Progesterone effect on intracellular inorganic sulphate in uterine epithelial cells

The effect of progesterone on the available intracellular sulphate pool in subcultured glandular epithelial cells from guinea-pig endometrium is reported. Progesterone in concert with 17β-estradiol was shown to cause an increase in the available intracellular sulphate pool. The maximum effect was obtained for 10 −8 M and 10 −7 M progesterone. This effect of progesterone on the available intracellular sulphate pool essentially concerned the intracellular inorganic sulphate and was inhibited by the antiprogesterone steroid RU 486 (5 × 10 −7 M). Sulphate incorporation into the endometrial epithelial cells was suppressed by the inhibitor of anion transport diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and the protein synthesis inhibitor, cycloheximide. These results would suggest that a sulphate transport system may be involved in the accumulation of the intracellular sulphate, stimulated by progesterone. This phenomenon could be an early process in the preparation of the endometrium for implantation.