Mirtazapine decreased induction and expression of cocaine + nicotine-induced locomotor sensitisation in rats

Abstract

Objectives: Concurrent abuse of cocaine and nicotine is considered a public health problem. To date, no effective therapy has been known to reduce the reinforcing effects of concurrent use of cocaine and nicotine. Mirtazapine, an antagonist of the α2-adrenoceptor and the 5-HT2A/C and the 5-HT3 receptors has proven effective in reducing the cocaine, nicotine and methamphetamine behavioural effects in humans and animals. Our study evaluated the effect of mirtazapine on enhancing locomotor activity during the induction and expression of locomotor sensitisation induced by a cocaine + nicotine mixture.Methods: Wistar rats were dosed with cocaine, nicotine or cocaine + nicotine combination. Mirtazapine (30 mg/kg, i.p.) was administered during the extinction phase.Results: Mirtazapine decreased cocaine + nicotine-induced locomotor activity and induction and expression of locomotor sensitisation. In addition, we found that co-administration of mecamylamine and mirtazapine significantly enhanced the effect of mirtazapine on cocaine + nicotine-induced locomotor activity during induction and expression of behavioural sensitisation.Conclusions: Our results suggest that mirtazapine demonstrated efficacy in decreasing the psycho-stimulant effects of concurrent use of cocaine and nicotine.