Abstract

DDT is a pesticide still indiscriminately used in several Third World countries. It contaminates the environment, including food, thus affecting human health and the survival of wild animals. It has been reported that its o,p' isomer exerts estrogen-like activity that has not been detected for the p,p' isomer. This study investigates the possible estrogenic activity of p,p'-DDT on genomic and nongenomic parameters of estrogen action. Additionally, its effects on the degranulation of eosinophil leukocytes in the blood were investigated. Female nonovariectomized immature rats and female adult ovariectomized rats were intravenously injected with p,p'-DDT dissolved in dimethyl sulfoxide or with estradiol-17?. The animals were killed at 6 or 24 h after treatment, the uterine horns excised, fixed in neutral formalin, and submitted to further histological procedure. Samples of blood were collected into glass vials containing EDTA and processed for evaluation of eosinophil degranulation. The results revealed myometrial hypertrophy and the development of edema in superficial and deep endometrial stroma under the effect of DDT, at 24 h after treatment, similarly to the effect of estradiol-17?. Further, they revealed an increase in degranulation of the blood eosinophils at 6 and 24 h after treatment with estradiol or DDT. The results confirm the estrogenic activity of the least toxic DDT isomer, for both genomic responses and eosinophil-mediated nongenomic responses and explain in part the reproductive effects of the pesticide in humans and in wild animals. Further, considering its effects on blood eosinophils, suggests a possible interaction with immune regulation and other processes where eosinophils play a role.