Fig 1. Schematic representation of the procedure of Experiment 1.

Rats were trained to self-administer nicotine for 12 days followed by removal of both nicotine and associated cues to extinguish responding. Across a minimum of six extinction sessions, rats were treated with either the HDAC inhibitor, sodium butyrate (NaB; immediately or six hours following each session), or vehicle (Veh). Reinstatement of nicotine-seeking was then assessed through three reinstatement tests, each separated by a minimum of two further extinction sessions.