<P> One of the areas where the concept of hormesis has been explored extensively with respect to its applicability is aging . Since the basic survival capacity of any biological system depends on its homeostatic ability, biogerontologists proposed that exposing cells and organisms to mild stress should result in the adaptive or hormetic response with various biological benefits . This idea has now gathered a large body of supportive evidence showing that repetitive mild stress exposure has anti-aging effects . Exercise is a paradigm for hormesis in this respect . Some of the mild stresses used for such studies on the application of hormesis in aging research and interventions are heat shock, irradiation, prooxidants, hypergravity and food restriction . Some other natural and synthetic molecules, such as celasterols from medicinal herbs and curcumin from the spice turmeric have also been found to have hormetic beneficial effects . Such compounds which bring about their health beneficial effects by stimulating or by modulating stress response pathways in cells have been termed "hormetins". Hormetic interventions have also been proposed at the clinical level, with a variety of stimuli, challenges and stressful actions, that aim to increase the dynamical complexity of the biological systems in humans . </P> <P> Mitochondria are sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine triphosphate (ATP), a source of chemical energy . Reactive oxygen species (ROS) have been regarded as unwanted by - products of oxidative phosphorylation in mitochondria by the proponents of the free - radical theory of aging promoted by Denham Harman . The free - radical theory suggests that the use of compounds which inactivate ROS, such as antioxidants, would lead to a reduction of oxidative stress and thereby produce an increase in lifespan . </P> <P> ROS may perform an essential and potentially lifespan - promoting role as redox signaling molecules which transduce signals from the mitochondrial compartment to other compartments of the cell . Increased formation of ROS within the mitochondria may cause an adaptive reaction which produces increased stress resistance and a long - term reduction of oxidative stress . This kind of reverse effect of the response to ROS stress has been named mitochondrial hormesis or mitohormesis and is hypothesized to be responsible for the respective lifespan - extending and health - promoting capabilities of glucose restriction and physical exercise . </P> <P> Hormesis may also be induced by endogenously produced, potentially toxic agents . For example, mitochondria consume oxygen which generates free radicals (reactive oxygen species) as a by - product . It was previously proposed on a hypothetical basis that such free radicals may induce an endogenous response culminating in increased defense capacity against exogenous radicals (and possibly other toxic compounds). Recent experimental evidence strongly suggests that this is indeed the case, and that such induction of endogenous free radical production extends life span of a model organism . Most importantly, this extension of life span is prevented by antioxidants, providing direct evidence that toxic radicals may mitohormetically exert life extending and health promoting effects . Since mitochondrial activity was found to be increased in the previously mentioned studies, this effect cannot be explained by an excess of free radicals that might mark mitochondria for destruction by lysosomes, with the free radicals acting as a signal within the cell to indicate which mitochondria are ready for destruction, as proposed by Nick Lane . </P>

Name a drug that has the opposite effect as alcohol