Role of venlafaxine in relapse to methamphetamine seeking: Potential treatment option for drug dependence

OBJECTIVES: To investigate the effects of venlafaxine (VEN) on the relapse of methamphetamine (METH)-induced conditioned place preference (CPP) in rats. METHODS: This study was conducted at the Department of Pharmacology and Toxicology, and the Addiction and Neuroscience Research Unit, College of Pharmacy, Taif University, Taif, Kingdom of Saudi Arabia between May 2017 and October 2018. A total of 32 male Wistar rats were used in this study. Rats were divided to receive either METH or saline during the conditioning phase. Following the acquisition of METH-induced CPP, the animals were randomly divided to receive saline or VEN for 21 days instead of METH during the extinction training. The reinstatement was initiated by re-exposure to a single dose of METH to test any anti-reinstatement effects of VEN. RESULTS: Two-way repeated measures Analysis of Variance (ANOVA) (time × chamber) was used to analyze time spent in conditioning chambers, while distance traveled was analyzed using one-way ANOVA. Saline or VEN, when administered alone, did not affect CPP or locomotor activity results. A priming intraperitoneal injection of METH reinstated CPP in the animals treated with saline during the extinction phase. Interestingly, VEN treatment blocked METH-induced CPP. CONCLUSION: Venlafaxine effects on the reinstatement of METH-induced CPP are not likely due to nonspecific effects on locomotor activity. This beneficial effect of VEN on relapse to METH-induced CPP could be due to its antidepressant effects. Venlafaxine can thus be a potential therapeutic option in the treatment of relapse to METH-seeking behaviors.