皮质酮对大鼠海马颗粒细胞层长时程增强效应的抑制作用

通过胞外记录大鼠海马颗粒细胞层诱发电位观察了皮质酮对麻醉大鼠海马神经突触可塑性的影响. 结果显示，皮质酮(1, 4 和10 mg·kg^-1, ip)有使单刺激大鼠海马颗粒细胞层基础群峰电位(PS)幅度升高的趋势，但同对照相比无显著性差异. 给予大鼠穿行通路以串刺激(60 Hz, 30次)可使海马颗粒细胞层PS幅度持续增高，增幅达70%-80%，说明在海马诱生长时程增强效应(LTP). 预先1 h给予大鼠皮质酮(1, 4和10 mg·kg^-1, ip）可剂量依赖地降低串刺激诱导的PS幅度的升高，说明皮质酮可抑制海马颗粒细胞层LTP的诱生. 结果提示，皮质酮可损伤大鼠海马神经突触可塑性.

Inhibitory effect of corticosterone on the formation of long-term potentiation in rat hippocampal dentate gyrus

The effect of corticosterone (Cort, 1, 4 and 10 mg·kg^-1, ip) on the hippocampal synaptic plasticity was observed by recording evoked potentials extracellularly induced by tetanic stimulation in rat hippocampal dentate gyrus. The experimental results showed that application of Cort tended to increase the basal amplitudes of population spikes (PS) induced by single stimulation, however, compared with that in control group, the differences were not statistically significant. After delivery of tetanic stimulation (60 Hz, 30 pulses) to perforant pathway, long-term potentiation (LTP) was induced in control group with PS amplitudes elevated persistently. Treatment with Cort 1 h before tetanus dose-dependently decreased the amplitudes of PS induced by the tetanic stimulation, demonstrating that Cort inhibited the formation of LTP in rat hippocampal dentate gyrus. The present results suggest that Cort decreases the synaptic plasticity of hippocampus.