Effect of ethanol extract of Rivea hypocrateriformis on the estrous cycle of the rat.

The ethanol extract of Rivea hypocrateriformis was administered orally at the dose levels of 200 and 400 mg/kg body weight to adult albino rats and resulted in an irregular estrous cycle with shortened estrus and metestrus, and with lengthened proestrus in non-dose dependent manner. Significant decreases in number of graffian follicles and corpora lutea and significant increases in number of atretic follicles in treated rats during experimental period indicated the antiovulatory effect of the extract. Increases in the weight of the uterus, its thickness and diameter indicated the uterotrophic effect of the extract. The significant increase in the level of cholesterol in the tissues of treated rats indicated the inhibition of steroidogenesis of cholesterol by ovarian endocrine tissues. Restoration of normal estrous cycles after withdrawal of treatment indicate the reversible effect of ethanol extract in rats. Copyright 2002 Elsevier Science Ireland Ltd.