Cocaine-induced liver disease in the European eel, Anguilla anguilla.

Cocaine is a potent psychostimulant and highly addicting drug, causing hepatotoxicity in humans, laboratory animals and fish1. Due to the worldwide use of cocaine, it is detected in surface waters2; despite its low concentrations, cocaine induces toxic effects in the European eel3,4. In this study, the effect of cocaine on the liver of the European eel was evaluated. A stock solution of 0.006 mg/mLcocaine free-base in ethanol was prepared. Male silver eels were exposed for fifty days to 20 ng/ Lof cocaine; untreated control, vehicle control and two post-exposure recovery groups (exposed to cocaine and then deprived of it and only exposed to tap following parameters were evaluated: liver morphology; cytochrome oxidase (COX) activity, as a marker of oxidative metabolism5; caspase-3 activity, as a marker of apoptosis activation6; GRP78 expression, as a marker of the unfolded protein response7; blood glucose level, as a marker of stress8; serum levels of alanine aminotransferase (ALT) and C-reactive protein (CRP), markers of liver injury8,9. In the exposed eels, loss of parenchymal cells and lipid content, and necrotic areas were observed. COX and caspase-3 activities, GRP78 expression, blood glucose level, ALT and CRP levels increased. In the post-exposure recovery eels COX returned to control values, caspase-3 activity was lower whereas GRP78 expression, blood glucose level, ALT and CRP levels were higher than controls. These results show that even low cocaine concentrations affect the eel liver, suggesting potential impact on the survival of this species. References 1. Arinç E, Bozcaarmutlu A. J Biochem Mol Toxicol 2003;17:169-76. 2. Rosi Marshall EJ, et al. J Hazard Mater 2015;282:18-25. 3. Capaldo A, et al. Sci Tot Environ 2018;640-641:862-73. 4. Capaldo A, et al. Ecotoxicol Environ Saf 2019;169:112-9. 5. Lionetti L, et al. Cell Mol Life Sci 2004;61:1366-71. 6. Brentnall M, et al. BMC Cell Biol 2013;14:32. 7. Kaufman RJ. Genes & Devel 1999;13:1211-33. 8. Banaee M, et al. Pest Biochem Physiol 2011;99:1-6. 9. Giannini EG, et al. CMAJ 2005;172:367-79.