The effect of 5-hydroxytryptamine and 5-hydroxytryptophan on extra-pyramidal function

Abstract

Intraperitoneal administration of 5-hydroxytryptophan (5-HTP) induced a special form of gnawing behaviour and stereotyped movements of the head and forelegs when given to iproniazid-pretreated rats. These effects have not been described previously. Implantation of 5-HT into the rostro-ventral part of the corpus striatum, induced only gnawing behaviour, while only tremor was caused by the implantation of 5-HT or 5-HTP into the substantia nigra. Accordingly, two sites of action of 5-HT were found: the rostro-ventral part of the corpus striatum for gnawing behaviour and the substantia nigra for tremor. To confirm these findings, bilateral lesions were separately made in both these areas and 5 days later, 5-HTP was administered i.p. (with iproniazid pretreatment). The results obtained confirmed the rostro-ventral part of the corpus striatum as the site of action for gnawing behaviour, but they did not confirm the substantia nigra as the only site of action for the tremor.