Fig. 4.

Dose–response relationship of haloperidol in counteracting METH-evoked stereotypy in sensitized wild-type mice (A) and μ-OR knockout mice (B). Both genotypes of mice were i.p. injected with METH (10 mg/kg) for 7 consecutive days to initiate sensitization. On day 11, after 4 abstinent days, each group of mice was injected s.c. with saline or one dose of haloperidol and then, 30 min later, injected with METH (10 mg/kg, i.p. injection). Animal stereotyped behaviors were monitored and scored at 15-min intervals for 5 hr.