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Ethanol addictively enhances the in vitro cardiotoxicity of cocaine through oxidative damage, energetic deregulation, and apoptosis

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Abstract

Cocaine (COC) is frequently consumed in polydrug abuse settings, and ethanol (EtOH) is the most prominent co-abused substance. Clinical data and experimental evidence suggest that the co-administration of COC with EtOH can be more cardiotoxic than EtOH or COC alone, but information on the molecular pathways involved is scarce. Since these data are crucial to potentiate the identification of therapeutic targets to treat intoxications, we sought to (i) elucidate the type of interaction that occurs between both substances, and (ii) assess the mechanisms implicated in the cardiotoxic effects elicited by COC combined with EtOH. For this purpose, H9c2 cardiomyocytes were exposed to COC (104 µM–6.5 mM) and EtOH (977 µM–4 M), individually or combined at a molar ratio based on blood concentrations of intoxicated abusers (COC 1: EtOH 9; 206 µM–110 mM). After 24 h, cell metabolic viability was recorded by the MTT assay and mixture toxicity expectations were calculated using the independent action (IA) and concentration addition (CA) models. EtOH (EC50 305.26 mM) proved to act additively with COC (EC50 2.60 mM) to significantly increase the drug in vitro cardiotoxicity, even when both substances were combined at individually non-cytotoxic concentrations. Experimental mixture testing (EC50 19.18 ± 3.36 mM) demonstrated that the cardiotoxicity was fairly similar to that predicted by IA (EC50 22.95 mM) and CA (EC50 21.75 mM), supporting additivity. Concentration-dependent increases of intracellular ROS/RNS and GSSG, depletion of GSH and ATP, along with mitochondrial hyperpolarization and activation of intrinsic, extrinsic, and common apoptosis pathways were observed both for single and combined exposures. In general, the mixture exhibited a toxicological profile that mechanistically did not deviate from the single drugs, suggesting that interventions such as antioxidant administration might aid in the clinical treatment of this type of polydrug intoxication. In a clinical perspective, the observed additive mixture effect may reflect the increased hazards at which users of this combination are exposed to in recreational settings.

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Acknowledgements

This work received financial support from National funds [Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência (FCT/MEC)] and European Union funds [Fundo Europeu de Desenvolvimento Regional (FEDER POCI/01/0145/FEDER/007728)] under the program PT2020 (UID/MULTI/04378/2013), the framework of Quadro de Referência Estratégico Nacional (QREN) (NORTE-01-0145-FEDER-000024), and Programa Operacional Competitividade e Internacionalização (COMPETE). To all financing sources the authors are greatly indebted. Ricardo Jorge Dinis-Oliveira acknowledges FCT/MEC for his Investigator Grant (IF/01147/2013). Maria Enea acknowledges FCT/MEC for her grant PD/BD/109634/2015.

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Correspondence to Diana Dias da Silva.

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Martins, M.J., Roque Bravo, R., Enea, M. et al. Ethanol addictively enhances the in vitro cardiotoxicity of cocaine through oxidative damage, energetic deregulation, and apoptosis. Arch Toxicol 92, 2311–2325 (2018). https://doi.org/10.1007/s00204-018-2227-7

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  • DOI: https://doi.org/10.1007/s00204-018-2227-7

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