Intragastric drug self-administration by rats exposed successively to morphine and ethanol.
Male Sprague-Dawley rats were implanted with intragastric cannulas for self-administration of drug solutions by bar-pressing on a continuous reinforcement schedule in 10-hour daily sessions. Similar levels of responding were observed for doses per infusion of 3.0 mg/kg morphine sulfate and 25 mg/kg ethanol in separate groups of rats. When rats that showed self-administration of a morphine solution over a 5-day period were than given access instead to ethanol for 5 days, the number of infusions taken did not deviate significantly between the two periods. However, rats selected from a small minority that failed to take morphine under these conditions also failed to manifest ethanol self-administration behavior. The data can be seen to support a possible concurrence or similarity between innate factors determining acceptance or rejection of morphine and ethanol as objects of self-administration behavior.
D000437:Alcoholism / Q000523:psychology*; D000818:Animals; D006801:Humans; D007441:Intubation, Gastrointestinal; D007700:Kinetics; D008297:Male; D009021:Morphine Dependence / Q000523:psychology*; D051381:Rats; D012646:Self Administration