Hernandez L L, Powell D A, Gibbs C M
Dorn Veteran's Hospital, Columbia, SC 29201.
Behav Brain Res. 1990 Dec 7;41(1):71-9. doi: 10.1016/0166-4328(90)90055-j.
Rabbits were treated intravenously with either naloxone-HCl (0.5 mg/kg) or saline vehicle prior to aversive pavlovian conditioning and extinction training; heart rate conditioned responses and concomitant multiple-unit activity in the amygdaloid central nucleus were compared. Multiple-unit activity evoked by the conditioned stimulus increased during conditioning and decreased during extinction in saline-treated rabbits; naloxone treatment attenuated evoked neuronal activity but enhanced bradycardiac conditioned responses. Correlational analysis showed that, in 3 of 8 animals in the saline-treated group, larger increases in multiple-unit activity corresponded to smaller bradycardiac responses. Naloxone treatment did not alter the frequency or magnitude of this relationship, but it did augment the training-induced decrements in evoked neuronal activity at placements that were correlated with bradycardiac response magnitude. These data suggest that conditioned decreases in central nucleus neuronal activity normally may serve to disinhibit vagal mechanisms as conditioned bradycardia develops and that the neural circuits that produce these responses are sensitive to opioid modulation.
在进行厌恶性巴甫洛夫条件反射和消退训练之前，给兔子静脉注射盐酸纳洛酮（0.5毫克/千克）或生理盐水载体；比较了心率条件反应以及杏仁核中央核中的伴随多单位活动。在生理盐水处理的兔子中，条件刺激诱发的多单位活动在条件反射期间增加，在消退期间减少；纳洛酮处理减弱了诱发的神经元活动，但增强了心动过缓条件反应。相关性分析表明，在生理盐水处理组的8只动物中的3只中，多单位活动的较大增加对应于较小的心动过缓反应。纳洛酮处理并未改变这种关系的频率或幅度，但它确实增强了训练诱导的与心动过缓反应幅度相关的位置处诱发神经元活动的减少。这些数据表明，随着条件性心动过缓的发展，中央核神经元活动的条件性降低通常可能起到解除迷走神经机制抑制的作用，并且产生这些反应的神经回路对阿片类药物调节敏感。
