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Physiological and pharmacological regulation of 20-kDa growth hormone

Abstract

The 20-kDa growth hormone (GH) is generated from alternative splicing of the primary transcript of full-length 22-kDa GH. We have studied the regulation of 20-kDa GH over a range of pathophysiological conditions and in response to pharmacological stimulation using isoform-specific enzyme-linked immunosorbent assays (ELISAs). Mean 24-h levels of 20- and 22-kDa GH were higher in acromegaly and lower in GH deficiency than in normal subjects, with the 20-to-22-kDa ratio not different between the three groups. In normal subjects, 20-kDa GH was secreted in a pulsatile manner throughout the day, with peaks coinciding with those of 22-kDa GH. However, the half-life of 20-kDa GH (18.7 +/- 0.8 min) was significantly longer than that of 22-kDa GH (14.7 +/- 0.8 min; P < 0.02). Insulin-induced hypoglycemia, androgen, and oral estrogen caused a parallel and proportionate increase in both isoforms. Octreotide suppressed 20-kDa less rapidly than 22-kDa GH in blood. Administration of recombinant 22-kDa GH in normal subjects rapidly reduced the 20-kDa GH levels. In conclusion, 20-kDa GH is cosecreted with and circulates at a constant proportion of 22-kDa GH. The 20-kDa GH level is reduced by administration of exogenous 22-kDa GH, suggesting rapid negative feedback regulation on pituitary release.

Type Journal
ISBN 0193-1849 (Print)
Authors Leung, K. C.;Howe, C.;Gui, L. Y.;Trout, G.;Veldhuis, J. D.;Ho, K. K. :
Publisher Name AM J PHYSIOL-ENDOC M
Published Date 2002-01-01 00:00:00
Published Volume 283
Published Issue 4
Published Pages E836-43
URL http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12217902
Status Published In-print