González Marín MC1, Coune F1, Naassila M1
1INSERM ERi 24 (GRAP), Amiens, France
Ethanol induced behavioral sensitization (EIBS) is thought to play a role in drug taking behavior and relapse after abstinence. However, the exact role of sensitization in addictive behaviors remains poorly understood. In this context, we investigated to our knowledge for the first time, the operant ethanol self administration procedure and the motivation to self administer ethanol (breakpoint) depending on the vulnerability to develop sensitization: i.e. in both EIBS resistant and EIBS prone outbred female Swiss mice. To induce sensitization, mice were treated once a day with 2.5 g ethanol/kg during 10 days and challenged with the same dose of ethanol 7 days later. EIBS was characterized by a significant increase in locomotion between the challenge day and day 1 and then considered as the ‘EIBS prone’ group. When the difference was not significant mice were considered as the ‘EIBS resistant’ group. Mice were then trained to nose poke for a 20% ethanol solution reinforcer under a FR2 schedule of reinforcement. Motivation was assessed more directly with a progressive ratio schedule. Our results show that there is a positive correlation between EIBS and both the level of intake and motivation. Interestingly, acquisition of ethanol self administration was faster in sensitized mice that also display a quick and long lasting increase in ethanol intake during the first sessions and that the increase is long lasting. These results further support that EIBS vulnerability is crucial in the development of addictive behaviors.