Aging-inducing effects have been attributed to many organs and substances, but the sophisticated system, which our body and especially brain are, remains mysterious, as many puzzles are unsolved (if they ever will be so). According to researchers, one more mechanism behind aging has been recently revealed: stem cells in the hypothalamus seem to regulate aging processes.
Image Credit: Sciencemag.org
A portion of the brain with a variety of functions, hypothalamus is one of the most fascinating brain parts to study.
It’s difficult to overestimate its role in the body, as it governs processes related to development, metabolism, sleep, reproduction and growth. However, even this impressive list of hypothalamus’s areas of interest turned out to be incomprehensive: a team of researchers from Albert Einstein College of Medicine showed that at least one more function can be attributed to this polymath organ – it regulates aging processes.
The story of revealing that hypothalamus plays a significant role in aging processes started in 2013, when this very team of investigators found that systemic aging has a lot to do with hypothalamus.
In the team’s new study, they conducted a series of mice experiments to find out whether it is the loss of hypothalamic stem cells that contributes to body deterioration. The researchers believe their findings could help extend lifespan and prevent conditions associated with aging.
The team reported that there is a special group of stem cells located in the brain part hypothalamus, which take part in formation of new neurons in the brain and regulate aging processes. According to them, the pool of such stem cells is limited, and their amount decreases over time. When significant decline in their numbers occurs, aging starts to manifest itself.
However, the damage done by the “hypothalamic stem cell scarcity” can be reversed, as their experiments showed. It can be done two ways. The first one is by means of restoring their population, and the other one is injecting the molecules these cells produce.
In order to study what happens to the body when paucity of these stem cells occurs, the investigators looked at what happens in the bodies, and brains in particular, of lab mice.
Mice are considered to be old when they are two years of age, so the team monitored and estimated hypothalamic stem cell loss in mice and found that the numbers started to decline at the age of 10 months, and detectable consequences of it, which are signs of aging, became visible several months later. By the time the mice turned 2 or so, their hypothalamuses had been almost completely devoid of stem cells.
However, it remained unclear whether there was a causation, not association, so they wanted to know if it was the pool of stem cells being depleted that was triggering aging processes in the body, or vice versa.
They took a group of middle-aged lab rodents and destroyed some of the stem cells found in their hypothalamuses. This led to significant acceleration of processes related to aging, compared to those seen in normal mice. Stem cell disruption also resulted in premature death of the rodents.
At the next stage of the experiment series, the investigators injected the cells into brains of control old animals and middle-aged rodents with their own pool of stem cells disrupted. Either group had aging processes slowed down, including endurance decline, cognitive ability decline, coordination decline, etc.
The mechanics behind
The team reported that it was the microRNAs released by these cells that had such impact on the body. These miRNAs regulate gene expression, and extracting them and injecting into the cerebrospinal fluid of mice led to the changes similar to those seen in the previous experiment.
The investigators believe the findings can help develop therapies that could prevent age-related diseases and reverse aging processes.
Hypothalamic stem cells control ageing speed partly through exosomal miRNAs – Nature.com
What is the function of the hypothalamus? – Medicalnewstoday.com