What is the difference between real sugar and artificial sweeteners?? Not Just Taste!
Not long after sweetness receptors were identified in the mouths of rats 20 years ago, scientists were trying to get rid of those taste buds. But they were surprised to find that the rats were somehow able to recognize and prefer natural sugars over artificial sweeteners, even without the perception of taste.
According to research by Diego Bohórquez, an associate professor of medicine and neurobiology at Duke University School of Medicine, the answer to this question lies much deeper in the digestive tract, in the upper part of the intestine just behind the stomach.
“We’ve identified the cells that make us eat sugar, and they’re located in the gut,” said Bohórquez. Infusion of sugar directly into the lower intestine or colon does not have the same effect. The sensing cells are located in the upper part of the intestine, he said.
After discovering an intestinal cell called a neurite, Bohórquez and his research team pursued the important role this cell plays as the connection between what’s inside the gut and the effects of the gut. it’s in the brain. The gut, he argues, speaks directly to the brain, changing our eating behaviour. And in the long run, these findings could lead to entirely new treatments for the disease.
Originally called enteroendrocrine cells for their hormone-secreting abilities, specialized neurons can communicate with neurons via rapidly synaptic connections and are distributed throughout the mucosal layer. mesentery of the upper intestine.
In addition to generating relatively slow-acting hormone signals, the Bohórquez team showed that these cells also produce fast-acting neurotransmitter signals to the vagus nerve and then the brain. within milliseconds.
Bohórquez says his team’s latest findings further show that neurons are the sensory cells of the nervous system like the taste buds in the tongue or the retinal cones in the eye that help us see color.
“These cells act like retinal cones that are capable of sensing wavelengths of light,” Bohórquez said. “They sense traces of sugar against the sweetener and then they release different neurotransmitters that go into different cells in the vagus nerve, and eventually, the animals know’ this is sugar’ or ‘this is a sweetener.'”
In a small experiment, researchers showed that real sugar stimulates the nerve cells of mice and humans to release glutamate as a neurotransmitter. The artificial sugar triggers the release of another neurotransmitter, ATP.
Using a technique called optical genetics, the scientists were then able to turn nerve cells on and off in the intestines of a live mouse to show whether the animal’s preferences for whether the real pathway is controlled by signals from the gut.
The key enabling technology for optical genetics work is a new flexible waveguide developed by MIT scientists. This flexible fiber transmits light throughout the intestines of living animals to trigger a genetic response that silences nerve cells.
When their neurons were switched off, the animals no longer showed a clear preference for real sugar.
“We trust our gut with the food we eat,” says Bohórquez. “Sugar has both taste and nutritional value, and the gut can determine both.”
“Many people struggle with sugar cravings, and we now have a better understanding of how the gut perceives sugar (and why it makes sugar),” said co-first author Kelly Buchanan, a former Duke University School of Medicine. artificial sweeteners do not curb cravings). student is currently a resident physician at Massachusetts General Hospital. “We hope to target this circuit to treat diseases we see every day in the clinic.”
In future work, Bohórquez said he will show how these cells also recognize other macronutrients. “We always talk about ‘gut consciousness’ and say things like ‘trust your gut,’” says Bohórquez.
“We were able to change the behavior of mice from the gut, and this gives him great hope for new therapies that target the gut,” said Bohórquez.
Source: Eurekalert
