Acute physical dependence upon morphine in rats

A versatile procedure for rapid induction of narcotic addiction in the rat utilizing intravenous injections

“…These procedures are therefore not useful where short-term treatment of experimental animals is desired. Recently, Coussens, Crowder, and Smith (1973) and Teiger (1974) showed that physical dependence on narcotics can be rapidly induced in the rat by either continuous or discontinuous injections of morphine solutions. FollOwing these suggestions, we tested several schedules of injections in order to select a safe and versatile procedure which could be easily applied in behavioral and conditioning studies.…”

Naloxone antagonism of hyperactivity in morphine-treated hamsters

“…According to a dependence/withdrawal hypothesis, naloxone-induced hypoactivity is the result of naloxone-precipitated withdrawal in morphine-dependent animals. The plausibility of this hypothesis rests upon demonstrations in dogs (Jacob & Michaud, 1974), mice (Stevens & Klemm, 1979), and rats (Coussens, Crowder, & Smith, 1973) that dependence and withdrawal symptoms are manifest after acute administration of low doses of morphine, comparable to those employed in our work with the hamster (e.g., Schnur, 1985a). The purpose of the present work was to investigate naloxone reversal of morphineelicited hyperactivity as a function of exposure to morphine.…”