2019-06-28, 12:30 PM
Sweet, fatty foods could remodel the brain to drive overeating
Kelly Serwick
Kelly Serwick
Quote:Neurobiologist Garret Stuber and a team at the University of North Carolina at Chapel Hill wanted to understand the brain changes that accompany obesity. They were particularly interested in an area at the bottom of the brain known to regulate feeding, called the lateral hypothalamus. With collaborators in the United Kingdom, Stuber—now at the University of Washington in Seattle—sequenced RNA from cells in this area of the mouse brain and grouped them according to what genes they expressed. By comparing gene expression between obese mice on a high-fat diet and control animals on a standard one, the researchers identified a subset of neurons that changed most dramatically with the obesity-inducing diet.
That set expressed the gene for an excitatory signaling molecule, glutamate. The researchers used a two-photon microscope to observe these so-called glutamatergic cells in the brains of living mice. They endowed the cells with a gene that made them fluoresce when they took up calcium—an indicator of neural firing. Then they watched the cells while mice lapped calorie-rich sugar water from a spout. If a lean mouse had just eaten, the neurons were more active in response to the sugar than if it had just been fasting. The cells seemed to act as a brake, signaling, “That’s enough!”
But as lean mice became obese from a diet high in fat and sugar, these cells became less lively. By 12 weeks after the diet switch, the glutamatergic cells were roughly 80% less active in response to the sugar drink, the team reports today in Science.