Changes in metabolic hormones and trace elements in CSF in active smokers indicate oxidative damage to brain cells

Abstract

Objective This study aimed to reveal associations between metabolic hormones in cerebral spinal fluid (CSF) and cigarette smoking-induced weight gain and to explore the underlying mechanism. Methods A total of 156 adult men were included, comprising active smokers and nonsmokers. In addition to demographic information and body mass index (BMI), plasma levels of ApoA1 and ApoB, high-density lipoprotein, low-density lipoprotein, cholesterol, triglyceride, alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase in the participants were measured. Moreover, the metabolic hormones adiponectin, fibroblast growth factor 21 (FGF21), ghrelin, leptin, and orexin A, as well as the trace elements iron and zinc in CSF, were assessed. Results Compared to nonsmokers, active smokers showed higher BMI, and elevated CSF levels of FGF21, Zn, and Fe, but decreased levels of metabolic hormones adiponectin, ghrelin, leptin, and orexin A. Negative correlations existed between CSF FGF21 and ghrelin, between CSF Zn and ghrelin, as well as between CSF Fe and orexin A in active smokers. Furthermore, elevated CSF FGF21 and Zn predicted ghrelin level decrease in the smokers. Conclusion These data relate smoking-induced weight gain to its neurotoxic effect on the neurons that synthesize metabolic hormones such as adiponectin, ghrelin, leptin, or orexin A in the brain, by disrupting mitochondrial function and causing oxidative stress in the neurons.