Figure 1.
Effect of previous repeated injections of nicotine (0.35 mg/kg), MDMA (2.5 mg/kg), cocaine (15 mg/kg), or amphetamine (2.5 mg/kg) twice daily for 15 d on subsequent instrumental behavior. The animals were tested together, but for clarity the effects of each drug are presented separately, using the same saline-treated control group. A (active responses) and B (inactive responses) show the effects of previous nicotine exposure; C, D, MDMA; E, F, cocaine; G, H, amphetamine. Data are represented as means ± SEM.