Please use this identifier to cite or link to this item: http://hdl.handle.net/10553/53727
Title: Estrogen antagonism on T-3 and growth hormone control of the liver microsomal low-affinity glucocorticoid binding site (LAGS)
Authors: Lopez-Guerra, A
Chirino, R
Navarro, D
Fernandez, L 
Boada, LD 
Zumbado, M 
Diaz-Chico, BN 
UNESCO Clasification: 32 Ciencias médicas
Keywords: Male-Rat Liver
H-3 Dexamethasone Binding
Gene-Expression
Steroid-Hormones
Thyroid-Hormones, et al
Issue Date: 1997
Publisher: 0960-0760
Journal: Journal of Steroid Biochemistry and Molecular Biology 
Conference: 10th Congress of the International-Society-for-Endocrinology 
Abstract: Male rat liver microsomes contain a low-affinity glucocorticoid binding site (LAGS) capable of binding all natural glucocorticoids and progesterone with a K-d from 20 to 100 nM. The LAGS level is under endocrine control by T-3, glucocorticoids and GH. These hormones act synergistically at physiological concentrations to increase the LAGS level. Since female rats show a LAGS level that is much lower than the males (0.15 vs 23 pmol/mg protein, respectively), here we investigated whether estradiol could decrease the LAGS in the male rat. Orchiectomized (OX) male rats showed a higher LAGS level than intact rats. This effect was reversed by implanting a Sylastic capsule containing testosterone. When the OX rats were implanted for 20 days with estrogen capsules that provided an estradiol level in serum of 40 pg/ml, their LAGS level decreased from 23 to 0.2 pmol/mg protein. This effect was not observed in intact male rats and can be partially reversed by testosterone implants into OX rats. Both hypophysectomized male rats and hypothyroid-orchiectomized male rats showed very low levels of LAGS. Administration of physiological doses of GH and/or T-3 to these rats greatly increased their LAGS level (from 0.3 to 15 and 16 pmol/mg protein, respectively). Implantation of estrogen capsules to these rats two weeks prior to starting treatment completely inhibited the increase in the LAGS level in response to T-3, and significantly decreased the response to hGH, and to a combination of hGH and T-3. These results suggest that physiological estradiol levels call antagonize the LAGS induction by T-3 and hGH in the male rat, and could be responsible for the low level of LAGS in the female rat. Moreover, estrogen capsules also inhibited the increase in the body and hepatic weights observed after hGH treatment, which suggests a powerful inhibitory effect of low estradiol levels on the male rat liver functions under regulation by T-3 and/or GH. (C) 1997 Elsevier Science Ltd. All rights reserved.
URI: http://hdl.handle.net/10553/48090
ISSN: 0960-0760
DOI: 10.1016/S0960-0760(97)00123-4
Source: Journal Of Steroid Biochemistry And Molecular Biology[ISSN 0960-0760],v. 63 (4-6), p. 219-228
Appears in Collections:Artículos
Show full item record

Google ScholarTM

Check

Altmetric


Share



Export metadata



Items in accedaCRIS are protected by copyright, with all rights reserved, unless otherwise indicated.