Acute cocaine exposure alters spine density and long-term potentiation in the ventral tegmental area.

Growing evidence indicates that the expression of synaptic plasticity in the central nervous system results in dendritic reorganization and spine remodeling. Although long-term potentiation of glutamatergic synapses after cocaine exposure in the ventral tegmental area (VTA) has been proposed as a cellular mechanism underlying addictive behaviors, the relationship between long-term potentiation and dendritic remodeling induced by cocaine on the dopaminergic neurons of the VTA has not been demonstrated. Here we report that rat VTA cells classified as type I and II showed distinct morphological responses to cocaine, as a single cocaine exposure significantly increased dendritic spine density in type I but not in type II cells. Further, only type I cells had a significant increase in the AMPA receptor:NMDA receptor ratio after a single cocaine exposure. Taken together, our data provide evidence that increased spine density and synaptic plasticity are coexpressed within the same VTA neuronal population and that only type I neurons are structurally and synaptically modified by cocaine.