Effects of YM-09151-2, a potent and selective dopamine D2 antagonist, on the ambulation-increasing effect of methamphetamine in mice.

The ambulation-increasing effect of methamphetamine (2 mg/kg, s.c.) was markedly reduced by YM-09151-2 at 0.01 mg/kg, s.c., in drug-naive mice. The development of reverse tolerance to the ambulation-increasing effect of methamphetamine was also inhibited almost completely when 0.01 mg/kg, s.c., of YM-09151-2 was administered concomitantly in each administration. However, YM-09151-2, at 0.01 mg/kg, was partially suppressed the effect of methamphetamine in mice that exhibited reverse tolerance to methamphetamine.