Figure 2.

The locomotor sensitization to low dose of amphetamine is selectively abolished in GR^D1Cre mice. Locomotor activity is expressed as the sum of ¼ turns in a circular cylinder per hour following repeated drug or saline injections. (A) Locomotor sensitization to 1 mg/kg amphetamine daily injections in control (gray circles) and GR^D1Cre mice (black squares). White circles and white squares represent control and GR^D1Cre mice, respectively, which received daily injections of saline followed by a challenge injection of amphetamine 1 mg/kg on the test day. Amphetamine (1 mg/kg) induced locomotor sensitization that was abolished in GR^D1Cre mice at day 16; interaction Genotype × Treatment F_{(1, 28)} = 5.2; saline vs. drug: P < 0.01; control vs. mutant: ^**P < 0.01. (B) Locomotor sensitization to 1 mg/kg amphetamine daily injections in control (gray circles) and GR^DATCre (black diamond) mice. White circles and white squares represent control and GR^DATCre mice, respectively, which received daily injections of saline followed by a challenge injection of amphetamine 1 mg/kg following an 8-day withdrawal period. Interaction Genotype × Treatment F_{(1, 33)} = 0.16; saline vs. drug: P < 0.001; control vs. mutant: P = 0.6. (C,D) are same than (A,B), respectively, but with 2 mg/kg amphetamine. n = 8–10 per group. (C) Interaction Genotype × Treatment F_{(1, 36)} = 1.72; saline vs. drug: P < 0.001; control vs. mutant: P = 0.67. (D) Interaction Genotype × Treatment F_{(1, 37)} = 0.27; saline vs. drug: P < 0.001; control vs. mutant: P = 0.21.