HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Edwards, C. A. Articles by Scanlon, M. F. Search for Related Content PubMed Articles by Edwards, C. A. Articles by Scanlon, M. F.

The aim of this study was to investigate the role of thyroid hormones and glucocorticoids on GH secretion. Secretion of GH in response to GH-releasing hormone (GHRH) (5 µg/kg) was markedly (P < 0·001) decreased in hypothyroid rats in vivo (peak GH responses to GHRH, 635 ± 88 µg/l in euthyroid rats vs 46 ±15 µg/l in hypothyroid rats). Following treatment with tri-iodothyronine (T₃; 20 µg/day s.c. daily for 2 weeks) or cortisol (100 pg/day s.c. for 2 weeks) or T₃ plus cortisol, a marked (P <0·01) increase in GH responses to GHRH was observed in hypothyroid rats (peak GH responses, 326 ±29 µg/l after T₃ vs 133+19 µg/l after cortisol vs 283 ± 35 µg/l after cortisol plus T₃). In contrast, none of these treatments modified GH responses to GHRH in euthyroid animals. Hypothyroidism was also associated with impaired GH responses to the GH secretagogue, HisD-Trp-Ala-Trp-D-Phe-Lys-NH₂ (GHRP-6). Secretion of GH in response to GHRP-6 in vivo was reduced (P <0·01) in hypothyroid rats (peak GH responses, 508 ± 177 µg/l in euthyroid rats vs 203 ± 15 µg/l in hypothyroid rats). In-vitro studies carried out using monolayer cultures of rat anterior pituitary cells derived from euthyroid and hypothyroid rats showed a marked impairment of somatotroph responsiveness to both GHRP-6 and somatostatin in cultures derived from hypothyroid rats. In summary, our data suggest that thyroid hormones and glucocorticoids influence GH secretion by modulating somatotroph responsiveness to different GH secretagogues.

Journal of Endocrinology (1989) 121, 31–36

This article has been cited by other articles:

				A. Giustina and J. D. Veldhuis Pathophysiology of the Neuroregulation of Growth Hormone Secretion in Experimental Animals and the Human Endocr. Rev., December 1, 1998; 19(6): 717 - 797. [Abstract] [Full Text]