糖原合酶激酶-3β抑制剂阻断伏隔核可卡因诱导的突触传递异常的研究

发布时间：2018-04-20 17:32

本文选题：可卡因 + 伏隔核　；参考：《苏州大学》2015年博士论文

【摘要】：可卡因是一类成瘾性物质,主要作用于单胺转运体,抑制突触间隙内多巴胺的再摄取,从而间接导致突触间隙内多巴胺含量的增加。近年来,糖原合成酶激酶-3β(Glycogen synthase kinase 3β,GSK3β)在可卡因中枢兴奋及成瘾中的作用受到广泛关注。大鼠给予可卡因后导致伏隔核(Nucleus accumbens,Nac)核(Core)中的GSK3β磷酸化降低,并且GSK3β抑制剂能够缓解可卡因诱发的神经兴奋作用以及成瘾,但是,其作用的突触传导机制尚不清晰。GSK3β、可卡因、多巴胺与突触传导之间的相互关系仍需进一步的实验研究。本研究利用动物行为学、脑片膜片钳和胞外电信号记录等技术手段,探索GSK3β在可卡因中枢兴奋及成瘾中的作用及机制。我们发现,在整体动物中非特异性的GSK3抑制剂氯化锂(100 mg/kg,i.p.)以及特异性的GSK3β抑制剂SB216763(2.5 mg/kg,i.p.)能够有效抑制可卡因(20 mg/kg,i.p.)引起的大鼠过度自发活动,而且可卡因抑制了伏隔核(Nac)核区中等棘突神经元(MSN)细胞放电,氯化锂及SB216763同样能够阻断可卡因的这一效应。在急性分离的脑片中,预先灌流SB216763(5μM)能够缓解可卡因(10μM)引起的伏隔核(Nac)核(Core)区AMPA受体以及NMDA受体介导的EPSC(兴奋性突触后电流)的减弱效应,而且该效应是通过激活多巴胺D1受体来实现的。进一步的研究发现,可卡因能够抑制MSN神经元突触前膜谷氨酸的释放,但对静息电位及膜电阻并无影响,GSK3β抑制剂SB216763也能够抑制可卡因在伏隔核的突触前功能。同时,可卡因能够激活D2受体,降低MSN细胞内在兴奋性(intrinsic),而GSK3β抑制剂不能影响可卡因的这一效应。连续五天给予SD大鼠可卡因(20 mg/kg i.p.),可使AMPA/NMDA比值明显增加,而GKS3β抑制剂SB216763可以明显缓解这一效应,这提示我们GSK3β抑制剂能够有效干扰可卡因引起的突触可塑性变化。以上结果表明,可卡因通过激活突触前D1受体,抑制Nac核区MSN神经元的谷氨酸传导,降低其放电频率,进而减少抑制性神经递质γ-氨基丁酸(GABA)的投递,导致其他脑区的广泛性兴奋,引起可卡因的神经兴奋作用,长期的可卡因作用导致突触重塑,诱发成瘾。GSK3β抑制剂SB216763可以消除多巴胺引起的伏隔核谷氨酸释放减少,从而阻断可卡因对Nac的抑制效应,最终抑制可卡因引起的动物过度自发活动。同时,SB216763能够阻断可卡因引起的突触可塑性变化,可能是其抑制可卡因成瘾的机制之一。
[Abstract]:Cocaine is a kind of addictive substance which acts mainly on monoamine transporter and inhibits the reuptake of dopamine in synaptic space which indirectly leads to the increase of dopamine content in synaptic space. In recent years, the role of glycogen synthase kinase 3 尾 -Glycogen synthase kinase 3 尾 -GSK3 尾 in cocaine central excitability and addiction has attracted wide attention. GSK3 尾 phosphorylation in nucleus accumbens nucleus nucleus nucleus was decreased after cocaine administration in rats, and GSK3 尾 inhibitor alleviated the neuroexcitatory effect and addiction induced by cocaine. However, the mechanism of synaptic conduction of cocaine was not clear. GSK3 尾, cocaine. The relationship between dopamine and synaptic conduction needs further experimental study. The purpose of this study was to explore the role and mechanism of GSK3 尾 in cocaine central excitation and addiction by means of animal behavior, brain patch clamp and extracellular electrical signal recording. We found that lithium chloride, a nonspecific GSK3 inhibitor in the whole animal, was 100mg / kg / kg i.p.) And specific GSK3 尾 inhibitor SB216763(2.5 mg / kg i.p. Effective inhibition of cocaine 20 mg / kg i.p.) Moreover, cocaine inhibited the discharges of median spinous neurons in the nucleus accumbens nucleus. Lithium chloride and SB216763 also blocked the effect of cocaine. In acutely isolated brain slices, preperfused SB216763(5 渭 M could attenuate the attenuated effects of AMPA receptors in the nucleus accumbens nucleus of the nucleus accumbens and the excitatory postsynaptic currents mediated by the NMDA receptors in the nucleus accumbens of the nucleus accumbens induced by 10 渭 M cocaine. And this effect is achieved by activating dopamine D 1 receptor. Further studies showed that cocaine could inhibit the release of glutamate from the presynaptic membrane of MSN neurons, but had no effect on the resting potential and membrane resistance. The GSK3 尾 inhibitor SB216763 could also inhibit the presynaptic function of cocaine in nucleus accumbens. At the same time, cocaine can activate D2 receptor and decrease the excitability of intrinsicine in MSN cells, but GSK3 尾 inhibitor can not affect this effect of cocaine. For five consecutive days, the AMPA/NMDA ratio of SD rats was significantly increased by 20 mg/kg i.p.. The GKS3 尾 inhibitor SB216763 could attenuate this effect, which suggested that GSK3 尾 inhibitor could effectively interfere with the synaptic plasticity induced by cocaine. These results suggest that cocaine inhibits glutamate conduction in MSN neurons in the Nac nuclear region by activating presynaptic D1 receptors, reduces its discharge frequency, and thus reduces the delivery of the inhibitory neurotransmitter GABA. It leads to extensive excitement in other brain regions, the neuroexcitatory effect of cocaine, long-term cocaine action leads to synaptic remodeling, and SB216763, an addictive. GSK3 尾 inhibitor, can eliminate the dopamine-induced decrease in glutamate release in nucleus accumbens. The inhibition effect of cocaine on Nac was blocked, and the excessive spontaneous activity induced by cocaine was finally inhibited. At the same time, SB216763 can block the change of synaptic plasticity induced by cocaine, which may be one of the mechanisms of inhibiting cocaine addiction.
【学位授予单位】：苏州大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R96

【相似文献】