Adolescent nicotine alters dendritic morphology in the bed nucleus of the stria terminalis

Abstract

Adolescent nicotine increases dendritic elaboration in several areas associated with the extended amygdala. It also increases anxiety-like behavior in adulthood. An unresolved question is whether adolescent nicotine alters dendritic structure in the bed nucleus of the stria terminalis (BNST), which may contribute to altered anxiety-like behavior. To investigate this possibility, adolescent male Sprague–Dawley rats were administered nicotine (0.5mg/kg/day) 3 days a week for 2 consecutive weeks, starting at postnatal day P (32). 17 days following the end of dosing, brains were processed for Golgi–Cox staining, and neurons were digitally reconstructed in three dimensions. Animals previously treated with nicotine exhibited an increase in the total number of branches and total length of dendrites on BNST neurons. Sholl analysis revealed an increase in the number of intersections with concentric spheres, increased amount of dendritic material within concentric spheres, and an increase of dendritic branching within concentric spheres occurring between 20 and 300μm from the soma in dendrites. Collectively, our results show that adolescent nicotine alters dendritic structure (by triggering new branch growth), and, by inference, connectivity of the BNST, which may contribute to alterations in behavior induced by adolescent nicotine.