Regionalized Gene Expression of Prolactin and Growth Hormone in the Chicken Anterior Pituitary Gland

Messenger ribonucleic acid (mRNA) levers of PRL and GH in perifused cephalic and caudal lobes of the anterior pituitary gland of the chicken were determined by Northern blot analysis and are related to hypothalamic peptide perifusion. Perifusion of vasoactive intestinal peptide (VIP, 10 and 100 nM) significantly increased both PRL secretion and levels of PRI mRNA in the cephalic lobe, whereas no effects of VIP were observed in the caudal lobe. In contrast, growth hormone-releasing factor (GRF) (1-100 nM) did not induce an increase in either GH secretion or levels of GH mRNA in the cephalic lobe but did increase GH secretion and levels of GH mRNA in the caudal lobe. In addition, forskolin perifusion increased secretion and levels of PRL and GH mRNA in both cephalic and caudal lobes, respectively. These results indicate that gene expression of PRL and GH in response to VIP and GRF, respectively, is localized to specific lobes of the anterior pituitary gland, but that they may share, in part, a common second messenger pathway, namely, cAMP.