Fig. 6.

Nicotine reduces GAD₆₇ promoter methylation in the FC. V: received saline for four times a day for 5 days. N: received nicotine (4.5, 9, or 22 μmol/kg s.c. four times a day for 4 days) and saline on the fifth day. V+M: received saline for 2 days followed by methionine (5 mmol/kg, twice a day) for 3 days. N+M: received nicotine (22 μmol/kg) for 4 days. On the third and fourth days of nicotine treatment, mice also received methionine. On the fifth day, nicotine was suspended and mice received only methionine. Each value is the mean ± SE of three mice. Overall one-way ANOVA for GAD₆₇ promoter methylation yielded a P < 0.001. **, P < 0.01 for Student-Newman-Keuls multiple comparison between V versus V+M and V+M versus N+M; *, P < 0.05 for V versus N and V versus N+M.