Chronic fluoxetine treatment and maternal adversity differentially alter neurobehavioral outcomes in the rat dam

The incidence of stress and stress-related disorders with the transition to motherhood, such as postpartum depression, is estimated to be 20%. Selective serotonin reuptake inhibitor (SSRI) medications are currently the antidepressant of choice to treat maternal mood disorders. However, little is known about the effects of these medications on the maternal brain and behavior. Therefore, the present study investigated how a commonly used SSRI, fluoxetine, affects neurobehavioral outcomes in the mother using a model of maternal adversity. To do this, gestationally stressed and non-stressed Sprague-Dawley rat dams were treated with either fluoxetine (5 mg/kg/day) or vehicle. Dams were divided into four groups: (1) Control + Vehicle, (2) Control + Fluoxetine, (3) Stress + Vehicle and (4) Stress + Fluoxetine. Fluoxetine or vehicle was administered to the dam during the postpartum period via osmotic minipump implants (Alzet) for 28 days. Results show that chronic fluoxetine treatment, after exposure to gestational stress, significantly decreased serum levels of corticosteroid binding globulin and increased hippocampal neurogenesis. In the absence of maternal stress, fluoxetine treatment alone significantly increased maternal arched-back nursing of pups, increased anxiety-related behavior, and decreased serum levels of corticosterone and corticosteroid binding globulin in the dam. This research provides important information on how SSRIs may act on the behavior, physiology, and neural plasticity of the mother. Although this is a first step in investigating the role of antidepressant treatment on the mother, much more work is needed before we can understand and improve the efficacy of these medications to treat mood disorders in pregnant and postpartum women.