动物实验 z-bo 2020-08-28 442

　　People always say that what you eat will change, so does eating old meat make you grow old? This may sound far-fetched, but experiments with mice, flies, and yeast indicate that this may indeed be the case.

　　People do not yet understand the basic causes of aging. A dominant idea is that the body will accumulate cell damage during its lifetime. This may include oxidative damage to cells caused by byproducts of aerobic respiration and DNA damage.

　　Vadim Gladyshev of Harvard University in the United States is curious whether body tissues can get cell damage from food.

　　Food is broken down and used as building blocks for many cellular processes, so eating old organic matter (which has more molecular damage on its own) may make animals age faster than eating fresh organic matter with less molecular damage.

　　In order to test this theory, Gladyshev and his team cultivated yeast made from old or fresh yeast in a culture medium, and fed fruit flies with food made from old and new flies. They also studied mice fed with old venison and young venison. These animals are fed these special foods from early adulthood to the rest of their lives.

　　Old food shortened the lifespan of yeast by 18% and fruit flies by 13%. In mice, old food shortened the lifespan of female mice by 13%, but it had no significant effect on male mice. Gladyshev believes that if the sample size is increased, they may see this effect in both sexes, and he believes that the results of yeast, fruit flies and female mice support his hypothesis.

　　But Jo?o Pedro de Magalhaes of the University of Liverpool is not convinced of this conclusion. He believes that the research results can explain the wide nutritional differences in the composition of old and new meat, rather than age-related molecular damage. "There are different nutrition between old animals and new animals." He said, "The taste of lamb is different from that of old lamb."

　　Gladyshev's team managed to control this variable in the diet of mice by ensuring that old and new meat contained the same amount of fat, carbohydrates, and protein. But he admits that they cannot guarantee that all ingredients are the same. "This may also be a factor." He said.

　　De Magalhaes believes that molecular damage is not all, and some aspects of aging may be written into the programming of human development. "We don't know exactly why we grow old. There is evidence pointing to a series of molecular damage, but there are other similar programming mechanisms at work." He said.