University of Michigan (UM) researchers have discovered that oxidative stress experienced early in life increases subsequent stress resistance later in life.
Examining a type of roundworm called C. elegans, UM researchers found that worms that produced more oxidants during development lived longer than worms that produced fewer oxidants.
That other stochastic factors, besides genetics and environment, might be involved in determining variability in lifespan becomes clear in the case of C. elegans, a popular model system among aging researchers in part because every hermaphroditic mother produces hundreds of genetically identical offspring.
However, even if kept in the same environment, the lifespan of these offspring varies to a surprising extent.
The researchers discovered that during development, C. elegans worms varied substantially in the amount of reactive oxygen species they produce.
Reactive oxygen species, or ROS, are oxidants that every air-breathing organism produces. The researchers discovered that instead of having a shorter lifespan, worms that produced more ROS during development actually lived longer.
"Experiencing stress at this early point in life may make you better able to fight stress you might encounter later in life," said UM postdoctoral researcher and lead author of the study Daphne Bazopoulou.
When the researchers exposed the whole population of juvenile worms to external ROS during development, the average lifespan of the entire population increased.
The researchers then sorted thousands of C. elegans larvae according to the oxidative stress levels they have during development.
By separating worms that produced large amounts of ROS from those that produced little amounts of ROS, they showed that the main difference between the two groups was a histone modifier, whose activity is sensitive to oxidative stress conditions.
The researchers found that the temporary production of ROS during development caused changes in the histone modifier early in the worm's life.
How these changes persist throughout life and how they ultimately affect and extend lifespan is still unknown. What is known, however, is that this specific histone modifier is also sensitive to oxidative stress sensitive in mammalian cells.
"The general idea that early life events have such profound, positive effects later in life is truly fascinating. Given the strong connection between stress, aging and age-related diseases, it is possible that early events in life might also affect the predisposition for age-associated diseases, such as dementia and Alzheimer's disease," said Ursula Jakob, a UM professor of molecular, cellular and developmental biology.
In the next step, the researchers want to figure out what key changes are triggered by these early-life events.
Oxidative stress happens when cells produce more oxidants and free radicals than they can deal with.
It's part of the aging process, but can also arise from stressful conditions such as exercise and calorie restriction.