Schwarz K S, Cunningham C L
Department of Medical Psychology, Oregon Health Sciences University, Portland 97201-3098.
Psychopharmacology (Berl). 1990;101(1):77-84. doi: 10.1007/BF02253722.
Classical conditioning of morphine hyperthermia was examined using an explicit conditioned stimulus (CS) paired with intravenous (IV) morphine administration. Rats were implanted with a jugular vein cannula and a biotelemetry device for monitoring body temperature. The animals were housed 24 h/day in the chambers in which all testing occurred. The CS was a 15-min light/noise stimulus. The unconditioned stimulus (US) was an infusion of morphine (5 mg/kg). Rats were assigned to either the Paired group, which received morphine with the CS, or the Unpaired group, which received explicitly unpaired presentations of the CS and US. The CS-morphine pairings resulted in development of a conditioned hyperthermic response in the Paired group evoked by the CS in the absence of morphine. The development of morphine hyperthermia was more rapid in the Paired group in the presence of the CS than in its absence in the same group and more rapid in the Paired group than in the Unpaired group during the CS. These results clearly show that learning affects the response to morphine administered repeatedly. In contrast to previous studies, conditioned hyperthermia was elicited within 15 min by a discrete CS in a situation where the response was not confounded by handling or the stress of injection.
使用与静脉注射吗啡配对的明确条件刺激（CS）来研究吗啡热反应的经典条件作用。给大鼠植入颈静脉插管和用于监测体温的生物遥测装置。动物每天24小时饲养在进行所有测试的实验室内。CS是15分钟的光/噪声刺激。无条件刺激（US）是注射吗啡（5毫克/千克）。大鼠被分为配对组，即CS出现时注射吗啡；或非配对组，即CS和US明显不配对呈现。CS与吗啡配对导致配对组在无吗啡情况下由CS诱发产生条件性热反应。在CS存在时，配对组中吗啡热反应的发展比同一组中CS不存在时更快，并且在CS期间，配对组比非配对组发展更快。这些结果清楚地表明学习会影响对反复注射吗啡的反应。与先前的研究不同，在反应不受处理或注射应激干扰的情况下，离散的CS在15分钟内就能引发条件性热反应。
