猫初级视皮层BDNF表达年龄相关性差异研究

Study on Age- related Morphological Changes of BDNF Expression in the Primary Visual Cortex of Cat

通过揭示脑源性神经营养因子(BDNF)在青年猫与老年猫初级视皮层(Primary visual cortex)中表达情况,特别是探讨猫视皮层BDNF表达的年龄差异性及可能产生的突触可塑性方面的影响,揭示视觉衰退机制的影响因素及机理。本实验采用免疫组织化学ABC法标记猫初级视皮层各层BDNF免疫阳性细胞。免疫染色切片置于Olympus光学显微镜下观察采集图像,Image-Pro Express 6.0软件处理BDNF免疫阳性细胞计数及免疫阳性反应强度测量,所得相关数据借助SPSS 13.0统计软件分析处理。结果显示,BDNF在青年组及老年组猫视皮层各层中均有表达;与青年组相比,老年组猫初级视皮层各层中BDNF阳性细胞密度显著下降(P<0.01),其免疫阳性反应强度亦呈显著下降(P<0.01)。结果提示,猫初级视皮层中BDNF表达水平存在增龄性下降,提示脑源性神经营养因子活动减弱引起的突触可塑性的改变可能是引起视觉功能衰退的重要原因之一。

This study compared the expression of brain- derived neurotrophic factor（ BDNF） in the primary visual cortex between young adult and old cats,especially the age- related difference of BDNF expression in cat＇s visual cortex and the possible influence on synaptic plasticity,trying to probe into the influencing factors and neural mechanisms that mediate aging- related visual function declines. BDNF- IR cells in each cortical layer were labeled using immunohistochemical techniques. Staining sections were observed under Olympus optical microscope and photographed with a digital camera. The density of BDNF- IR cells and immunoreactive intensity were measured with Image- Pro Express 6. 0 software. BDNF proteins were widely expressed in all cortical layers of young adult and old cats. Compared with the young adult cats,the density of BDNF- IR cells in each cortical layer of old cats was significantly decreased（ p〈0. 01）. Furthermore,BDNF- IR intensity in the old group of cats,as indicated by the mean optical density,was significantly weaker than that in the young adult group（ p〈0.01）. Aging results in a significantly decreased expression of BDNF proteins. This indicates that changes of synaptic plasticity,which are caused by the decreased activity of BDNF,might be one of the important factors that cause a compromised inhibition in the central visual nucleus and a declined visual function in senescent individuals.