Relación entre el estrés oxidativo mitocondrial y la velocidad del envejecimiento

Although many theories have been put forward on the causes of ageing, the explanation that has received greatest support in the scientific literature is the free radical theory. The present article reviews the studies published on the relationship between maximal longevity of the distinct animal species and their endogenous antioxidant levels and oxygen radical generation. Most studies on experimental supplementation with antioxidants indicate that they can increase life expectancy but do not change maximal longevity. Moreover, endogenous antioxidants are negatively correlated with maximal longevity. However, the intensity of mitochondrial production of oxygen radicals and oxidative damage to mitochondrial DNA are lower in longevous animals than in shortlived animals. Longevous animals also show a lower grade of fatty acid unsaturation in tissue membranes than short-lived species. Caloric restriction, the only experimental procedure that reduces the rate of ageing, also reduces mitochondrial production of free radicals and oxidative damage to mitochondrial DNA. This decrease occurs in complex I. These results suggest that similar mechanisms are used to increase longevity in caloric restriction and during the evolution of animal species with different rates of ageing and that these mechanisms include a decrease in mitochondrial oxidative stress.