Developmental fluoxetine exposure differentially alters central and peripheral measures of the HPA system in adolescent male and female offspring.

A significant number of women suffer from depression during pregnancy and the postpartum period. Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat maternal depression. While maternal stress and depression have long-term effects on the physical and behavioural development of offspring, numerous studies also point to a significant action of developmental exposure to SSRIs. Surprisingly, preclinical data are limited concerning the combined effect of maternal depression and maternal SSRI exposure on neurobehavioural outcomes in offspring. Therefore, the aim of the present study was to determine how maternal fluoxetine treatment affects the developing HPA system of adolescent male and female offspring using a model of maternal adversity. To do this, gestationally stressed and non-stressed Sprague-Dawley rat dams were chronically treated throughout lactation with either fluoxetine (5mg/kg/day) or vehicle. Four groups of male and female adolescent offspring were used: (1) Prenatal Stress+Fluoxetine, (2) Prenatal Stress+Vehicle, (3) Fluoxetine alone, and (4) Vehicle alone. Primary results show that developmental fluoxetine exposure, regardless of prenatal stress, decreases circulating levels of corticosterone and reduces the expression of the glucocorticoid receptor (GR), and its coactivator the GR interacting protein (GRIP1), in the hippocampus. Interestingly, these effects occurred primarily in male, and not in female, adolescent offspring. Together, these results highlight a marked sex difference in the long-term effect of developmental exposure to SSRI medications that may differentially alter the capacity of the hippocampus to respond to stress.