Genistein alters oestrous cyclicity, oocyte fertilization and implantation process in rats

Abstract

Background: The occurrence of phytoestrogens in food gaining increasing attention due to the acclaimed health benefits.

Objective: This study examined the effect of genistein on estrous cyclicity, fertilization of ovulated oocytes, foetal weight, female hormones and possibilities of reversal of any detrimental effects in rats.

Methods: Estrous cycle was monitored before and during genistein administration, blood samples were collected for hormonal analysis at terminal days. Some rats were sacrificed on second day of pregnancy, the oviducts were
removed and flushed for collection of fertilized and unfertilized oocyte.

Results: Genistein adversely altered the estrous cycle with significant reduction in body-weight gained, increase in uterine weight, reduction in the percentage of the ovulated oocyte that were fertilized despite no significant change in the number of ovulated oocyte. Pregnancy was characterized with reduction in circulating progesterone level along with significant reduction in number of implants, corpora lutea count, pituitary weight and foeto-placenta weight. The increased resorption of implants was attributed to the reduction in progesterone level and a reduction in the surviving corpora lutea. These adverse effects were not reversed within the seven days recovery allowed of administration.

Conclusion: Results also showed that oral exposure to genistein not only alters oestrous cyclicity and fertilization of ovulated oocytes, but exposure during pregnancy in rats, precipitates adverse effects on pregnancy due to its inhibitory effects on corporal luteum survival, and progesterone production.

Keywords: Genistein, oocyte, foetal growth, corpora lutea count, female hormone, Hotzman strain rat