Brandão M L, Rees H, Witt S, Roberts M H
Department of Physiology, University of Wales College, Cardiff, U.K.
Brain Res. 1991 Mar 1;542(2):266-72. doi: 10.1016/0006-8993(91)91577-n.
Previous studies have shown that stimulation of the rat anterior pretectal nucleus (APtN) strongly depresses a spinal reflex to noxious heat without causing significant aversion or depression of other motor responses. It is not known if APtN stimulation can similarly reduce the aversiveness of electrical stimulation of the brain, nor is it known if APtN stimulation is itself rewarding or aversive. This study used a simple switch-off paradigm to examine the rewarding properties of APtN stimulation at different sites throughout the nucleus and also used the tail-flick test to determine if the stimulation produced antinociception. The effects of APtN stimulation on the behavioural and autonomic responses to electrical stimulation of the medial hypothalamus (MH) and the nucleus raphe magnus (NRM) were also examined. The results show that electrical stimulation of dorsal APtN was rewarding and also caused antinociception which lasted for 50 min. However, sites which gave the strongest reward were not necessarily those which gave the greatest antinociception, as these effects were not correlated. Electrical stimulation of ventral APtN induced only aversive effects. The aversive and autonomic effects of MH stimulation were significantly reduced by conditioning stimulation of dorsal APtN. However, the very similar escape and autonomic effects of NRM stimulation were unaffected by APtN stimulation. These results suggest that electrical stimulation of the dorsal parts of the APtN has positive rewarding properties as well as the well-known antinociceptive effects. The antiaversive effects of dorsal APtN stimulation may be due in part to the inhibition of central substrates of aversion as well as inhibition of sensory neurones.
先前的研究表明，刺激大鼠前顶盖前核（APtN）会强烈抑制对有害热刺激的脊髓反射，而不会引起明显的厌恶感或其他运动反应的抑制。目前尚不清楚刺激APtN是否能同样降低脑电刺激的厌恶感，也不清楚刺激APtN本身是具有奖赏性还是厌恶感。本研究采用简单的关闭范式来研究在整个核团不同部位刺激APtN的奖赏特性，同时也使用甩尾试验来确定刺激是否产生抗伤害感受作用。还研究了刺激APtN对内侧下丘脑（MH）和中缝大核（NRM）电刺激的行为和自主反应的影响。结果表明，背侧APtN的电刺激具有奖赏性，并且还会引起持续50分钟的抗伤害感受作用。然而，给予最强奖赏的部位不一定是给予最大抗伤害感受作用的部位，因为这些效应并不相关。腹侧APtN的电刺激仅诱导厌恶效应。背侧APtN的条件刺激显著降低了MH刺激的厌恶和自主效应。然而，NRM刺激非常相似的逃避和自主效应不受APtN刺激的影响。这些结果表明，APtN背侧部分的电刺激具有积极的奖赏特性以及众所周知的抗伤害感受作用。背侧APtN刺激的抗厌恶效应可能部分归因于对厌恶中枢底物的抑制以及对感觉神经元的抑制。
