Study of neurotransmitters in the brain of SNAP25 mutant mouse.

25 kDa突触体相关蛋白(SNAP-25)是神经递质释放所必需的突触前蛋白。Snap-25还可能参与轴突的伸展和离子通道功能的调节。在此之前，我们证明了蛋白激酶C(PKC)通过在质膜附近招募分泌小泡来磷酸化SNAP-25的Ser187，并促进神经递质的释放。为了了解依赖于PKC的SNAP-25的磷酸化在脑功能中的生理作用，我们利用“敲门”技术产生了一个突变的小鼠，用ALA替换了Ser187。我们发现，纯合子突变的小鼠表现出各种异常行为，如强烈的趋思性、多动或冷冻样行为。在本研究中，我们首先检测了不同脑区、丘脑、下丘脑、杏仁核、皮质、海马体、小脑、脑干和纹状体的神经递质水平。测定的氨基酸有谷氨酸、甘氨酸、牛磺酸、精氨酸和γ-氨基丁酸。测定的单胺类有去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)、3-甲氧基-4-羟基苯甘醇(MHPG)、二羟基苯乙酸(DOPAC)、高香草酸(HVA)和5-羟基吲哚乙酸(5-HIAA)。我们发现杏仁核和海马区去甲肾上腺素水平显著降低。接下来，我们研究了杏仁核多巴胺和5-羟色胺对高钾胁迫和下丘脑束缚应激反应的差异。在短期高钾胁迫下，人鼠和野鼠的DA和5-羟色胺反应无显著差异，而在长期应激下，人鼠的DA反应明显弱于野鼠。我们还发现，束缚应激引起下丘脑中多巴胺和5-羟色胺的增加。与野生型相比，同系小鼠DA反应明显减弱。

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.