The effect of p-chlorophenylalanine on the pethidine- or methadone-induced decrease in locomotor activity of rats.
Either pethidine HCl (50 mg/kg s.c.) or methadone HCl (8 mg/kg s.c.) produced a prominent decrease in locomotor activity of rats. Pretreatment of rats with p-chlorophenylalanine (p-CPA, 320 mg/kg i.p.) 48 h before the narcotic injection significantly antagonized the activity-decreasing effects of narcotics. When rats pretreated with p-CPA were given 5-hydroxytryptophan (75 mg/kg s.c.) 30 min before narcotic administration, the activity-decreasing response to narcotics was restored. Thus, a decrease in locomotor activity induced in rats by either pethidine or methadone is probably mediated by serotonergic mechanisms.
D000818:Animals; D003864:Depression, Chemical; D010134:Fenclonine / Q000494:pharmacology*; D008297:Male; D008614:Meperidine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008691:Methadone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D013997:Time Factors
D008614:Meperidine; D010134:Fenclonine; D008691:Methadone