Impairment of testicular function in electronic cigarette (e-cig, e-cigs) exposed rats under low-voltage and nicotine-free conditions

Despite the lack of knowledge of the effects of electronic cigarettes (e-cigarettes, e-cigs) on public health, they have been proposed as a part of smoking cessation efforts. Recently, several basic scientific studies have pointed out how e-cigs can generate carcinogens, such as e-cig liquid thermal degradation by-products, and how the exposure can lead to genomic damage through inhibiting DNA repair or disrupting the redox homeostasis. However, scientific studies have pointed out how e-cigs can generate carcinogens and their release could be avoided setting the device to a low-voltage regimen. To test this feasibility, we show the effects of e-cig vapour generated from a low-voltage device filled with a nicotine-free liquid on rat testicular functions. The chemical analysis revealed the presence of carbonyls, such as formaldehyde, acetaldehyde and acrolein. Rats exposed reported a lower relative testis weight and higher levels of lactate dehydrogenase (LDH) as tissue damage marker, along with an impairment of 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and glucose-6-phosphate dehydrogenase (G6PDH) as key enzymes in the steroidogenesis pathway. The pro-oxidative environment was confirmed by the higher amount of reactive oxygen species (ROS), the development of lipid peroxidation and protein carbonylation, as well as from the disruption of antioxidant capability. Finally, we observed a higher rate of DNA unwinding in white blood cell line and boosted lipoxygenase (LOX)-linked activity, a tumour promotion marker. Even with the device setting at weak conditions, our results if extrapolated to humans suggest that exposure to e-cig vapours might alter gonads function in male vapers.