海洛因使大鼠背侧海马功能和Glu/GABA递质系统紊乱

Heroin causes disorders of the function of dorsal hippocampus neurons and of the Glu/GABA neurotransmitters in the hippocampus of rats

目的探讨海洛因依赖对大鼠背侧海马神经元功能以及海马谷氨酸(Glu)和γ-氨基丁酸(GABA)递质系统的影响。方法按剂量逐日递增原则,1日2次,连续9 d皮下注射海洛因建立其依赖SD大鼠模型。采用玻璃微电极细胞外记录大鼠海马神经元自发放电,比较放电形式和频率的变化。并用氨基酸自动分析仪测定大鼠海马Glu和GABA含量。结果海洛因依赖组大鼠背侧海马神经元放电以中频(51.02%)、单个不匀(61.22%)为主,对照组则以低频(58.70%)为主,形式分布均一(P<0.05);海洛因对腹侧海马神经元放电无影响(P>0.05);依赖大鼠海马Glu含量下降,GABA含量增加(P>0.05),Glu/GABA比值低于对照组(P<0.05)。结论海洛因更易损伤大鼠背侧海马神经元功能;Glu/GABA递质系统的紊乱可能是海洛因损害大鼠学习记忆能力的机制之一。

Aim To study the impact of heroin on the function of the dorsal hippocampus neurons, and determine the content of glutamate （Glu） and gamma-aminobutyric acid （GABA） and their content ratio in the hippocampus of rats. Methods Heroin was injected subcutaneously twice a day for 9 days according to the principle of daily increasing dose in the heroin-dependent Sprague-Dawley rats. The unit discharges of the hippocampus neurons were observed in rats by the extracellular single-unit recording with glass microelectrodes. Besides,the content of glutamate and gamma-aminobutyric acid in the hippocampus of other rats was measured with the amino-acid automatic analysis apparatus. Results The spontaneous discharges of the dorsal hippocampus in the dependent rats were primarily middle frequency （ 1 ～ 10 Hz,51.02% ） and single,irregular discharge form （ 61.22% ） , whereas low frequency （ 〈 1Hz, 58.70%） and equal ratio of three discharge forms was found in the control group （P 〈 0.05）. The discharge of ventral hippocampus neurons was unaffected by heroin （P 〉 0. 05 ）. There was a decreasing trend in the content of glutamate and an increasing trend in that of gamma-aminobutyric acid in the hippocampus although there was no significant difference between two groups （P 〉 0. 05 ） , the content ratio of glutamate to gamma-aminobutyric acid in the hippoeampus of the dependent rats was lower than that in the control group （ P 〈 0.05 ）. Conclusions The dorsal hippocampus of rats is highly vulnerable to damage from heroin. The disorder of the Glu/GABA neurotransmitters in the hippocampus caused by heroin may be one of the mechanisms impairing the learning and memory of rats.