大鼠室旁核大细胞电生理学特征的衰老性变化——逆向鉴定指标的改变

Aging changes of electophysiological characters of magnocellular paraventricular neurons of hypothalamus in rats:Changes of indexes for antidromic identification

目的 研究下丘脑室旁核 (PVT)大细胞逆向动作电位 (AP) 3指标的增龄性变化 ,为中枢神经系统的衰老性变化提供电生理学依据。方法 应用神经垂体逆向电刺激 ,于 PVN内进行玻璃微电极细胞外记录逆向 AP的方法 ,观察青、中、老 3组大鼠逆向 AP的阈值、潜伏期及跟随率的变化。结果 在中年及老年组大鼠上诱发逆向 AP的阈值高于青年组大鼠 (P<0 .0 5) ;老年大鼠逆向 AP阈值<0 .5 m A的神经元比例少于青年组大鼠 (P<0 .0 5) ;老年大鼠逆向 AP潜伏期较青年鼠延长 (P<0 .0 1 ) ;老年大鼠与青年大鼠逆向 AP对高频刺激的跟随能力存在差别。结论 老年大鼠 PVN大细胞兴奋性降低 ,纤维传导速度减慢 ,兴奋后不应期延长 。

Objective To investigate the aging changes of three indexes for antidromically induced action potential of magnocellular neurons of paraventricular nucleus(PVN) of hypothalamus,and thus provide electrophysiological evidence for aging changes of central nervous system.Methods By antidromic stimulation of neurohypophyseal and microelectrode extracellular recording of the antidromically induced action potentials(APs) in PVN,the threshold,latency and following frequency of antidromic APs of three groups of young,adult and old rats were observed.Results The threshold for inducing antidromic APs in old rats(0 59±0 24 mA) was higher than that in young rats(0 51±0 28 mA);the latency of antidromic Aps in old rats was longer(14 4±3 0 ms) than that in young rats(11 8±2 5) ms and adult rats(11 7±1 5) ms.In addition,the upper limit of following frequency of antidromic APs in old rats was lower.Conclusions The excitablity and conduct velocity of magnocellular paraventricular neurons and fibers decreased and the refractory period after each excitation prolonged,indicating there is functional degeneration of some neurons in some parts of central nervous system.