Circadian periodicity and effect of gender, age, diet and smoking on circulating plasma lipid peroxides and antioxidant enzymes in healthy Indians of different age groups

This study aims at assessing circadian rhythm characteristics of oxidants and antioxidants, testing for any effect of gender, age, diet and smoking status. Blood samples from clinically healthy Indians (103 males and 59 females, 7–75 years of age) were collected at 6-hour intervals for 24 hours for determination of MDA, SOD, CAT, GPx and GR. Data were analyzed by the single and population-mean cosinor to estimate circadian rhythm characteristics. The latter were further analyzed by multi-factor analysis of variance. A marked circadian rhythm was documented for all variables. Its parameters were found to undergo marked changes as a function of age. Males differed from females in terms of the rhythm-adjusted mean (MESOR) of CAT and GPx and of the 24-hour amplitude of GR. The MESOR of GPx differed between vegetarians and omnivores. Smoking status affected the MESOR of MDA and CAT and the 24-hour amplitude of CAT. As oxidative stress is being reported for most diseases, the mapping of circadian rhythms in oxidant and antioxidant enzymes in health may help refine reference values, thereby allowing the early detection of pathophysiological conditions, prompting the early institution of treatment. Abbreviations: CAT: Catalase; FRAP: Ferric Reducing Antioxidant Power; GPx: Glutathione Peroxidase; GR: Glutathione Reductase; GSH: Glutathione; MDA: Malondialdehyde; MESOR: Midline Estimating Statistic Of Rhythm; ROS: Reactive Oxygen Species; SCN: Suprachiasmatic Nuclei; SOD: Superoxide Dismutase; TBARs: Thiobarbituric acid reactive substances; XPA: Xeroderma Pigmentosum, Complementation Group A (DNA Damage Recognition And Repair Factor).