between the gut and the brain. But researchers have been hard pressed to understand exactly how gut microbes—or the molecules they make—influence the brain.
Gabanyi and colleagues started with genetically engineered mice: Some were designed to lack Nod2, and others were engineered to produce a fluorescent tag that marked wherever the molecular detector was made. The first evidence that muropeptides influence appetite came from the mice without Nod2. Compared with regular mice, these rodents gained extra weight as they aged. That suggested, Gabanyi says, that the muropeptides may provide a “full” signal to the brain that is absent in Nod2-free mice.
The experiments also showed radioactive muropeptides build up more in female mouse brains than in male brains, and have stronger effects on females, Gabanyi says. Older female mice lacking Nod2 in the brain ate more per meal than mice that had not been genetically modified. They also maintained a higher body temperature and tended to spend less time building nests to stay warm—indicating that Nod2 might have other physiological roles.
Together, the new experiments identify a direct mechanism by which bacteria can control the brain, says Livia Hecke Morais, a neurobiologist at the California Institute of Technology. Until now, demonstrations of such direct connections “have been lacking,” adds Margaret McFall-Ngai, a developmental biologist at the Carnegie Institution for Science.
When I get I'll my appititte goes up.Maybe this can bring about a breakthrough.
LorenzAdlung
I need to get my appetite in check 🐻