不同阿片受体激动剂对海马培养神经元微小兴奋性突触后电流的影响

目的：探讨不同阿片受体激动剂对海马培养神经元微小兴奋性突触后电流（mEPSCs）的影响。方法：原代培养新生sD大鼠海马神经元18d，荧光倒置显微镜下选择健康神经元入组，分别在培养液中加入阿片受体激动剂吗啡（浓度为10μmol·L-1[D—pen2，D—pen5]一enkephalin（DPDPE）和埃托啡（浓度均为1μmol·L-1）处理3d，对照组不加药。全细胞模式记录mEPSCs，用软件MiniAnalysis6．0（Synaptosoft，Inc）对mEPSCs频率及幅度进行分析。结果：吗啡显著降低了海马神经元mEPSCs的频率和幅度，与对照组相比，频率和幅度分别下降了38．5％和38．0％（均P〈0．01）；埃托啡对mEPSCs的幅度无影响（P〉0．05），但频率增加了26．O％（P〈0．05）；DPDPE对mEPSCs的频率及幅度均无影响（P〉0．05）。结论：不同的阿片受体激动剂由于其引起受体内化的能力不同，对神经元兴奋性突触传递有不同的突触后作用。

Effects of Different Opioid Receptors Agonist on Miniature Excitatory Postsynaptic Current in Cultured Hippocampal Neurons

Aim： To investigate the effects of different opioid receptors agonist on miniature excitatory postsynaptic currents in cultured hippocampal neurons. Methods： Hippocampal neurons were prepared from rats with postnatal 1 day and incubated for 18 days. The neurons were randomly divided into four groups （each group n=10）. One group was taken as control and other groups were treated for 3 days by opioid receptors agonists morphine dose： 10μmol·L-1, [D-pen2, D-pen5]-enkephalin （DPDPE） and etorphine （both dose： 1μmol·L-1）, respectively. The miniature excitatory postsynaptic currents （mEPSCs） were recorded and analyzed with MiniAnalysis 6.0（Synaptosoft, Inc）. Results： Chronic treatment with morphine significantly decreased the frequency of mEPSCs by 38.5% [from （4.57 ± 0.20）Hz to （2.81 ± 0.26）Hz, P〈0.01], and also significantly decreased the amplitude of mEPSCs by 38% [from （11.36 ± 0.36） pA to （7.05 ± 0.25）pA, P〈0.01]. In contrast, etorphine increased the frequency of mEPSCs by 26%[from （2.81 ± 0.26）Hz to （5.81 ± 0.29）Hz, P〈0.05] and had no significant effect on the amplitude of mEPSCs（P〉0.05）. DPDPE had no significant effect on both frequency and amplitude of mEPSCs （P〉0.05）. Conclusion： Different opioid receptors agonists have differential effects on excitatory synaptic transmission depending on their abilities to internalize the opioid receptors.