ROLE OF OXIDATIVE STRESS IN AGING

In this article is presented a synthesis of the complex relationships between oxidative stress ageing. Free radicals are produced in a conti nous way but they are also quickly removed by very efficient defence s ystems. The studies trying to increase the antioxidants uptake in the diet or to produce transgenic animals overexpressing antioxidant enzym es did not lead to increased life span in mammals. Only transgenic dro sophils for SOD and catalase lived longer than the parents wild type. At the cellular level, oxidative stresses speed up-the passage of fibr oblasts from young to old morphotypes. This shift increases with stres s intensity but is also influenced by the quantity of energy available to the cell. Thermodynamics of open systems very well account for the experimental observations of cell response to stresses, oxidative str ess being only one of the challenges faced by living cells. Oxidative stresses must be considered in relationship with the level of defence and turnover systems as affecting continuously various cellular functi ons with sometimes excessive production in pathological situations. In this case, a global response of the cell is observed which is the res ult of complex mechanisms linked to cell activation and changes in gen e transcription.