Duration of analgesia and hyperactivity in mice after single injections (S.C. and I.V.) of heroin.
ED50 values for analgesia (tail-clip method) at 30 min after heroin HCl administered i.v. or s.c. in groups of Swiss-Webster mice were not significantly different. Nor was the duration of the analgesia following various doses of heroin significantly different after i.v. or s.c. injections, although there was a tendency for the latter route to have a longer effect. Hyperactivity (mean levels in groups of 5 mice, measured by an Activity Meter), though variable, was increased after s.c. injections of heroin in a dose-related manner up to doses of 10 mg/kg. Larger doses progesssively prolonged the peak levels of hyperactivity. Because the degree and duration of both analgesia and hyperactivity were parallel over a wide range of doses of heroin HCl in these mice, a close relationship between the two underlying mechanisms seems very likely.
D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D003932:Heroin / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D013268:Stimulation, Chemical; D013997:Time Factors
D003932:Heroin