Number of infusions obtained by rats self-administering nicotine with an olfactogustatory cue and different concentrations of CS₂.

<p>(a) The number of daily infusions obtained by rats that received 500 ppm CS₂ was significantly higher than all other groups. (b) The average number of infusions obtained during the last five sessions was compared between different oral cues. * p<0.05, Tukey HSD; ** p<0.01, Tukey HSD; ***: p<0.001, Repeated measures ANOVA.