Impact of e-cigarette refill liquid with or without nicotine on liver function in adult rats

This study was conducted to evaluate the effects of e-cigarette refill liquid administration alone or with nicotine on the antioxidant defense status, functional and histopathological changes in adult rat liver tissue. For this purpose, 32 rats were treated for 28 days as follows: control group was injected intra-peritoneally with physiological saline; e-cigarette 0% treated group received an intra-peritoneal injection of e-liquid without nicotine diluted in physiological saline, e-cigarette-treated group received an intra-peritoneal injection of e-liquid containing 0.5 mg of nicotine/kg of body weight/day diluted in physiological saline and nicotine-treated group received an intra-peritoneal injection of 0.5 mg of nicotine/kg of body weight/day diluted in physiological saline. In e-liquid without nicotine-exposed group, activities of the liver biomarkers aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase increase. Interestingly, oxidative stress indicators showed decreased total protein content, associated with a reduction in the antioxidant enzymes activities superoxide dismutase, catalase and glutathione-S-transferase, and an elevation in malondialdehyde content, highlighting the promotion of lipid peroxidation and oxidative stress. Histological studies identified inflammatory cells infiltration and cell death. Thus, e-liquid seems to promote oxidative tissue injuries, which in turn lead to the observed histopathological finding. In comparison, nicotine alone induced less oxidative stress and less histopathological disorders, whereas e-liquid with nicotine gave rise to more histopathological injuries. Thereby, e-liquid, per se, is able to induce hepatotoxicity and supplementation with nicotine worsens this state.