Potentiating effect of morphine upon d-methamphetamine-induced hyperthermia in mice. Effects of naloxone and haloperidol.
We have examined changes in rectal temperature of mice after subcutaneous administrations of d-methamphetamine alone or methamphetamine plus morphine. Methamphetamine 5 mg/kg produced slight hyperthermia, while simultaneous administration of morphine (25-100 mg/kg), which alone produces hypothermia, potentiated markedly the increase in body temperature by methamphetamine. Methamphetamine showed a hyperthermic effect in a dose-dependent manner in the presence of morphine. The hyperthermia due to methamphetamine plus morphine was avoided by pretreatment with 10 mg/kg naloxone. When animals were pretreated with 2.5 mg/kg haloperidol, hyperthermia due to methamphetamine alone was completely abolished, while that due to methamphetamine plus morphine was still observed. These results showed that dopamine may be implicated in methamphetamine hyperthermia and a haloperidol-nonsensitive mechanism may be involved in the methamphetamine-morphine hyperthermia.
Funahashi
M
M
Department of Legal Medicine, Osaka University School of Medicine, Japan.
Kohda
H
H
Hori
O
O
Hayashida
H
H
Kimura
H
H
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D004357:Drug Synergism; D005334:Fever / Q000139:chemically induced*; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D008694:Methamphetamine / Q000633:toxicity*; D051379:Mice; D009020:Morphine / Q000633:toxicity*; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*
D009270:Naloxone; D008694:Methamphetamine; D009020:Morphine; D006220:Haloperidol