Effect of intraperitoneal injection of buprenorphine (Bup) (0, .03, .3, 3.0, and 6.0 mg/kg) on ethanol intake in Marchigian Sardinian alcohol-preferring rats. The drug was given 90 min before ethanol access, and alcohol consumption was monitored at 30, 60, 90, and 120 min. Values represent the mean (±SEM) of 10 subjects. Difference from control subjects: *p < .05; **p < .01. Veh, vehicle.