Thompson D M, Moerschbaecher J M
J Exp Anal Behav. 1981 Nov;36(3):371-80. doi: 10.1901/jeab.1981.36-371.
Pigeons acquired a different four-response chain each session by responding sequentially on three keys in the presence of four colors. The response chain was maintained by food presentation under a fixed-ratio schedule. Errors produced a brief timeout but did not reset the chain. When either morphine or naloxone was administered alone, the overall response rate decreased with increasing doses. The rate-decreasing effect was accompanied by an increase in percent errors with morphine but not with naloxone. Both effects of morphine were antagonized by doses of naloxone that were ineffective when given alone. The antagonism was selective in that naloxone (3 mg/kg) completely blocked the error-increasing effect but not the rate-decreasing effect of the higher doses of morphine. The view that naloxone is a specific narcotic antagonist was supported by the finding that naloxone failed to antagonize the rate-decreasing and error-increasing effects of d-amphetamine, pentobarbital, and phencyclidine.
鸽子在每次实验中通过在四种颜色出现时依次对三个按键做出反应来习得不同的四反应链。反应链通过固定比率程序下的食物呈现来维持。错误会导致短暂的超时，但不会重置反应链。单独给予吗啡或纳洛酮时，总体反应率会随着剂量增加而降低。吗啡导致反应率降低的同时伴随着错误百分比的增加，而纳洛酮则不会。吗啡的这两种效应都被单独给药时无效的纳洛酮剂量所拮抗。这种拮抗作用具有选择性，即纳洛酮（3毫克/千克）完全阻断了较高剂量吗啡增加错误的效应，但没有阻断其降低反应率的效应。纳洛酮未能拮抗右旋苯丙胺、戊巴比妥和苯环己哌啶降低反应率和增加错误的效应，这一发现支持了纳洛酮是一种特异性麻醉拮抗剂的观点。
