Plasticity in the lateral habenula after adult-newborn interactions

Parenting is essential for the well-being of newborns. Laboratory virgin female mice exhibit parental behaviors, including pup retrieval, a phenotype that becomes progressively more efficient when exposed to multiple pups. Yet, the neuronal substrate that supports such behavioral improvement remains unexplored. Previous studies highlight the lateral habenula (LHb) as a substrate for parental behaviors in virgin females. Notably, a population of LHb cells innervated by the excitatory bed nucleus of the stria terminalis (BNST) shows increased activity during pup retrieval. Consistently, perturbation of BNST-LHb pathway abolishes such behavior. Thus, we hypothesize that in virgin females, synaptic plasticity in LHb shapes neuronal function during the pup retrieval females perform across multiple newborns.To test this hypothesis, we first assessed pup retrieval performance by dividing different groups of virgin females into those exposed to one pup, seven pups or only to the behavioral context. Subsequently, we performed whole-cell patch-clamp recording in acute brain slices to assess LHb synaptic strength by examining GABAARs- and AMPARs-mediated transmission.Our results showed an increased retrieval probability in virgin females exposed to multiple pups, while no retrieval occurred in the single-pup exposure group. One hour after the last pup exposure, no significant differences were detected in either evoked or spontaneous AMPARs- and GABAARs-mediated synaptic transmission onto LHb cells.These data indicate that excitatory/inhibitory balance in LHb is not affected after pup retrieval in virgin females. Ongoing experiments want to test whether LHb intrinsic properties or synaptic adaptations at specific inputs are instead affected after multiple pup exposure.