Involvement of opioid receptors in phencyclidine-induced enhancement of brain histamine turnover in mice.
When the histamine (HA) turnover in the brain of mice was estimated on the basis of the pargyline-induced accumulation of tele-methylhistamine (t-MH), a predominant metabolite of brain HA, the enhancing effect of phencyclidine (PCP) on the HA turnover was antagonized by a large dose of naloxone. However, a dopamine receptor antagonist haloperidol, which is also a potent sigma receptor antagonist, did not inhibit the effect of PCP on the HA turnover. [D-Ala2,D-Leu5]enkephalin, a prototypic delta opioid agonist, markedly enhanced the HA turnover. The effect of this peptide was demonstrated not only when the HA turnover was determined by the pargyline-induced t-MH accumulation but when it was estimated by the HA depletion induced by alpha-fluoromethylhistidine, a specific inhibitor of histidine decarboxylase. A sigma agonist, SKF-10047, and a kappa agonist, ethylketazocine, had no PCP-like enhancing effect on the HA turnover. These results suggest that PCP enhances the brain HA turnover in mice by stimulating, probably indirectly, endogenous opioid systems.
D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000378:metabolism*; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D016314:Ethylketocyclazocine; D006220:Haloperidol / Q000494:pharmacology; D006632:Histamine / Q000378:metabolism*; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D010620:Phenazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D010622:Phencyclidine / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*
D000701:Analgesics, Opioid; D008762:Methylhistidines; D011957:Receptors, Opioid; D009270:Naloxone; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D007649:Ketamine; C028309:alpha-fluoromethylhistidine; C012134:SK&F 10047; D006632:Histamine; D010293:Pargyline; D006640:Histidine Decarboxylase; D010620:Phenazocine; D010622:Phencyclidine; D003496:Cyclazocine; D006220:Haloperidol