Cocaine-induced locomotor activity. One group of mice were given only saline (“untreated”, n =12). The other groups were challenged with cocaine 100 mg/kg i.p., 1 hr after the following i.p. pretreatments (all 1 hr beforehand, except vaccine): enzyme (CocH, 1 mg/kg, n = 10), antibody (AB, 8 mg/kg, n = 8, data not shown), vaccine (Vac, n = 11), antibody plus enzyme (AB + CocH, n = 12), and vaccine plus enzyme (Vac + CocH, n = 6). Statistical significance: **(p < 0.01 vs CocH-only treatment).