Epigenetics in Reproductive Aging: Involvement of Oxidative Stress

Epigenetic alterations are one of the distinctive characteristics of aging. Epigenetics changes throughout the reproductive life of humans. The major epigenetic parameters viz. DNA methylation, histone modification, and chromatin modeling are altered in the oocyte and sperm due to aging. Also, aging is accompanied by oxidative stress resulting in oocyte and sperm DNA damage. Oxidative stress occurs when the body’s antioxidant defense mechanism is overwhelmed by free radicals or pro-oxidant molecules such as nitrogen and reactive oxygen species, which are generated during normal cellular metabolism. This phenomenon is accompanied by a decline in the cell repair machinery, resulting in a wide range of DNA damage and distortion in cellular epigenetics. Still more, free radicals can directly or indirectly interfere with some epigenetic processes of the cell. For example, free radicals can impart the genome methylation profile by forming oxidized DNA lesions. Given the deleterious impact of oxidative stress on aging and cellular epigenetic profile, the ingestion of external antioxidants is encouraged to circumvent its side effects. This chapter provides insight into the interconnection between epigenetic alterations (histone modification, chromatin remodeling, DNA methylation and miRNA), reproductive aging, and oxidative stress.