Differences in extracellular dopamine concentrations in the nucleus accumbens during response-dependent and response-independent cocaine administration in the rat
Differences in extracellular dopamine concentrations in the nucleus accumbens during response-dependent and response-independent cocaine administration in the rat
复制标题
DOI：
10.1007/s002130050365
复制
发表时间：
1997-09-01
影响因子：
3.4
通讯作者：
Dworkin, SI
中科院分区：
文献类型：
--
作者：
Hemby, SE;Co, C;Dworkin, SI
研究表明，伏隔核（NAcc）多巴胺神经传递参与可卡因的强化和直接作用。本研究采用同窝配对设计，进一步探讨NAcc细胞外多巴胺浓度（[DA]（e））与可卡因自我给药的关系。（南非; 0.33 mg/inf），而第二只大鼠同时接受与SA（YC）输注相结合的可卡因输注，在测试期间，使用体内微透析结合微孔HPLC程序评估NAcc [DA]（e）和可卡因浓度（[COC]）。在自我给药期间，SA组和YC组的[DA]（e）和[COG]显著升高;然而，在给药的第一个小时，SA组的[DA]（e）高于YC组，尽管[COC]没有显著差异。第二天，对先前允许自我给予可卡因的大鼠给予与前一天的输注模式相结合的反应非依赖性可卡因输注。[DA]（e）显著高于基线水平，但显著低于这些受试者自我施用可卡因时获得的浓度。[COG]在两天的会议期间没有显着不同。SA和YC组之间或第1天和第2天之间的基线[DA]（e）无显著差异。此外，探针植入后1天和2天的体外探针回收率无显著差异。这些结果表明，给予可卡因的背景显著改变了对同等脑浓度可卡因的神经化学反应。当可卡因输注的递送取决于大鼠的行为时，NAcc [DA]（e）显著增加，表明在可卡因强化的神经过程中的作用。
Studies indicate that nucleus accumbens (NAcc) dopamine neurotransmission is involved in the reinforcing and direct effects of cocaine. The present study was initiated to explore further the relationship of NAcc extracellular dopamine concentrations ([DA](e)) and cocaine self-administration using a yoked littermate design, Tn the first experiment, one rat from each litter was trained to self-administer cocaine IV (SA; 0.33 mg/inf) under a fixed ratio 2 schedule, while a second rat received simultaneous infusions of cocaine yoked to the infusions of the SA (YC), NAcc [DA](e) and cocaine concentrations ([COC]) were assessed during the test sessions using in vivo microdialysis combined with microbore HPLC procedures. [DA](e) and [COG] were significantly elevated in the SA and YC groups during the self-administration session; however, [DA](e) were greater in the SA group compared to the YC group in the first hour of the session, even though [COC] were not significantly different. On the following day, the rats previously allowed to self-administer cocaine were administered response-independent cocaine infusions yoked to the infusion pattern from the previous day. [DA](e) were significantly elevated above baseline levels during the session but were significantly less than concentrations obtained when cocaine was self-administered by these subjects. [COG] during the sessions were not significantly different between the two days. Baseline [DA](e) were not significantly different between the SA and YC groups or between Day 1 and Day 2. Furthermore, there was no significant difference in the in vitro probe recovery between one and two days following probe implantation. These results suggest that the context in which cocaine was administered significantly altered the neurochemical response to equivalent brain concentrations of cocaine. NAcc [DA](e) was significantly increased when the delivery of cocaine infusions was contingent on the behavior of the rat, indicative of a role in the neural processes underlying cocaine reinforcement.