μ型阿片肽受体对癫痫敏感大鼠海马NR2B表达的影响

目的探讨μ型阿片肽受体（MORs）介导大鼠癫痫敏感性形成过程中海马NMDA2B受体（NR2B）表达变化。方法红藻氨酸（KA）皮下注射建立大鼠癫痫发作模型，采用脑立体定位及微渗透泵技术，海马内微量注射MORs激动剂PL017，或和拮抗剂β-FNA。7d后通过阈下剂量KA检测大鼠癫痫发作敏感性，应用原位杂交方法观察海马CA1区锥体细胞及齿状回颗粒细胞NR2B表达变化。结果PL017可显著增加大鼠海马CA1区锥体细胞和齿状回颗粒细胞NR2BmRNA（＋）神经元数及平均灰度。β-FNA则明显降低两个脑区的NR2BmRNA（＋）神经元数及平均灰度。结论MORs介导癫痫发作敏感性形成机制与NR2B表达上调有关。

Effects of mu.opioid receptors on hippocampal NR2B expression in rats with seizure susceptibility

Objective To investigate hippocampal NMDA receptor 2B （NR2B） expression in the rats with seizure susceptibility mediated by mu-opioid receptors （MORs）. Methods The SD rats were injected subcutaneously with a convulsive dose （ 10 mg/kg） of kainic acid （KA）. Normal saline （NS） , selective MORs antagonistβ--FNA or selective MORs agonist PL0tTwere infused constantly into the ventral hippocampi for 7 days by mini-osmotic pumps. Seven days later, all the rats were given subcutaneously with subcon- vulsant dose of KA （5 mg/kg） to determine the situation of seizure susceptibility. Then the expression of NR2B mRNA in CA~ py- ramidal neurons and dentate gyms granule cells （DGCs） of hippocampus was examined by in situ hybridization. Results The num- ber of NR2B mRNA positive neurons of CA1 and DGCs was increased in KA ＋ PL017 group comparing with normal group and KA ＋ NS group, and the density of NR2B mRNA neurons was enhanced in KA ＋ PL017 group comparing with normal group. The number and the density of NR2B mRNA positive neurons of CA1 and DGCs were decreased significantly in KA ＋ IS-FNA group comparing with normal, KA ＋ NS and KA ＋ PLol7 groups. Conclusion It is indicated that the seizure susceptibility of rats mediated by MORs was related to the up-regulation of hippocampal NR2B.