Poster abstracts
Poster number 83 submitted by Courtney Dye
Microglia depletion facilitates the display of maternal behavior and alters activation of the maternal brain network in nulliparous female rats
Courtney Dye (Neuroscience Graduate Program ), Dominic Franceschelli (Psychology Department ), Benedetta Leuner (Psychology Department, Neuroscience Department ), Kathryn M. Lenz (Psychology Department, Neuroscience Department, Institute of Behavioral Medicine Research)
Abstract:
During the course of a pregnancy, brain circuitry important for aversion behavior needs to be inhibited, while reward-related pathways need to be activated for the successful onset of maternal care in the postpartum period. We have previously demonstrated that there are also significant neuroimmune changes that emerge during pregnancy and persist into the postpartum period. This most prominently includes decreased numbers of microglia, the brain’s innate immune cell, across limbic brain regions important for maternal care. Here we tested the hypothesis that this microglial downregulation is important for the onset and display of maternal behavior. To test this, we recapitulated the peripartum neuroimmune profile by depleting microglia in non-mother (i.e., nulliparous) female rats who are typically not maternal but can be induced to behave maternally towards foster pups after repeated exposure, a process called maternal sensitization. BLZ945, a selective colony-stimulating factor 1 receptor (CSF1R) inhibitor, was administered systemically to nulliparous rats, which led to ~75% decrease in microglia number. BLZ- and vehicle-treated females then underwent maternal sensitization and tissue stained for ∆fosB to examine activation across maternally relevant brain regions. We found BLZ-treated females with microglial depletion met criteria for displaying maternal behavior significantly sooner than vehicle-treated females and displayed increased pup-directed behaviors. Microglia depletion also reduced threat appraisal behavior in an open field test. Notably, nulliparous females with microglial depletion had decreased numbers of ∆fosB+ cells in the medial amygdala and periaqueductal gray, and increased numbers in the prefrontal cortex and somatosensory cortex compared to vehicle. Our results provide novel evidence that microglia regulate maternal behavior in adult females, possibly by shifting patterns of the activity in the maternal brain network.
Keywords: microglia , maternal behavior