(A) Experimental timeline to test the role of Cav1.3 channels during development of cocaine psychomotor sensitization. (B–D) Cav1.2DHP−/− mutant mice were pretreated with either vehicle (v) or nifedipine (n; 25 mg/kg, i.p.) prior to each saline (s) or cocaine (c) injection during the development of cocaine sensitization (15 mg/kg, i.p. cocaine once a day for five days), generating four treatment groups, v-s, n-s, v-c, n-c. Twenty-one days later mice were challenged with cocaine and NAc tissue was used to examine S831 (B), S/I (C), and S845 (D) GluA1 levels. A saline control group was included. Nifedipine significantly lowered S831 P-GluA1 (B) and surface GluA1 (C) levels compared to vehicle treated mice. Nifedipine had no effect on S845 P-GluA1 levels (D). (E) Experimental timeline to test the role of Cav1.3 channels at expression of cocaine psychomotor sensitization (D–F) Twenty-one days following cocaine pre-exposure (15 mg/kg, i.p. cocaine once a day for five days), Cav1.2DHP−/− mutant mice were pretreated with nifedipine 30 min prior to a cocaine challenge. Following behavioral testing NAc tissue was examined for S831 (D), S/I GluA1 (E), and S845 (F). *p < 0.001 vs. s-s. †p < 0.01 vs. v-c. Data represent mean ± SEM.