[Effects of beta-phenylethylamine derivatives on the central nervous system. (5) The effect of intracerebral administration of tyramine on head twitching in mice pre-treated with isocarboxazid].

Effects of drugs on head-twitches induced by tyramine (Ty) in isocarboxazide (Iso) pretreated mice were studied and the following results obtained: 1) In beta-phenylethylamine derivatives, p-hydroxyamphetamine in non-treated and Iso-pretreated mice and Ty in Iso-pretreated mice produced head-twitches. 2) Injection of 5-HTP (i.c. and i.p.) into mice induced head-twitches. 3) Although head-twitches were not induced by a low dose of 5-HTP (20 mg/kg, i.p.), in Iso pretreated mice, the number of headtwitches increased markedly in the Iso-Ty treated group when Ty was injected i.c. in Iso+5-HTP (20 mg/kg) pretreated mice. 4) When Iso-Ty was injected into alpha-methyl-p-tyrosine pretreated mice, the number of head-twitches increased markedly compared with Iso-Ty treated group. 5) When Iso-Ty was injected into mice sustained with p-chlorophenylalanine, the number of head-twitches decreased markedly compared with the Iso-Ty treated group. 6) The number of head-twitches decreased markedly when Iso-Ty was injected into dimetotiazine pretreated mice, however the administration of Iso-Ty in haloperidol pretreated mice had no influence on head-twitches. 7) It is concluded that serotonin is the acting mediator in the head-twitch response.