Behavioral Testing.

CPP was performed in a rectangular apparatus consisting of two side chambers with different contextual cues. Mice were paired with cocaine in one of the chambers and saline in the other chamber. After pairing, during a choice test, mice were allowed to freely explore the entire apparatus and preference for each chamber was determined. During extinction animals were placed into the chamber with free access. For reinstatement, animals were injected with 5 mg/kg cocaine i.p. immediately before being placed into the chamber with free access. For DREADD experiments, CNO (5 mg/kg) was administered 1 h before the session.