Can our taste buds take us on a slippery slope toward obesity?
That’s the question Kathryn Medler and several of her students are getting close to answering as they continue research in a laboratory on the University at Buffalo North Campus in Amherst.
“We’re really trying to understand how the cells that sit in your tongue detect the chemicals in your food and translate that into a signal that your brain can understand,” said Medler, associate professor of biological sciences.
Medler has determined that mice who become obese by eating a high-fat diet need more fat and sugar as they gain weight to get the same sense of pleasure in their brains. If she and other researchers can prove the same holds true for humans, and figure out how taste buds communicate with the brain, researchers may one day be able to help the obese lose weight with more effective treatments or medications.
“If you open up your brain and pour a pound of sugar on it, it’s not going to respond,” Medler said. “The cells in your tongue change that sugar into a signal for your brain, and we’re trying to figure out how they do that.”
Is this something a lot of people are looking at these days?
It’s not a huge field, but it is an important one. I think as the unfortunate growth of the obesity epidemic is having such a big impact on the health system, we’re starting to see that we do need to understand this process.
Talk about your research.
We have a control group of mice and we have a group of mice that are fed a high-fat diet and become obese. The cells from the obese mice don’t respond as well to certain taste stimuli, so they’re not tasting the food as well. There’s lots of potential implications for that. We can’t tell what it means for sure, but we do know that the cells not only send a signal to your brain to say, ‘This is sweet,’ they also send information to the centers of the brain that want you to eat more or stop eating. Those reward centers get information from the taste buds. If they’re not getting the proper signals, a mouse, or a human, is not going to get the right information to know, ‘All right, you’ve had enough calories. You can stop eating now.’ If you don’t get the right message, you don’t want to stop.
The book “Salt, Sugar, Fat: How the food giants hooked us” makes the argument that the food industry has learned how to turn on pleasure centers of the brain and turn off ‘I’m full’ centers to get us to keep eating. Some of your research seems to be getting at that.
Right, not from the chemical standpoint, but just what your body is doing. The long-term implications of that is ‘Why is it so hard for obese people to stop eating so much?’ We all know what we’re supposed to do: If you can’t walk down the stairs because you’re too fat, don’t eat as much. But we’re evolutionarily programmed. Most of the time people have been alive, food has been a limited resource, so you eat when you can. We have a very strong drive to eat something. If you enjoy it, you eat more. It is almost like a feed forward thing. … But obesity just keeps getting worse and it’s spreading now to the developing countries. It’s not just a problem for the rich anymore because processed foods are relatively accessible and readily cheap. … You’re obese and you have too many calories in your body, but now it’s disregulated your whole system. It’s like a snowball effect.
We’re hoping some of our research is going to help us understand the process a little better, because once we understand it, then we can figure out how to treat it, or fix it.
What have you discovered so far?
There’s been a lot of work done by other people that shows that the brain is different in obese animals and obese humans. Researchers have determined that obese people taste things differently, but we don’t understand how that happens. We know that some of the brain chemistry in the taste system is altered in the central nervous system, but no one had ever really looked at these (taste) cells. But these are the very first cells that start the pathway of taste, those taste receptor cells in your tongue. If you don’t have these working, then the rest of it’s not going to work, right?
Messages are coming from these cells and going up into the brain. When you know that obesity is affecting this pathway, it’s important to know where. Is it the information that’s being carried back to the brain or is it in the brain?
What we’ve found, or what we’re showing, is that the very first cells in the initiation of taste … are not working as well. The numbers of cells that respond to sweet go down and, when they respond, they don’t respond as well.
So that has all these implications for other studies. Is obesity having a direct affect on the brain or is it because it’s having an affect on these (taste) cells and they’re not sending the right messages to the brain? The taste cells are also easy to get to, so if we can manipulate them back to normal, that’s much easier – say, an additive in the food that’s going to change the way the cells work – than trying to locate a specific spot in your brain and give you a cranial injection, right? That’s hard to do, so if we can get the very first part of the pathway, that’s a much more attractive target.
On the Web: Learn more about Medler’s work at blogs.buffalonews.com/refresh.