HYPOTHALAMIC ORGANIZATION OF CORTICOLIBERIN (CRF) PRODUCING STRUCTURES

Publisher Summary This chapter discusses the hypothalamic organization of corticoliberin or corticotrophin releasing factor (CRF) producing structures. The search to localize more precisely the possible origin of the CRF fibers in the stalk-median eminence (SME) started in the anterior hypo-thalamus where Krieger and Lang found detectable amounts of CRF activity in the supra-optic, paraventricular, and suprachiasmatic nuclei. As the trials made it unlikely that the suprachiasmatic nuclei contribute much to the CRF pool of the SME, the best candidate seemed to be the paraventricular nucleus. This idea is also supported by morphological studies showing a close parallelism between pituitary-adrenal activity and the amount of secretory material in the external zone of the SME, which originated from the PVN. Many but not all CRF producing nerve cells are in the anterior hypothalamus in such a localization that knife lesions of the paraventricular nuclei either destroy the cells or transect their axons on their way towards the SME. A pathway important for ACTH release, probably containing CRF axons, enters the medial basal hypothalamus (MBH) via the lateral retrochiasmatic area. A large majority of the CRF containing axons are transected by an antero-lateral cut around the MBH. The hypothalamic control of ACTH secretion has a surprisingly large functional reserve and a potential for restoration of function after incomplete destructions.