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Theories of aging
Aging represents changes which affect all levels of the organization of living matter, and these natural age changes in an organism are called gomeorezy.
Today there is a set of the theories trying to explain aging it both the adaptation and regulatory theory of aging and not less interesting theory of apoptosis, but any of them is not capable to explain fully that difficult process which happens at all levels of an organism, beginning from a molecule, then – a cell, fabric and body. Every year the amount of new knowledge of this process increases that leads to the birth of new theories of aging.
Telomerny theory of aging
In the 1960th the gerontologist from the USA L. Heyflik found out that human cells of skin can share only limited number of times (from 40 to 60), however he could not explain this phenomenon. In 10 flyings, A.M. Olovnikov who at that time is one of the staff of Institute of biochemical physics of the Russian Academy of Sciences on the basis of Heyflik's data, made the assumption that the limit cell fission is explained by the fact that at each cell division the chromosome is a little shortened.
The science knows that chromosomes have trailer sites (telomeres) which, owing to doubling, are gradually shortened, and over time the cell cannot share any more, and then it loses viability. It also is the reason of aging, according to the telomerny theory. Olovnikov's hypothesis was subject in the mid-eighties to when telomeraza enzyme which was capable to complete the shortened ends of a chromosome in cells of tumors that allowed them to be immortal was discovered. By the way, the limit in 50 divisions is fair not for each cells, for example, stem or cancer cells can share uncountable number of times.
By the way, itself A.M. Olovnikov decided afterwards that this theory does not explain the aging reason, and it put forward the redusomny theory of aging. According to its postulates, linear molecule DNA of a redusoma (and the redusoma is the small nuclear particle which is located in subtelomerny parts of a chromosome), is gradually shortened because of reduction of its linear molecule DNA covered with proteins that leads to reduction of various genes which are contained in it. This shortening of molecules DNA of a redusoma serves as a gage of biological time and is the reason of aging.
Elevatsionny theory of aging (neuroendocrinological theory)
In the 1950th the Soviet scientist V. M. Dilman put forward idea that there is a uniform regulatory mechanism which defines patterns of changes of various systems of an organism connected with age. The hypothalamus acts as the main link of this mechanism. Speaking more precisely, reduction eventually, abilities of perception of a hypothalamus of level of hormones in blood, and its sensitivity to signals of a nervous system are basic reasons of aging.
Thereof, the amount of the circulating hormones increases that leads to various diseases, inherent to advanced age (obesity, a hypertension, a climax, diabetes, atherosclerosis and others). All this leads to aging and death.
Afterwards, on the basis of these researches and supervision it was established that it leads to age changes in work of reproductive system. Dilman claimed that aging is a by-product of ontogenesis – development of an organism. Elevatsionny theory of aging promoted opening of new approaches to senilism prevention, and related diseases.
Adaptation and regulatory theory of aging
it was developed by the Ukrainian gerontologist V. V. Frolkis in the 1960th. It is based on representation that an old age genetically programmed process, however V. V. Frolkis assumed that age development is defined by balance of process of aging and process of the "anti-aging" (vituakt) directed to increase in life expectancy. The scientist developed a gene regulatory hypothesis according to which he primary mechanism of aging is disturbance of work of regulatory genes. And disturbance of gene regulation leads to diabetes, atherosclerosis, Parkinson and Alzheimer's diseases. The concept of gene regulatory therapy, for the prevention of development of age pathologies was right there put forward.
Theory of free radicals
This theory was put forward by scientists D. Harman and N. Emmanuel in the 1950th. According to the free radical theory, action of free radicals – oxygen forms which are synthesized in mitochondrions is causes of infringement of work of cells. Oxygen is required to cells for cellular respiration, however the part of oxygen can be transformed to so-called "active" forms of oxygen. Free radicals are capable to leave places where there is in it a need and is capable to damage DNA, RNA, lipids of cellular membranes and a squirrel. From surplus of free radicals the substances possessing antioxidant properties, for example, various vegetables and fruit, and also vitamins A, E and Page help.
Theory of apoptosis (theory of suicide of cells)
Belongs to the academician V.P. Skulachev. According to theory postulates, apoptosis is the programmed process of aging of a cell. Each cell, after passing of the life cycle or in it will occur a mutation, has to die and give way to new, young cells. This hypothesis bears the same sense as the telomerny theory of aging. At apoptosis the cell "samorazbiratsya", and its parts can be used by the next cells as construction material. Happens also to mitochondrions if in them it is formed excesses of free radicals. When there is too much died mitochondrions, products of their disintegration lead to apoptosis, i.e. suicide. And aging appears when in an organism of cells is born less, than is born new.
Theory "aging by mistake" (or theory of vegetative mutations)
This hypothesis was made by the physicist M. Stsillard in 1954 in the USA. According to its researches, ionizing radiation reduces the term of life of live organisms, and there are mutations in molecules DNA that leads to aging. Thus, the reason of aging of an organism, on Stsillarda, are mutations. However, the theory of vegetative mutations does not explain why people who were not exposed to radiation grow old. The follower Stsillarda – M. Orgel claimed that with age in an organism the genetic damages caused by mutations – accidental collect, and the caused various factors (strema, viruses, ultraviolet rays), damages of DNA collect that leads to aging and wear of an organism.
Exist as well other theories of aging, for example, the theory of cross stitchings, it makes similar sense, as well as the theory of free radicals, the theory one-time (spent) disputes and some other.
Thus, mechanisms of aging are difficult. Today there are several theories which in something contradict one another, and in something – supplement. In modern biology much attention is paid to problems of aging, and, it is possible, in the future, with increasing knowledge of this problem, means will be found to slow down aging and to prolong human life.
Section: Gerontology (Ageing)