Regarding brain regions, the hypothalamus is one of those that most attracts our attention due to its multitasking ability : it helps control our temperature, hunger, sleep, emotions and sexual desire. But this is not all. Now, a study led by scientists from the Albert Einstein College of Medicine in New York (USA) has found that the hypothalamus is also responsible for keeping us young thanks to a supply of neural stem cells that regulate our aging. That is, stem cells in the hypothalamus of the brain govern the rapid aging that occurs in the body.
This discovery, thanks to experiments with mice, could lead to new strategies to prevent age-related diseases and extend the lifespan of humans.
Specifically, experts have identified exactly the neurons that control aging: a small population of adult neural stem cells, which are known to be responsible for the formation of new brain neurons.
“Our research shows that the number of hypothalamic neural stem cells naturally declines during the life of the animal, and this decline accelerates aging, but we also found that the effects of this loss are not irreversible: by replenishing these stem cells or the molecules they produce , it is possible to reduce and even reverse various aspects of aging throughout the body, “says Dongsheng Cai, study leader to the journal Nature.
To study whether stem cells from the hypothalamus were the key to aging, the researchers looked at the fate of those cells in a group of healthy rodents. As the mice grew older, the number of hypothalamic stem cells began to decline at the age of about 10 months , that is, several months before the usual signs of aging appear in these animals. By two years of age – the old age of mice – most of the hypothalamus stem cells had disappeared.
They then decided to look at what happened if hypothalamic stem cells were selectively disrupted in middle-aged mice: “This disruption greatly accelerated aging compared to control mice, and animals with disrupted stem cells died much earlier than normal.” Cai clarifies.
What would happen if we added stem cells to the hypothalamus? Would it counteract aging?
To answer this question, the scientists injected hypothalamic stem cells into the brains of middle-aged mice whose stem cells had been destroyed, as well as the brains of old normal mice. In both groups of animals, the treatment delayed or reversed aging.
Hypothalamic stem cells appear to exert a powerful anti-aging effect by releasing molecules called microRNAs (miRNAs). They are not involved in protein synthesis, but rather play a key role in regulating gene expression. The miRNAs are packaged into tiny particles called exosomes , which hypothalamic stem cells release into the cerebrospinal fluid of mice.
By extracting exosomes containing miRNAs from hypothalamic stem cells from the mice, the researchers decided to inject them into the cerebrospinal fluid of two groups of mice: middle-aged mice whose hypothalamic stem cells had been destroyed and normal, middle-aged mice. The result was that aging significantly decreased in both groups of animals, not only in terms of tissue or muscular endurance, but also in coordination, social behavior and cognitive ability.
This finding has been completely new and unexpected and although there is no guarantee that the same physiological function works in humans, we could be facing the first step towards the effective slowing down of the aging process and the treatment of age-related diseases.
Referencia: Hypothalamic stem cells control ageing speed partly through exosomal miRNAs. Nature (2017) doi:10.1038/nature23282
