Cocaine plus nicotine mixture enhances induction and expression of behavioral sensitization in rats

Background: Psychoactive substance abuse is a health problem worldwide. Has been reported a high prevalence of use of tobacco and cocaine, either separately or in combination. Clinical and animal studies have suggested that the concurrent use of cocaine and nicotine reinforces the potency of one or both drugs and that nicotine may enhance the reinforcing effects of cocaine. Our study evaluated the combined effects of cocaine and nicotine on locomotor activity during the induction and expression phases of locomotor sensitization a physiological mechanism that plays an important role in establishing some of the defining characteristics of drug abuse. Methods: We used Wistar rats which were dosed with cocaine, nicotine or cocaine and nicotine combination and recorded their locomotor activity in different phases of the experiment. Results: We found that a daily dose of cocaine combined with nicotine enhanced cocaine- and nicotine-induced locomotor activity, as well as induction and expression of locomotor sensitization. Moreover, we found that pretreatment with nicotine enhanced the locomotor sensitization expression. Conclusion: These results suggest that concurrent use of cocaine and nicotine may result in co-abuse of these drugs.