Abstract
Estradiol (E2) and testosterone (T) can stimulate growth by increasing GH secretion. Sex steriods can also regulate growth affecting GH receptor (GHR) expression in target tissues. In order to stydy the effect of physiological concentrations of E2 and T on GHR expression, we measured liver GHR mRNA by solution hybridization-RNase protection assay in rabbits treated with E2 or T. Three to five immature rabbits in each group received a s.c. pellet containing placebo, E2 (0.1; 0.5; 1.5; or 5.0 mg) or T(15, 50, or 100 mg). Liver RNA samples were hybridized to a 32 P labelled GHR antisense riboprobe and digested with RNase. After gel electrophoresis a specific 370 base long protected band, corresponding to GHR mRNA, was quantitated by autoradiography and densitometry. Liver GHR mRNA levels were significantly lower than that in controls in animals treated with 1.5 (62%; p < 0.025) and 5.0 mg of E2 (13%; p<0.003), and significantly higher in those treated with 100 mg of T (230%; p<0.01). From these findings we conclude that E2 and T, at physiological concentrations, have an opposite effect on GHR expression. The decrease on GHR expression by E2 might explain the inhibitory effect of moderate dose of estrogens on growth.
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Domené, H., Yu, Y., Marin, G. et al. 34 DIFFERENTIAL: REGULATION OF GROWTH HORMONE RECEPTOR EXPRESSION BY ESTRADIOL AND TESTOSTERONE. Pediatr Res 36, 677 (1994). https://doi.org/10.1203/00006450-199411000-00058
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DOI: https://doi.org/10.1203/00006450-199411000-00058