Spontaneous and METH-stimulated locomotor activity in wildtype (WT) and ICER knockout (KO) mice.

<p>METH (1 mg/kg) was administered once per day on Days 1, 3, 5, 7, 9, 13, and 20 in WT (<i>n</i> = 13) and ICER-KO (<i>n</i> = 13) mice. <i>a</i>. ime-course of spontaneous locomotor activity before and after METH administration on Day 1. The data are expressed as mean ± SEM beam breaks in 5 min bins. The arrow indicates the start of a METH injection. <i>b</i>. Time-course of spontaneous locomotor activity before and after METH administration on Day 20. The data are expressed as mean ± SEM beam breaks in 5 min bins. The arrow indicates the start of a METH injection. <i>c</i>. METH-induced locomotor sensitization. The data are expressed as mean ± SEM beam breaks during the 60 min period after METH injection (1 mg/kg). *<i>p</i><0.05, significant difference in locomotor activity scores between WT and KO mice.