Figure 5.

Increased nicotine self-administration in cKO mice. A, Total distance traveled (left) and distance traveled across test segments (right) in open field assay showed no significant differences between genotype. B, Total time in center (left) and time in center across test segments (right) did not differ between genotype. C, Active and inactive lever presses during food training across test session did not differ by genotype. D, Active and inactive lever presses for nicotine show increased self-administration for cKO mice (Sidak’s *p < 0.05, ***p < 0.001). E, cKO mice earned more total nicotine infusions in first three nicotine test sessions (t test, *p < 0.05). F, Nicotine infusions earned by control and cKO mice in dose–response paradigm (Sidak’s, **p < 0.005).