Researchers led by Lige Leng at Xiamen University found that Menin, a protein that helps restrain inflammation in the hypothalamus, declines with age in certain neurons. When they selectively disabled Menin in genetically modified mice, the animals developed greater hypothalamic inflammation, thinner skin, reduced bone mass, worsening cognitive performance, and modestly shortened lifespans. That suggests the loss of Menin helps drive aging rather than merely accompanying it.
Using gene delivery to restore Menin in the ventromedial hypothalamus of older mice reversed several age-related changes within 30 days: skin became thicker, bone mass increased, and learning, memory, and balance improved. Treated mice also lived longer than untreated controls in a separate survival analysis.
The team traced part of the effect to D-serine, an amino acid that supports NMDA receptors involved in memory formation. Menin controls an enzyme in the serine-production pathway, and when Menin fell, D-serine levels dropped. Supplementing older mice with D-serine improved learning and memory in just three weeks. The authors caution that D-serine supplements are not equivalent to eating serine-rich foods, and because the results come from mice, human implications remain uncertain.