Nihon Sanka Fujinka Gakkai zasshiJul 1, 1993

Steroid hormones influence calcium changes and oxytocin receptor levels in human uterine muscle cells after oxytocin stimulation

Circadian Biology Weekly Brief ↗PubMed ↗

Updated Apr 4, 2026

Abstract

The addition of 10(-6) M dehydroepiandrosterone sulfate (DHAS) raised intracellular calcium levels by 207% following oxytocin stimulation in human myometrial cells.

Oxytocin stimulation resulted in a 100% increase in intracellular calcium levels.
Dehydroepiandrosterone sulfate (DHAS) significantly enhanced calcium response, while progesterone decreased it to 64%.
DHAS accelerated the rate of calcium increase, whereas progesterone slowed it down.
Oxytocin receptors of 350kD and 39kD were extracted from human myometrial plasma membranes for binding studies.
DHAS improved the binding affinity of oxytocin receptors, while progesterone reduced their maximum binding capacity.
Steroid hormones may influence calcium responses through effects on receptor levels shortly before oxytocin stimulation.

Simplified

It is considered that steroid hormones, the concentrations of which vary during pregnancy, play an important role in the initiation of delivery. In the present study, we measured intracellular Ca2+ ([Ca2+]i) change following oxytocin stimulation in cultured human myometrial cells with fura-2, a fluorescent Ca2+ indicator. We also studied the effect of the steroid hormones on changes in [Ca2+]i due to oxytocin stimulation. When the [Ca2+]i change due to 10(-6) M oxytocin reached 100%, the addition of 10(-6) M DHAS (dehydroepiandrosterone sulfate) just before the stimulation raised the [Ca2+]i level to 207%, whereas that of 10(-6) M progesterone dropped to 64%. Moreover DHAS accelerated the speed of increase until the maximum response of [Ca2+]i, while progesterone decelerated it. In another study, human myometrial plasma membrane was solubilized in 7.5mM CHAPSO solution and applied to a binding study. Oxytocin receptors of two different molecular weights, namely 350kD(OTR-1) and 39kD(OTR-2), were extracted from solubilized plasma membrane by employing a gel filtration column. Binding assays were performed for OTR-1 and OTR-2 in the presence of DHAS and progesterone (10(-5) M). The results showed that DHAS enhanced the binding affinity of the receptors, whereas progesterone reduced the maximum binding capacity. It is therefore considered that the steroid hormones added just before oxytocin stimulation might act on receptor levels and modify intracellular Ca2+ response over short periods.

Steroid hormones influence calcium changes and oxytocin receptor levels in human uterine muscle cells after oxytocin stimulation

Abstract

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