Nihon Sanka Fujinka Gakkai zasshiSep 1, 1993

Steroid hormone effects on oxytocin receptor levels in human uterine muscle cells

Circadian Biology Weekly Brief ↗PubMed ↗

Updated Apr 4, 2026

Abstract

Estradiol increased oxytocin receptor binding values to 36.20 pM/mg protein at 72 hours in cultured human myometrial cells.

Oxytocin receptor binding values increased in the presence of estradiol at concentrations of 10(-8) M and 10(-7) M over 72 hours.
Dehydroepiandrosterone sulfate at 10(-5) M showed almost no effect on oxytocin receptor expression when combined with estradiol.
Cortisol at 10(-5) M decreased oxytocin receptor expression induced by estradiol.
Progesterone inhibited the increase in oxytocin receptor expression caused by estradiol in a concentration-dependent manner.
The concentration of progesterone that reduced oxytocin receptor binding by 50% was 2.7 x 10(-6) M.

Simplified

In the present study, we have examined the steroid hormone effect on oxytocin receptor (OTR) expression in human myometrial monolayer culture. The myometrial cells were cultured for 24-72 hours in serum-free media with various concentrations of steroid hormones. The plasma membrane of the cultured cells was then collected. The 125I-oxytocin(OT) was employed for a binding assay and the mean binding and dissociation constant were evaluated by Scatchard analysis. 1. The OT binding values in the presence of estradiol free, 10(-8) M, and 10(-7) M at 72 hours were 19.85, 28.12, and 36.20pM/mg protein, respectively. 2. The OT binding values in the presence of estradiol (10(-7) M) at 24, 48, and 72 hours were 17.85, 23.72, and 36.20pM/mg protein, respectively. 3. Dehydroepiandrosterone sulfate (10(-5) M) exerted almost no effect on the OTR expression by estradiol (10(-7) M). Cortisol (10(-5) M) decreased the amount of OTR expressed by estradiol. 4. The changes in OTR expression caused by estradiol (10(-7) M) were inhibited according to the concentration by progesterone. The concentration of progesterone at which OT binding was reduced 50% was 2.7 x 10(-6) M (E/P ratio = 0.037). These results suggested that estradiol increased the amount of OTR discovered in human myometrial cells in a time and concentration dependent manner, while progesterone inhibited the changes in OTR expression by estradiol in a concentration dependent manner. Thus, it was indicated that the changes in the E/P ratio during pregnancy which regulate the OTR expression control the myometrial contraction.

Steroid hormone effects on oxytocin receptor levels in human uterine muscle cells

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