Prior to abstinence and subsequent exercise, saccharin or control interventions, daily patterns and levels of responding for nicotine did not vary between the intervention groups or between females subsequently tested during estrus (exercise, n=6; saccharin, n=7; and control, n=6) versus non-estrus phases (exercise, n=9; saccharin, n=12; control, n=14). Mean (±SEM) number of responses for nicotine as a function of extended-access day for females subsequently tested on extinction/reinstatement responding during estrus (A) versus non-estrus phases (B) in each of the three intervention groups. Insets show mean (±SEM) daily nicotine intake (mg/kg) across the 10-day extended-access period for females tested during estrus versus non-estrus phases in each of the groups. A dashed line and an asterisk indicates a significant decrease in responding from the 1st session to the last 3 sessions (p<0.05).