METHODS: Two rat models were used: (i) ovariectomised, sex-steroid replaced and (ii) intact, at different phases of oestrous cycle. A day after completion of sex-steroid treatment or following identification of oestrous cycle phases, rats were sacrificed and expression and distribution of these proteins in uterus were identified by Western blotting and immunohistochemistry, respectively.
RESULTS: Expression of TRα-1, TRβ-1, TSHR, VDR, RAR and ERK1/2 in uterus was higher following estradiol (E2) treatment and at estrus phase of oestrous cycle when E2levels were high. A relatively lower expression was observed following progesterone (P) treatment and at diestrus phases of oestrous cycle when P levels were high. Under E2influence, TRα, TRβ, TSHR, VDR, RAR and ERK1/2 were distributed in luminal and glandular epithelia while under P influence, TSHR, VDR abn RAR were distributed in the stroma.
CONCLUSIONS: Differential expression and distribution of TRα-1, TRβ-1, TSHR, VDR, RAR and ERK1/2 in different uterine compartments could explain differential action of thyroid hormone, TSH, vitamin D, and retinoic acid in uterus under different sex-steroid conditions.