DNA damage susceptibility and repair in correlation to calendric age and longevity.

ABSTRACT

In two mouse strains, SAM P (senescence acceleration prone) and SAM R (senescence acceleration resistant), of different longevities, with a ratio of P/R=12), the DNA status in the course of aging has been investigated using the DNA Alkaline Filter Elution (AFE) technique. Six different organs (brain, liver, heart, lung, intestine, and muscle) have been used in each of the four animals of a given age. Earlier it had been shown, that DNA is damaged the more the higher the age of the animal. DNA damage susceptibility, measured after exposure of organ pieces to nitroquinoline-N-oxide (NQO), is also significantly increased at higher ages, while repair, measured of NQO damaged tissue after 3 h incubation in full medium is significantly reduced. In the strain with shorter longevity the damage increments and the repair deficiencies are drastically deviating from those with higher longevity. These findings of strong coupling of the DNA status to aging as well as longevity suggest causative relations.