Saulskaya N, Marsden C A
Department of Physiology and Pharmacology, University of Nottingham Medical School, Queen's Medical Centre, United Kingdom.
Brain Res. 1995 Nov 6;698(1-2):114-20. doi: 10.1016/0006-8993(95)00848-k.
In vivo microdialysis combined with HPLC-EC analysis was used to monitor extracellular glutamate and GABA in the medial nucleus accumbens of Lister hooded rats during acquisition and expression of a conditioned emotional response. Footshock paired with tone (acquisition of conditioned emotional response) causes a significant decrease in extracellular glutamate during the period of footshock followed by a marked, but short lasting increase when the rats return to their home cage. Expression of the conditioned emotional response on exposure to the contextual cue produces no change in glutamate during exposure to the contextual cue, but a short lasting increase after. Thus, both the conditioned emotional response and footshock are associated with marked, but short lasting, increases in extracellular glutamate in the nucleus accumbens which, in both cases, occurred after the aversive stimuli, i.e., when the rats are returned to their home cage. In contrast, when control rats are exposed to the testing box without giving footshock there is an increase in extracellular glutamate during the exposure period and this is accompanied by exploratory behaviour. The conditioned emotional response (contextual cue), footshock and exposure of the control rats to the test box all resulted in increased extracellular GABA during exposure to the test situation. These results suggest that increases in extracellular glutamate in the medial nucleus accumbens caused by the conditioned emotional response or footshock are probably associated with relief from, rather than response to danger.
采用体内微透析结合高效液相色谱-电化学检测分析法，监测利斯特氏有帽大鼠伏隔核内侧在条件性情绪反应的习得和表达过程中细胞外谷氨酸和γ-氨基丁酸（GABA）的水平。足部电击与音调配对（条件性情绪反应的习得）会导致在足部电击期间细胞外谷氨酸显著减少，随后当大鼠回到其饲养笼时会出现明显但持续时间较短的增加。暴露于情境线索时条件性情绪反应的表达在暴露于情境线索期间谷氨酸水平无变化，但之后会有短暂的增加。因此，条件性情绪反应和足部电击均与伏隔核中细胞外谷氨酸明显但持续时间较短的增加有关，在这两种情况下，这种增加都发生在厌恶刺激之后，即当大鼠回到其饲养笼时。相比之下，当对照大鼠暴露于测试箱而不给予足部电击时，在暴露期间细胞外谷氨酸会增加，并且这伴随着探索行为。条件性情绪反应（情境线索）、足部电击以及对照大鼠暴露于测试箱均导致在暴露于测试情境期间细胞外GABA增加。这些结果表明，由条件性情绪反应或足部电击引起的伏隔核内侧细胞外谷氨酸增加可能与从危险中解脱而非对危险的反应有关。
