Fig. 1

Drug injection and experimentation schedule. Mice were treated with saline or nicotine solution (0.175 mg/kg free-base) once daily for three days. On the following day, mice were treated with saline or mecamylamine solution (MEC; 0.3 mg/kg). All behavioral tests commenced 10 min after the last injection (saline or mecamylamine). Mice treated only with saline were designated as the control group (black). Mice treated with three days of saline followed by mecamylamine were designated the mecamylamine (MEC) group (gray). Mice treated with three days of nicotine followed by saline were designated the early spontaneous withdrawal (SW) group (blue). Mice treated with three days of nicotine followed by mecamylamine were designated the early precipitated withdrawal (PW) group (red)