RESUMEN
Zearalenone, a mycotoxin with estrogenic activity, is used in vivo to study its effect on some steroid transforming enzymes. The enzyme activities of 5 beta-reductase [EC. 1.1.1.125] and 17 beta-hydroxysteroid dehydrogenase [EC. 1.1.1.25] are involved in the metabolism of progesterone and estradiol-17 beta-. These hormones are responsible for the formation of mature ovum and prevention of abortion in females. Zearalenone was injected subcutaneously at a dose of 3.3 mg/kg body weight to female mature rats at estrus phase. Control rats were injected with 0.5 ml corn oil. After 48 hours treatment time, liver, uterine tissues and serum samples were used for enzymes assay using spectrophotometric methods. The activity of 5 beta reductase from hepatic and uterine preparations and serum samples was significantly higher in Zearalenone treated rats than that of control group [p < 0.0001]. The results also showed a significant increase in the activity of 17 beta-hydroxysteroid dehydrogenase [17beta-HSD] in the samples obtained from Zearalenone treated rats as compared with that of the control group [P < 0.0001]. Furthermore, the estrogenic effect of Zearalenone on the uterine weights of female rats was noted