+ Translate

Regulation of growth hormone release: evidence against negative feedback in rat pituitary cells

, : Regulation of growth hormone release: evidence against negative feedback in rat pituitary cells. Endocrinology 108(6): 2287-2292

To determine if the anterior pituitary gland is the site of negative feedback inhibition of GH [growth hormone] release, the effect of GH and multiplication-stimulating activity (MSA), a member of the somatomedin family, on isolated rat anterior pituitary cells in primary culture was studied. The effect of GH was examined in 2 ways: by adding to the cultures human GH (10-20 .mu.g/ml) which was biologically active in the rat, but not cross-reactive in the rat GH (rGH) radioimmunoassay and by comparing rGH secretion in cultures of different cell densities. No suppression of either basal or prostaglandin[PG]E1-stimulated rGH release was found. An enhancement observed in serum-free conditions at high human GH concentrations was interpreted as a nonspecific response to protein, because bovine serum albumin produced the same effect. When added in the presence of serum, MSA (1-500 ng/ml) had no effect on rGH secretion. In the absence of serum, there were 71 and 30% increases in the basal and PGE1-stimulated rates of hormone release, respectively, possibly attributable to a trophic effect of MSA. Five other hormones [epidermal growth factor, nerve growth factor, placental lactogen, prolactin, and proinsulin] having structural or functional similarity to either GH or somatomedin also failed to inhibit rGH secretion. These results do not support the hypothesis that GH or somatomedin exerts a negative feedback effect on GH release directly on the anterior pituitary gland. Most likely, the hypothalamus or a higher brain center is the site for such regulation.

(PDF same-day service: $19.90)

Accession: 006288295

PMID: 6112137

DOI: 10.1210/endo-108-6-2287

Submit PDF Full Text: Here

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Related references

Berelowitz M.; Szabo M.; Firestone S.; Chu L.; Hintz R.; Frohman L.A., 1980: Somatomedin c effects on hypothalamic somatostatin and pituitary growth hormone release in vitro evidence for a negative feedback role in the regulation of growth hormone secretion. Clinical Research 28(4): 760A

Barb, C.R.; Hausman, G.J., 2009: Insulin-like growth factor-I feedback regulation of growth hormone and luteinizing hormone secretion in the pig: evidence for a pituitary site of action. Three experiments (EXP) were conducted to determine the role of insulin-like growth factor-I (IGF-I) in the control of growth hormone (GH) and LH secretion. In EXP I, prepuberal gilts, 65 ± 6 kg body weight and 140 days of age received intracereb...

Veldhuis, J.D.; Iranmanesh, A.; Pincus, S., 1996: Reduction of intrinsic negative feedback regulation of neuroendocrine axes increases the approximate entropy of the pituitary hormone release process for TSH, GH, and LH. Society for Neuroscience Abstracts 22(1-3): 1346

Rosenthal, S.M.; Silverman, B.L.; Wehrenberg, W.B., 1991: Exogenous growth hormone inhibits bovine but not murine pituitary growth hormone secretion in vitro: evidence for a direct feedback of growth hormone on the pituitary. To test the hypothesis that one aspect of growth hormone (GH) regulation involves a direct effect of GH on its own secretion at the level of the pituitary, we evaluated the effects of human GH on basal and GH-releasing factor (GRF)-induced GH secr...

Farmer, C.; Lapierre, H., 1995: Negative feedback of insulin-like growth factor-I on growth hormone secretion by porcine pituitary cells. Pituitaries from female Yorkshire pig fetuses (90 d, n = 26; 110 d, n = 17) and 6-mo-old pigs (n = 5) were enzymatically dispersed, plated, and cultured for 47 h. The cells were then rinsed and incubated for 22 h with testing media containing 0, 5...

Foresta, C.; Bordon, P.; Rossato, M.; Mioni, R.; Veldhuis, J.D., 1997: Specific linkages among luteinizing hormone, follicle-stimulating hormone, and testosterone release in the peripheral blood and human spermatic vein: evidence for both positive (feed-forward) and negative (feedback) within-axis regulation. We have investigated possible (negative) feedback and (positive) feed-forward activity within the human male gonadotropic axis by measuring serum concentrations of LH, FSH, and testosterone in blood sampled frequently and for a prolonged interval...

Sartin, J.L.; Coleman, E.S.; Steele, B., 1996: Interaction of cyclic AMP- and calcium-dependent mechanisms in the regulation of growth hormone-releasing hormone-stimulated growth hormone release from ovine pituitary cells. Growth hormone-releasing hormone (GHRH)-stimulated growth hormone (GH) release from the sheep pituitary is mediated through Ca(2+)-and cyclic AMP-dependent mechanisms. The initial Ca2+ influx is suggested to result from depolarization, whereas a s...

Schernthaner G.; Stephenson J.; Pietschmann P., 1988: No evidence for negative feedback regulation of growth hormone secretion via somatomedin c in insulin dependent diabetic patients. Diabetes Research & Clinical Practice 5(SUPPL 1): S95

Hashizume, T.; Kanematsu, S., 1995: Additive effects of pituitary adenylate cyclase. Activating polypeptide and growth hormone releasing hormone on the release of growth hormone from cultured bovine anterior pituitary cells. Additive effects of pituitary adenylate cyclase-activating polypeptide (PACAP) with growth hormone releasing hormone (GHRH) on the release of growth hormone (GH) were studied in cultured bovine anterior pituitary cells. The combined stimulatory ef...

Houben, H.; Denef, C., 1992: Negative regulation by dexamethasone of the potentiation of neuromedin C-induced growth hormone and prolactin release by estradiol in anterior pituitary cell aggregates. The bombesin-like peptide neuromedin C (NMC) stimulated the release of growth hormone (GH) and prolactin (PRL) from adult male rat anterior pituitary cell aggregates cultured in serum-free medium. This effect, particularly on GH release, was signi...