Does chorionic gonadotropin hormone have a direct action on uterine contractions?

ABSTRACT

Direct effect of chorionic gonadotropin hormone on uterine contraction in non pregnant and pregnant rats in early and late pregnancy was investigated in the present work. Isolated uteri suspended in organ bath containing Kreb's solution of PH 7.4 at 37C bubbled with carbogen were used. Spontaneous uterine contractions were recorded using isotonic transducer and an ossilograph. It was observed that CG inhibited the amplitude and frequency of uterine contractions. The mechanism of action was investigated. It was found that CG was not acting by increasing cAMP or cGmp or by decreasing calcium influx through voltage operated calcium channels or by decreasing calcium release from the internal myometrial store. But, CG may act by decreasing calcium influx through receptor operated calcium channels and by modulation of prostaglandins synthesis. Thus, CG can be considered one of the hormones which maintain uterine quiescence during pregnancy by direct action