Researchers from the Albert Einstein College of Medecine in New York managed to prove that the hypothalamus, a small part of the brain located in the central nervous system and already known for helping with growth and development, is somehow responsible for aging. Studying it could be key in the fight against aging.

Long long life, hypothalamus lutte vieillissement
Long long life, hypothalamus lutte vieillissement

For this study, experiments were conducted on the hypothalamus of mice. First, researchers looked at the immune response of the hypothalamus, since it is know to trigger symptoms like weight gain and hypertension, which are strongly associated with aging. Previous studies proved that two proteins, NFkB and IKKB, were responsible for the immune response of the hypothalamus.  By observing mice of different ages, researchers have noticed that this protein was not active in young mice, but became activated in middle-age mice and that older the mice, the more the protein was activated, and the more significant its role became in the aging process. The following step was to link activating NF-kB/IKKB and aging. Simultaneously, the research team tried to define if their inhibition could trigger an “anti-aging” effect, what they managed to prove after a series of experiments activating/inhibiting both proteins.

By taking the research on these activations one step further, researchers found that they also triggered the inhibition of one hormone, GnRH, whose role is to regulate sexual and reproductive hormones. They proceeded to check if that hormone, linked to NF-kB/IKKB was responsible for aging. By injecting older mice with GnRH, the researchers came to the surprising conclusion that it was responsible for neurogenesis (the formation of new neurons) no matter the age of the subject. However, aging is characterized by a slower neurogenesis ; GnRH would then slow down aging [1].

Later on, in 2017, the same research team managed to find the cells responsible for aging inside the hypothalamus, stem cells that are normally responsible for the renewal of exosome neurons. By studying mice aging patterns again, the researchers found out that the older the mice were, the less of those stem cells they found in the hypothalamus. After a certain age, those cells were almost completely gone. In order to prove that these cells did in fact trigger aging, they tested a few mice by completely pulling out those cells, and the results showed that the mice aged much faster and died even quicker than normal, and so that the molecules let out by those stem cells, called microRNA (miRNA) which are themselves contained in exosome particles, had an effect on the aging process. The most surprising and promising part of this article was that the researchers injected the exosomes in the hypothalamus of two types of middle-aged mice : mice with no stem cells and mice with healthy stem cells. In both cases, aging was significantly slowed physically (tissue analysis, muscle stamina and coordination) and it showed as well in the behaviour of the mice (social behaviour and cognitive functions). Even if the “anti-aging” part of the miRNA remains to be discovered, these experiments prove that it is indeed possible to slow down aging [2].

In conclusion, by studying the hypothalamus, these studies allowed to prove that it is a the heart of very promising leads in the fight against aging: inhibiting NF-kB/IKKB proteins in order to maintain GnRh production, and find the precise area where the miRNA contained in stem cells slow down aging, in order to fight the health conditions linked to aging and thus push back aging as much as possible.

Sources :

[1] Guo Zhang, Juxue Li, Sudarshana Purkayastha, Yizhe Tang, Hai Zhang, Ye Yin, Bo Li, Gang Liu, and Dongsheng Cai (2013). Hypothalamic programing of systemic aging involving IKKB/NF-kB and GnRH. Nature.

[2] Yalin Zhang, Min Soo Kim, Baosen Jia, Jingqi Yan, Juan Pablo Zuniga-Hertz, Cheng Han and Dongsheng Cai (2017). Hypothalamic stem cells control ageing speed partly through exosomal miRNAs. Nature.

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