Work

Regulation of growth hormone secretion from human fetal pituitaries : interactions between growth hormone releasing factor and somatostatin

Year: 1987

Type: article

Abstract: Using an explant culture system, we have demonstrated that human somatotropes respond to growth hormone releasing factor (GRF) and somatostatin (SRIF) from as early as 9.5 weeks of fetal age.Responsiveness to GRF increases significantly as a function of age up to midgestation while SRIF inhibition of basal growth hormone (GH) release does not change.SRIF has little effect on GRF-stimulated GH secretion from early gestation pituitaries, but its ability to block GRF stimulation gradually increases with fetal age from 9.5 to 16 weeks.The response to GRF remains predominant throughout this developmental period : 100 times more SRIF than GRF must be added to the cultures in order to block the GRF stimulatory effect and maintain GH secretion at basal (control) levels.Finally, adding SRIF 30 min prior to the GRF does not increase the inhibitory activity of SRIF.Our data suggest that the mechanisms that permit an interaction between GRF and SRIF are developing, but slowly, in the early to midgestation human fetal somatotrope and that GRF stimulatory pathways predominate.This may help to explain the very high levels of GH in fetal serum during the first half of gestation.Introduction.Serum growth hormone (GH) levels are detectable as early as 9-10 weeks of gestation in the human ; they rise rapidly, reaching a peak (= 130 ng/ml) at 20- 24 weeks, then decrease gradually until birth (Kaplan and Grumbach, 1976).However, even at the end of gestation, circulating levels of GH are high : they are significantly elevated above what is seen in the normal adult and are often in the range found in acromegalics.Using a pituitary culture system, we have been investigating the ontogeny of pituitary responsiveness to known regulators of somatotrope activity, to ( * ) This work was supported by the Medical Research Council of Canada.

Source: annales de biologie animale biochimie biophysique

DOI: 10.1051/rnd:19870402

Authors: Cynthia G. GOODYER, J.-M. SELLEN, Maria FUKS, Charlotte L. BRANCHAUD, Y. LEFEBVRE

Institutions: Montreal Children's Hospital, Hôpital Notre-Dame, McGill University

Language: English

Topic: Growth Hormone and Insulin-like Growth Factors

Subfield: Endocrinology, Diabetes and Metabolism

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: Medical Research Council Canada, Medical Research Council