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目的比较不同年龄组大鼠初级视皮层中脑源性神经营养因子(BDNF)及抑制性神经递质γ-氨基丁酸(GABA)表达的年龄相关性变化,为探讨老年性视觉功能衰退的细胞分子机制提供线索。方法 Nissl染色显示视皮层分层并用于神经元计数;免疫组织化学法标记大鼠视皮层中BDNF及GABA免疫阳性神经元。光镜下观察并用Image-Pro Express 6.0分析软件进行细胞密度统计和免疫反应吸光度值测量。结果青年、中年及老年组(每组n=6)大鼠初级视皮层各层的神经元平均密度差异不显著;但与青年组大鼠相比,中年组及老年组大鼠初级视皮层各层中BDNF及GABA免疫阳性神经元密度显著下降,BDNF及GABA免疫反应强度明显减弱;与中年组大鼠相比,老年组大鼠视皮层各层中BDNF及GABA免疫阳性神经元密度及其反应强度亦明显降低。在衰老过程中,大鼠初级视皮层各层内GABA表达的减少与BDNF表达的降低具有高度的相关性。结论大鼠初级视皮层中BDNF和GABA的表达随着衰老出现进行性下降,衰老过程中BDNF分泌的减少可能引起脑内抑制性神经递质GABA表达下调,这可能是介导老年性视觉功能衰退的重要途径之一。
Objective To compare the age-related changes in the expression of brain-derived neurotrophic factor (BDNF) and inhibitory neurotransmitter γ-aminobutyric acid (GABA) in primary visual cortex of different age groups in rats. Molecular mechanisms provide clues. Methods Nissl staining showed that the visual cortex was stratified and used for counting neurons. Immunohistochemical staining of BDNF and GABA immunoreactive neurons in the visual cortex of rats. Light microscope observation and Image-Pro Express 6.0 analysis software for cell density statistics and immunoreactivity absorbance measurements. Results There was no significant difference in the average density of neurons in the primary visual cortex of young, middle-aged and elderly patients (n = 6 each group). However, compared with the young rats, the primary visual acuity The density of BDNF and GABA immunoreactive neurons in the cortical layers decreased significantly and the intensity of BDNF and GABA immunoreactivity decreased significantly. Compared with the middle-aged rats, the density of BDNF and GABA immunoreactive neurons And its reaction intensity is also significantly reduced. During aging, the decrease of GABA expression in each layer of rat primary visual cortex is highly correlated with the decrease of BDNF expression. Conclusions The expression of BDNF and GABA in the primary visual cortex of rats decreased progressively with aging. The decrease of BDNF secretion during aging may result in the down-regulation of GABA expression in the brain, which may be mediated by the deterioration of senile visual function One of the important ways.