Fig. 2.
Effects of nicotine (a), 4-nitro-PFEB (b), and 4-nitro-PFEB+ 0.4 mg/kg nicotine (c) on percentage drug (nicotine) lever responding (%DLR; filled circles, left y-axis) and response rate (resp/s; open circles, right y-axis) in rats trained to discriminate 0.4 mg/kg nicotine from saline. Points above VEH and NIC refer to control tests conducted with vehicle and the training drug prior to each dose effect determination. Values represent the mean (±SEM) of six rats per treatment. Significant differences (p<0.05) in response rate relative to VEH control as determined by Dunnett’s post hoc are denoted by asterisk. For challenge test data, significant differences in %DLR relative to NIC control as determined by Dunnett’s post hoc are denoted by number symbol