INDIVIDUAL DIFFERENCES IN THE NUMBER OF MITOCHONDRIAL DNA COPIES: THE EFFECt OF SOCIO-DEMOGRAPHIC FACTORS

According to the published data, the number of copies of mitochondrial DNA (mtDNA copy-number) reflects the efficiency of mitochondria functioning and, hence, the amount of cell-produced energy (in the form of ATP), which is an important indicator of the normal functioning of an organism. Differences in mtDNA copy-number are caused by a complex effect of various environmental factors including chemical, biological or physiological stress, age, and embryonic development. However, to date it remains unknown, which factors and at what age have the most significant impact on mtDNA copy-number and cause greater allostatic load. Therefore, the present study aimed to assess the involvement of various socio-demographic parameters in manifesting mtDNA copy-number in healthy individuals aged 18-25 years (N=1065). The analysis of the relative mtDNA copy-number was carried out by quantitative real-time PCR. As a result of multiple linear regression analysis including socio-demographic factors as predictors of the relative mtDNA copy-number, the optimal model was obtained (r2 = 0.03; F = 10.83; P <0.05), where age (beta = -0.02; P <0.01) and childhood maltreatment (beta = 0.05; P = 0.05) were the most statistically significant predictors. The data obtained confirm the role of mitochondria as key components in the physiological response to stress in humans and also indicate that the processes of gradual reduction in the energy efficiency of mitochondria begin even at the age of 18-25 years.