Is a little radiation useful?
The destructive effects of high doses of radiation are well known to both specialists and the general public. Traditionally, it was believed that exposure to small doses causes less pronounced damage, but can lead to serious problems in the future. However, researchers at the University of Wisconsin-Madison, working under the leadership of Randy Jirtle, have demonstrated that in small doses, radiation has a positive effect on the health of a special line of mice. Moreover, it turned out that the use of antioxidants, such as vitamins C and E, neutralize these positive effects.
Experts have long known that it is not always possible to judge the effects of small doses of the same compounds by the influence of high doses. Substances that are poisons in high doses, in small concentrations can stimulate growth or have a positive effect on health. This observation is of a general nature, but it should not be neglected.
The authors conducted experiments on linear mice known as viable yellow agouti mice. These animals are used to study the effect of diet, chemical compounds and other environmental factors on gene activity. Agouti mice have a genetic defect that causes the activation of the agouti gene in cells of all tissues. This causes the yellow color of the animals' fur, as well as their predisposition to obesity, diabetes and cancer. However, methylation of the agouti gene under the influence of chemical compounds, stress or other factors blocks its activity, changing the color of animals to brown and ridding them of obesity and other health problems.
The researchers irradiated pregnant female mice in such a way that the dose received by developing embryos fell into the range of 0.4-7.6 centigrays. (A person receives comparable radiation during an X-ray examination at the dentist.) The animals of the control group were placed in an X-ray machine, but were not exposed to radiation. The offspring of irradiated females who received radiation at a dose of 0.7-7.6 centigrays differed from the offspring of the control group females by a large number of male cubs with an increased level of methylation of the agouti gene, which was manifested by a brownish coat color. The maximum effect was observed in the cubs of females who received a dose of radiation in the range of 1.4-3 centigrays.
The introduction of antioxidants into the diet of pregnant females prevented methylation of the agouti gene. This suggests that, at least partially, the active oxygen forms neutralized by antioxidants are responsible for the radiation-induced methylation of the agouti gene.
According to experts, despite the fact that the mice used in the experiment had a genetic anomaly, low doses of radiation can also be useful for humans. Before antibiotics became firmly established in medical practice, some doctors treated infections of the ears and paranasal sinuses with small doses of X-rays. Low doses of radiation are sometimes used to treat arthritis in patients who for some reason cannot take anti-inflammatory drugs. Radioactive radiation modulates the immune system by changing epigenetic labels on the DNA of immune cells.
Article by A.J. Bernal et al. Adaptive radiation-induced epigenetic alterations mitigated by antioxidants is published in FASEB Journal.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru according to Science News: A little radiation is good for mice.
09.11.2012