Electrophysiological correlates of melanocyte-stimulating hormone activity in the frog
Abstract
Conducted 2 experiments with a total of 55 male frogs (Rana pipiens) to examine (a) the electrophysiological activity of the preoptic hypothalamus, postoptic hypothalamus, and ventral forebrain in Ss injected with synthetic alpha melanocyte-stimulating hormone (MSH); and (b) pigmentary changes in Ss injected with MSH or receiving electrical stimulation in either the preoptic or postoptic hypothalamus. Injection of MSH into the dorsal lymph sac produced darkening of the skin and increased electrical activity in preoptic hypothalamic areas. Electrical stimulation of the preoptic hypothalamus elicited darkening which was similar in time course to MSH. Results are interpreted as indicating an autoregulatory preoptic hypothalamic inhibition of pituitary MSH release. (17 ref.)