Compared with slimmer counterparts, obese mice had fewer taste cells that responded to sweet and bitter stimuli, according to a new study. In addition, the cells that did respond to sweetness reacted relatively weakly.
“Studies have shown that obesity can lead to alterations in the brain, as well as the nerves that control the peripheral taste system, but no one had ever looked at the cells on the tongue that make contact with food,” says lead scientist Kathryn Medler, associate professor of biological sciences at the University at Buffalo.
“What we see is that even at this level—at the first step in the taste pathway—the taste receptor cells themselves are affected by obesity,” Medler says. “The obese mice have fewer taste cells that respond to sweet stimuli, and they don’t respond as well.”
How an inability to detect sweetness might encourage weight gain is unclear, but past research has shown that obese people yearn for sweet and savory foods though they may not taste these flavors as well as thinner people.
Medler says it’s possible that trouble detecting sweetness may lead obese mice to eat more than their leaner counterparts to get the same payoff.
Learning more about the connection between taste, appetite, and obesity is important, she says, because it could lead to new methods for encouraging healthy eating.
“If we understand how these taste cells are affected and how we can get these cells back to normal, it could lead to new treatments,” Medler says. “These cells are out on your tongue and are more accessible than cells in other parts of your body, like your brain.”
The study, published in PLOS ONE, compares 25 normal mice to 25 of their littermates who were fed a high-fat diet and became obese.
To measure the animals’ response to different tastes, the research team looked at a process called calcium signaling. When cells “recognize” a certain taste, there is a temporary increase in the calcium levels inside the cells, and the scientists measured this change.
The results: Taste cells from the obese mice responded more weakly not only to sweetness but also to bitterness. Taste cells from both groups of animals reacted similarly to umami, a flavor associated with savory and meaty foods.
Source: University at Buffalo