Document Detail

Altered release of growth hormone from dispersed adenohypophysial cells of streptozotocin diabetic rats. I. Effects of growth hormone releasing factor and somatostatin.
MedLine Citation:
PMID:  2575447     Owner:  NLM     Status:  MEDLINE    
As growth hormone has been implicated in the "dawn phenomenon," an early morning rise in serum glucose, we have studied the control of growth hormone release in diabetes using an acutely dispersed system of adenohypophysial cells from normal or diabetic rats (65 mg/kg streptozotocin, 8 days before sacrifice; serum glucose, 490 +/- 17 mg/dL). Growth hormone release is normally controlled by the two hypothalamic hormones, growth hormone releasing factor and somatostatin. We have found cells of the diabetic rats exhibit changes in sensitivity that result in increased growth hormone release in static incubation. In normal cells, rat growth hormone releasing factor increases growth hormone release three- to four-fold with an EC50 of 151 +/- 27 pM (n = 7). In contrast, in cells from diabetic rats, there was a significant (twofold) increase in sensitivity to growth hormone releasing factor (EC50 = 75 +/- 15 pM, n = 7) which resulted in increased growth hormone release with lower but not maximal (10 nM) growth hormone releasing factor. Basal nonstimulated release was unchanged. Somatostatin inhibition of stimulated growth hormone release was reduced (n = 7); half-maximal inhibition occurred with 0.21 +/- 0.03 nM (normal) and 0.76 +/- 0.17 nM somatostatin (diabetic). In perifusion the peak secretion rate was significantly lower for diabetic cells stimulated by a maximal dose of growth hormone releasing factor. These studies suggest somatotrophs of diabetic rats have altered sensitivity in vitro to the controlling hormones growth hormone releasing factor and somatostatin.
M S Sheppard; B A Eatock; R M Bala
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  67     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1989 Oct 
Date Detail:
Created Date:  1990-03-09     Completed Date:  1990-03-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  1315-20     Citation Subset:  IM    
Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
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MeSH Terms
Diabetes Mellitus, Experimental / metabolism*
Growth Hormone / secretion*
Growth Hormone-Releasing Hormone / pharmacology*
Pituitary Gland, Anterior / cytology,  drug effects,  secretion*
Rats, Inbred Strains
Somatostatin / pharmacology*
Reg. No./Substance:
51110-01-1/Somatostatin; 9002-72-6/Growth Hormone; 9034-39-3/Growth Hormone-Releasing Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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