Rada P V, Mark G P, Hoebel B G
Department of Psychology, Princeton University, NJ 08544-1010, USA.
Brain Res. 1998 Jan 26;782(1-2):228-34. doi: 10.1016/s0006-8993(97)01283-3.
It is known that lateral hypothalamic stimulation or self-stimulation can release dopamine in the nucleus accumbens (NAc). The present experiment illustrates that an aversively motivated behavior can also do this. Rats were prepared with microdialysis probes in the NAc and electrodes in the lateral hypothalamus (LH) or medial hypothalamus (MH). Automatic stimulation of the LH increased extracellular dopamine in the NAc 30% as reported earlier. The animals would perform both self-stimulation to turn the current on and stimulation-escape to turn it off, suggesting a combination of reward and aversion. Escape responding increased extracellular dopamine (DA) 100%, even though there was less total stimulation. Automatic stimulation of the MH did the opposite of the LH by decreasing accumbens dopamine (-20%), and the animals would only perform stimulation-escape, indicative of pure aversion. But again, extracellular DA in the NAc increased 100% during escape responding. Thus DA can be released during negative reinforcement when an animal's behavior is reinforced by escape from lateral or medial hypothalamic stimulation. This suggests that DA release was correlated with stimulation-escape behavior, rather than the aversiveness of automatic stimulation.
已知刺激下丘脑外侧或自我刺激可使伏隔核（NAc）释放多巴胺。本实验表明，一种出于厌恶动机的行为也能做到这一点。给大鼠在伏隔核植入微透析探针，并在下丘脑外侧（LH）或下丘脑内侧（MH）植入电极。如先前报道，自动刺激下丘脑外侧会使伏隔核细胞外多巴胺增加30%。动物会进行自我刺激以开启电流，也会进行逃避刺激以关闭电流，这表明存在奖励与厌恶的结合。逃避反应使细胞外多巴胺（DA）增加了100%，尽管总的刺激较少。自动刺激下丘脑内侧的效果与下丘脑外侧相反，会使伏隔核多巴胺减少（-20%），并且动物只会进行逃避刺激，这表明是纯粹的厌恶。但同样，在逃避反应过程中，伏隔核细胞外多巴胺增加了100%。因此，当动物通过逃避下丘脑外侧或内侧刺激得到强化时，多巴胺可在负强化过程中释放。这表明多巴胺的释放与逃避刺激行为相关，而非自动刺激的厌恶程度。
