Decline in the hypothalamic Menin may play a key role in aging, according to a study. The findings reveal a previously unknown driver of physiological aging, and suggest that supplementation with a simple amino acid may mitigate some age-related changes. Leng and colleagues showed that Menin, a hypothalamic protein, is a key inhibitor of hypothalamic neuroinflammation. They observed that the level of Menin in the hypothalamus, but not astrocytes or microglia, declines with age. Another change was a decline in levels of the amino acid D-serine, known to be a neurotransmitter and sometimes used as a dietary supplement. The authors...