皮质酮对大鼠海马CA1区长时程抑制的影响

The effects of corticosterone on long-term depression in the hippocampal CA1 neurons of rats

目的观察皮质酮对大鼠海马CA1区锥体神经元产生的长时程抑制(LTD)的影响。方法断头法分离Wistar大鼠海马半脑,切片机切出400μm厚度的海马脑片。对照组不加任何药品,皮质酮组、D-APV组和D-APV+皮质酮组的脑片分别以10μmol/L皮质酮、50μmol/LD-APV和50μmol/LD-APV+10μmol/L皮质酮预孵60min。记录基础兴奋性突触后电流(EPSC)10min,然后给予低频刺激(LFS),记录LTD的表达情况。结果对照组给予LFS后,产生LTD,LFS后EPSC值为基础值的58.2%(P<0.05);皮质酮组给予LFS后EPSC值为基础值的45.4%(P<0.05),明显低于对照组(P<0.05);给予NMDA受体特异性拮抗剂D-APV后,D-APV组和D-APV+皮质酮组大鼠海马CA1区LFS不能诱发LTD。结论该实验条件诱发的LTD是NMDA受体依赖型的,10μmol/L皮质酮使大鼠海马CA1区锥体神经元LTD表达增强。

Objective. To investigate the effects of corticosterone on long-term depression （LTD） in the hippocampal CA1 pyramidal neurons of rats. Methods Wistar rats were killed by cervical dislocation and hippocampal slices （400 μm） were prepared. The slices were divided into four groups. After slices were incubated with 10 μmol/L corticosterone, 50 μmol/L D-APV or 50 μmol/L D-APV＋10μmol/L corticosterone in corticosterone group, D-APV group or D-APV＋ corticosterone group individuaily for 60 min. No drugs were applied in control group. The Schaffer collateral-commissural pathway was stimulated with low frequency stimulation（LFS）. Excitatory postsynaptic currents（EPSCs） were recorded by whole-cell patch-clamp technique. The holding potential was -50 mV during LFS. Results LTD could not be induced in D-APV group and D-APV＋corticosterone group. In control group, LTD was induced and EPSCs were 58. 2% of the baseline after LFS. LTD was also induced in corticosterone group, but EPSCs were 45.4% of the baseline after LFS,which was significantly lower than that in control group. Conclusion D-APV inhibits the inducement of LTD in this experiment. 10 μmol/L corticosterone enhances the development of LTD in the hippocampal CA1 pyramidal neurons of rats.