Lower levels of a brain protein called Menin went hand in hand with signs of aging in mice — and putting the protein back improved memory, balance, skin thickness, and bone mass, according to experiments published March 16, 2023, in the open-access journal PLOS Biology.
The research
Lige Leng of Xiamen University in Xiamen, China, and colleagues focused on the hypothalamus, a small region that helps coordinate metabolism and has been linked to how the body ages. Earlier work from the same group found that Menin helps restrain inflammation in this region. The new question was whether losing that protection could help set age-related decline in motion.
In mice, Menin levels fell with age in specific neurons of the ventromedial hypothalamus, an area involved in metabolism. The same drop was not seen in astrocytes or microglia, two support cell types — a sign the change was targeted to particular cells rather than a broad loss across the region.
To test cause and effect, the team used conditional knockout mice, genetically engineered so Menin could be selectively removed. Cutting Menin in younger mice increased hypothalamic inflammation and brought on aging-related traits: lower bone mass, thinner skin, cognitive decline, and a modestly shorter lifespan.
Menin loss also disrupted a chemical pathway used for signaling between brain cells. Mice with less Menin had lower levels of D-serine, an amino acid that helps activate receptors involved in learning and memory — the same receptors that let neurons adjust connection strength, a process needed for storing information. An enzyme involved in making D-serine, itself regulated by Menin, became less active.
In a second set of experiments, the researchers delivered the gene for Menin into the hypothalamus of 20-month-old mice — elderly, by mouse standards. Thirty days later, treated animals showed thicker skin and greater bone mass, plus better scores on tests of learning, cognition, and balance. Hippocampal D-serine rose. The study also reported longer lifespan in treated mice.
A simpler test gave mice D-serine in drinking water for three weeks. Cognition improved, including in older animals.
Why it matters
Signs of aging we usually treat as separate — memory slips, thinning skin, weaker bones — may share a common thread running through the hypothalamus. That reframes aging research: instead of chasing each decline on its own, scientists can ask whether a single brain pathway nudges several at once. It also highlights inflammation and brain-cell signaling as two levers worth understanding.
The D-serine finding is the part most likely to be misread. Serine appears in soybeans, eggs, fish, and nuts, but the form built into dietary proteins is L-serine. The body can convert L-serine into D-serine, yet the two are not interchangeable — and eating those foods is not the same as receiving the experimental D-serine treatment. Supplement claims built on this mouse work are ahead of the evidence.
What you can do
There is no Menin supplement, and mouse results do not translate directly to people. What holds up in human research is unglamorous: regular aerobic exercise, consistent sleep, and managing chronic inflammation through diet and medical care are the levers most reliably tied to cognitive health. If you have concerns about memory or cognition, treat online claims about "anti-aging" amino acids with caution and talk to a clinician.
Source: ScienceDaily Mind & Brain
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