453: Ancient enzyme guides healthy eating in mammals

Ancient enzyme guides healthy eating in mammals:

An ancient enzyme in the brains of mammals acts as an innate nutritionist of sorts, guiding them to make healthy choices about what to eat, according to new work published in the April issue of Cell Metabolism. The molecular mechanism is likely to be important in all mammals, including humans, that eat a varied diet comprised of meat and vegetables, the researchers said.

David Ron, of the New York University School of Medicine, and his colleagues found in mice that an enzyme known as GCN2 kinase sets off a cascade of events that relays information to the brain about the amino acid content of foods, enabling the animals to adjust their intake in favor of a more balanced meal. The same enzyme in yeast also acts as an amino acid sensor, earlier work has shown.

"This ancient pathway in mice recognizes drops in blood amino acid levels that occur following consumption of food with an imbalanced composition," said Ron. "That recognition culminates in a behavioral response that limits consumption of the imbalanced food and favors, by default, a more balanced diet."

The new findings confirm and extend a recent report by Dorothy Gietzen at the University of California, Davis, detailing the same pathway in rats. …

The findings reveal that the ancient amino acid-sensing pathway affects feeding behavior by activating a brain circuit that biases consumption against imbalanced food sources, the researchers said.

While the findings are in mice, "there's no reason to believe that the same mechanism isn't at work in humans," Ron said.

Why isn't there any reason to doubt that it works in people, too? Common descent. Following the evolution of this gene will reveal a lot about metabolism in different groups. Different species can synthesize different amino acids, and need different amounts of others. Understanding how they detect deficiencies and how the gene has adapted to different circumstances will reveal a lot about the history of modern species.