Fig. 3.

Nicotinic receptor regulation after nicotine withdrawal in the presence or absence of ABT-089 or ABT-107. Homogenate-binding experiments with a saturating concentration of [³H]EB were performed on hippocampal, cortical, striatal, and thalamic tissues from animals treated long term with nicotine for 2 weeks and then long term with ABT-089 or ABT-107 for 2 weeks during withdrawal from nicotine. Additional treatment groups include animals treated with long-term saline (4 weeks), long-term nicotine (4 weeks), and animals treated with nicotine for 3 weeks and then withdrawn from nicotine for 7 days (via nicotine minipump removal and spontaneous withdrawal). Data are mean (±S.E.M.) of treatment groups. *P < 0.01, **P < 0.001, ***P < 0.0001 compared with saline (n = 5–10).