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During and following pregnancy, women are at high risk of experiencing depression, for which fluoxetine (FLX; brand names Prozac, Sarafem, Rapiflux) is the most commonly prescribed treatment. An estimated 1.4-2.1% of pregnant women use this medication, which inhibits the reuptake of serotonin and thereby increases serotonergic activity at the synapse. Serotonin acts as a cue guiding numerous neurodevelopmental processes, and changes in the concentration of serotonin can disrupt normal in utero brain development and organization in humans and other animals, thus providing a mechanism by which maternal intake of FLX might alter neural development and ultimately behaviour. Despite this possibility, long-term alterations of behaviour and the brain have not been well studied in individuals exposed to FLX during pregnancy or soon after birth, perhaps because conducting such studies beyond infancy presents significant challenges. To remedy this problem, many researchers have turned to modelling the effects of developmental FLX exposure in non-human animals, primarily rodents. The body of literature on this topic has expanded considerably over the past several years, yet a comprehensive review is lacking. In order to fill this gap, we have summarized the findings of those studies describing the long-term behavioural and neurophysiological effects of FLX exposure in non-human animals in early development. We also discuss methodological considerations and common shortcomings of research in this area. The precise nature of the long-term effects of developmental FLX exposure remains difficult to specify, as these effects appear to be highly variable and dependent on numerous factors. Overall, however, it is clear that early FLX exposure in non-human animals can alter the development of the brain in ways that are relevant to behaviour in adulthood, decreasing exploration and social interaction, and in some cases altering anxiety- and depression-like behaviours.

Rationale: Fluoxetine (Flx; brand names Prozac, Sarafem, Rapiflux), a selective serotonin reuptake inhibitor, is prescribed for the treatment of depression in pregnant women; however, this commonly prescribed medication could affect fetal brain development as Flx crosses the placenta. The available data concerning the anatomical and behavioural consequences of perinatal exposure to Flx during early development on adult behaviour are limited and often contradictory. Objectives: To further delineate the long-term behavioural effects of altering 5-HT during development, we examined the effects of perinatal Flx exposure on the behaviour of male mice as adults. Methods: Dams were treated with approximately 25 mg/kg/day of Flx from embryonic day 15 to postnatal day 12, and the behaviour of the adult offspring was assessed. Results: We found that perinatal Flx exposure leads to increased aggression, improved spatial memory, and reduced anxiety-like behaviour. This exposure did not cause memory deficits, changes in sensory processing, or changes in gross motor function. Conclusions: Our results suggest that while perinatal exposure to Flx may have long-term effects on adult behaviour, these effects appear limited and not necessarily detrimental.

Our results suggest that, in mice, perinatal exposure to either FLX, or PS, or their combination, leads to discernible, persistent changes in their circadian systems as adults.