Effect of growth hormone in an experimental model of protein hypercatabolism induced by glucocorticoids.
OBJECTIVE
The aims of the study were to evaluate whether growth hormone could be beneficial in a model of hypercatabolism induced by glucocorticoids and to examine its effects on ACTH, corticosterone and IGF-1 levels. The effects of growth hormone on the expression of both glucocorticoid receptor and tyrosine aminotransferase were also evaluated.


METHODS
Fifty Wistar rats were divided into five groups and treated as follows: (A) daily subcutaneous injection of growth hormone (4.8 IU/kg/day) and oral placebo, (B) daily injection of placebo and oral dexamethasone (3 mg/kg/day), (C) daily injection of growth hormone and oral dexamethasone, (D) daily injection of placebo and oral placebo, and (E) no treatment. The animals were decapitated seven days after initiating treatment.


RESULTS
Growth hormone did not modify the weight loss induced by dexamethasone. Glucocorticoid receptor expression was significantly lower in group A than in group E. An increase in tyrosine aminotransferase was observed in group C.


CONCLUSIONS
Growth hormone did not exert any beneficial effect in this model of hypercatabolism. Growth hormone decreased glucocorticoid receptor expression. This fact could explain its beneficial effect when protein hypercatabolism is not the predominant phenomenon. Growth hormone induced the hyperexpression of tyrosine aminotransferase, thus suggesting an amplifying effect on the glucocorticoid action.
Cantón
A
A
Department of Endocrinology, St Bartholomew's Hospital, London, UK. acanton.germanstrias@gencat.net
Trainer
P J
PJ
Martinez-Cáceres
E
E
Simó
R
R
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology; D019382:Human Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008659:Metabolic Diseases / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D014444:Tyrosine Transaminase / Q000235:genetics / Q000378:metabolism
D005938:Glucocorticoids; D011506:Proteins; D011965:Receptors, Glucocorticoid; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D014444:Tyrosine Transaminase; D003345:Corticosterone