Similarities between the pharmacological actions of quipazine and serotonin

Experiments have been carried out to establish possible similarities between the actions of quipazine, 2-(1-Piperazinyl) quinoline maleate, a smooth muscle stimulant, and serotonin. When tested on diverse structures, quipazine was found to elicit effects similar to those of serotonin. Thus, it stimulated the rat uterus, the rabbit aorta, the guinea pig ileum, the guinea pig trachea, and induced bronchoconstriction in the guinea pig and local edema in the rat. The effects on the uterus, the aorta and the lung were antagonized by methysergide; those on the ileum by morphine and phenoxybenzamine, and the edema in the rat by BOL 148. Previous contact of guinea pig ileum segments with quipazine antagonized the responses to serotonin. Changes of behavior observed in cats after the administration of quipazine were abolished by the previous administration of cyproheptadine. All these findings suggest that quipazine and serotonin may exert their actions through stimulation of the same type of receptors.