Nicotine is associated with smoking dependence and vascular inflammation through cotinine: A mediation analysis

INTRODUCTION The main alkaloid component in cigarettes is nicotine. Cotinine, a metabolite of nicotine, is capable of causing dependence effects through endless mechanisms modulated by the ion channel nicotinic acetylcholine receptors nAChRs. Nicotine and cotinine can also cause damage to blood vessels through a chronic inflammatory process mediated by the Ligand-Tie2 Angiopoietin Receptor system. Hypoxic conditions that occur due to vascular inflammation cause a decrease in the concentration of nitric oxide (NO). This study aimed to evaluate the relationship between NO levels and cotinine through the expression of nAChRs that mediate the nicotine dependence mechanism and Tie2 (Tyrosine Kinase 2) expression. METHODS A cross-sectional study was conducted with 200 participants grouped into two groups based on their smoking status: 100 smokers and 100 non-smokers. All participants were men aged 20–40 years with no history of cardiovascular disease, diabetes mellitus, or dyslipidemia, and were not currently on medication. According to the parameters used, all blood samples were taken from peripheral blood for analysis using the ELISA kit or Colorimetric Assay Kit. RESULTS Cigarette consumption increases blood cotinine concentrations in smokers and causes dependence by modulating nAChRs. The study indicates an emerging cycle regarding nicotine–cotinine consumption and nAChRs expression. In addition, the data in this study showed a significant relationship (p<0.001) regarding the cycle formed with decreased NO levels as a result of damage caused by Tie2-mediated inflammation. CONCLUSIONS There is a relationship between NO levels and cotinine through nAChRs, which mediate the nicotine dependence mechanism and Tie2 expression.