Effects of cold acclimation and central opioid processes on thermoregulation in rats

被引:9
作者
Wilson, JR
Howard, BA
机构
[1] Department of Psychology, University of Manitoba, Winnipeg
基金
加拿大自然科学与工程研究理事会;
关键词
cold acclimation; DAMGO; core temperature; heat escape; telethermistors; rats;
D O I
10.1016/0091-3057(95)02124-8
中图分类号
B84 [心理学]; C [社会科学总论]; Q98 [人类学];
学科分类号
03 ; 0303 ; 030303 ; 04 ; 0402 ;
摘要
Two experiments, using centrally administered [D-Ala(2)-MePhe(4)-Gly(ol)(5)]enkephalin (DAMGO), a selective mu-opioid agonist, assessed the thermoregulatory consequences of cold acclimation. Experiment 1 assessed whether cold acclimation influenced DAMGO hyperthermia at room temperature. Sialoadenectomized rats were implanted with ICV cannulae and IP Mini-Mitters. After 3 weeks of exposure to 5 degrees C (cold acclimation) or 22 degrees C (non-cold acclimation) rats were pretreated with IP naltrexone HCl (2 mg/kg b.wt.) or vehicle (0.15 M saline) and later administered a 5-mu l ICV injection of 0.15 M saline, 0.1, or 1.0 mu g DAMGO. Cold acclimation exerted little effect on core temperature but potentiated DAMGO hyperthermia in a dose-dependent, naltrexone-reversible, activity-independent manner. Experiment 2 assessed the effect these same manipulations exerted on operant escape from a convective source of mild heat (37 degrees C). Duration of heat escape increased with cold acclimation in a naltrexone-resistant manner, yet was not influenced by DAMGO in either non-cold-acclimated or cold-acclimated rats. These findings suggest that two central adaptations occur with cold acclimation: A non-mu-opioid process that increases heat sensitivity and a mu-opioid process that potentiates hyperthermia but fails to alter heat escape due to mu-opioid-mediated analgesia.
引用
收藏
页码:317 / 325
页数:9
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