Although it has been recognized for over a decade that hypothalamic-pituitary disconnection (HPD) in fetal sheep prevents the late gestation rise in plasma cortisol concentrations, the underlying mechanisms remain unclear. We hypothesized that reductions in adrenal responsiveness and ACTH receptor (ACTH-R) expression may be mediating factors. HPD or sham surgery was performed at 120 days of ges...

The present study assessed the ability of primary cultures of rat anterior pituitary cells to secrete bioactive ACTH in the presence of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). The bioactivity of the secreted pituitary cell ACTH was determined by its ability to stimulate secretion of corticosterone from primary cultures of rat adrenal cells. ACTH from basal or CRH stimulated pituitary cel...

Urocortin (Ucn) is a newly identified mammalian member of the CRF family of peptides. Ucn activates CRF receptors (both CRF-R1 and CRF-R2) with greater potency than CRF itself, suggesting that Ucn may play an endogenous role in eliciting (at least some) CRF receptor-mediated events. Because the most characterized physiological function of CRF receptors is the activation of pituitary ACTH secret...

o-Nitrophenyl sulfenyl-modified ACTH (NPS-ACTH) stimulated steroidogenesis acutely in bovine fasciculata-reticularis cells without increase in cellular cAMP synthesis. Application of NPS-ACTH to the cultured cells induced Ca2+ signals in individual cells as detected by video-enhanced microscopic fluorescence measurements. The percentage of Ca2+ signaling cells corresponded well with the increas...

Plasma ACTH and corticosteroid concentrations were measured by radioimmunoassay in chronically catheterized fetuses of 32 pregnant sheep. Fetal plasma ACTH levels 38+/-5 pg/ml (means+/-SEM) were slightly (P < 0.05) lower than maternal 54+/-4 pg/ml levels. No general rise in fetal plasma ACTH concentration was noted before 140 days gestation; however, fetal plasma corticoid levels began to incre...

URQUHART, JOHN. Adrenal blood Juw and the adrenocortical response to corticotropin. Am. JPhysiol. 2og(6) : I 162-l 168. 1g65.-The effect of variations in adrenal blood flow on the adrenocortical response to ACTH was studied. The rate of blood flow through the perfused canine adrenal gland was a significant parameter in its response to ACTH. This effect was largest when the concentration of ACTH...

To differentiate between ectopic ACTH syndrome and Cushing's disease, we examined the gene expression of CRF, POMC and glucocorticoid receptor in pituitary adenomas and in ectopic ACTH-producing tumors. CRF increased plasma ACTH levels in all patients with Cushing's disease and in some patients with ectopic ACTH syndrome whose tumors contained CRF and CRF mRNA. In CRF non-responders, no CRF was...

A commercial immunoradiometric assay kit designed for the measurement of endogenous adrenocorticotropin (ACTH) concentrations in human plasma does not detect the molecule in plasma samples from cats. It was hypothesized that the inability of the assay to detect the molecule was related to variation(s) in the amino acid sequence of cat ACTH, compared with human ACTH. Cat ACTH complementary DNA w...

Presence of adrenocorticotropic hormone (ACTH) was investigated in tissues from 150 cases of primary breast cancer. ACTH peptides were detected in 16.7% cases and ACTH expression was higher in post-menopausal cancers. A significant association was noticed between the presence of ACTH and the positive estrogen receptor (ER) status of tumors. The study indicated a probable role of these ectopic A...