Effects of fluoxetine and imipramine in rat fetuses treated during a critical gestational period: a macro and microscopic study.

Objective: To evaluate morphological alterations in rat fetuses treated with fluoxetine and imipramine during the "critical" period of gestation.

Method: Fifteen female rats were separated into three groups (n = 5) and treated with 10 mg/kg/day of test substances on the ninth, tenth and eleventh day of pregnancy: G1, fluoxetine; G2, imipramine hydrochloride; G3 (control), saline. On day 21, cesarean sections were performed to release the fetuses, whose bodies were weighed and macroscopically analyzed. The placenta was also weighed. The fetuses were then fixed and their encephala removed and weighed. Sections of the frontal lobe were taken for histological neuron counting.

Results: G1 and G2 showed the highest fetal body weight. Placental weight showed statistical differences (p < 0.01): G1 weighed more than G2 and G3. Otherwise, G2 exhibited the highest encephalon weight, statistically differing from G3 (control) and fluoxetine-treated G1 (p < 0.01). However, G1 did not statistically (p > 0.01) differ from the control group. G3 showed the highest number of neurons per area when compared to G1 and G2 (p < 0.01).

Conclusion: The use of antidepressants in rats caused an increase in fetal weight and a decrease in the number of fetal frontal lobe neurons, thus suggesting that the use of antidepressants by pregnant women can induce depression in fetuses due to alterations in their neural development.