The effect of steroid hormone on oxytocin receptor expression in primary human uterine myometrial cell culture
Adachi, S.; Oku, M.; Fujii, E.; Otsuki, T.; Ichijyo, M.; Morimoto, K.
Nihon Sanka Fujinka Gakkai Zasshi 45(9): 987-993
1993
ISSN/ISBN: 0300-9165 PMID: 8396613 Document Number: 405907
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.