Investigation of the effect of hydrogen peroxide on the chromosomes of young and elderly individuals.

Active oxygen species have been considered to be responsible for the aging process and for the induction and initiation of neoplastic processes. The effect of hydrogen peroxide, an active oxygen species, was investigated in the chromosomes of three young women (20-21 years of age) and of three elderly women (73-79 years of age) in a culture medium favorable to the appearance of folate-sensitive fragile sites. Hydrogen peroxide at a final concentration of 5 X 10(-6) during the final hours of culture caused a significant increase in hypodiploidy and structural aberrations, chromatid gaps in particular, only in the cultures from the three elderly women, suggesting that the chromosomes of older women are more sensitive to this agent than those of younger women. The preferential chromosome loss in both treated and untreated cultures from the elderly women involved chromosome X. The preferential sites for structural aberrations were 9p12, a constitutive heterochromatin site and 6q21, where the gene of mitochondrial superoxide dismutase, an enzyme involved in antioxidant processes in the cell, is located. Hydrogen peroxide significantly intensified the effect naturally occurring in the cells of elderly persons, such as hypodiploidy and increased structural aberrations, thus acting at the chromosome level in a manner similar to that of the natural aging process of the organism.