ADAPTIVE RESPONSE AND OXIDATIVE STRESS

The ability of a cell, tissue, or organism to better resist stress damage by prior exposure to a lesser amount of stress is known as adaptive response. It is observed in all organisms in response to a number of different cytotoxic agents. One of these agents, oxidative stress, is known to induce an adaptive response in bacteria that is accompanied by the induction of many proteins. De novo protein synthesis is required for adaptive response to oxidative and other types of stress, indicating that newly synthesized protective proteins are necessary for adaptation. Adaptive response to oxidative stress also has been observed in mammalian cells. Several studies suggest it is necessary to first preexpose mammalian cells to a somewhat toxic oxidative stress in order to observe significant resistance to a subsequent highly lethal dose of oxidant. Cross-resistance of oxidatively stressed cells to other toxic agents including gamma- and X-irradiation, heat shock, aldehydes, heavy metals, MNNG, N-ethylmaleimide, and heme also has been reported. Understanding oxidant adaptive response in more detail and identifying the protective proteins involved may prove to be of clinical benefit.