阻断杏仁核扩展区域内的GABA(A)受体可减弱酒精偏好(P)大鼠腹侧被盖区中D(2)对酒精动机行为的调节作用。

Blockade of GABA(A) receptors within the extended amygdala attenuates D(2) regulation of alcohol-motivated behaviors in the ventral tegmental area of alcohol-preferring (P) rats.

作者信息

Eiler William J A, June Harry L

机构信息

Psychobiology of Addictions Program, Department of Psychology, Indiana University-Purdue University, Indianapolis, IN 46202, USA.

出版信息

Neuropharmacology. 2007 Jun;52(8):1570-9. doi: 10.1016/j.neuropharm.2007.03.001. Epub 2007 Mar 12.

Abstract

The dopamine (DA) mesolimbic pathway, which originates from DA cell bodies within the ventral tegmental area (VTA), has been shown by various studies to play a role in the mediation of various drugs of abuse including alcohol (EtOH). It has been suggested that the VTA's control of EtOH reward is mediated in part by the D2 receptors within the VTA. These receptors may be under the regulation of reciprocal GABAergic inputs from forebrain components of the mesolimbic path such as the nucleus accumbens (NAcc), a classic EtOH reward substrate, and the bed nucleus of the stria terminalis, a substrate recently implicated in EtOH reinforcement, forming a self-regulating feedback loop. To test this hypothesis, D2 regulation of EtOH self-administration (SA) was evaluated by the microinfusion of the D2 antagonist eticlopride into the VTA of P rats, which produced profound reductions in EtOH SA in the highest (20.0 and 40.0microg) doses tested in both BST/VTA and NAcc/VTA implanted P rats. To determine the role of GABA in the mediation of EtOH SA, a 32.0ng dose the non-selective GABA antagonist SR 95531 was microinfused into the BST producing no effect on responding for EtOH and into the NAcc which lead to a reduction in EtOH responding. Finally, the hypothesis that GABA innervation of the VTA from the mesolimbic forebrain may influence EtOH SA was examined by the simultaneous infusion of eticlopride (40.0microg) into the VTA and SR 95531 (32.0ng) into either the BST or NAcc. This combination infusion completely attenuated the reduction in EtOH SA observed with the 40.0microg dose of eticlopride alone in both groups of animals. These results suggest that while the D2 receptors within the VTA regulate EtOH-motivated behaviors, this is modulated by GABAergic input from the mesolimbic forebrain, specifically from the BST and NAcc.

摘要

多巴胺(DA)中脑边缘通路起源于腹侧被盖区(VTA)内的DA细胞体,各种研究表明,该通路在介导包括酒精(EtOH)在内的各种滥用药物中发挥作用。有人提出,VTA对EtOH奖赏的控制部分是由VTA内的D2受体介导的。这些受体可能受中脑边缘通路前脑成分(如伏隔核(NAcc),一种经典的EtOH奖赏底物,以及终纹床核,一种最近与EtOH强化有关的底物)的相互GABA能输入的调节,形成一个自我调节的反馈回路。为了验证这一假设,通过将D2拮抗剂依替必利微量注入P大鼠的VTA,评估D2对EtOH自我给药(SA)的调节作用,在植入BST/VTA和NAcc/VTA的P大鼠中,最高测试剂量(20.0和40.0μg)的依替必利使EtOH SA显著降低。为了确定GABA在介导EtOH SA中的作用,将32.0ng剂量的非选择性GABA拮抗剂SR 95531微量注入BST,对EtOH反应无影响,注入NAcc则导致EtOH反应减少。最后,通过同时向VTA注入依替必利(40.0μg)和向BST或NAcc注入SR 95531(32.0ng),检验中脑边缘前脑对VTA的GABA神经支配可能影响EtOH SA的假设。在两组动物中,这种联合注入完全减弱了单独使用40.0μg剂量依替必利时观察到的EtOH SA降低。这些结果表明,虽然VTA内的D2受体调节EtOH驱动的行为,但这受到中脑边缘前脑,特别是BST和NAcc的GABA能输入的调节。

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