The gradual deterioration of physiological functions that accompanies aging is a fundamental characteristic of all living organisms. Recent work suggests that all the events involved in this aging are controlled by a very small region of the brain, the hypothalamus. Our lifestyles can either accelerate this aging or, if we adopt healthy lifestyle habits, slow it down.
All living organisms, whether bacterial, plant or animal, absolutely must convert the energy present in the environment to create and maintain complex and ordered structures capable of self-replicating through cells. Life is therefore a very costly process, which requires a constant supply of energy to counter the fundamental tendency of matter to adopt a disorganized state. This continual effort, on the other hand, is inevitably associated with the appearance of damage at the cell level, which over time causes a drop in their function and a general decrease in the “performance” of living organisms. What is called aging is therefore the tangible expression of the “cost of life”, that is to say the traces left by the incessant work of our cells to create order out of disorder.
Aging starts in the brain
Even if we mainly notice aging by certain external signs, in particular changes in the appearance of the skin (wrinkles, age spots), it is all of our organs that age simultaneously. But how are the body’s cells programmed to age in such a coordinated fashion?
To solve this enigma, a team of researchers from the Albert Einstein College of Medicine in New York investigated the potential role of the hypothalamus, a very small region of the brain well known for its importance in controlling the main physiological functions. (metabolism, growth, reproduction). They first made the surprising observation that aging was associated with a marked increase in the activation of the inflammatory cascade in the brain. Microglial cells, a class of inflammatory cells (macrophages) whose role is to defend the brain against foreign bodies, become more active with age and secrete inflammatory molecules (TNF) which cause the creation of a climate of chronic inflammation. This inflammation particularly affects the region of the hypothalamus and profoundly modifies its functioning.
How are the body’s cells programmed to age in such a coordinated way?
For example, researchers have noted that the production of GnRH, the chief hormone responsible for the synthesis of sex hormones in both men and women, decreases considerably with aging. It seems that this decrease plays a key role in the loss of physiological functions that occurs with age, because the simple administration of GnRH, or even the inhibition of the inflammatory process in aged models, is sufficient to reduce several typical physiological changes. of aging such as decreased bone mass, atrophy of epidermal cells and reduced cognitive functions.
Slow down aging
These observations are very important, because they suggest that, even if aging is an inevitable phenomenon, it would nevertheless be possible to slow down this process by minimizing the degree of chronic inflammation that prevails inside the body.
In this sense, several aspects of our lifestyle that are associated with a longer life, in particular diet, body weight and regular physical activity, are all known to exert a powerful anti-inflammatory action. It is therefore likely that the beneficial effect of these good lifestyle habits is at least partly linked to a reduction in inflammation in the brain and, by extension, to the aging of all the organs of the body.
Zhang G et al. Hypothalamic programming of systemic aging involving IKK-, NF-B and GnRH. Nature; 497: 211-216.