Repeated cocaine administration into the rat ventral tegmental area produces behavioral sensitization to a systemic cocaine challenge.

The aim of the present study was to investigate the capacity of repeated administration of cocaine (5 nmol/side) or the selective dopamine re-uptake inhibitor GBR 12909 (15 nmol/side) into the ventral tegmental area (VTA) to initiate behavioral sensitization to systemically administered cocaine (15 mg/kg, intraperitoneally). Following 1 week of withdrawal from intra-VTA treatment, cocaine or GBR 12909 pretreated animals displayed sensitized locomotor and rearing behavior to acute systemic cocaine administration. These data support the possibility that increased dopamine transmission in the VTA is involved in the cellular events that determine the initiation of behavioral sensitization to cocaine.