JP2009120501A - Composition for preventing onset of psychiatric disorder, and method for evaluating possibility of onset of psychiatric disorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for preventing onset of psychiatric disorder, and to provide a method for evaluating the possibility of the onset of the psychiatric disorder. <P>SOLUTION: The composition contains an unsaturated fatty acid or an oil and fat containing at least one unsaturated fatty acid as a constituent fatty acid. The composition is regulated so as to be fed to the body at an immature stage of the brain tissue. The possibility of the onset of the psychiatric disorder by individual is evaluated based on a bonding strength by amplifying Fabp7 gene by using a genome DNA isolated from the individual as a template, and measuring the bonding strength between the polypeptide encoded by the Fabp7 gene and the unsaturated fatty acid. In another embodiment, the possibility of the onset of the psychiatric disorder by the individual is evaluated based on a base sequence by determining the base sequence of the Fabp7 gene on the genome DNA isolated from the individual. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composition for preventing the onset of a mental illness and a method for evaluating the possibility of the onset of a mental illness.

  Schizophrenia is one of psychiatric disorders that develops after puberty and exhibits various psychiatric symptoms such as hallucinations and delusions, and is said to affect about 1% of the population worldwide.

  Also, if any of the parents develops schizophrenia, the child's onset rate is about 10%. Thus, genetic factors are thought to exist in the onset of schizophrenia. However, even if one of the identical twins develops, the other 40% do not develop schizophrenia. Thus, the development of schizophrenia is not completely determined by genetic factors, and it is considered that both genetic factors and environmental factors exist.

  In addition, schizophrenic patients are known to have weakened sensory filter functions that unnecessarily shut out unnecessary noises in addition to psychiatric symptoms. It is considered one of Sensory filter function can be examined physiologically using the criterion of prepulse inhibition. Prepulse suppression is reduced in schizophrenia and some of its families, and prepulse suppression is thought to be related to the likelihood of developing schizophrenia. Prepulse suppression disorders are also associated with bipolar emotional disorder (manic depression), obsessive-compulsive disorder (obsessive compulsive disorder), attention deficit hyperactivity disorder (ADHD), Tourette syndrome, and Huntington's disease Is known and is suggested to be common to many psychiatric disorders (see Non-Patent Documents 1 and 4).

  In addition, it is known that the incidence of schizophrenia in children is doubled when pregnant mothers are famined through painful incidents in Dutch Hanger Winter and China. However, there was no knowledge about what nutrient deficiencies specifically in pregnant mothers would worsen the incidence of schizophrenia in children.

As a drug for treating schizophrenia, a psychotropic drug that inhibits the action of dopamine is generally used, and in recent years, a drug targeting serotonin or glutamic acid has been developed.
Swerdlow NR, Geyer MA. (1998). Using an animal model of deficient sensorimotor gating to study the pathophysiology and new treatments of schizophrenia. Schizophr Bull. 24: 285-301. Coti Bertrand P, O'Kusky JR, Innis SM (2006) Maternal dietary (n-3) fatty acid deficiency alters neurogenesis in the embryonic rat brain.J Nutr 136: 1570-1575. Xu LZ, Sanchez R, Sali A, Heintz N (1996) Ligand specificity of brain lipid-binding protein. J Biol Chem 271: 24711-24719. Perry W, Minassian A, Feifel D, Braff DL. (2001) .Sensorimotor gating deficits in bipolar disorder patients with acute psychotic mania.Biol Psychiatry 50: 418-24.

  However, conventional drugs cannot completely recover the symptoms of schizophrenia. Furthermore, no technique has been known for preventing the onset of schizophrenia. There is also a need for a technique for determining whether it is necessary to prevent the onset of mental disorders such as schizophrenia.

  This invention is made | formed in view of the said subject, and it aims at providing the technique which prevents the onset of mental illness including schizophrenia, and the technique which evaluates the onset possibility of a mental illness.

  The present inventors have intensively studied to solve the above problems, and firstly found that the Fabp7 (also referred to as BLBP) gene is involved in prepulse suppression. Prepulse suppression is an index of a sensory filter function that unnecessarily shuts out unnecessary noise in the surroundings, and improving this can also lead to an improvement in concentration. Further, as described above, prepulse inhibition is an index of various mental diseases, and improving this has a high probability of leading to treatment or prevention of mental diseases.

  As a result of further investigation, in order to improve the prepulse suppression, the present inventors have found that more FABP7 protein is present in the stage where the brain tissue is immature, particularly in the fetus stage where the brain is not completed. We have found that it is preferable to function. FABP7 protein is known to bind to long-chain fatty acids and exhibit their functions (see Non-Patent Documents 2 and 3).

  Based on the above findings, the present inventors have found that if a long-chain fatty acid is supplied into the body when the brain tissue is immature, the onset of mental illness can be prevented, and the present invention has been completed.

  The composition according to the present invention is a composition for preventing the onset of a mental illness, and includes (a) a long-chain fatty acid, or (b) an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid. The brain tissue is prepared to be supplied to the body at an immature stage. The long chain fatty acid is more preferably an unsaturated fatty acid, further preferably a ω3 unsaturated fatty acid, and still more preferably docosahexaenoic acid.

  It is known that fatty acids can be supplied to a fetus when a pregnant mother ingests fatty acids (see Non-Patent Document 2). That is, if a long-chain fatty acid is administered to a pregnant mother, the long-chain fatty acid is supplied to the fetus, and the onset of mental illness after the birth of the fetus can be prevented. As described above, the composition according to the present invention may be prepared in an embodiment (an embodiment in which the composition is supplied to the fetus through the mother body) administered placenta.

  The composition according to the present invention is suitable for preventing the onset of a psychiatric disorder selected from the group consisting of schizophrenia, bipolar emotional disorder, obsessive compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, and Huntington's disease. Can be used.

  The composition according to the present invention is a composition for improving prepulse inhibition, comprising (a) a long-chain fatty acid, or (b) an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid, It is characterized in that the tissue is prepared to be supplied to the body at an immature stage. The long chain fatty acid is more preferably an unsaturated fatty acid, further preferably a ω3 unsaturated fatty acid, and still more preferably docosahexaenoic acid.

  As described above, if long-chain fatty acids are administered to a pregnant mother, the long-chain fatty acids are supplied to the fetus, which can improve prepulse suppression in the fetus (and even after its birth). As described above, the composition according to the present invention may be prepared in an embodiment (an embodiment in which the composition is supplied to the fetus through the mother body) administered placenta.

  The evaluation method according to the present invention is a method for evaluating the possibility of the onset of a mental illness, comprising a step of amplifying a Fabp7 gene using a genomic DNA isolated from an individual as a template, and a polypeptide encoded by the amplified Fabp7 gene A step of measuring a binding force between the polypeptide and a long-chain fatty acid, and a step of evaluating the likelihood of developing an individual's mental illness based on the measured binding force. It is characterized by inclusion.

  The evaluation method according to the present invention is a method for evaluating the possibility of onset of a mental illness selected from the group consisting of schizophrenia, bipolar emotional disorder, obsessive compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, and Huntington's disease. It can be used suitably.

  In the evaluation method according to the present invention, the long chain fatty acid is more preferably an unsaturated fatty acid, further preferably a ω3 unsaturated fatty acid, and still more preferably docosahexaenoic acid.

  The evaluation method according to the present invention also includes a step of determining a base sequence of at least a part of the Fabp7 gene present on genomic DNA isolated from an individual, and the individual or its progeny based on the determined base sequence. And a step of evaluating the possibility of the onset of mental illness.

  The composition according to the present invention is also a composition for preventing the onset of a mental illness, comprising (a) a long-chain fatty acid, or (b) an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid. Even if the brain tissue is prepared to be supplied to the body in an immature stage with respect to an individual evaluated as having a high possibility of developing a mental illness by the evaluation method according to the present invention, Good.

  The composition according to the present invention contains a long-chain fatty acid or an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid, and is supplied to the body when the brain tissue is immature. Can be prevented. In particular, when the composition according to the present invention is administered to a pregnant mother, it is possible to prevent the onset of mental illness after the birth of the fetus.

  The composition according to the present invention also contains long-chain fatty acids or fats and oils containing at least one long-chain fatty acid as a constituent fatty acid, and is supplied to the body when brain tissue is immature, thus improving prepulse suppression. can do. In particular, when the composition according to the present invention is administered to a pregnant mother, it is possible to improve prepulse inhibition after the fetus is born.

  Moreover, if the evaluation method concerning this invention is used, the onset possibility of a mental illness can be evaluated.

(1: Composition)
The composition according to the present invention includes a long-chain fatty acid or an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid. In the present specification, the term “composition” refers to a form in which various components are contained in one substance.

  In this specification, a long-chain fatty acid refers to a fatty acid having 8 or more carbon atoms, and includes saturated fatty acids such as palmitic acid and stearic acid, and unsaturated fatty acids such as docosahexaenoic acid and arachidonic acid. These long chain fatty acids may be modified such as methylation. Moreover, a free form may be sufficient and it may be esterified. That is, it may be in the form of fats and oils in which at least one long-chain fatty acid is an ester bond with glyceride and the long-chain fatty acid is at least one constituent fatty acid. Such fats and oils are easily hydrolyzed in the living body and can supply a predetermined unsaturated fatty acid. Oils and fats include triglycerides and phospholipids.

  Among long chain fatty acids, unsaturated fatty acids, particularly ω3 unsaturated fatty acids such as docosahexaenoic acid can be suitably used. It is known that the ω3 unsaturated fatty acid has a high affinity for the FABP7 protein (see Non-Patent Document 3). The ω3-unsaturated fatty acid refers to an unsaturated fatty acid having 3 carbon atoms (including carbon at the fatty acid terminal) from the fatty acid terminal to the carbon having the closest double bond.

  The composition according to the present invention is supplied into the body when the brain tissue is immature. This improves prepulse inhibition (PPI) or prevents the onset of mental illness.

  Prepulse suppression is an index of sensory filter function as described above. Startle reflexes occur when large sound stimuli are applied to humans and animals, but small sound stimuli (prepulses; they are small enough not to cause startle reflexes themselves) immediately before a large sound stimulus (pulse) (for example, just before 0.1 seconds) Sound), the startle reflex associated with loud sound stimulation is suppressed. This phenomenon is called prepulse suppression. When the magnitude of the startle reflection when the prepulse is not given is a, and when the magnitude of the startle reflection when the prepulse is given is b, (ab) / ax The value is given as 100 (%) (see FIG. 1).

  The composition according to the present invention can be supplied with a long-chain fatty acid to a fetus whose brain is not completed. Then, by supplying a long-chain fatty acid to a fetus whose brain is not completed, the function of the fetal FABP7 protein is enhanced. As shown in the examples described later, Fabp7 is a gene involved in prepulse inhibition, and can enhance prepulse inhibition in the postnatal life of the fetus by enhancing its action when the brain is not completed. And worsening of prepulse suppression is caused by psychiatric disorders such as schizophrenia, bipolar emotional disorder (manic depression), obsessive-compulsive disorder (obsessive compulsive disorder), attention deficit / hyperactivity disorder (ADHD), Tourette syndrome, and Huntington's disease. Since it can be an indicator of disease, improving prenatal suppression of prepulses in the fetus can prevent these mental disorders for the fetus. The composition according to the present invention can be preferably used for preventing schizophrenia among the above mental disorders.

  In this specification, the stage where brain tissue is immature means a stage where the number of brain cells can change. For example, in the case of a human brain, brain formation begins two weeks after fertilization, and differentiation into the cerebrum, cerebellum, brain stem, etc. is started 40 days after fertilization. And after 9 months of fertilization, the appearance is almost the same as that of an adult brain, and the number of brain cells does not increase after 1 to 2 months after birth.

  In order to supply the composition according to the present invention into the body when the brain tissue is immature, for example, it is preferable to administer the fetus via the placenta via the mother during pregnancy. It can also be administered orally or parenterally to infants up to 1 to 2 months of age. Specifically, for example, it may be mixed with milk and administered.

  Specifically, transplacental administration via a maternal body during pregnancy can be performed by administering the composition according to the present invention to the mother orally or parenterally. When the composition according to the present invention is administered to the mother, it can be digested and absorbed in the mother and supplied to the fetus through the placenta.

  In addition, the composition according to the present invention is obtained by using the method according to the present invention, which will be described later, or a method for evaluating the onset possibility of a mental illness of an offspring thereof, as a result of evaluating the possibility that the onset is high. More preferably it is prepared to be administered.

  The composition according to the present invention includes a long-chain fatty acid or an oil and fat containing at least one long-chain fatty acid as a constituent fatty acid, and can be conveniently administered orally or parenterally. It may be in the form. That is, the form of the composition according to the present invention may be a food form such as a solid food such as breads, cakes, cookies, pies and pasta, a beverage such as juice, or an injection solution. It may be in the form of drugs such as infusion, syrup, powder, granule, tablet, capsule, enteric solvent, troche and the like.

  The composition according to the present invention may contain other components in addition to the long-chain fatty acid or fats and oils having at least one long-chain fatty acid as a constituent fatty acid. Depending on the purpose, known additives that can be usually used in the field of food or pharmaceutical preparations can be added. Examples of such additives include excipients, binders, disintegrants, lubricants, corrigents, stabilizers, and the like, but are not particularly limited. More specifically, when the composition is in a solid form, for example, excipients such as lactose, glucose, sucrose and mannitol; disintegrants such as starch and sodium alginate; magnesium stearate and talc Lubricants; binders such as polyvinyl alcohol, hydroxypropyl cellulose, gelatin; surfactants such as fatty acid esters; additives such as plasticizers such as glycerin can be included in the composition.

  When the composition is liquid, for example, saccharides such as water, sucrose, sorbitol, and fructose; glycols such as polyethylene glycol and propylene glycol; oils such as sesame oil, olive oil, and soybean oil; p-hydroxy Additives such as preservatives such as benzoates can be included in the formulation.

  The administration route of the composition is not particularly limited, and may be either oral or parenteral. It is preferable that oral administration is possible from the viewpoint of easy administration. The dosage of the composition is appropriately set according to the administration route, the form of the composition, the age or weight of the mother, and the like, and is not particularly limited.

  The above long-chain fatty acids or fats and oils containing long-chain fatty acids as constituent fatty acids are often contained in vegetable oils and animal fats. In particular, fish oils such as sardines, horse mackerel, mackerel, salmon, and herring are known to contain a large amount of ω3 unsaturated fatty acids and fats and oils containing ω3 unsaturated fatty acids as constituent fatty acids, and can be suitably used in the present invention. . Moreover, the long chain fatty acids as described above are commercially available and may be purchased. That is, it is only necessary to obtain a long chain fatty acid, and the method is not particularly limited.

(2: Evaluation method)
The present invention also provides a method for evaluating the possibility of the onset of mental illness. The evaluation method according to the present invention comprises a step of amplifying a Fabp7 gene using genomic DNA isolated from an individual as a template, a step of producing a polypeptide encoded by the amplified Fabp7 gene, and the polypeptide and a long-chain fatty acid. And a step of evaluating a possibility of developing a mental illness of the individual or its progeny based on the measured binding strength.

  The individual refers to animals including humans and non-humans, and includes living bodies, fetuses, fertilized eggs and the like. Isolation of genomic DNA from an individual may be performed according to a conventional method, and tissue, blood, cells, etc. may be collected and DNA extracted.

  For amplification of the Fabp7 gene using the isolated genomic DNA as a template, for example, a well-known conventional PCR method may be used. For example, the accession number of the human Fabp7 gene is NM_001446, which has the base sequence shown in SEQ ID NO: 1. The accession number of the mouse Fabp7 gene is NM_021272, and has the base sequence shown in SEQ ID NO: 2. Based on this information, those skilled in the art can easily design suitable primers for amplifying the Fabp7 gene. Specifically, for example, a single-stranded oligonucleotide having a base sequence corresponding to 15 to 30 bp near both ends of the Fabp7 gene of each organism can be suitably used as the primer.

  The production of the polypeptide encoded by the amplified Fabp7 gene is obtained by, for example, incorporating the Fabp7 gene into a recombinant expression vector, introducing it into a host capable of expression by a known method, and translating it in the host. The polypeptide may be purified. The expression vector preferably incorporates a promoter that functions in the host so as to express the foreign polynucleotide. The method for purifying the recombinantly produced polypeptide varies depending on the host used, the nature of the polypeptide, but well-known methods (for example, ammonium sulfate precipitation or ethanol precipitation, acid extraction, anion or cation exchange chromatography). Phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxyapatite chromatography, and lectin chromatography).

The binding force between the produced polypeptide and the long chain fatty acid can be measured, for example, by synthesizing a polypeptide encoded by the amplified Fabp7 gene and incubating it with the long chain fatty acid. It can be carried out by obtaining _a binding constant Ka based on the law of mass action by separating the chain fatty acid bound and the free long chain fatty acid and measuring the respective molar concentrations (non-patent) Reference 3).

  The long-chain fatty acid used in the evaluation method according to the present invention is more preferably an unsaturated fatty acid, further preferably a ω3 unsaturated fatty acid known to have high affinity with the FABP7 protein, and the FABP7 protein. Even more preferred is docosahexaenoic acid, which is considered as a natural ligand.

Separation of FABP7 protein and long chain fatty acid bonded to free long chain fatty acid may be performed using, for example, a column that adsorbs only lipids. For example, a Sephadex column having a hydroxyalkyl group such as Lipidex 1000 is used. through, those bonded with FABP7 protein and a long chain fatty acid and eluted with elution buffer, such as KP _i buffer, the released long-chain fatty acids by elution with methanol or the like, it is possible to perform the separation.

  The binding force can also be measured using a well-known and conventional acrylodan-labeled fatty acid-binding intestinal protein (ADIFAB) or a well-known and conventional isothermal titration calorimetry.

Based on the measured binding force, the evaluation of the possibility of the onset of a mental illness in an individual or its progeny is considered to be because the higher the binding power, the higher the activity of FABP7. It can be evaluated that the possibility of developing is low. On the other hand, when the binding force is low, the activity of FABP7 is considered to be weak, so it can be evaluated that the prepulse inhibition is low and the onset of mental illness is high. This evaluation, for example, based on the association constant K _a was determined as described above, it can be done qualitatively or quantitatively. In addition, according to the present invention, when an individual is evaluated to have a high possibility of developing a mental illness, it can be evaluated that a progeny of the mental illness is also high in the offspring.

  The evaluation method according to the present invention includes mental disorders such as schizophrenia, bipolar emotional disorder (manic depression), obsessive-compulsive disorder (obsessive-compulsive disorder), attention deficit hyperactivity disorder (ADHD), Tourette syndrome, and Huntington's disease. Although it can be used for evaluating the possibility of developing a disease, it can be suitably used for evaluating the possibility of developing schizophrenia.

  As another evaluation method according to the present invention, a step (a) of determining a base sequence of at least a part of the Fabp7 gene present on genomic DNA isolated from an individual, and based on the determined base sequence, And an evaluation method including the step (b) of evaluating the onset possibility of the mental illness of the individual or its offspring.

  In the step (a), it is only necessary to obtain information on the base sequence for evaluating the onset possibility of the mental illness of the individual or its progeny. Specifically, the expression level of the Fabp7 gene or the Fabp7 gene is encoded. Information for predicting the binding force between the FABP7 protein and a long-chain fatty acid such as docosahexaenoic acid may be obtained, and more specifically, although not limited thereto, the FABP protein and docosa It is only necessary to obtain information on a base sequence including a SNP site that can replace the 61st threonine of the FABP7 protein, which changes the binding force with oxaenoic acid.

  Further, the method used in the step (a) is not particularly limited, but a well-known and commonly used base sequence determination method may be used, and a direct sequence method or other standard methods for determining a base sequence can be used. When the above evaluation is performed using a specific gene polymorphism as an index, only a nearby sequence including the gene polymorphism needs to be determined. Further, it is also possible to adopt a conventional method for detecting single nucleotide polymorphism (SNP) or other gene polymorphism such as invader method, TaqMan PCR method and the like.

  In the step (b), the evaluation of the possibility of the onset of mental illness in the individual or its progeny is based on the nucleotide sequence information obtained in the step (a), the expression level of the Fabp7 gene, or the FABP7 protein encoded by the Fabp7 gene. Predicting the binding force between glycine and a long-chain fatty acid such as docosahexaenoic acid, and assessing the onset of mental illness in the individual or its progeny based on the prediction. Specifically, when the expression level of the Fabp7 gene is changed as compared with that of a healthy person (for example, when the expression level is decreased when the brain is immature or when the expression level is increased in an adult) Or when the binding force between FABP7 protein and docosahexaenoic acid (DHA) decreases, it is evaluated that the individual or a progeny of a mental illness having the individual as a parent is highly likely to develop. The

  The method for predicting the expression level of the Fabp7 gene is not particularly limited. Specifically, for example, a method for predicting the presence or absence of a gene polymorphism that affects the expression of the gene can be exemplified. . It is a well-known fact that gene polymorphisms in gene intron regions, enhancer regions, etc., for example, do not cause mutations in the amino acid sequence of the protein itself, but there are examples of greatly changing its production (gene expression). is there.

  In addition, as a method for predicting the binding force between FABP7 protein and docosahexaenoic acid (DHA), for example, the binding force between wild-type and mutant FABP7 protein and docosahexaenoic acid (DHA) can be determined by the method described above. This can be done by accumulating the actually measured data and referring to the data table and the base sequence information determined in step (a). In addition, as will be described later in the Examples, when there is a gene mutation, referring to the three-dimensional structure information of the FABP7 protein, whether the mutation causes a structural change in the binding region with DHA in the FABP7 protein. It can be done as an index.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  Moreover, all the academic literatures and patent literatures described in this specification are incorporated herein by reference.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this does not limit this invention at all.

[Example 1: QTL analysis for prepulse suppression]
Mouse QTL analysis was performed using prepulse inhibition as an index.

  Mouse prepulse inhibition (PPI) was measured as shown in FIG. That is, sound stimulation was given to the mouse fixed on the platform, and the size of the body movement (muscle reflex) of the mouse with respect to the sound stimulation was measured. At this time, when the magnitude of the startle reflection when the prepulse is not given is a, and when the magnitude of the startle reflection when the prepulse is given is b, (ab) / a × 100 (%) Prepulse inhibition was measured. The measuring instrument was purchased from Med Associates.

  FIG. 2 is a more detailed illustration of the prepulse suppression measurement. As shown in FIG. 2, the prepulse suppression measurement starts after a 10 minute adaptation period. After 50 ms of silence, give 20 ms of prepulse sound (0 (no prepulse), 72, 74, 78, 82, or 86 dB), and after 100 ms, give 40 ms of pulse sound (120 dB) Gave. The startle reflex was measured for 100 milliseconds thereafter. The time from the pulse sound at this time to the startle reflection is hereinafter referred to as latency. The above was considered as one trial, and the trial was performed several times with 10 to 20 seconds opened.

  First, prepulse suppression was measured for a plurality of mouse strains, and among strains having a stable prepulse suppression value, strain B6 (C57BL / 6NCrlCrlj, Charles River Laboratory, Japan), which has large prepulse suppression, and A system C3 (C3H / HeNCrlCrj, Charles River Laboratory, Japan) with small prepulse suppression was obtained. As shown in FIG. 3, B6 and C3 show almost the same prepulse inhibition both at 7 weeks after birth and 12 weeks after birth, and in the period from 7 weeks after birth to 12 weeks after birth, It is considered stable. Therefore, the subsequent measurement of prepulse suppression was performed 8 to 9 weeks after birth.

  Next, the female of B6 and the male of C3 were multiplied to obtain 1010 F2 individuals (497 males and 513 females). For these F2 individuals, prepulse suppression was measured, and the genotype of each F2 individual was determined by Dietrich WF, Miller J, Steen R, Merchant MA, Damron-Boles D et al. (1996) A comprehensive genetic map of the QTL analysis was performed by discriminating with a known microsatellite marker based on mouse genome. Nature 380: 149-152. The genotype was determined by PCR using a 3730xl DNA analyzer (Applied Biosystems) and fluorescently labeled primers. In the above QTL analysis, in addition to the result when the magnitude of the prepulse sound was changed, the magnitude (ASR) and latency (latency) of the startle reflection itself were also analyzed.

  In the QTL analysis, first, a CTL (composite interval mapping) method was used to perform a first-stage QTL analysis, and then chromosomes (chromosomes 1, 3, 7, 10, and For 13), a second-stage QTL analysis was performed.

  In the second-stage QTL analysis, data was divided into male mice and female mice using the MIM (Multiple Interval Mapping) method. The results for the female are shown in FIG. 4, and the results for the male are shown in FIG.

  As shown in FIG. 4, in the female, it can be seen that there is a peak in the chromosome 10, but only an ambiguous result was obtained for the position. On the other hand, as shown in FIG. 5, a sharp peak was obtained by analyzing males.

  From the 30 genes present in the peak, the present inventors proceeded with the analysis of Fabp7 based on a unique viewpoint. The Fabp7 gene had no difference in sequence between the C3 mouse and the B6 mouse in the coding region, and it was highly possible that the gene was not responsible for prepulse suppression. The present inventors proceeded with the analysis based on their own intuition. However, as described later, it was proved by a complementation test that Fabp7 is a gene responsible for prepulse inhibition (FIG. 10).

[Example 2: Analysis of Fabp7 expression]
For the Fabp7 gene, expression was measured at various brain sites and developmental stages. The results are shown in FIG. In the figure, CX is cerebral cortex, FC is frontal lobe, HP is hippocampus, CE is cerebellum, OB is olfactory brain, E16 is embryonic day 16, P0 is immediately after birth, P7 is postnatal day 7, and Adult (8W) is 8 weeks old, * indicates a statistically significant difference (P <0.05). As shown in FIG. 6, in the frontal lobe, the expression level of Fabp7 is higher in the B6 mouse than in the C3 mouse on the seventh day after birth, but at 8 weeks of age, the C3 mouse More.

  The frontal lobe is known to be involved in schizophrenia, and the difference in prepulse suppression between the B6 and C3 mice is also likely due to the difference in the expression level of Fabp7 on the seventh day of life. Is expensive.

  In addition, since the mouse is born in a state where the brain is not completed, from the viewpoint of the developmental stage of the brain, the seventh day after birth corresponds to the state in the womb again in humans.

  Therefore, the above facts support the inventors' idea that pre-pulse suppression after birth of the fetus can be improved by supplying unsaturated fatty acids to the fetus.

  FIG. 7 is a diagram showing a pre-cut section of the brain on embryonic day 16 (E16) and immediately after birth (P0) stained with an antibody for FABP7 protein. As shown in FIG. 7, a large amount of FABP7 protein is expressed on the 16th day of embryogenesis and immediately after birth, and is particularly found around the ventricle (where neurogenesis is thriving).

  FIG. 8 is a diagram showing the results of analysis of Fabp7 mRNA expression in the brain on embryonic day 15 (E15), immediately after birth (P0), and postnatal day 70 (P70) by Northern blot analysis. Gapdh indicates a control. As shown in FIG. 8, the expression of Fabp7 mRNA gradually decreases and is hardly seen in the living body.

  As described above, it is suggested that FABP7 protein is involved in neurogenesis. This is consistent with our view that FABP7 protein is particularly useful in the unfinished brain.

[Example 3: Analysis of Fabp7 knockout mouse]
Fabp7 knockout mice were prepared from B6 strain mice by well-known and conventional methods. FIG. 9 shows the results of measuring the prepulse inhibition (PPI) of the knockout mouse and comparing it with the wild type B6 strain mouse. As shown in FIG. 9, Fabp7 knockout mice had reduced prepulse inhibition.

  Next, a complementation test was performed to confirm that Fabp7 was indeed the responsible gene of the peak in the QTL analysis. Specifically, a wild type B6 strain mouse (denoted as Q / Q), a cross of a wild type B6 strain mouse and a C3 strain mouse (denoted as Q / q), wild type B6 A strain obtained by multiplying a mouse of a strain and a Fabp7 knockout mouse (denoted as Q /-) and a strain of breeding a mouse of the C3 strain and a Fabp7 knockout mouse (denoted as q /-) were prepared, and prepulse suppression ( PPI) was measured. At this time, if [PPI of (Q / Q)-(PPI of (Q /-))] is significantly different from [PPI of (Q / q)-(q /-)], Fabp7 has the above peak. Judged to be involved. FIG. 10 shows the result. As shown in FIG. 10, a significant difference was seen, demonstrating that Fabp7 was indeed involved in the peak.

  In addition, as shown in FIG. 11, the Fabp7 knockout mouse had a significant difference in latency as compared with the wild type.

  As a pathological hypothesis of schizophrenia, there is a “NMDA lowering hypothesis” that neurotransmission via the NMDA receptor is reduced. One reason for this is the fact that phencyclidine, which has NMDA receptor antagonistic action, causes schizophrenia symptoms, particularly by repeated ingestion, and the condition worsens when ingested by schizophrenic patients. Therefore, MK-801 having the same action as phencyclidine was repeatedly administered to Fabp7 knockout mice, and the results were observed. FIG. 12 shows the result. The vertical axis | shaft of FIG. 12 shows the amount of induced actions, and a horizontal axis shows the time after MK-801 administration. As shown in FIG. 12, as a result, the amount of induced behavior was enhanced as compared with the wild-type mouse. This indicates that Fabp7 knockout mice are as sensitive to NMDA receptor antagonists as human schizophrenia, and support the inventors' view that Fabp7 is involved in schizophrenia.

  In the C3 strain of mice, the expression of Fabp7 gene was decreased in the frontal lobe, which was in the pre-completion stage of the brain on the 7th day after birth, and we investigated how this led to a decrease in prepulse suppression in the adult stage.

  When the degree of neurogenesis was evaluated using Fabp7 knockout mice, it was found that neurogenesis in the brain was reduced by disruption of the Fabp7 gene. FIG. 13 is a diagram showing a comparison of each part of the brain between a wild type and a knockout mouse. A to C are photographs showing the state of the hippocampal dentate gyrus at 4 weeks of age. A shows the expression of GFAP (a marker of neural stem cells / early progenitor cells), and B shows PSA-NCAM (of late progenitor cells). Marker expression is shown. Both have reduced expression in knockout mice. C shows the expression of BrdU (5-bromo-2'-deoxyuridine, a marker for new cell), and D shows the number of cells expressing BrdU. As shown in CD, there is a decrease in neoplastic cells in knockout mice.

  From the above results, when the expression of Fabp7 gene is reduced in the developmental period of the brain, it leads to a decrease in proliferation of nerve cells and changes in the neural network after growth. It was suggested that a decrease occurred.

[Example 4: Analysis of Fabp7 in human]
FIG. 14 shows the expression of the Fabp7 gene in the postmortem brain of an American who developed schizophrenia. The three graphs represent the controls for Fabp7 in place of GAPD, ACTB, or PGK1, respectively. As shown in FIG. 14, Fabp7 expression was increased in the brains of adult schizophrenic patients, as did the C3 strain of mice. This suggests that a similar mechanism works in mice and humans.

  In addition, in order to examine whether the increase in Fabp7 expression is due to the drug taken, the psychotropic drug halolidate (therapeutic agent for schizophrenia: the main pharmacological action is the effect of dopamine, a neurotransmitter). The expression of the Fabp7 gene was examined by chronic administration of the receptor (inhibition of the receptor), but the drug did not increase the expression (FIG. 15). Therefore, the change in expression of the Fabp7 gene is considered to be due to a disease.

  Next, whether or not individual differences in the Fabp7 gene genome affect the onset of schizophrenia was examined by examining the SNP of the Fabp7 gene. As a result, it was found that the region of the Fabp7 gene containing SNPs with amino acid changes is associated with the onset of Japanese schizophrenia (FIG. 16).

  The upper diagram of FIG. 16 represents the genomic structure of the Fabp7 gene and the position of the SNP. The lower figure shows that Block2 consisting of SNP3, SNP4, SNP5, and SNP6 in the genomic region of Fabp7 gene is associated with schizophrenia. SNP3 is a SNP in which the 61st threonine is replaced with methionine, and is particularly relevant. FIG. 17 is a schematic diagram showing the crystal structure of Fabp7 protein. As shown in FIG. 17, the 61st threonine is near the site to which docosahexaenoic acid (DHA) binds, and if its amino acid changes, the affinity for DHA may change.

  As described above, in the case of Japanese schizophrenia, there is a possibility that the difference in the strength of binding between FABP7 protein and docosahexaenoic acid affects the disease susceptibility. From the above, the Fabp7 gene is considered to have an effect on the likelihood of schizophrenia due to changes in the expression level in the brain and SNPs on the genome.

  The present invention can be used in the fields of food and drug production and genetic diagnosis.

It is a figure explaining the measuring method of the prepulse suppression of a mouse | mouth. It is a figure explaining the measuring method of prepulse suppression in detail. It is a graph which compares the prepulse suppression of the mouse | mouth of B6 type | system | group, and the mouse | mouth of C3 type | system | group. It is a figure which shows the result of the QTL analysis about a female mouse | mouth. It is a figure which shows the result of the QTL analysis about a male mouse | mouth. It is a graph which shows the measurement result of expression in a various brain region and a developmental stage of Fabp7 gene. It is the photograph which shows what dye | stained the forehead slice of the brain with the antibody of FABP7 protein. It is a photograph which shows the expression of Fabp7 mRNA in a brain. It is a graph which compares a Fabp7 knockout mouse | mouth with the B6 strain | stump | stock mouse | mouth about prepulse suppression. It is a figure which shows the result of a complementarity test. It is a graph which compares a Fabp7 knockout mouse | mouth with a B6 strain | stump | stock mouse | mouth about latency. It is a graph which compares the Fabp7 knockout mouse | mouth with the mouse | mouth of B6 strain | stump | stock about the amount of induced behaviors after MK-801 administration. It is a figure which shows the comparison of each site | part of the brain of a wild type and a knockout mouse. It is a graph which shows the expression of Fabp7 gene in the postmortem brain of the American who developed schizophrenia. It is a graph which shows the result of administering a psychotropic drug to a mouse. It is a figure which shows SNP of Fabp7 gene in a Japanese patient with schizophrenia. It is a schematic diagram which shows the crystal structure of FABP7 protein.

Claims (18)

A composition for preventing the onset of mental illness,
Long-chain fatty acids, or fats and oils comprising at least one long-chain fatty acid as a constituent fatty acid,
A composition prepared so that brain tissue is supplied into the body at an immature stage.   2. The composition of claim 1, wherein the composition is prepared to be supplied via a matrix.   The psychiatric disorder is a psychiatric disorder selected from the group consisting of schizophrenia, bipolar affective disorder, obsessive compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, and Huntington's disease. 2. The composition according to 2.   The said long-chain fatty acid is unsaturated fatty acid, The composition as described in any one of Claims 1-3 characterized by the above-mentioned.   The composition according to claim 4, wherein the unsaturated fatty acid is a ω3 unsaturated fatty acid.   The composition according to claim 5, wherein the ω3 unsaturated fatty acid is docosahexaenoic acid. A composition for improving prepulse inhibition comprising:
Long-chain fatty acids, or fats and oils comprising at least one long-chain fatty acid as a constituent fatty acid,
A composition prepared so that brain tissue is supplied into the body at an immature stage.   8. The composition of claim 7, wherein the composition is prepared to be supplied via a matrix.   The composition according to claim 7 or 8, wherein the long-chain fatty acid is an unsaturated fatty acid.   The composition according to claim 9, wherein the unsaturated fatty acid is a ω3 unsaturated fatty acid.   The composition according to claim 10, wherein the ω3 unsaturated fatty acid is docosahexaenoic acid. Amplifying the Fabp7 gene using genomic DNA isolated from an individual as a template;
Producing a polypeptide encoded by the amplified Fabp7 gene;
Measuring the binding force between the polypeptide and a long chain fatty acid;
A method for evaluating the onset possibility of a mental illness comprising the step of evaluating the onset possibility of a mental illness of the individual or its progeny based on the measured binding force.   The psychiatric disorder is a psychiatric disorder selected from the group consisting of schizophrenia, bipolar affective disorder, obsessive compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, and Huntington's disease. The evaluation method described.   The evaluation method according to claim 12 or 13, wherein the long chain fatty acid is an unsaturated fatty acid.   The evaluation method according to claim 14, wherein the unsaturated fatty acid is a ω3 unsaturated fatty acid.   The evaluation method according to claim 15, wherein the ω3 unsaturated fatty acid is docosahexaenoic acid. Determining the base sequence of at least a part of the Fabp7 gene present on genomic DNA isolated from an individual;
And a step of evaluating the onset possibility of the mental illness of the individual or its progeny based on the determined base sequence. A composition for preventing the onset of mental illness,
Long-chain fatty acids, or fats and oils comprising at least one long-chain fatty acid as a constituent fatty acid,
Prepared so that brain tissue is supplied to the body in an immature stage with respect to an individual evaluated as having a high possibility of developing a mental illness by the evaluation method according to any one of claims 12 to 17. A composition characterized by comprising: