Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Though sex steroids are found to influence thyroid pathogenesis in human and in animals, their role in normal thyroid growth and thyrocyte proliferation is not yet understood fully. The present study is addressed to know the effect of testosterone and estradiol on the basal and TSH-induced thyrocyte proliferation in immature and adult rats in vitro. The male and female Wistar rats were gonadectomized (GDX) and one group of GDX rats were supplemented with either testosterone or estradiol. After the experimental period, the rats were sacrificed by decapitation and thyroid glands were removed, washed in Hank's Balanced Salt Solution (HBSS), pH 7.4 and digested with the enzyme mixture containing 0.08% collagenase and 0.12% dispase in HBSS. The isolated follicles were washed thrice with Dulbecco's modified Eagle's medium (DMEM) containing 0.5% fetal bovine serum (FBS), and were cultured in Falcon's tissue culture flasks containing 5 ml DMEM with FBS (5%) transferrin (5 microg/ml), hydrocortisone (10(-8) M), somatostatin (10 microg/ml), insulin (10 microg/ml) and glycyl-L-histidyl-L-lysine acetate (10 microg/ml). The cells (2.5 x 10(4)) were exposed to various exponential doses of TSH or testosterone (6.25-800 ng/ml) or estradiol (6.25-800 pg/ml). It is suggested from the present study that both TSH and sex steroids enhance thyrocyte proliferation. The mitogenic effect of TSH is greater than that of sex steroids. Sex steroids modulate TSH-induced cell proliferation in a gender-specific manner.
Steroids 2002 Jun
PMID:Testosterone and estradiol differentially regulate TSH-induced thyrocyte proliferation in immature and adult rats. 1199 29

Thyroid gland is one of the non-classical target organs for sex steroids. Presence of androgen and estrogen receptors in the neoplastic and non-neoplastic thyroid glands of mammalian species is well documented. The aim of the present study is to elucidate the changes in serum and thyroidal sex steroids, and their receptors in the thyroid gland of rats from immature to adult age under gonadectomized (GDX) and sex steroids replaced conditions. Normal Wistar male and female rats from immature to adult age (day 21, 30, 45, 60 and 160 post-partum (pp)) were used in the present study. One group (I) of rats was GDX at an early age (day 10 pp) and the other group (II) at the adult age (day 120 pp). Group I rats were sacrificed at different experimental periods such as 21, 30, 45 and 60 days pp, and group II rats were sacrificed at day 160 pp. Another group of GDX rats from group I and II were replaced with physiological doses of testosterone or estradiol. Serum and thyroidal concentrations of sex steroids were estimated by RIA method and the concentrations of receptors by radioreceptor assay. Gonadectomy significantly decreased serum and thyroidal testosterone and estradiol and concentrations of androgen receptor (AR) and estrogen receptor (ER) in the thyroid. Replacement of sex steroids to GDX rats restored the normal level of sex steroids, AR and ER. Therefore, it is suggested from the present study that (i). sex steroids up-regulate their own receptors in the thyroid, (ii). sex steroids may influence thyroid growth and the proliferation of thyrocytes by modulating their receptor concentrations in the thyroid.
Steroids 2002 Dec
PMID:Testosterone and estradiol up-regulate androgen and estrogen receptors in immature and adult rat thyroid glands in vivo. 1244 Nov 85