Neuropeptide Y does not inhibit the release of α-MSH from the pars intermedia of the rat adenohypophysis

Neuropeptide Y in concentrations from 10−8 to 10−6 M inhibits the release of α-MSH from the frog (Rana pipiens) pituitary in a reversible, sustained, and concentration-related manner. However, it does not inhibit the release of α-MSH from the rat pars intermedia. Thus, while neuropeptide Y may play a role in the control of α-MSH release in amphibia, it appears not to be a regulatory peptide for the mammalian pars intermedia.