Oxidative Medicine and Cellular Longevity / 2013 / Article / Tab 1

Review Article

Effects of Caloric Restriction on Cardiac Oxidative Stress and Mitochondrial Bioenergetics: Potential Role of Cardiac Sirtuins

Table 1

Major biological theories of aging.

(A) The programmed theory

(1) Programmed theory
 Telomere shortening theory
Aging is the result of a sequential switching of certain genes. Telomere plays a role in the genomic instability with aging.
(2) Neuroendocrine theoryBiological clocks act through the neurohumoral system to control the pace of aging.
(3) Immunological theoryThe immune system is programmed to decline, which leads to an increased vulnerability to acute and chronic inflammation, resulting in aging and death.

(B) The damage or error theory (Nonprogrammed theory)

(1) Wear and tear theoryCells and tissues have vital parts that wear out, that leads to aging.
(2) Rate of living theory
 Metabolic theory
The greater a rate of basal oxygen metabolism, the shorter its lifespan.
(3) Cross-linking theory
 Glycation theory
The accumulation of modified constituents, such as cross-linked and glycated proteins, damages cells and tissues, resulting in aging.
(4) Free radical theory
 Oxidative stress theory
 Mitochondrial theory
Free radicals and reactive oxygen species (ROS) cause cellular damage and the accumulation of oxidative damage leads to aging. Mitochondria are a main source of ROS and also a target of ROS.
(5) Somatic DNA damage theoryDNA damages occur continuously in living cells. Most of these damages are repaired, whereas some accumulate, resulting in cellular dysfunction and aging. In particular, damages to mitochondrial DNA lead to mitochondrial dysfunction.