Changes in Operant Behavior During Deprivation- and Antagonist-Induced Withdrawal States
A series of repeated administrations of morphine will produce a state of dependence in most mammalian species. Morphine dependence is identified by a characteristic, unique set of behavorial, somatic, sympathetic, and parasympathetic signs known as the withdrawal syndrome when the organism is either deprived of morphine or when a morphine antagonist (e.g., nalorphine, naloxone) is administered. In rhesus monkeys which have received a series of morphine injections (3 mg/kg sc., q6h) for a month or more, deprivation-induced withdrawal signs are minimally evident following 12 hours of deprivation and become maximal at 32–48 hours of deprivation (Seevers and Deneau, 1963). The antagonist-induced syndrome begins within minutes following subcutaneous antagonist administration and the total reaction may be complete within 2–4 hours if the dose is moderate (Seevers and Deneau, 1963). The difference in time course of these methods of inducing withdrawal signs is the major distinguishing characteristic since the pattern of signs is otherwise remarkably comparable. It has been shown that in animals with a history of morphine administration changes in behavior produced by antagonists may be found under conditions where overt deprivation-induced withdrawal changes are not demonstrable. For example, operant behavoir (Goldberg and Schuster, 1969) may provide additional distinguishing characteristics of the different methods of inducing withdrawal signs.
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