Effects of Methanol Extract of <em>Piper umbellatum</em> Leaves on Contraceptive and Sexual Behaviour in Rodents

Résumé

Effects of methanol leaves extract of Piper umbellatum on conception and sexual behaviour were investigated in rodents. The leaves of Piper umbellatum, a rapidly growing shrub of Piperaceae family has a reputation as a fertility regulating plant among the Ibibio tribe of South-South region of Nigeria. This study was designed to investigate if the leaves possess any true contraceptive properties. Adult female rats and mice, having regular estrus cycle confirmed by daily smear analysis were used. The selection of animals for use in the study was determined by the presence of at least two consecutive 4-day estrus cycle. The animals were administered with 192 - 576 mg/kg body weight intraperitoneally (i.p) of extract in divided doses for 4 days. On the 5th day, fertile males were introduced using 3:1 (F/M) ratio and were allowed to remain with females until the experiment was terminated. Estrogenic and antiestrogenic activities of the extract were assessed in bilaterally ovariectomized immature rats, estrus and ovulatory effects were determined on sexually matured female rats while mount frequency, lordosis frequency, lordosis latency and lordosis quotient were the indices of female sexual behaviour determined. The extract protected the rodents from conception from one to three gestational periods. There were no fetal abnormalities observed in the pups. It also caused a significant (p<0.001) dose-dependent increase in uterine wet weight and vaginal opening; however, its vaginal cornification was not progressive in rats. It inhibited in a dose-related fashion regular estrus cycle and ovulation respectively. The extract increased both lordosis quotient and its frequency while the latency was decreased indicating involvement of phytoestrogen in the extract. The exhibited contraceptive effects which confirm its folkloric use may in part be due to its secondary metabolites which included phenols and saponins among others.