Effect Upon the Analgesic Action of Reserpine of Central Nervous System Stimulants and Drugs Affecting the Metabolism of Catechol- and Indole-Amines

Abstract

Abstract The effect upon the analgesic action of reserpine of central nervous system stimulants and of drugs affecting the metabolism of catechol-and indole-amines as measured in mice by a hot-plate method has been analysed. The analgesic effect, which has a maximal intensity 48 hr. after injection of the alkaloid, is partially or totally counteracted by MAO inhibitors, LSD-25 and 5-hydroxytryptophan. Central nervous system stimulants given to reserpinised mice before each test were effective in reducing the reaction time to the heat stimulation only 24 and 48 hr. after reserpine. DOPA showed no significant ability to reduce the analgesic effect of reserpine. In the light of these findings a suggestion has been made that 5-hydroxytryptamine rather than catecholamines would be involved in the mechanism of the analgesic effect due to reserpine and since central nervous system stimulants are able to reduce this action initially but are ineffective later, part of the effect is thought to be due to sedation of the animals, the participation of the stimulants being confined to a direct antagonism against the sedation. The lasting analgesic effect is supposed to correspond to a lack of 5-hydroxytryptamine in the cerebral structures.