The hormetic effects of hypergravity on longevity and aging.

This paper reviews the literature on the effects of hypergravity (HG, gravity levels higher than 1g, the terrestrial gravity) on longevity and aging. The different studies showed that life-long exposures to high gravity levels decreased longevity and accelerated the age-related decline observed on some physiological and behavioral variables. In contrast, chronic exposure to HG increased resistance to heat in young and middle-aged Drosophila melanogaster. A short exposure to HG at the beginning of adult life increased male longevity and delayed behavioral aging in D. melanogaster. All these results show that HG acts as a hormetic factor. Long exposures to HG have deleterious effects on longevity and aging, whereas short exposures have beneficial effects. Some potential mechanisms of action of the beneficial effects of HG are also reviewed here. However, the ones tested so far (heat shock proteins and antioxidant defense) have proven unable to explain the hormetic effects of HG and their mechanisms of action are still unknown.