Studies on the Conditions Determining the Inhibitory Effect of Somatostatin on Adrenocorticotropin, Prolactin and Thyrotropin Release by Cultured Rat Pituitary Cells
Abstract:Somatostatin (SRIH) is a physiological inhibitor of growth hormone (GH) secretion, but its role in the regulation of adrenocorticotropic hormone (ACTH), prolactin (PRL) and thyroid-stimulating hormone (TSH) release is unclear. SRIH (1 pM to 1 µM) did not affect basal and corticotropin-releasing hormone (CRH)-stimulated ACTH release by normal rat pituitary cells cultured in medium with 10% fetal calf serum (FCS). In cells deprived of serum for 48 h, or preincubated with the glucocorticoid-receptor-blocking agen… Show more
“…There is more convincing evidence for the effects of SRIF in rats: it inhibited CRH-stimulated ACTH release from isolated pituitary cells (Lamberts et al 1989) and inhibited CRH release from hypothalami in vitro (Tizabi & Calogero 1992). Thus SRIF is effective at both the hypothalamic and anterior pituitary levels in rodents, but the absence of evidence for an effect of SRIF in normal human subjects suggests that this peptide plays little part in regulating the human HPA axis.…”
“…There is more convincing evidence for the effects of SRIF in rats: it inhibited CRH-stimulated ACTH release from isolated pituitary cells (Lamberts et al 1989) and inhibited CRH release from hypothalami in vitro (Tizabi & Calogero 1992). Thus SRIF is effective at both the hypothalamic and anterior pituitary levels in rodents, but the absence of evidence for an effect of SRIF in normal human subjects suggests that this peptide plays little part in regulating the human HPA axis.…”
“…On the other hand, SS inhibited CRH-and vasopressin induced ACTH release by cultured cells prepared from long-term adrenalectomized rats [29]. Moreover, in serum-deprivedor in rat pituitary cells pre-treated with the glucocorticoid blocking agent RU-38146, SS inhibited CRH-induced ACTH secretion already at low nanomolar concentrations, whereas in serum cultured cells SS was unable to influence ACTH secretion [30]. In humans, systemic SS infusion did not suppress basal-or angiotensin II-, ghrelin-or CRH-induced ACTH or cortisol concentrations [31][32][33].…”
Section: Ss and Sst In The Regulation Of Normal Acth Secretionmentioning
“…Somatostatin suppresses TSH secretion from the pituitary gland (Lamberts et al, 1989), and its analogues are therefore used for the treatment of TSH-producing adenomas (Beck-Peccoz et al, 1989).…”
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