Effects of mild heat shocks at young age on aging and longevity in Drosophila melanogaster.

Young adult flies were submitted to heat shocks (37 degrees C) of various durations (5, 10, 20, 40 or 60 min daily) for 1, 2 or 3 weeks. A slight longevity increase, in both sexes, was only observed with the lowest heat shock. Longer shocks had neutral or negative effects. Flies submitted to the procedure providing a longevity increase did not show a delayed behavioral aging but survived longer at 37 degrees C than control flies. This higher thermotolerance was not associated with an increased hsp70 induction. The results are discussed in connection with hormesis and previous results showing that hypergravity, an other mild stress, increases longevity and delays behavioral aging: different mild stresses may have contrasting effects on aging and longevity.