Endocrine influences on tissue serotonin content of the rat

¹ Departments of Medicine and of Pathology, Harvard Medical School; and Medical Clinic, Peter Bent Brigham Hospital, Boston, Massachusetts
² Department of Medicine and of Pathology, Harvard Medical School; and Medical Clinic, Peter Bent Brigham Hospital, Boston, Massachusetts

The effect of endocrine influences on the serotonin concentration of rat brain and gastrointestinal viscera was determined by a spectrophotofluorimetric technique. Animals subjected to the removal of hypophysis, adrenals, parathyroids, thyroid, or testes showed no change in tissue 5-hydroxytryptamine (5-HTA) content. A significant increase in gastric 5-HTA concentration was observed after pituitary section, but this result was attributed to gastric atrophy. Morphological studies of the stomach revealed a loss of parenchymal cell elements with preservation of the enterochromaffin system after hypophysectomy. The administration of corticotropin, testosterone, or methacholine chloride to healthy animals did not produce any alterations in 5-HTA levels. This study indicates that tissue serotonin stores in the rat are unaffected by profound endocrine changes. The stability of gastrointestinal serotonin content was also demonstrated after drug-induced cholinergic stimulation.