ACTH OF PITUITARY PARS-INTERMEDIA

  • 1 January 1976
    • journal article
    • review article
    • Vol. 72  (3) , 261-276
Abstract
The intermediate lobe probably contains corticotropic cells that are morphologically similar to those of the adenohypophysis. ACTH molecules extracted from the intermediate lobe do not differ from those from the adenohypophysis. Immunocytochemical studies confirmed the presence of ACTH in the intermediate lobes of all species studied so far [including mammals, fish and birds], and stimulate the question of the mechanism of ACTH synthesis at this level. The interrelationships between different peptides of the intermediate lobe, including LPH [lipotropic hormone], ACT, CLIP [corticotropin-like intermediate peptide] and MSH [melanotropic hormone] require further investigations. The intermediate lobe synthesizes and releases ACTH in vitro. This release can be stimulated by crude extracts of the median eminence or of cerebral cortex and does not seem to be controlled by the CRF [corticotropin-releasing factor]. Although ACTH of the intermediate lobe intervenes in vivo in the response to a neurogenic stress, one may not assume that the intermediate lobe alone plays an important role in the maintenance of the adrenal cortex, as the adrenals are similarly affected by hypophysectomy or pars distalis removal.