Cocaine-induced conditioned place preferance. (A) OVX rats were conditioned with one of five doses of cocaine (0, 2.5, 5, 10, or 15 mg/kg i.p.) or saline on alternating days for six consecutive days and then pretreated with a single s.c. injection of EB (5 μg) or peanut oil (PO) 30 min prior to the test for cocaine conditioned place preference (CPP; PostTest). PO-treated (white bars) rats expressed CPP to the 5 and 10 mg/kg conditioning doses of cocaine (p < 0.05), but not the 2.5 or 15 mg/kg doses. EB-treated rats (black bars) demonstrated an inhibition of CPP to the 5 mg/kg dose, but expressed a significant preference to the higher doses of cocaine (10 and 15 mg/kg; p < 0.05). n = 7–10 rats per group. * indicates a significant difference from zero (p < 0.05). ** indicates a significant difference between EB and PO treatment groups within a dose (p < 0.05). (B) Locomotor activity during the CPP PostTest as measured by total photobeam breaks over the 15 min testing period for PO treated (white bars) and EB-treated (gray bars) at each of the five conditioning doses of cocaine. Neither dose nor EB treatment prior to the CPP PostTest affected locomotor activity.