Inducing a preference for morphine in rats without premedication.

摘要: “ADDICTION” to morphine and morphine-type drugs can be shown in laboratory animals several ways. Among the most convincing1 are experiments which rats monkeys induced administer drug themselves either by drinking solutions of it2,3 or pressing levers release intravenous injections through an implanted catheter4,5. Standard experimental procedures involve a period premedication: daily increasing doses given for 2–3 weeks order make “passively” dependent on drug. Injections then stopped have withdrawal symptoms6,7 only relieved more morphine; so they learn seek self-administer Monkeys will, however, press even without premedication, though such learning is much slower. Some will also voluntarily drink solutions, bitter, but others persistently reject them unless pre-medicated (personal communication from Seevers). In rats, premedication has usually been considered essential kind self-administration, premedicated initially if choice between water, probably because bitter taste.