Avaliação do efeito estrogênico do Ginkgo biloba em ratas Wistar impúberes

Abstract

The use of hormonal therapy in menopause is not absent of risks being related to adverse effects such as pulmonary embolism and cancer due to its use. In these cases, phytoestrogens, the estrogenic compounds present in plants, can be used as an alternative to the hormonal treatment. There is already proof of efficacy and safety in their use. Ginkgo biloba extract, one of the most consumed phytotherapics in the world, used to the treatment of circulatory and neurologic disturbs, produced estrogenic effect in vitro in MCF7 tumoral cells and promoted alteration in the vaginal epithelium of mice, suggesting a possibility of being used as a phytoestrogen. However, there are not conclusive studies in vivo indicating the estrogenic effect of any Ginkgo biloba extract, being this the objective of this work. In this experiment seventy 22 day-old impuberal Wistar rats were used. The rats were weighed and randomly distributed into seven groups with ten animals each. The negative control group received 0.4mL of distilled water, by gavage. The positive control group received 1 µg/Kg of 17α-estradiol in 0.3mL of mineral oil, by subcutaneous injection. The treated groups received Ginkgo biloba extract in doses of 4, 40, 100, 500 and 1000mg/Kg/day, administered in 0.4mL of aqueous solution, by gavage. The administration of the solutions occurred once a day during three days. After 24 hours from the last day of treatment the presence of vaginal opening was analyzed and the animals were euthanized to remove the reproductive tract. The uterus was separated from the vagina and from the ovaries and then weighted. The uterine horns and the vagina were fixed to histomorphometric analysis and vaginal mucosa and uterine superficial epithelium thickness were measured. Statistical comparisons were made, using ANOVA, followed by post hoc Tukey or Dunnett T3. The level of significance of tests was α = 0.05. The Ginkgo biloba treatment did not alter the body weight neither the uterine weight. The vaginal mucosa thickness was thinner in the animals that received 1000mg/Kg of the extract. In the animals treated with 4, 40, 100 and 500mg/Kg of Ginkgo biloba it was observed that the uterine superficial epithelium was thicker. We conclude that the Ginkgo biloba extract studied showed indications of an estrogenic effect when administered to Wistar rats with doses of 4, 40, 100 and 500mg/Kg and an anti-estrogenic effect with a dose of 1000mg/Kg.