The effects of embelin (a benzoquinone compound of plant origin) on some reproductive parameters of female sprague-dawley rats.
Embelin is a plant extract widely used as a herbal medicine against a wide range of ailments in humans. Its use has been associated with sexual debility in male subjects. Studies have shown that it actually posses anti-fertility properties in male laboratory animals. In female rats, it has been shown to cause fetal resorption and to reduce ovarian weights. However, studies in the female have not explicitly elucidated the changes that take place at endocrinological level; neither have they described ovarian morphological changes nor the evolution of estrous cycles associated with embelin exposure. This study aimed to accomplish the above. The effects of embelin on the evolution of estrous cycles, progesterone and estradiol profiles and ovarian histopathology were examined. Thirty adult (4 months old) regularly cycling female Sprague-Dawley rats were used. They were given I mllkg bwt. Corn oil (groupI-control, n=10); or embelin dissolved in corn oil at 10 mg/kg bwt. (groupll-experimental, n=10) and 20 mg/kg bwt. (groupl lI-experimental, n=10). The treatments were given subcuteneously on alternate days for 20 days. Thus, each animal received a total of 10 injections by the end of the experiment. Oestrous cycles were monitored daily by vaginal cytology. Ovarian histopathology and progesterone and estradiol levels were assessed by standard procedures. Subcutaneous injections of embelin in this animal model resulted in the disruption of the regular oestrous cycle patterns. Specifically, 3 animals out of lOin group II (10 mg/kg bwt. ) and 4 animals out of lOin group III (20 mg/kg bwt. ) essentially remained in dioestrus by the fifth injection. There was a significant depression of plasma estradiol (P<0.05) and progesterone (P<0.02) at both dose levels. Histopathological evaluation of the ovaries from the embelin treated rats revealed the presence of abnormal follicles. In most follicles, the oocytes showed distortions in their symmetries. There were no significant changes in the liver and pituitary glands. In a separate experiment, mixed ovarian cells were isolated from another set of normally cycling rats and directly challenged with embelin in vitro. ix Results from theses studies revealed that embelin also suppresses estradiol and progesterone secretion by isolated mixed ovarian cells. These data demonstrate that embelin suppresses plasma estradiol and progesterone levels; disrupts the evolution of the regular oestrous cycles and also affects ovarian morphology in rats. The results further demonstrate that embelin probably exerts its effects by acting directly on ovarian cells.