论文部分内容阅读
γ-氨基丁酸(GABA)是成年哺乳动物脑内主要的抑制性神经递质,但电生理的研究表明,GABA在成熟皮质神经元的树突部位可以产生兴奋性作用,但该现象的形态学基础,目前尚不清楚。GABA产生兴奋性作用的关键主要依赖于神经元胞内的氯离子浓度,其中Na+-K+-Cl-共转运体1(NKCC1)促进细胞内Cl-堆积,而K+-Cl-共转运体2(KCC2)则外排胞内的Cl-,降低胞内的Cl-浓度。本研究应用免疫荧光组织化学双重标记结合荧光强度分析,检测NKCC1和KCC2在成年大鼠脑皮质和培养的大鼠脑皮质神经元树突和胞体的表达和分布情况。结果显示:成年大鼠皮质神经元的胞浆和细胞膜均有NKCC1的表达,而KCC2主要表达在神经元胞体和树突膜上,其中NKCC1在神经元树突上的表达水平比胞体高,而KCC2的表达水平在树突和胞体膜上没有明显差异。皮质神经元经培养20d后,NKCC1和KCC2在树突和胞体的表达模式与在体的分布相类似。本研究结果提示,NKCC1在大鼠皮质神经元树突的表达较多,可能是GABA兴奋神经元树突的原因。
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the adult mammalian brain, but electrophysiological studies have shown that GABA can exert an excitatory effect on the dendritic site of mature cortical neurons, but the morphology of this phenomenon The basis for learning is not yet clear. The key to the excitatory effect of GABA is mainly dependent on the chloride ion concentration in neurons, in which Na + -K + -Cl- co-transporter 1 (NKCC1) promotes intracellular Cl- accumulation, whereas K + -Cl- co-transporter 2 ( KCC2) is outside the exocytosis of Cl-, reduce intracellular Cl- concentration. In this study, we used immunofluorescence histochemistry double labeling combined with fluorescence intensity analysis to detect the expression and distribution of NKCC1 and KCC2 in dendrites and somatic cells of adult rat cerebral cortex and cultured cortical neurons. The results showed that: the expression of NKCC1 in the cytoplasm and membrane of adult rat cortical neurons, and KCC2 mainly in the neuronal somatic cell and dendritic membrane, NKCC1 neurons dendrites in the expression level higher than the cell body, and KCC2 expression levels in dendrites and somatic membranes did not differ significantly. After cultured for 20 days, the expression patterns of NKCC1 and KCC2 in dendrites and soma were similar to those in vivo. Our results suggest that NKCC1 is expressed more in dendrites of rat cortical neurons and may be responsible for dendrites of GABA-stimulated neurons.