The acquisition of self administration of sucrose and ethanol solutions did not differ between genotypes. Both genotypes performed a similar number of sessions to criterion at each concentration (10%0%: U = 31.5, p = 0.648; 10%3%: U = 28.0, p = 1.00; 10%5%: U = 22.5, p = 0.448; 7%5%: U = 27.5, p = 0.951; 10%10%: U = 28.0, p = 1.00; Fig. 2A). When allowed to lever press to gain access to increasing concentrations of ethanol in a sucrose solution, KO mice did not differ from WT in either the number of active lever presses (genotype by reinforcer interaction, F(4,52) = 0.721, p = 0.486, ε = 0.462; main effect of genotype, F(1,13) = 0.019, p = 0.893; Fig. 2B) or the number of reinforcers earned (genotype by reinforcer interaction, F(4,52) = 0.486, p = 0.604, ε = 0.456; main effect of genotype, F(1,13) = 0.034, p = 0.858; Fig. 2C) in 30 minutes. The genotypes performed to a similar level at all concentrations, both reducing their number of reinforcers as the ethanol concentration increased (Main effect of concentration, F(4,52) = 12.357, p<0.001, ε = 0.456).
