rats. In addition, baclofen’s efficacy in decreasing ethanol intake differed across the rat lines, when the rats were placed on a progressive-ratio operant schedule; such that 1.7 and 3 mg/kg doses were effective in P and sP rats, whereas only the 3 mg/kg dose was effective in AA rats. Interestingly, the 3 mg/kg dose of baclofen increased the latency to respond under the fixed-ratio schedule in all three lines, but the 3 mg/kg dose of baclofen increased the latency to respond under the progressive-ratio schedule in the P and AA rat lines only. Similarly, GS39783’s efficacy in decreasing ethanol intake differed across the rat lines, when the rats were placed on a fixed-ratio operant schedule; such that the 25, 50 and 100 mg/kg doses were effective in P and sP rats, whereas only the 50 and 100 mg/kg doses were effective in AA rats. As with baclofen, GS39783’s efficacy in decreasing ethanol intake differed across the rat lines, when the rats were placed on a progressive-ratio operant schedule as well; such that the 25, 50 and 100 mg/kg doses were effective in P and sP rats, but none of the doses were effective in AA rats. Regarding latency to respond,
