Embriogênese inicial em ratas Wistar tratadas com extrato de Ginkgo biloba

Abstract

The Ginkgo biloba extract (EGb) is mainly used in the treatment for and in the prevention of neurodegenerative diseases. It is also used in the treatment for dizziness, age-related memory loss and as an anti-inflammatory. Effects of EGb on reproduction include fertilization inhibition through the reduction of spermatozoa viability and oocyte degeneration. When administered to male mice, EGb led to alterations in the weight of organs such as the prostate, and in the reproductive behavior of these animals (leading to lower pregnancy rates and embryo death increase). In female rats, EGb was proved to cause intra-uterine growth retardation, this effect being thought to be related to its estrogenic activity. Other studies have also shown EGb estrogenic effects. Adequate levels of estrogen, progesterone and prostaglandins are known to be very important to tubal transit and uterine implantation. Hence, there is the possibility of EGb causing embryonic development alterations when administered in the beginning of pregnancy. Investigating this possibility is the aim of this thesis. In order to achieve that, the following experimental protocol was carried out with 68 nulliparous pregnant Wistar rats. The rats were randomly distributed into four experimental groups (n=17): Control, Gb 3.5, Gb 7 and Gb 14, which were treated, respectively, with zero, 3.5, 7.0 and 14.0mg/Kg/Day of EGb diluted in 1mL of distilled water through gavage, once a day, during the first eight days of pregnancy. Rats were euthanized in the 15th day of pregnancy, through total exsanguination under anesthesia. The following parameters were assessed: clinical signs of maternal toxicity – such as feed and water intake alterations, body weight alterations, hyper or hypoactivity, piloerection, stereotypy, biochemical and hematological profile and death –; number of corpora lutea; maternal organs (ovaries, liver and kidneys) weight; maternal hematological and biochemical profiles; fetuses and placentas weight; number of viable, resorpted and dead fetuses; fetal malformations in both superior and inferior members, neural tube closure and facial morphology. Amongst the parameters evaluated, alterations were found only in the maternal hematological profile. There was significant raise in the cholesterol level and reduction in the levels of ALT, urea and creatinine for the animals treated with 7 and 14mg/Kg/day of EGb. No significant alteration was found for other maternal and fetal parameters evaluated. Hence, it seems that treatment with EGb during both tubal transit and implantation periods did not cause toxic effects to the maternal organism of Wistar rats. Neither did it induce deaths, intra-uterine growth retardation or fetal malformation. There is also evidence that EGb could present hepatoprotective and nephroprotective effects when administered to Wistar rats during pregnancy in the dosages of 7 and 14 mg/Kg/day.