Effect of hypothalamic neuropeptides on corticotrophin release from quarters of rat anterior pituitary gland in vitro

Abstract

The effect of six hypothalamic peptides on the basal release of ACTH and that induced by arginine vasopressin (AVP) or by ovine corticotrophin releasing factor (oCRF) from fragments of the rat anterior pituitary gland incubated in vitro was investigated. Dose–response curves to AVP and to oCRF were obtained, and the response to a low dose of oCRF was potentiated by a low dose of AVP. Basal release of ACTH was not affected by any of the peptides in concentrations in the range 10−12 to 10−6 mol/l, and only substance P (SP) and somatostatin (SRIF) inhibited significantly the response to oCRF in a dose-related manner. The responses to a range of doses of oCRF or AVP were reduced by 10−8 and 10 − 6 mol SP or SRIF/1, and to a greater extent by the higher dose. Except in the case of 10−6 mol SRIF/1 on the response to AVP, the response was not further diminished by preincubation of the tissue with the peptide before the stimulating agent was added. The inhibition of the responses to AVP or oCRF by 10−9 mol SP/1 was not potentiated by its combination with either 5 × 10−10 or 10−8 mol SRIF/1; the inhibitory effects were merely additive. The results suggest that although SRIF and SP are able to modulate the release of ACTH from the anterior pituitary gland, they do so only at a high concentration. In the case of SRIF these concentrations are several orders of magnitude higher than those reported to be present in the hypophysial portal blood and therefore a physiological role for this peptide in the control of ACTH secretion is unlikely. J. Endocr. (1984) 100, 219–226

Evidence for arginine vasopressin as the primary activator of the HPA axis during adjuvant‐induced arthritis

“…In vitro incubation of anterior pituitaries and RIA of ACTH Anterior pituitary incubations were performed essentially by the method described previously (Nicholson et al, 1984). Briefly fresh anterior pituitaries from SD and PVG rats were quartered and two quarters incubated per well in 1 ml KrebsRinger medium containing bovine serum albumin (BSA, 0.1%) and ascorbic acid (0.01%) under 95% 02/5% CO2 at 37°C.…”

Pharmacological management of Cushing's syndrome: an update

“…In vitro studies suggested that normal corticotroph only responds to somatostatin with inhibition of ACTH release if the cells have been cultured in glucocorticoid free medium (70)(71)(72)(73)(74). In agreement with this is the finding that ACTH secretion in normal individuals is not affected by infusion of somatostatin or octreotide but is affected in patients with Addison's disease (75,76).…”

Binding of an iodinated substance P analogue to cultured anterior pituitary prolactin- and luteinizing hormone-containing cells.

“…However, the influence of SP on the release of other anterior pituitary hormones is more complex. It has been reported that corticotropinreleasing hormone and arginine-vasopressin-stimulated release of corticotropin from anterior pituitaries was inhibited by addition of SP to the incubation medium (Nicholson et al, 1984). Recently, another study could not confirm any effect of SP on corticotropinreleasing hormone-stimulated release of corticotropin from dispersed anterior pituitary cell cultures (Chawdrey et al, 1990).…”