Gaiardi Margherita, Bartoletti Maria, Gubellini Carla, Bacchi Angela, Babbini Mario
Institute of Pharmacology, University of Bologna, Via Irnerio 48, I - 40126 BolognaItaly.
Pain. 1983 Sep;17(1):83-89. doi: 10.1016/0304-3959(83)90130-6.
The effect of a naloxone or a dexamethasone pretreatment on the conditioned analgesia resulting from the exposure of rats to an experimental chamber repeatedly paired with a grid shock was investigated. Shock induced disruption of bar pressing activity was taken as a behavioral measure of pain responsiveness. It was found that a 6, but not a 3, mg/kg dose of naloxone i.p. is hyperalgesic in unconditioned rats and effectively antagonizes conditioned analgesia. Dexamethasone (up to a dose of 2 + 1 mg/kg i.p. 23 and 1 h prior) did not alter the pain responsiveness of unconditioned rats, but caused a dose dependent suppression of conditioned analgesia. These results are discussed in terms of an opiate pituitary mechanism subserving conditioned analgesia.
研究了纳洛酮或地塞米松预处理对大鼠反复暴露于与电网电击配对的实验箱所产生的条件性镇痛的影响。电击引起的压杆活动中断被用作疼痛反应性的行为指标。结果发现，腹腔注射6mg/kg而非3mg/kg剂量的纳洛酮对未形成条件的大鼠具有痛觉过敏作用，并能有效对抗条件性镇痛。地塞米松（腹腔注射剂量高达2+1mg/kg，分别于23小时和1小时前注射）并未改变未形成条件的大鼠的疼痛反应性，但却引起了条件性镇痛的剂量依赖性抑制。根据一种服务于条件性镇痛的阿片-垂体机制对这些结果进行了讨论。
