Involvement of 5-hydroxytryptamine in the analgesic action of pethidine and morphine in mice.
1 Groups of mice were pretreated with the 5-hydroxytryptamine (5-HT) depletors, fenfluramine or p-chlorophenylalanine (PCPA), followed by pethidine or morphine. 2 Fenfluramine alone produced a short lasting analgesia but PCPA was without any effect. 3 Pethidine and morphine both increased hot plate reaction times measured after 30 min. 4 Pretreatment with PCPA attenuated morphine analgesia but did not affect pethidine analgesia. Fenfluramine did not alter the response to either analgesic. 5 PCPA produced a significant depletion of brain 5-HT levels which was not reversed by the analgesics. The fenfluramine-induced decrease in 5-HT was reversed by morphine but not by pethidine. 6 The results support the involvement of 5-HT in the antinociceptive action of morphine in the mouse.
D000700:Analgesics; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D010134:Fenclonine / Q000494:pharmacology; D005277:Fenfluramine / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D008614:Meperidine / Q000494:pharmacology*; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects; D012701:Serotonin / Q000502:physiology*; D014364:Tryptophan / Q000378:metabolism
D000700:Analgesics; D005277:Fenfluramine; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D009020:Morphine; D014364:Tryptophan; D008614:Meperidine; D010134:Fenclonine