Heroin and morphine: aversive and analgesic effects in rats.
Although a number of studies demonstrate morphine-induced taste aversions, no such reports exist for heroin. In a conventional taste aversion paradigm, rats were injected with one of six heroin doses (0.5-12.0 mg/kg) after consuming a novel saccharin solution (Experiment 1). When the saccharin was reintroduced a second time no significant reduction in consumption occurred at any of the doses tested. It was therefore concluded that heroin does not readily induce a taste aversion. In Experiment 2, morphine was tested in an identical taste aversion paradigm and, as expected, a significant taste aversion did result at two of the doses tested. Experiment 3 demonstrated that heroin produced analgesia equal to or greater than morphine when comparing dosages of heroin which failed to induce a CTA with CTA-inducing morphine dosages. Thus, whereas heroin is more potent than morphine as an analgesic, heroin is less potent than morphine as a CTA-inducing agent.
D000700:Analgesics; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects; D003932:Heroin / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D013649:Taste / Q000187:drug effects
D000700:Analgesics; D003932:Heroin; D009020:Morphine