The Paraventriculo-Infundibular Corticotropin Releasing Factor (CRF)—Immunoreactive System of the Rat — I. Morphological Aspects

The hormone production of the anterior pituitary is influenced by neurosecretory materials produced in neurons of the prosencephalon (Szentâgothai et al., 1962). The bioactive substances released from nerve endings of the median eminence and the pituitary stalk are taken up by hypophyseal portal vessels, which distribute them to the pars distalis of the pituitary gland (Harris, 1955). The stimulatory effect of diencephalic extracts upon the hormone secretion of adrenocorticotroph cells (Guillemin and Rosenberg, 1955; Saffran and Schally, 1955) proved the existence of corticotropin releasing factor (CRF). In the last three decades, several substances were proposed to be CRF’s or at least modulators of the adrenocorticotroph hormone (ACTH) releasing substance (for review see Saffran and Schally, 1977; Yasuda et al., 1982). Vale et al. (1981) have rencently reported the isolation of a 41-amino acid peptide from ovine hypothalamic tissue, with potent activity to stimulate the secretion of ACTH and beta-endorphin.