THE ROLE OF ADENOSINE 3′,5′-CYCLIC MONOPHOSPHATE AND CATECHOLAMINES IN THE PIGMENT MIGRATION PROCESS IN XENOPUS LAEVIS

Abstract

ABSTRACT The mediating role of 3,5-AMP in the MSH induced pigment dispersion, is demonstrated in several ways. The amount of 3,5-AMP in darkened skins is about twice the amount present in lightened skins. Inhibition of 3,5-AMP degradation by theophylline results in a dispersion of the pigment granules. Inhibition of 3,5-AMP synthesis by acetylcholine prevents dispersion of the granules in the presence of MSH. In Xenopus laevis the dispersion reaction is stimulated by catecholamines. This stimulation is brought about by adrenergic receptors. Using adrenergic receptor blocking agents, some insight in the stimulation has been obtained in larval as well as in adult animals. Finally, an attempt has been made to explain the pigment aggregation by an intensified breakdown of 3,5-AMP by the enzyme phosphodiesterase.