Dopaminergic agents differentially regulate both processing and content of α-N-acetylated endorphin and α-MSH in the ovine pituitary intermediate lobe

Abstract

Hypo thai a mo-pi tui tary disconnection (HPD) in the sheep results in a two-fold increase in pituitary intermediate lobe (!L) immunoreactive(ir)-a-N-acetylated endorphin (NacEP) and ir-ri-melanocyte-stimulating hormone (MSH) content. The rise in IL NacEP content is accompanied by a markedly altered pattern of processing, in that NacEPi1-27 becomes the dominant molecular species with a complementary fall in Nacα-EPand Nacγ-EP. To determine if these effects reflect the loss of descending dopaminergic neuronal input to the !L, we have chronically treated two groups (n = 4 per group) of normal sheep with the dopamine antagonist haloperidol or the dopamine agonist bromocriptine; a group of HPD s..