Corticotropin-releasing factor receptors in rat pituitary gland: autoradiographic localization

Corticotropin-releasing factor (CRF) receptors were localized in rat pituitary gland by an in vitro labeling light microscopic autoradiographic technique using the radioiodinate ovine CRF analog, [Nle21,125I-Tyr32]-CRF. Our data confirms the existence of CRF receptors in anterior pituitary and demonstrates the presence of specific CRF binding sites in the intermediate lobe of rat pituitary. The distribution of CRF binding sites closely resembles the clustering of corticotrophs in anterior lobe and the uniform distribution of opiomelanocortin-producing cells in the intermediate pituitary. These results suggest that endogenous CRF plays a physiological role in regulating secretion of pro-opiomelanocortin-derived peptides from both anterior and intermediate lobes of rat pituitary.