Emerging evidence assigns a role of intestinal microbiota (IM) and bidirectional gut-brain axis in mood disorders. However, studies addressing the involvement of IM in substance use disorder (SUD) are limited. It has been shown that cocaine administration induces gut dysbiosis and chronic treatment with antibiotics enhances its rewarding property. Accordingly, we have recently demonstrated that repeated exposure to volatilized cocaine alters the structure and diversity of the rat IM. In this sense, IM modulation by probiotic bacteria could attenuate cocaine behavioral changes. The present study aims to evaluate if chronic oral administration of three probiotic Lactobacillus strains (L. johnsonii; L. rhamnosus; L. reuteri) prevents the behavioral effects induced by the repeated exposition of a smokable form of cocaine in rats. Animals were pretreated via oral syringe-feeding with the bacterial mixture (1x10E8 CFU in 0.5 ml skim milk) or vehicle (skim milk) for 28 days. During days 22 to 28, rats were daily exposed to cocaine (25 mg) by pulmonary inhalation and the locomotor activity was assessed. Preliminary results indicate a progressive stimulant effect of cocaine (locomotor sensitization) while bacteria do not seem to prevent this effect. Ongoing experiments will confirm these results. Additionally, anxiety and depressive-like behaviors will be addressed. Our findings will contribute to understand the role of IM and the potential therapeutic of Lactobacillus strains in SUD.