Relapse to alcohol abuse is often caused by exposure to potent alcohol-associated cues. Therefore, disruption of the cue-alcohol memory can prevent relapse. It is believed that memories destabilize and become prone for updating upon their reactivation through retrieval, and then re-stabilize within 6 h during a "reconsolidation" process. We recently showed that relapse to cocaine seeking could be prevented by counterconditioning the cocaine-cues with aversive outcomes following cocaine-memory retrieval, in a place conditioning paradigm. However, to better model addictionrelated behaviors, self-administration models are necessary. Here, we demonstrate that relapse to alcohol seeking can be prevented by aversive counterconditioning conducted during alcoholmemory reconsolidation, in conditioned place preference (CPP) and operant self-administration paradigms, in mice and rats, respectively. We found that the reinstatement of alcohol-CPP was abolished only when aversive counterconditioning with water-flooding was given shortly after alcohol-memory retrieval. Furthermore, rats trained to lever-press for alcohol showed decreased context-induced renewal of alcohol-seeking responding when the lever-pressing was counterconditioned with foot-shocks, shortly, but not 6 h, after memory retrieval. These results 0suggest that aversive counterconditioning can prevent relapse to alcohol seeking only when performed during alcohol-memory reconsolidation, presumably by updating, or replacing, the alcohol memory with aversive information. Also, we found that aversive counterconditioning preceded by alcohol-memory retrieval was characterized by upregulation of brain-derived neurotrophic factor (Bdnf) mRNA expression in the medial prefrontal cortex, suggesting that Bdnf plays a role in the memory updating process.
Operant self-administration, Conditioned place preference, BDNFAlcohol place conditioning (days 2-9): Training started 24 h after the Baseline test with one session per day over 8 days, with the sliding door closed. On days 3, 5, 7, and 9, mice were administered with alcohol (1.8 g/kg; i.p.) and immediately confined to the paired compartment for 5 min. On the alternate days (days 2, 4, 6, and 8), mice were administered with saline and were confined to the unpaired compartment for the same duration as on the alcohol-conditioning day.Paired compartments were counterbalanced.Place preference test 1 (day 10): Place preference test was identical to the Baseline stage, and served to index alcohol-CPP (Cunningham et al., 2003). Preference was defined as an increase in the percent of time spent in the alcohol-paired compartment during the Place preference test 1 compared to the Baseline test. Mice that did not show CPP (minimum of 5% change) were excluded from the experiment (3 from Experiment 1; 4 from Experiment 2).Memory retrieval and aversive counterconditioning (days 11-14). Prior to this stage, mice were assigned to different experimental conditions, Retrieval and No Retrieval (matched for CPP scores and sex). Training began 2...