Japan, the number of patients with dementia has increased with rapid aging, which has become a social problem. On the other hand, even healthy individuals frequently forget things or decrease their ability to learn with age, but these phenomena are also said to be due to neurodegeneration in the brain. Health foods and medicines that can be prevented against these functional declines are desired, but none of them are definitive.

  It is considered that promotion of differentiation of nerve cells is an effective defense means against diseases and physiological phenomena caused by these abnormal brain functions.

  The differentiation, maintenance, and repair of nerve cells are controlled by physiologically active substances such as neurotrophic factor (BDNF) secreted from glial cells existing around the nerve cells. Nerve growth factor (NGF) is known as a representative neurotrophic factor, but NGF has an action of differentiation, maintenance and repair of nerve cells, and is important for promoting functional recovery of the cranial nervous system. Protein. However, since NGF is a polymer, it cannot pass through the blood-brain barrier, and development as a medicine or food to be taken orally is not easy. In addition, effective gene therapy is far from practical use. Therefore, low molecular weight compounds that have NGF-like or NGF-like properties that enhance the action of NGF and pass through the blood brain barrier are desired.

  PC12 cells derived from rat adrenal pheochromocytoma are known to stop proliferation of the cells by adding NGF and differentiate into neural-like cells having neurites, and have a neuronal differentiation promoting action It is a model cell that is frequently used in the search for.

  To date, many agents that promote differentiation of neural cells targeting PC12 cells have been identified and disclosed. (Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6). However, these active ingredients are macromolecular peptides with poor absorbability and stability, non-natural products by chemical synthesis methods, or natural products that are products of microorganisms, It has no experience and has problems in terms of safety. As for the new sesquiterpene derived from Cordyceps sinensis (Patent Document 7), which is an experienced food, it is difficult to extract and purify from Cordyceps sinensis because it is a rare component, and it is difficult to synthesize it from a precursor. It is difficult to use as food. In addition, fatty acids having an action of promoting the formation of neural networks have also been presented, but the activity at low concentrations is low, the intake of large amounts of fatty acids becomes excessive in calories, and metabolism is disturbed by other physiological activities of fatty acids. (Patent Document 8).

  There are other reports on peptides having a neuronal differentiation promoting action (Non-patent Document 1), but no peptide having a structure having protease resistance is shown.

  On the other hand, regarding peptides composed of the sequence of Gly-Pro-Ala, use as a wound treatment composition (Patent Document 9), collagen producing agent (Patent Document 10), and seasoning (Patent Document 11) are known. None of them are related to nerve cells in the brain.

JP 2008-189615 A JP 2006-42684 A JP 2000-125894 A Japanese Patent Laid-Open No. 11-49718 Japanese Patent Laid-Open No. 9-323928 Japanese Patent No. 3990477 JP 2003-252876 A JP 2007-217311 A JP-A-10-310534 JP 2003-137807 A International Publication No. 2004/107880 Pamphlet

Biosci. Biotech. Biochem. 67 (12), 2541-2547, 2003.

  An object of the present invention is to provide a nerve cell differentiation promoting agent having a nerve cell differentiation promoting activity and excellent in safety.

  As a result of intensive studies on components having neuronal differentiation promoting activity, the present inventors have found that Gly-Pro-Ala has excellent neuronal differentiation promoting activity, and have completed the present invention. .

That is, the gist of the present invention is as follows.
[1] A neuronal cell differentiation promoter comprising a peptide represented by Gly-Pro-Ala or a salt thereof as an active ingredient,
[2] The nerve cell differentiation promoting agent according to [1], which is orally administered,
[3] The nerve cell differentiation promoting agent according to [1], which is administered parenterally.

  The nerve cell differentiation promoting agent of the present invention has high nerve cell differentiation promoting activity, and since the peptide (Gly-Pro-Ala) as an active ingredient is derived from a living body such as collagen, it is also highly safe.

  In addition, it is known that most proteases present in the living body of humans and non-human animals are difficult to cleave the X-Pro bond and relatively difficult to cleave the Pro-Y bond. ing. Therefore, the peptide which is an active ingredient of the nerve cell differentiation promoting agent of the present invention has 3 residues and has high resistance to protease in vivo, and therefore can exist stably in vivo.

  Conventionally, bioactive peptides as pharmaceuticals have been administered by parenteral administration such as intravenous injection so as not to lose high bioactivity, and are limited to low molecular peptides that are easily absorbed through the mucosa. In fact, it has been widely applied in the medical field as seen in transmucosal absorption type insulin preparations. Therefore, since the peptide which is an active ingredient of the nerve cell differentiation promoting agent of the present invention is a low molecular weight of 3 residues, not only parenteral administration such as intravenous administration, intramuscular administration, subcutaneous administration, transdermal administration, etc. Even when administered orally, it is easily absorbed into the living body through the oral mucosa, stomach wall, intestinal wall and the like.

  As described above, the nerve cell differentiation promoting agent of the present invention is mainly composed of a low molecule that is easily absorbed into a living body, and is expected to exist as stably as possible in blood and in tissues and organs after absorption. Since the effective amount can reach the brain through the bloodstream regardless of the route, it is a nerve cell differentiation promoting agent capable of exerting physiological activity (nerve cell differentiation promoting activity) even with a small amount.

  Moreover, the neuronal cell differentiation promoting agent of the present invention has a low allergenicity because a peptide as an active ingredient is a low molecular weight molecule having 3 residues.

  Further, the neuronal differentiation promoting agent of the present invention is a peptide that is soluble in water, and is a highly stable peptide that does not easily oxidize or decompose even by heat treatment, etc., and thus has excellent storage stability and processability. .

  Various bioactive peptides having Gly-Pro-Ala as a partial sequence have been reported, but it is known that the bioactivity disappears or is enhanced only by deleting or modifying one residue of the peptide. Therefore, it is extremely difficult to estimate the neuronal differentiation promoting activity of Gly-Pro-Ala from similar peptides.

FIG. 1 is a graph showing the results of PC12 cell differentiation promoting effects in Examples. FIG. 2 is a diagram showing a state of the PC12 cell added with only NGF when observed with a microscope in the examples. FIG. 3 is a diagram showing a state of the PC12 cells added with NGF and peptide GPA when observed with a microscope in the examples. FIG. 4 is a diagram illustrating a state of the PC12 cells added with NGF and peptide GPM when observed with a microscope in the examples. FIG. 5 is a diagram showing a state of the PC12 cells added with NGF and peptide GPS when observed with a microscope in the examples.

Embodiments of the present invention will be described below.
The present invention has been found and completed for the first time that a peptide comprising the amino acid sequence of Gly-Pro-Ala has neuronal differentiation promoting activity.

  That is, the neurogenesis promoting agent of the present invention contains a peptide having an amino acid sequence represented by Gly-Pro-Ala (hereinafter abbreviated as a peptide used in the present invention) or a salt thereof. In the present specification, unless otherwise specified, an amino acid residue means an L-type amino acid residue.

Examples of the salt of the peptide used in the present invention include salts with alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, and organic bases such as lysine and ornithine that can be used as food.
The peptide represented by Gly-Pro-Ala, which is the active ingredient of the present invention, or a salt thereof may be isolated as a hydrate, various solvates, or a crystalline polymorphic substance. All of these isolates and mixtures are included.

  The peptide or salt thereof used in the present invention can be produced from a protein enzymatic degradation product by a known method, or can be produced by culturing a transformant containing DNA encoding the peptide. . Moreover, it can also manufacture according to the well-known peptide synthesis method. As a peptide synthesis method, for example, either a solid phase synthesis method or a liquid phase synthesis method may be used.

Examples of the protein include collagen, gelatin, elastin, and ginseng protein.
The enzymatic degradation of the protein is not particularly limited, such as the type of protein, the type of enzyme, and the reaction conditions. One or more Gly-Pro-Ala sequences are present in the protein serving as a substrate. Any conditions may be used as long as Gly-Pro-Ala is generated by enzyme digestion at a stage or more or by multiple kinds of enzyme digestion. For example, collagenase digestion of collagen or gelatin is applicable. After the enzymatic digestion, the peptide used in the present invention can be purified and isolated by combining ordinary purification methods such as solvent extraction / distillation / column chromatography / liquid chromatography / recrystallization. When the peptide obtained by the above method is a free form, it can be converted to an appropriate salt by a known method or a method analogous thereto, and conversely, when obtained by a salt, a known method or a method analogous thereto Can be converted to the free form or other salts.

  In addition, the well-known purification method similar to the above can be applied after the chemical synthesis reaction.

  In addition, as a method for producing the peptide used in the present invention by a genetic engineering technique, for example, a polynucleotide containing a base sequence encoding the peptide, preferably DNA, can be prepared. The DNA may be any of genomic DNA, genomic DNA library, cDNA derived from the above-mentioned raw materials, cDNA library derived from the above-mentioned raw materials, and synthetic DNA.

  The polynucleotide can be incorporated into a vector using a known method such as DNA ligase or restriction enzyme, and then the vector can be amplified in a host cell. There are no particular limitations on vectors, host cells, and the like as long as they are known. A large amount of the peptide used in the present invention can be obtained by separating and purifying the peptide of the present invention from the cultured host cells. The separation and purification method is not particularly limited as long as it is a known method.

  Among these, it is preferable to use an enzyme degradation product of a protein from the viewpoint of stable mass production.

  The nerve cell differentiation promoting agent of the present invention comprises the peptide or salt thereof as an active ingredient, and the peptide or salt thereof is a component derived from a living body having experience with food such as collagen, gelatin, elastin, or carrot protein. Therefore, it is highly safe and has low toxicity.

  The neuronal differentiation promoting agent of the present invention is, for example, for humans and non-human animals (for example, rats, mice, guinea pigs, rabbits, birds, sheep, pigs, cows, horses, cats, dogs, monkeys, chimpanzees, etc.) Can be administered.

  Since the nerve cell differentiation promoting agent of the present invention promotes the differentiation of nerve cells in the brain of the above-mentioned human or non-human animal, the neurological diseases in the brain (eg, Alzheimer's disease, Parkinson's disease, muscle atrophy) Can be used as a therapeutic agent for lateral sclerosis, dementia, depression).

Conventionally, various synthetic reagents are commercially available as therapeutic agents for neurological diseases, and these commercially available reagents have been reported to have various side effects. In addition, therapeutic agents for neurological diseases also have a problem that they require skill in the action of medication so as not to cause side effects.
In contrast, the nerve cell differentiation promoting agent of the present invention does not exhibit a strong physiological activity like an endogenous hormone because the peptide or salt thereof as an active ingredient is a low molecular weight peptide having only 3 residues. It is not considered. Therefore, it is excellent in safety in that it is considered to act mildly. Moreover, there is an advantage that it is excellent in safety from the point of experience of eating as a component in food since ancient times.

When the nerve cell differentiation promoting agent of the present invention is used as a therapeutic agent, the peptide or a salt thereof may be used alone or mixed with an excipient or carrier to form an orally administered agent, an injection, an infusion, a suppository, or the like. Can do.
The excipient and carrier have no problem as long as they are pharmaceutically acceptable, and the type and composition differ depending on the administration route and administration method.

  As an oral administration agent, various base materials can be selected according to the purpose, and examples thereof include tablets, capsules, candy, gummi, and beverages. Above all, when the peptide or its salt is continuously ingested in a small amount, it can be added to taste and ease and is more effective for continuous ingestion. Substrates such as strawberries, gummi or beverages are desirable. However, when a certain amount of the active ingredient is contained, the deliciousness of the active ingredient may be impaired, and in some cases, the physical properties of the base material itself may be changed. Therefore, when a certain amount of active ingredient such as several grams is continuously ingested, a so-called supplement is desirable, and a solid composition that can be taken with water or hot water is preferred.

  Examples of the solid composition include tablets, pills, capsules, fine granules, granules and the like. In such a solid composition, the peptide or a salt thereof contains at least one inert diluent, for example, various sugars such as sucrose, lactose and glucose, various sugar alcohols such as mannitol and sorbitol, and further hydroxy. Mixed with propylcellulose, crystalline cellulose, various starches, etc. The solid composition is prepared according to a conventional method using additives other than inert diluents, for example, lubricants such as magnesium stearate, disintegrants such as calcium calcium glycolate, stabilizers such as lactose, glutamic acid Alternatively, it may contain a solubilizer or solubilizer such as aspartic acid. In some cases, additives such as fragrances and sweeteners can also be used. In addition, tablets, pills, granules, and capsule granules containing granules can be sugar-coated with sugars such as sucrose and sugar alcohols such as maltitol, gelatin, hydroxypropylcellulose, hydroxypropylmethylcellulose as necessary. You can also apply a coating. The solid composition may be covered with a film of a gastric or enteric substance. Moreover, in order to improve the solubility of a formulation, a well-known solubilization process can also be performed.

  As an injection or infusion, it is desirable to mix the peptide or a salt thereof with physiological saline, various buffers, sugar solutions such as glucose, inositol, mannitol, and glycols such as ethylene glycol, propylene glycol, and polyethylene glycol. .

  In addition, as a suppository, the peptide or a salt thereof is mixed with a base such as an oleaginous base or a water-soluble base and, if necessary, an emulsifier, a suspending agent, etc. Examples include those prepared in a shape and prepared by a dissolution method, a cold pressure method, or a manual method.

  The content of the peptide or salt thereof in the preparation as the therapeutic agent varies depending on the kind of the preparation, but is usually 0.1 to 100% by weight, preferably 1 to 98% by weight. For example, when used as an injection, it is usually desirable to contain 0.1 to 30% by weight, preferably 1 to 10% by weight of the active ingredient.

In the case of a therapeutic agent, the dosage of the peptide or a salt thereof is usually 10 mg to 30 g, preferably 100 mg to 10 g by oral administration for adults per day for humans. It is administered in several divided doses. Further, in the case of parenteral administration such as an injection solution, the dose of the peptide or a salt thereof is usually 2 mg to 6 g, preferably 20 mg to 2 g per day for an adult human in general. It is administered once or divided into 2 to several times.
In some cases, a dose smaller than the above dose range is sufficient. If the subject is a non-human animal other than a human, the dose may be adjusted according to the above human.

  Moreover, since the nerve cell differentiation promoter of this invention is excellent in safety | security, it can also be used in combination with the compound and raw material which are said to have another brain function improvement effect. Examples of such compounds and materials include glucose, which is a nutrient source of the brain, purine derivatives such as caffeine that act on the nervous system, phosphatidylserine, phosphatidylcholine, arachidonic acid, docosahexaene, which are constituents of the brain. Examples thereof include lipids such as acids, compositions such as ginkgo biloba extract having an effect of improving blood flow, pyrroloquinoline quinone (PQQ) which is a coenzyme, oxidized coenzyme Q10, and reduced coenzyme Q10. The method of combination is not limited in any way, and one or more types that are suitable for the degree of expected effect, the taste surface such as taste, cost, processing suitability and stability can be used in combination. In this case, it is conceivable that not only the additive effect of the nerve cell differentiation promoting effect of the present invention and the effect of the compound or material used in combination, but also a healing rate and a therapeutic effect which are higher than expected. This is due to the combined effect of a plurality of materials having different action mechanisms.

  Moreover, the neurogenesis promoter of this invention can be used for the purpose of prevention of the neurological disease in a human and a non-human animal.

  When the neuronal cell differentiation promoting agent of the present invention is used in the hope of preventing neurological diseases, the effective amount thereof in the form of oral administration, injection, infusion, suppository, etc. as described above is human or It can be administered to non-human animals.

  Further, the nerve cell differentiation promoting agent of the present invention has extremely excellent safety, absorbability, low allergenicity, stability of physical properties and excellent processability, so that it is a food for infants such as prepared milk powder and baby food. Furthermore, it can also be used as a part of the raw material of the jelly-like nutritional food for the elderly and those who have difficulty swallowing.

  The dose of the peptide or salt thereof for the prevention of neurological diseases varies depending on the age, weight, symptoms, therapeutic effect, administration route, etc. of the subject and is appropriately set in consideration of these. In general, 0.1 mg to 30 g, preferably 1 mg to 10 g per day for an adult is suitable, and this is administered once a day or divided into 2 to several times a day. Since the dosage varies depending on the purpose of prevention and other various conditions, an amount smaller than the above dosage range may be sufficient. If the subject is a non-human animal, the dose may be adjusted according to the above human.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited by this.

(Experimental design)
PC12 cells were used to examine the neuronal differentiation promoting effect of the peptides. This purpose is to examine the differentiation promoting action of the test substance in the process of differentiation of neural stem cells into neural cells (hereinafter referred to as neural differentiation). As an experimental system, PC12 cells are used. PC12 cells are pheochromocytomas derived from the adrenal medulla, and are known to undergo neurite formation and elongation in the presence of nerve growth factor (NGF) and differentiate into catecholaminergic neuron-like cells (Green and). Tschler, 1976). This system can be observed relatively easily from a stem cell-like cell line to a neuron-like cell, and is therefore used worldwide to investigate the molecular mechanism of neuronal differentiation.

(Synthesis and purification of test sample)
Three types of peptides used as test samples, Gly-Pro-Ala (hereinafter referred to as GPA), Gly-Pro-Met (hereinafter referred to as GPM), and Gly-Pro-Ser (hereinafter referred to as GPS) are Wako Pure Chemical Industries Ltd. Purchased from the company. All were chemically synthesized by the F-moc method and all were purified by HPLC so that the purity was 99% or more.

(Measurement of nerve cell differentiation promoting activity)
In culturing PC12 cells, the culture solution was 85% RPMI 1640 (Invitrogen, product number 72400-047), 10% horse serum (Invitrogen, product number 16050-122), 5% calf serum (Sigma, product number F9423), and A culture dish containing 50 units / ml penicillin and 50 μg / ml streptomycin (Invitrogen, product number 15140-122), a culture dish coated with type IV collagen (Type IV Collagen), a 60 mm diameter plastic dish for cell culture (Iwaki, product number 12-018-004) was used. PC12 cells were obtained from DS Pharma Biomedical Co., Ltd. (Part No. 88022401), and the cells were placed in a culture dish containing 5 ml of the culture solution, and maintained in an incubator at 37 ° C. and 5% CO ₂ for a week. The medium was changed 1-2 times and the subculture was performed once a week.

For differentiation induction, for the convenience of microscopic observation, cells were covered on a cover slip (15 mm diameter circular glass flake, Matsunami, product number 15, No. 1) coated with collagen (1 mg / ml, Roche, product number 1 179 179). Was cultured. The day before differentiation induction, the PC12 cell suspension was placed in a 12-well plate (TPP, part number 92412) containing a coated coverslip so that the cell density was 2.5 to 10 × 10 ⁴ cells / cm ^2. Poured (0.6 ml cell suspension / well) and precultured in culture for 1 day. On the day of differentiation induction, remove the 12-well plate culture solution, wash once with RPMI 1640 medium (to remove cells that did not adhere to the serum or coverslip in the culture medium), and then add various differentiation induction media did. The differentiation induction medium was 99% RPMI 1640 medium, 1% horse serum, 50 units / ml penicillin, 50 μg / ml streptomycin, and NGF was added as a differentiation inducer to a final concentration of 50 ng / ml. As a negative control, a medium containing no NGF is used. Normally, neuronal differentiation of PC12 cells is not induced under these conditions. In addition, differentiation induction media containing various synthetic peptides (GPA, GPM, GPS) together with NGF at a final concentration of 10 μM were prepared, and the effects of each peptide on differentiation promotion were compared. PC12 cells were further cultured in an incubator for 1 week in these various differentiation-inducing media to induce differentiation into nerve-like cells. Multiple experiments were performed using at least two wells per sample per experiment.

  Nerve differentiation of PC12 cells was determined by the presence or absence of neurite formation. Neurites are usually observed from one to several per differentiated cell, have a long and narrow structure with a diameter of about 1 μm, a length of several μm to several hundred μm, and branching is also observed. In this experiment, in order to clearly observe neurites, attention was paid to tubulin, which is a main structural protein constituting neurites, and fluorescent antibody staining was performed using an anti-tubulin antibody. That is, after differentiation induction for 1 week, the differentiation induction medium in the 12-well plate was removed, PBS (phosphate buffered saline) containing 4% paraformaldehyde was poured, and the cells were fixed at room temperature for 15 minutes. Next, the cells were replaced with 100% methanol and left at −20 ° C. for 20 minutes to lyse the cell membrane and enhance antibody penetration, and then washed with PBS. Furthermore, in order to prevent non-specific adsorption of the antibody, it was treated with PBS (blocking solution) containing 3% serum for 10 minutes. The antibody solution consists of anti-tubulin-mouse monoclonal antibody (600-fold diluted, Sigma, product number C4585) chemically labeled with a fluorescent substance Cy3 in a blocking solution and SYTO13green (1,000-fold diluted, Molecular probe) as a nuclear stain. No. S7575) was added, and this was added to the pretreated cells and reacted at room temperature for 1 hour. Thereafter, the unreacted antibody was removed by washing with PBS, and finally a preparation was prepared using an encapsulating agent (50% glycerin).

  Observations were performed using an LSM510 laser-operated confocal microscope (Zeiss), observing green fluorescence (509 nm) of SYTO13green and red fluorescence (568 nm) of Cy3 with excitation light from an argon laser (488 nm) and a helium neon laser (543 nm). did. Fluorescence observation was performed at 200 × using a 20 × (20 ×) objective lens, and cells in different areas of the coverslip were randomly photographed (approximately 10 cells / image). Each sample was observed so that the number of cells was at least 150 or more. In the image analysis, cells having normal cell nuclei are measured by SYT13green nuclear staining to obtain the number of cells, and cells having neurites of 5 μm or more stained with Cy3 label-anti-tubulin antibody are counted to obtain the number of differentiated cells. did. For each image, the ratio of differentiated cells (number of differentiated cells / percentage of total cells) was calculated and subjected to statistical analysis (SPSS), and the promotion activity of each peptide in differentiation of nerve cells was examined.

(result)
One week after differentiation induction, in the negative control to which NGF was not added, differentiated cells having neurites of 5 μm or more positive with Cy3-labeled anti-tubulin antibody were not observed (data not shown). On the other hand, as shown in FIG. 1, cells having neurites were observed in the sample to which NGF (final concentration 50 ng / ml) was added, and the ratio of differentiated cells to the total number of cells was 21.3% (differentiated cells). Number: 372, Number of undifferentiated cells: 1376, total 1748; shown as NGF in FIG. 1). Next, analysis was performed on samples in which three different synthetic tripeptides (GPA, GPM, and GPS) were added together with NGF (final concentration 50 ng / ml) to a final concentration of 10 μM (FIG. 1 NGF + GPA, NGF + GPM, shown as NGF + GPS). The proportion of differentiated cells was 28.8% (differentiated cells: 46, undifferentiated cells: 114, total: 160) and 21.1% (differentiated 37, undifferentiated 138, total 175), 23.2 for each peptide. % (Differentiated 57, undifferentiated 189, total 246). In addition, when χ ² test was performed only for NGF, the comparison between NGF and NGF + GPA showed a two-sided significance probability of p <0.05, and GPA promotes neuronal differentiation of PC12 cells at a concentration of 10 μM. found. However, 10 μM GPM and GPS peptides were also subjected to χ ² test, and there was no significant difference (p values of 1.00 and 0.508, respectively), so that no nerve differentiation promoting effect was observed. I understood. That is, it is considered that GPA specifically promotes differentiation of PC12 cells, and from this, even for general neural stem cells (for example, neural stem cells found in human adult brain tissue) It is speculated that GPA is likely to promote neural differentiation.

2 to 5 show photographs of the PC12 cells after the staining. As shown in FIG. 3, in the PC12 cells to which GPA is added, a state in which the neurites are elongated for a long time is observed, and the state in which differentiation is promoted is well understood.
In addition, the PC12 cells to which GPA was added had a good culture state and showed no signs of cytotoxicity.

  The neuronal differentiation promoting agent of the present invention is preferably used as a therapeutic or preventive agent for neurological diseases such as anti-Alzheimer's disease, anti-Parkinson's disease, anti-amyotrophic lateral sclerosis, anti-dementia, and antidepressant Is done.

Claims (3)

  A nerve cell differentiation promoting agent comprising a peptide represented by Gly-Pro-Ala or a salt thereof as an active ingredient.   The nerve cell differentiation promoting agent according to claim 1, which is orally administered.   The nerve cell differentiation promoting agent according to claim 1, which is administered parenterally.