Corticotrophs, pituitary

Evain-BrionD, DonnadieuM, Roger M, Job JC. Simultaneous study of somatotrophic and corticotrophic pituitary secretions during ornithine infusion test. Clin Endocrinol (Oxf) 1982 17 119-122. 

In addition to the weU-defined opioid systems in the central nervous system, the three opioid peptides and their precursor mRNA have also been identified in peripheral tissues. ( -Endorphin is most abundant in the pituitary, where it exists in corticotroph cells with ACTH in the anterior lobe and in melanotroph cells with MSH in the intermediate lobe (59). Enkephalin and pre-pro-enkephalin mRNA have been identified in the adrenal medulla (60) and this has been the source of material for many studies of pro-enkephalin synthesis and regulation. Pre-pro-enkephalin mRNA has also been identified in the anterior and posterior lobes of the pituitary (61). mRNA for all three opioid precursors has been identified in the reproductive system (62—64). POMC... 

It can also be seen that preincubation with the potent glucocorticoid dexaraethasone under conditions which lead to an almost complete inhibition of ACTH secretion in corticotrophs of the anterior pituitary gland (85), has no inhibitory effect on either spontaneous or CRF-induced a-MSH secretion. 

Grino M, Guillaume V, Boudouresque F, Margioris AN, Grisoli F, Jaquet P, Oliver C, Conte-Devolx B (1988) Characterization of corticotropin-releasing hormone receptors on human pituitary corticotroph adenomas and their correlation with endogenous glucocorticoids. J Clin Endocrinol Metab 67(2) 279-83... 

Two neuropeptides, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) are released from parvoceUular neurons in the hypothalamic PVN to initiate a stress response. The terminal endings of these neurons, located in the median eminence of the hypothalamus, release CRH and AVP into the hypothalamic-hypophysial portal vessel system, where they travel to the anterior pituitary. The two neuropeptides act syn-ergistically on pituitary corticotrophs to activate the synthesis of pro-opiomelanocortin (POMC). This peptide, discussed in detail below, is processed to produce several peptides including adrenocorticotrophic hormone (ACTH), or corticotropin. ACTH released from corticotrophs travels via the bloodstream to act on cells in the zona fasciculata layer of the adrenal cortex, stimulating the synthesis and release of the glucocorticoids, cortisol (in humans) or corticosterone (in rodents). 

Adrenocorticotropic Hormone (ACTH) (Corticotropin) Anterior Pituitary (Corticotroph) 39 aa 2p25 Stimulates steroidogenesis in all three zones of the adrenal cortex, thereby increasing secretion of cortisol, DHEAS, and aldosterone. Stimulated by CRH and inhibited by cortisol. 

Cortisol is produced by the adrenal gland under the precise control of the hypothalamus and pituitary. The hypothalamus secretes corticotropin-releasing hormone (CRH) in response to stress. CRH acts on plasma membrane receptors in corticotrophic cells in the anterior pituitary to stimulate their release of... 

Besedovsky first showed in 1986 (B35) that rIL-ip increased ACTH and cortisol levels in mice. Corticotrophic cells from pituitaries incubated with IL-1 confirmed that it is a potent secretagogue for ACTH. In vivo increases in ACTH and corticosterone were blocked by antibodies to CRF, implying a hypothalamic site of action. lL-1 is also able to induce corticosteroine release directly from adrenal gland cells (S4, S5) but rIL-6 is even more potent in this respect and it synergizes with low concentrations of ACTH (S5). 

Synthesis The limbic system ultimately controls cortisone production by regulating release of corticotropin releasing hormone (CRH) from the hypothalamus via serotoninergic, dopaminergic and cholinergic neurons. CRH stimulates release of adreno-corticotrophic hormone (ACTH) from the anterior pituitary. ACTH activates adenylate cyclase in the adrenal cortex. The resulting cAMP activates protein kinase which enhances cholesterol esterase activity. Cholesterol esterase increases the amount of cholesterol available to mitochondria, where cortisone is made from cholesterol. ACTH also stimulates the conversion of cholesterol to pregnenolone, the first step in steroid synthesis. 

Pituitary Gonadotrophs and Corticotrophs Li et al. [1995] have constructed a model of membrane fluxes and calcium release from the endoplasmic reticulum of rat pituitary gonadotrophs. The membrane currents modeled include an L- and T-type calcium currents, delayed rectifier and calcium-sensitive potassium currents and a leak current. A modification of this model was used by LeBeau et al. [1997] to model pituitary corticotroph cells. 

AtT-20 anterior pituitary cells, an established hne of mouse corticotrophic cells, when stimulated with hpopolysaccharide secreted a 12.5 kDa protein that shared very high homology with human macrophage migration inhibitory factor MIF (Bernha-GEN et al. 1993). 

Pituitary corticotroph (ACTH) (A) 1. Fluorogenic amine content (catecholamine. 1. Low levels of rough (granular) endoplasmic... 

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