Glucocorticoid regulation of proopiomelanocortin gene expression in the pituitary gland of hypothalamopituitary intact and hypothalamopituitary disconnected sheep

Abstract

Proopiomelanocortin (POMC) gene expression in the anterior pituitary (AP) gland has previously been shown to be positively regulated by CRF and AVP and negatively regulated by glucocorticoids. In the neurointermediate lobe (NIL) of the pituitary, however, POMC gene expression is under tonic inhibitory dopaminergic control. In the present study we have used hypothalamopituitary intact (HPI), ovariectomized (OVX), and OVX/hypothalamopituitary disconnected (OVX/HPD) ewes to examine direct (i.e. non hypothalamic) effects of glucocorticoids on POMC gene expression in both the AP and the NIL. There was no difference between POMC mRNA levels in intact and OVX sheep. In intact animals treated with d..