Correlation between the Melatonin Level and Indicators of Aging and Fibrosis in Men in the European Part of the Arctic Zone of the Russian Federation

The results of correlation analysis between urine level of melatonin metabolite (6-sulfatoxymelatonin, 6-SMT) in urine and indicators of aging, interstitial fibrosis, and the antioxidant defense system in men in the Arctic are presented. A moderate negative correlation was found for 6-SMT with calendar age, biological age, and the p16(INK4a), leucocyte molecular marker of aging. A correlation of 6-SMT with fibrosis indices was found. It is manifested by a negative correlation with sulfated glycosaminoglycans in urine, with collagen markers (free hydroxyproline, peptide-bound hydroxyproline, and total hydroxyproline). The age-related decrease in the 6-SMT level may be associated with an age-related increase in interstitial fibrosis in northerners. A medium-strength positive association of 6-SMT with hormones was detected: the levels of free testosterone (r = 0.53, p = 0.0002), total testosterone (r = 0.43, p = 0.003), and cortisol (r = 0.33, p = 0.007). The negative correlations of 6-SMT with the content of ceruloplasmin (r = -0.63, p = 0.001) and SCORE scale (r = -0.52, p = 0.001) indicate an association of melatonin with the antioxidant defense system and the risk of cardiovascular pathology development.