Why do mice without taste buds still prefer real sugar to the fake stuff? ‘We’ve identified the cells that make us eat sugar, and they are in the gut,’ said one of the researchers. Specialized cells in the upper gut send different signals to the brain for sugar and sugar substitute.

Not long after the sweet taste receptor was identified in the mouths of mice 20 years ago, scientists attempted to knock those taste buds out. But they were surprised to find that mice could still somehow discern and prefer natural sugar to artificial sweetener, even without a sense of taste.

The answer to this riddle lies much further down in the digestive tract, at the upper end of the gut just after the stomach, according to research led by Diego Bohorquez, an associate professor of medicine and neurobiology in the Duke University School of Medicine.

In a paper appearing Jan. 13 in Nature Neuroscience, «we’ve identified the cells that make us eat sugar, and they are in the gut,» Bohorquez said. Infusing sugar directly into the lower intestine or colon does not have the same effect. The sensing cells are in the upper reaches of the gut, he said.

Having discovered a gut cell called the neuropod cell, Bohorquez with his research team has been pursuing this cell’s critical role as a connection between what’s inside the gut and its influence in the brain. The gut, he argues, talks directly to the brain, changing our eating behavior. And in the long run, these findings may lead to entirely new ways of treating diseases.

Originally termed enteroendrocrine cells because of their ability to secrete hormones, specialized neuropod cells can communicate with neurons via rapid synaptic connections and are distributed throughout the lining of the upper gut. In addition to producing relatively slow-acting hormone signals, the Bohorquez research team has shown that these cells also produce fast-acting neurotransmitter signals that reach the vagus nerve and then the brain within milliseconds.

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Materials provided by Duke University. Original written by Karl Leif Bates. Note: Content may be edited for style and length.