Sensitivity to oxidative stress is not always linked to aging, study shows

Scientists had previously believed that oxidative stress was implicated in the cause of many diseases, and had an impact on the body's aging process. However, in this study, the team discovered that sensitivity to oxidative stress is not necessarily associated with longevity.

To investigate whether there was any correlation between the biological aging process and sensitivity to atmospheric oxygen, the team compared the growth rate of lung and skin cells from connective tissues of 16 rodent species whose maximum lifespan ranged from 4 to 32 years.

Cells from rodents such as mice and capybaras were kept in culture using two different concentrations of oxygen -- either at 3% or at 21% -- and their growth rate was compared using state-of-the-art cell culturing methods. Cells (fibroblasts) from connective tissues from lung and skin were used in the experiment as they play a critical role in wound healing.

Laboratory mice were the only species that demonstrated extreme sensitivity to oxygen. Interestingly, cells from wild caught mice, naked mole rat, hamster, muskrat, woodchuck, capybara, paca, squirrel and beaver were mildly sensitive to oxygen whereas cells from rat, gerbil, guinea pig, deer mouse and chinchilla were not affected by oxygen concentration.

The data from the study is a major discovery and suggest that sensitivity to oxidative stress is not always associated with longevity. The team found those species in the oxygen non-sensitive group, including rat, gerbil, guinea pig and chinchilla tended to have a shorter lifespan. On the contrary, cells from the species that tend to live longer, including capybaras, pacas, naked mole rat and beaver, were more sensitive to oxygen.

Co-author, Dr Augusto Coppi from the School of Veterinary Medicine at the University of Surrey, said: "Our findings open up many areas to explore in the field of aging and regenerative medicine. With these new insights it would be very interesting to know whether non-rodent large mammals of veterinary interest including cats, dogs and horses would have the same reaction to oxygen to that found in rodents. Nowadays people regard antioxidants as the so-called 'elixir of life', however, our results cast doubt on this claim at least for some rodents, with mice being an exception."