老化大鼠髓鞘蛋白脂蛋白表达变化及意义

Change and significance of myelin proteolipid protein expression in aged rats

目的观察老化大鼠髓鞘蛋白PLP的改变、髓鞘结构、中枢传导功能变化及其关系。方法采用免疫组化方法检测大鼠老化时髓鞘蛋白PLP表达变化,透射电镜观察脑白质区域的超微结构变化,电生理方法记录中枢神经传导功能。结果PLP免疫组化:2组于纹状体、胼胝体、前联合、皮层下区均可见阳性染色。但老年组大鼠各部位PLP表达量明显减少,其积分光密度值明显增大(P<0.01)。白质区超微结构变化:老年大鼠轴突直径增加,轴突内含有巨大线粒体,轴突周围间隙扩大。髓鞘致密层分离,部分板层结构排列紊乱、破坏。中枢传导功能:2组间存在显著差别,老年大鼠中枢传导潜伏时较青年组显著延长(P<0.01)。结论髓鞘蛋白PLP表达减少,与髓鞘形态结构改变有关,髓鞘及轴突超微结构存在明显变化,是白质功能减退的重要原因,这种变化可能与大鼠老化时中枢神经传导功能降低有关。

Objective To investigate change of myelin proteolipid protein （PLP） expression, myelin structures, central conductive function and the relationship among them in aged rats. Methods Eighteen rats aging 18 -24 months and 18 at 6 -7 months were subjected. Immunohistochemistry was applied to detect the expressive changes of PLP. LEICA QWIN image analytical system was used to show integrated optical density （IOD） of PLP immunostaining. Transmission electron microscopy （TEM） was used to observe the ultrastructural changes of white matter in rats, such as myelin sheath and axon. The conductive latency of perforant pathway was recorded by electrophysiological methods to evaluate central conductive function of forebrain regions in rats. Results Immunohistochemistry showed PLP was positive expressed in the striatum, callosum, anterior commissure, subcortex regions in 2 groups. But the PLP expression was significantly decreased in aged group than in young group （P 〈 0. 01 ）. There were obvious differences in the ultrastructure of white matter. Aged rats had enlarged axons with megamitochondria in them and increased gaps among axon and myelin, separated compact layer, even confused, destructed in myelin sheath. The central conductive latency was increased significantly in aged group than young group （ P 〈 0. 01 ）. Conclusion Aged rats have decreased PLP expression, which might be relevant to the morphological and structural changes of myelin sheath, and have certain relation with the decline of conductive function during brain aging.