Goldberg S R, Gonzalez F A
J Pharmacol Exp Ther. 1976 Sep;198(3):626-34.
Behavior of squirrel monkeys was maintained under comparable 30-response fixed-ratio schedules of cocaine injection or fooc presentation. Every 30th key press in the presence of a green light produced an intravenous injection of 25 mug/kg of cocaine in one group of monkeys or delivery of a food pellet in a second group of monkeys. Each cocaine injection or food presentation was followed by a 1-minute timeout period, during which the green light was absent and responses had no programmed consequences. Responding at a mean rate of more than 1/sec was maintained in the presence of the green light during each daily session. Propranolol doses from 0.3 to 3.0 mg/kg i.m. had no effect on food-maintained responding but decreased cocaine-maintained responding by approximately 30%. The selective disruption of cocaine-maintained responding by propranolol appeared to depend on the cumulative cocaine dose. Decreases in cocaine-maintained responding after propranolol became increasingly pronounced as the session progressed. Similar progressive decreases in cocaine-maintained responding were produced by increasing the dose of cocaine per injection.
松鼠猴的行为在可卡因注射或食物呈现的类似30次反应固定比率程序下维持。在一组猴子中，绿灯亮起时每第30次按键会静脉注射25微克/千克可卡因，在另一组猴子中则会递送一粒食物丸。每次可卡因注射或食物呈现后会有1分钟的超时时段，在此期间绿灯熄灭，反应没有预设结果。在每个每日实验时段中，绿灯亮起时以平均每秒超过1次的速率反应得以维持。肌肉注射0.3至3.0毫克/千克的普萘洛尔对食物维持的反应没有影响，但使可卡因维持的反应降低了约30%。普萘洛尔对可卡因维持反应的选择性破坏似乎取决于累积可卡因剂量。随着实验时段的推进，普萘洛尔后可卡因维持反应的降低变得越来越明显。通过增加每次注射的可卡因剂量也会产生可卡因维持反应的类似逐渐降低。
