Serotonin content in the central nervous system of rats and cholinergic tremor

Oxotremorine did not alter the level of 5-HT and 5-hydroxyindoleacetic acid in different brain regions. The content of 5-HT in the striatum was diminished by electrolytic lesions of the raphe system, by microinjection of the selective depletor 5,6-dihydroxytryptamine into the raphe system and inhibition of synthesis by pCPA or pCAM. The intensity of oxotremorine-induced tremor was reduced only in some experimental groups without clear-cut correlation to the decreased 5-HT levels. In pCPA-pretreated animals resoring of 5-HT concentration by intrastriatal microinjection of 5-HT and ip administration of 5-HT did not reestablish tremor intensity. There is no evidence that cholinergic tremor is triggered indirectly and depends upon an intact 5-HT system.