Oxytocin inhibiting effect of the aqueous leaf extract of Ficus exasperata (Moraceae) on the isolated rat uterus.

The leaves of Ficus exasperata Vahl Enum. Pl. vahl (Moraceae) are used by traditional healers in Southern Nigeria and some parts of Africa to avoid preterm births. However, previous reports showed that the plant also exhibited uterine contractions at specific concentrations. This study is therefore aimed at investigating the purported uterine inhibitory aspect of the plant on the isolated rat uterus. The aqueous extract (AET) was tested on rhythmic spontaneous uterine contractions. Concentration-response relationships were obtained for oxytocin (OT), acetylcholine (ACh) and ergometrine (EGM), in the presence or absence of fixed concentrations of AET. Salbutamol (SBL) and verapamil (VER) were used as positive controls. AET, at 1.0 x 10(-2) mg/mL, significantly increased (p < 0.05) the EC50 of oxytocin-induced contractions but had no significant effect on ACh, EGM and spontaneous uterine contractions. However, SBL and VER significantly increased (p < 0.01) the EC50, of OT, ACh and EGM and significantly inhibited (p < 0.01) the frequency and amplitude of spontaneous uterine contractions. The aqueous leaf extract of F. exasperata inhibits oxytocin-induced uterine contractions at the concentration shown in this study. This observation may explain its folkloric use in counteracting preterm contractions and alleviating dysmenorrhoea.