Stress in biology and medicine, role in aging.

In this review, we present a short description of the history of stress in the medical literature followed by a recapitulation of its mechanisms, from the cellular to the organismal level and its role in aging. The medical importance of stress was first taken up as a subject of experimental medicine by physiologists, starting from Claude Bernard's concept of the stability of the "milieu intérieur", altered by stress, followed by others, culminating recently by the elucidation of its mechanisms at the cellular and molecular level. These studies showed that oxidative stress is one of the most important and most frequent form of biological aggression. Its accumulation over time is important for the burnout syndrome and for neuronal aging. There is however a positive side to it also, redox signaling plays an important role in the functional coordination of cellular activities. These mechanisms, still to be more completely evaluated, have to be taken in account for planning efficient protective therapeutic interventions.