On the question of the occurrence and metabolism of 5-hydroxytryptamine and related indole compounds in mammalian semen.

The content of 5-hydroxytryptamine was examined in the semen of man, bull, ram, boar and dog. Spectrophotofluorimetric and chromatographic analysis of extracts prepared by several methods has shown that the semen contains only minute quantities of 5-hydroxytryptamine, if any. One cannot attribute to 5-hydroxytryptamine the uterus-stimulating effect which the human seminal plasma is known to exert. Tryptophan, although present in the seminal plasma, is not converted to 5-hydroxytryptamine on incubation of semen. 5-Hydroxytryptophan is oxidatively deaminated, but not decarboxylated, by spermatozoa. 5-Hydroxytryptamine itself, like tryptamine and tyramine, is not deaminated by either whole semen or washed suspensions of ram spermatozoa.