Frisard Madlyn, Ravussin Eric
Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
Endocrine. 2006 Feb;29(1):27-32. doi: 10.1385/ENDO:29:1:27.
Aging can be defined as a progressive decline in the ability of the organism to resist stress, damage, and disease. Although there are currently over 300 theories to explain the aging phenomenon, it is still not well understood why organisms age and why the aging process can vary so much in speed and quality from individual to individual. The oxidative stress hypothesis is one of the prevailing theories of aging. This theory states that free radicals produced during cellular respiration damage lipids, proteins, and DNA thereby accelerating the aging process and increasing disease risk. Under normal conditions, the electron transport chain is the primary producer of the superoxide anion, which is precursor to other highly reactive species such as hydrogen peroxide and the hydroxyl radical. Oxidative stress accumulates when prooxidants overwhelm the antioxidant defense mechanisms. This is dependent on a number of factors including free radical production, susceptibility of tissue to stress, and strength of the defense and repair system. Oxidative stress has been implicated in a number of chronic disease states usually grouped under the umbrella of the metabolic syndrome and is thought to contribute to the aging process. It has been hypothesized that the production of free radicals is dependent on resting metabolic rate and this may have an impact on the aging process. However, other factors, such as mitochondrial function, may be important in the production of free radicals and the subsequent effect on aging and disease states.
衰老可定义为生物体抵抗压力、损伤和疾病的能力逐渐下降。尽管目前有300多种理论来解释衰老现象，但生物体为何会衰老，以及衰老过程在速度和质量上为何在个体之间存在如此大的差异，仍未得到很好的理解。氧化应激假说是衰老的主流理论之一。该理论认为，细胞呼吸过程中产生的自由基会损伤脂质、蛋白质和DNA，从而加速衰老过程并增加患病风险。在正常情况下，电子传递链是超氧阴离子的主要产生者，超氧阴离子是其他高反应性物质如过氧化氢和羟基自由基的前体。当促氧化剂超过抗氧化防御机制时，氧化应激就会积累。这取决于许多因素，包括自由基的产生、组织对压力的敏感性以及防御和修复系统的强度。氧化应激与许多通常归类于代谢综合征的慢性疾病状态有关，并被认为会促进衰老过程。据推测，自由基的产生取决于静息代谢率，这可能会对衰老过程产生影响。然而，其他因素，如线粒体功能，可能在自由基的产生以及随后对衰老和疾病状态的影响中起重要作用。
