The amount of melanophore-stimulating hormone in single pituitary glands of Xenopus laevis kept under various conditions

Abstract

The MSH (melanophore-stimulating hormone) content of single anterior and intermediate/posterior pituitary lobes of Xenopus laevis was determined using skin pieces of Anolis carolinensis as test objects. Significant changes in the MSH content of single intermediate/posterior lobes of Xenopus were found after adaptation during a 48 hour period to a black or to a white background. The ratios of the pigment-stimulating potencies of anterior to intermediate/posterior pituitary lobes are about 1:38 for white background-adapted Xenopus, and about 1:9 for black background-adapted animals. The results of the experiments indicate that under the given adaptation conditions the release of MSH is inhibited in white background-adapted Xenopus and the hormone stored in the pituitary. The hormone is continuously released in black background-adapted animals. Exposure to complete darkness does not deprive the pituitary of Xenopus laevis or that of Rana temporaria of its MSH.