Figure 2.

Intra-VTA infusion of GDNF does not induce CPP and does not alter locomotor activity in rats. A, Design and schedule of the GDNF place preference experiment: rats of the GDNF condition were infused into the VTA with GDNF (10 μg · μl⁻¹ · side⁻¹) and vehicle (PBS) 10 min before the 30 min conditioning paired and unpaired sessions, respectively. Rats of the vehicle condition received vehicle only. B, Place preference for GDNF is expressed as the ratio ± SEM of the time spent in the GDNF-paired and unpaired compartment. C, D, Horizontal locomotor activity measured as mean ± SEM of the number of beam breaks during the entire conditioning sessions (C) or by blocks of 5 min (D). n = 6–8.