Prenatal Effect of Fluoxetine on Nociceptive System Reactivity and Psychoemotional Behavior of Young Female and Male Rats

Reactivity of the nociceptive system, psychoemotional behavior and cognitive abilities in female and male rats born to mothers that were exposed to chronic injection of fluoxetine, a serotonin reuptake inhibitor, on days 9–20 of pregnancy were studied in a battery of behavioral tests during the prepubertal period. It was found that chronic injection of physiological saline to pregnant females evoked enhanced nociceptive responses in their offspring of both sexes while fluoxetine injection neutralized the effects of such an invasive intervention, demonstrating thereby the antinociceptive effect of this agent. Negative effects of maternal fluoxetine included a weight loss in the neonate offspring of both sexes and 25-day-old males, as well as the increased anxiety level in females only as detected in the elevated plus maze test. Fluoxetine had no effect on the level of depressive-like behavior in the forced swim test in rats of both sexes. The positive prenatal effect of fluoxetine manifested itself in males as an improved spatial learning ability in the Morris water maze; the anti-nociceptive effect of chronic fluoxetine injection, as compared to the pro-nociceptive effect of chronic saline injection, can also be considered as a positive effect of fluoxetine. Sex differences in the prenatal effect of fluoxetine were revealed in the anxiety level with more anxiety behavior in females.