Fig 3. Experiment 2: HDAC inhibition facilitates cue-extinction of nicotine self-administration.
(A) Active and inactive responses during acquisition of intravenous nicotine self-administration (IVSA; average of the last 3 sessions) and the first six days (E1–E6) and last day (LED) of extinction for rats treated with sodium butyrate (NaB; n = 9) and saline (n = 8) immediately after each extinction session; (B) Survival curve showing the percentage of rats in each group yet to meet the extinction criteria (active responses < 30% of last three days of acquisition). Dotted vertical line indicates the minimum number of extinction sessions.