Maternal care and maternal aggression are representative maternal behaviors in rodents. These behaviors are displayed alternatively. The dorsal raphe nucleus (DRN) regulates both nurturing and aggressive behaviors. In the present study, we examined whether the DRN are involved in regulating alternative display of maternal care and aggression. We first examined the neuronal activity in the the medial prefrontal cortex (mPFC) and lateral habenula (LHb), which send glutamatergic inputs into the DRN, in dams with a retrograde tracer Fluorogold injected into the DRN. The number of c-Fos- and Fluorogold-positive neurons in the mPFC and LHb increased in the dams that displayed biting behavior in response to an intruder, but remained unchanged in the dams that displayed nurturing behavior. Injections of N-methyl-D-aspartic acid (NMDA) receptor antagonists or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonists into the DRN inhibited biting behavior but not nurturing behavior. In contrast, injections of NMDA or AMPA into the DRN inhibited nurturing behavior. These results suggest that glutamatergic signals in the DRN, which may originate from the mPFC and/or LHb, regulate the preferential display of biting behavior over nurturing behavior in dams.

To: 要旨(抄録)