A, Effects of tropicamide and AMPH on phosphorylation and expression of ERK1/2 in the CPu. B, Effects of tropicamide and AMPH on phosphorylation and expression of ERK1/2 in the NAc. C, Effects of tropicamide and AMPH on phosphorylation and expression of ERK1/2 in the mPFC. Representative immunoblots are shown to the left of the quantified data. Rats were given an i.p. injection of vehicle (Veh) or tropicamide (Tro, 5 mg/kg) 5 min prior to saline or AMPH (1 mg/kg, i.p.) and were sacrificed 15 min after final injection for Western blot analysis of changes in pERK1/2 and ERK1/2 expression. Data are presented as means ± SEM (n = 4 per group) and were analyzed with two-way ANOVA followed by post hoc tests: pERK2 in the CPu (tropicamide: F(1,12) = 58.62, P < 0.0001; AMPH: F(1,12) = 56.00, P < 0.0001; interaction: F(1,12) = 9.56, P = 0.0093), NAc (tropicamide: F(1,12) = 39.31, P < 0.0001; AMPH: F(1,12) = 32.00, P = 0.0001; interaction: F(1,12) = 1.928, P = 0.19), and mPFC (tropicamide: F(1,12) = 23.73, P = 0.0004; AMPH: F(1,12) = 32.57, P < 0.0001; interaction: F(1,12) = 1.532, P = 0.24). *p < 0.05 versus vehicle + saline, and +p < 0.05 versus tropicamide + saline and vehicle + AMPH.