Free radical theory of aging: new data against
Over the past forty years, the so-called free radical theory of aging has dominated official science, explaining age-related changes in the body by the influence of oxidative stress. In other words, cell aging, according to the proponents of this hypothesis, is caused by the accumulation of oxygen ions, free radicals and peroxides (often referred to under the general name "reactive oxygen species", ROS).
However, experimental data that do not agree with the theory are gradually beginning to appear. In the February issue of the journal PLoS Genetics, an interesting article was published by researchers from McGill University (Canada), convincingly proving the absence of a link between oxidative stress and aging. The data of Canadian scientists indicate an inverse relationship: the life expectancy of some organisms with a partially impaired ability to resist the accumulation of ROS does not decrease, but increases.
"The problem with the theory is that it is based only on the correlation of two events, the totality of evidence," explains Siegfried Hekimi from McGill University. – Indeed, the older the body, the more it suffers from oxidative stress. Due to this, this hypothesis has been strengthened: people take correlation for a causal relationship."
Dr. Hekimi's group experimented on Caenorhabditis elegans, nematodes widely used as a model organism in various studies. Scientists have gradually "turned off" five genes responsible for the production of a special group of enzymes (superoxide dismutases, SOD), which are designed to protect cells from the effects of ROS. In the course of observations of "mutated" organisms, no reduction in life expectancy was observed in any of them, although oxidative stress developed much more actively. At the same time, one of the obtained varieties of worms demonstrated increased viability.
A graph of the increase in the lifespan of nematodes with "switched off" mitochondrial SOD. The indicators of ordinary worms are marked in black, the results of the two studied alleles of "mutated" individuals are highlighted in color (image from the journal PLoS Genetics).
"A mutation that increases life expectancy is associated with mitochondrial SOD," Mr. Hekimi explains this phenomenon. – These results are consistent with previous studies that have determined the leading role of mitochondria in the aging process. It seems that the suppression of mitochondrial activity with the help of ROS benefited the nematodes."
Nevertheless, it would be a big mistake to assume that oxidative stress has a positive effect on the body. "ROS, without any doubt, harm us," Dr. Hekimi warns against misinterpretation of the results of the study. "We just showed that they are probably not related to aging."
The full version of the report on the work carried out can be downloaded from the website of the journal PLoS Genetics.
Prepared based on the materials of PhysOrg.
Dmitry Safin, "Kompyulenta"Portal "Eternal youth" www.vechnayamolodost.ru