Why do we age? With old age come certain physical impairments (reduced eye sight and hearing) and health consequences (decreased bone density, diabetes, impaired memory and cognitive decline). Why would the human body voluntarily permit a process that seems exclusively disadvantageous? Many theories and “solutions” have been proposed in order to address and target the biological basis of the aging phenomenon. Some argue that plastic surgery, health spas and anti-aging creams hold the key to aging with grace and health. Others argue for healthy eating in conjunction with exercise. Which strategy should the general public follow?
In October 2015, Ileana Soto and colleagues published an article on the interaction that exists between aging, activation of the innate immune system (the body’s first line of defense for fighting an infection) and neurovascular dysfunction. They reasoned that a deeper understanding of these processes might elucidate the biology of aging. The authors studied the neural function of young (4 month old) and old (21 month old) mice using neuro-histological analysis (a neuronal analyzer). They found old mice had pericyte (cells present in the blood brain barrier) loss and astrocyte (a glial cell in the brain) dysfunction. The abnormal presence as well as function of these cells led to inflammation of the brain and increased presence of C1QA (an important molecule to activate immune cells) in old mice. Interestingly, when old mice were subject to exercise C1QA levels decreased (less inflammation) and synaptic plasticity increased.
The authors found that an astrocyte protein, Apolipoprotein E (APOE) (an anti-inflammatory molecule necessary for lipid breakdown) decreased significantly in old mice. The reduction of APOE was not seen when old mice were subjected to exercise. This showcases a possible connection between APOE and age-related neural dysfunction. To test its function, APOE-deficient mice and APOE-sufficient mice were exercised from midlife to old age. Deficient mice when exercised did not show improved neural histology, in contrast to sufficient mice, which showed dramatically improved neural histology. APOE seems to be a crucial molecule for the maintenance of neural function during old age.
Ileana Soto and colleagues have shown that exercise in old mice improves and preserves neurovascular function, resulting in a more youthful brain. Understanding the biology of aging along with the benefits of exercise will prevent individuals from getting old, while allowing them to get older easily and healthily.