海洛因戒断大鼠位置偏爱及海马神经元膜电性质的变化

目的 研究海洛因戒断期大鼠的位置偏爱性和海马CA1区神经元电生理特性,并探讨行为变化与神经元膜电性质变化之间的关系。方法 制作海洛因慢性给药戒断大鼠模型,对大鼠Y型迷宫位置偏爱行为及其海马CA1区神经元膜电特性,以及电镜下海马皮质突触结构的变化进行观察,并与对照组比较。结果 海洛因慢性给药戒断期,大鼠Y型迷宫位置偏爱显著增强(P<0.01),其海马CA1区神经元静息膜电性质,与对照组相比无显著差异(P>0.05),但动作电位(AP)半幅时程和10％-90％衰减时间缩短(P<0.01);兴奋性突触后电位(EPSP)幅值和曲线下面积增大(P<0.01)。电镜下见戒断组动物海马皮质神经突触间隙较对照组变窄,前膜和后膜内电子致密物聚集,密度增高。结论 海洛因慢性给药戒断模型,可引起大鼠明显的位置偏爱,且在不改变静息膜电特性的前提下,海马CA1区神经元AP和EPSP特性及突触结构产生了相应的改变。

Observation of place -conditioned preference in Y maze and electrical activities recorded in hippocampus pyramidal neurons during heroin withdrawal following chronic administration in rats

Objective To investigate Y maze place - conditioned preference and electrical activities of hippocampus CAl pyramidal neurons in rats with symptoms due to heroin withdrawal in order to analyze the relation between the altered behavior and the electrical property. Methods The model of fast heroin withdrawal following chronic administration was made in rats. The behavioral changes of place - conditioned preference by Y maze test, the electrophysiological parameters of hippocampus CAl neurons and place preference , and synaptic structure in hippocampus cortex by electron microscope were observed or recorded in rats with heroin withdrawal symptoms. The results were compared with those of control groups. Results Compared with control groups, place - conditioned preference in rats treated with heroin in Y maze was significantly reinforced (P <0. 01) . The resting membrane potential was not significantly different (P>0. 05) in hippocampus CAl , However, half amplitude duration of action potentials ( APs ) and 10%-90% de-caytime were shortened (P<0. 01) , The amplitude and the curve area of excitatory postsynaptic potentials (EPSPs) in CAl pyramidal neurons were reinforced (P <0. 01) in heroin withdrawal group. As detected by electron microscopy, the synaptic gap in hippocampus cortex of the withdrawal rat was narrowed, and the electronic dense matters accumulated and the density between the pre - and post - synaptic membrane increased as compared with those of the controls. Conclusion Chronic heroin withdrawal could notably induce place - conditioned preference in rat as tested by Y maze and significant changes of AP and EPSP properties without altering the resting membrane potential properties of hippocampus CAl neurons.