| Co-Investigator(Kenkyū-buntansha) |
MIYAOKA Hitoshi Kitasato University, School of Medicine, Department of Psychiatry, Professor, 医学部, 教授 (40209862)
TAKAHASHI Masami Kitasato University, School of Medicine, Department of Biochemistry, Professor, 医学部, 教授 (10318826)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic protein essential for neurotransmitter release. SNAP-25 may also be involved in neurite extension and the regulation of ion channel function. Previously, we demonstrated that protein kinase C (PKC) phosphorylated Ser187 of SNAP-25 and enhanced neurotransmitter release by recruiting secretory vesicles near to the plasma membrane. In order to know the physiological roles of PKC-dependent phosphorylation of SNAP-25 in brain function, we generated a mutant mouse having a substitution of Ser187 with Ala using "knock in" technology. We found that the homozygous mutant mice showed various abnormal behavior such as strong thigmotaxis, hyperlocomotion or freezing-like behavior. In the present study, firstly, we examined levels of neurotransmitters in homogenized samples of various brain regions, thalamus, hypothalamus, amygdala, cortex, hippocampus, cerebellum, brain stem and striatum. The amino acids measured in this study were glutamate, glycine, taurine, arginine and gamma aminobutyric acid (GABA). The monoamines measured were norepinephrine (NE), dopamine (DA), serotonin (5-HT), 3-methoxy-4-hydroxyphenylglycol (MHPG), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA). We found that the significant decrease of levels of NE in the amygdala and hippocampus. Next, we investigated the differences of responses of DA and 5-HT to high-potassium stress in the amygdale and restraint stress in the hypothalamus. Under short-time high-potassium stress, there were no significant differences in DA or 5-HT responses between homo and wild mouse, however, under the long-term stress, the responses of DA in homo mouse were significantly weak in comparison with those in wild mouse. We also found that restraint stress induced increases of dopamine and 5-HT in the hypothalamus. DA response was significantly weak in homo mouse in comparison with wild type.
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