微电泳氢化可的松对大鼠三个脑区神经元放电的快速效应

THE RAPID EFFECT OF THE IONTOPHORETICALLY APPLIED CORTISOL ON UNIT ACTIVITY OF NEURONS IN THREE BRAIN AREAS IN RATS

本实验的目的是检验糖皮质激素(GC)对不同脑区神经元的快速作用是否有差别。在尿酯麻醉大鼠的大脑皮层(CX)、海马(HPC)及下丘脑室旁核(PVN)等三个脑区比较了微电泳给予氢化可的松(HC)对神经元放电的影响。CX 对 HC 有反应的神经元数(4/50)远低于 HPC(10/36)及 PVN 的数目(9/35)。三个脑区的反应均以抑制为主。HC 引起 CX 神经元放电变化(兴奋或抑制)的潜伏期及后作用时程分别为9.6±6.5s及74.8±66.5s,HPC 的分别为22.7±24.0及24.2±14.5s 和17.58±2148s;PVN 的分别为14.5±11.5s 及21.0±10.5s。这些结果表明,GC 的快速效应在有反应神经元的百分比及后作用时程的长短等方面表现了按脑区不同而异。

The present study was undertaken to analyze whether the glucocorticoid(GC)effect was region specific in the brain.Na-cortisol-succinate(HC)wasapplied iontophoretically to cerebral cortex(CX),hippocampus(HPC)and PVNrespectively and the effect on unit discharge rate in these three brain areas werecompred.In cerebral cortex,the percentage of responsive neurons was only 8%(4/50),which was significantly lower than those in HPC(10/36,27.8%)and PVN(9/35,25.7%).The difference in the occurrence is paralleled with the known-distribution of traditional GC cytosolic receptors in the brain.In all the threebrain areas studied the main response to GC was inhibitory and the latencies ofthe responses were 9.6±6.5,22.7±24.0,and 14.5±11.5 s and the durations ofthe after-effect were 74.8±66.5(n=4),24.2±14.5(n=6)and 21.0±10.5 s(n=9)respectively.The shortness of the latencies once again suggests that themechanism involved is non-genomic.It is interest to note that in some HPCneurons the after-effect lasted for 1758±2148 s(n=4).The results show that therapid effect of GC on neurons is different in the three brain areas studied in regard-ing to the occurrence of responsive neurons and the duration of the after-effects.