Melanocyte-Stimulating Hormone Activity in Pituitaries of Frogs with Hypothalamic Lesions

Abstract

Melanocyte-stimulating hormone (MSH) activity in pituitaries of frogs with hypothalamic lesions was compared by bio-assay with the activity of this hormone in pituitaries of intact frogs. There was a significant loss of MSH activity following hypothalamic destruction. The specificity of the assays was substantiated by simultaneous assays of ACTH activity, which was found to be similar in both groups. MSH activity demonstrated by parabiosis was greater in body fluids of lesioned frogs than in the controls. It appeared, therefore, that there was increased pituitary secretion and decreased pituitary storage of MSH activity in frogs with hypothalamic lesions.