Human beings have been studying aging for a long time, but it was not until the 1940s that they began to systematically study aging from the aspects of physiology, biochemistry and morphology. So far, scholars at home and abroad have put forward more than ten theories about aging, and developed a large number of anti-aging drugs and biological products, which will leave garbage in the body while delaying aging, resulting in certain toxic and side effects. Laser can change the energy state of cells without leaving any trace. The long-term effect of low-intensity laser irradiation therapy is remarkable, and it can be used as a green anti-aging method in the 21st century. This paper reviews the anti-aging effect and its mechanism of low-intensity laser.
Low intensity laser and its anti-aging effect
Low intensity laser refers to a red or near-infrared laser with an output power of 1-500mw and a wavelength of 600-1100nm. Laser irradiation with a dose less than 2j/ cm2 can stimulate cell proliferation, while laser irradiation with a dose higher than 16j/ cm2 can inhibit cell proliferation. Low intensity laser irradiation therapy transfers energy at a very low energy level, so the heat, noise, vibration and other effects produced during the irradiation process are extremely small, not enough to cause adverse changes, and can be ignored. A large number of cell culture experiments in vitro show that He Ne laser is the most commonly used laser type in low-intensity laser irradiation therapy .
Compared with healthy cells, aging cells and pathological cells have the same surface receptors in a coherent state , which can be regulated by low-intensity laser to restore their functions. Studies have shown that low-intensity laser irradiation therapy can delay the aging of the body through the antioxidant system, immune system , circulatory system, endocrine system ] and cell level . Appropriate low-intensity laser can prolong the life of cells. use λ> 500nm broadband blue light irradiates cells 1-3 times a week (at a dose of 104j/ ㎡), which can promote the proliferation and prolong the life of diploid fibroblasts from adult skin (hu-274), mixed fetus (hu-278) and fetal lung (WI-38). After exposure to cool fluorescence for 2h a day for 150D, it was found that the life span of human fetal lung fibroblasts increased. The irradiated cells divided 70 times, while the non irradiated cells divided only 53 times.
Possible molecular mechanism of anti-aging effect of low intensity laser
2.1 mechanism of up regulation of cAMP level
Huangbeipei et al. Showed that with the growth and aging of Wistar rats, the cellular cAMP level increased and decreased. In other words, the increase of cAMP level is beneficial to prolong the life of cells. According to the bioinformatics model of low-intensity laser , 104j/ m2 of cold light can prolong cell life by increasing cAMP level. Generally, the use of red low-intensity laser in clinic can increase cAMP level, so it can be used for anti-aging. Low intensity laser irradiation can activate the body’s antioxidant system by increasing intracellular cAMP, such as increasing the concentration of catalase, superoxide dismutase (SOD), endogenous vitamin E, transferrin and so on. In addition, it can also increase the activity of some sulfur-containing enzymes to resist the instability of gene expression in the state of cell differentiation caused by gene mutation and repair enzyme damage caused by free radicals .
2.2 regulating the expression mechanism of genes related to cell aging
The genes related to cell aging can be roughly divided into two categories. One is the genes related to cell proliferation regulation, such as p16, p53, p21, Rb, etc; One is telomerase regulation related genes , and telomere shortening has become a sign in the process of cell aging . Telomere protein kinase and lipoprotein kinase activities play an important role in maintaining chromosome stability, which indicates that there are signal transduction pathways during telomere and cell cycle. Duan j et al. Showed that p16ink4a/prb pathway and telomerase activity play an important role in regulating cell aging. In China, the research group of Tong tanjun and zhangzongyu preliminarily proved that p16 gene is not only the main link in the genetic control program of cell aging, but also affects telomere length and cell life through the study on the mechanism and regulation of p16INK4a. Their research showed that inhibiting the expression of p16 gene prolonged the life span of cells, reduced the degree of aging, and slowed down the shortening of telomere length; On the contrary, the expression of p16 gene was increased, the cell life was shortened, the degree of aging was aggravated, and the telomere length was shortened significantly.
As discussed in the previous section, low-intensity laser can delay cell aging, but the mechanism has not been very clear. The research progress of aging at the gene level should provide a theoretical basis for studying the anti-aging effect of low-intensity laser. With the in-depth study of low-intensity laser, the application of low-intensity laser will be more and more widely, and its mechanism will become clearer. The shortcomings of low-intensity laser in clinical application will also be further improved.