Effects of repeated transcranial direct current stimulation (tDCS) on depression and addiction-related behaviors in mice
S. PEDRON1, J. MONNIN1,2, D. SECHTER1, E. HAFFEN1,2, V. VAN WAES1
1 EA 481 Laboratory of Integrative and Clinical Neuroscience, Besançon, France
2 INSERM CIC-IT 808 Clinical Investigation Centre for Innovative Technology, Besançon, France
This study is part of a wider translational project carried out in Besançon (France) on the efficacy of repeated transcranial direct stimulation (tDCS) in the treatment of major depression and in attempts to facilitate alcohol and smoking cessation. tDCS is a non-invasive, painless and safe brain stimulation procedure capable of modulating cortical excitability. Preliminary clinical studies have indicated that tDCS applied over the dorsal prefrontal cortex of dependent smokers and alcohol users reduces their desire for smoking and drinking, respectively. However, the neurobiological mechanisms underlying these effects remain unknown. Our goal was thus to develop a model of tDCS in mice to further evaluate the mechanisms of action of tDCS on addiction-related behaviors. To do so, anodal tDCS was applied transcranially in mice over the frontal cortex (2x20 min/day current for 5 consecutive days, intensity=0.2 mA). The control group underwent the same procedure but no current was applied. First, we assessed the impact of tDCS on stress-, anxiety-, and depression-related behaviors as well as on memory performances to get a general picture of the behaviors affected by this technique. Second, we evaluated the impact of tDCS on nicotine and alcohol consumption, as well as on the rewarding effect of nicotine, alcohol and cocaine. Finally, we tested whether tDCS could reduce withdrawal symptoms in adult mice that had been chronically exposed to nicotine or ethanol during their adolescence. Altogether, our data indicate that our protocol of tDCS has antidepressant properties, improves working memory, and reduces the reinforcing effect of several drugs of abuse, as previously reported in clinical studies. Interestingly, tDCS also decreases several symptoms associated with nicotine withdrawal. In conclusion, our animal model has potential value as a means for exploring the neurobiological changes that underlie the beneficial effects of tDCS on addiction-related behaviors.