Can our bodies discover sugar without tasting it?
Researchers from Columbia University have discovered sugar-sensing neurons in mice, that could lead to the development of new sweeteners.
Sugar is everywhere in today’s food system and among the most frequent ingredients in processed food items. It is often referred to as addictive.
Since refined sugar became widely available in america, the common consumption per person in the country increased by 10 times, to a lot more than 45 kilograms per year.
The Centers for Disease Control and Prevention (CDC) estimate that persons in the U.S. now derive around 14% of their daily calories from added sugar.
Such high consumption rates are concerning, given sugar’s association with type 2 diabetes and obesity, both which are increasing in the Western world.
Now, researchers from Columbia University, in NY, have identified a number of the brain mechanisms behind sugar consumption, which might make clear why sugar causes cravings that artificial sweeteners just can’t meet.
The findings can be purchased in the journal Nature.
Everything starts with taste receptors
Sugar is an important energy source for all animals, including humans. Therefore, we have evolved specialized neural circuits to identify and look for sugar, and these start in the mouth.
The tongue has specific taste receptors to find sweetness. These are activated by sugar, plus they send signals to the mind.
Interestingly, though, animals can form strong cravings for sugar, regardless if they lack the taste receptors for it, as the authors of the present study point out.
What’s more, they report, if animals without sweet taste receptors receive two drinks, one sweetened with sugar and the other with artificial sweetener, they still choose the sugary drink - despite being unable to taste either.
This suggests that the body may recognize sugar in another area, perhaps further down the digestive pathway.
To research, the researchers, from Columbia’s Zuckerman Institute, set out to search for these additional receptors in mice.
The gut-brain axis
The team commenced by administering sugar right to the gut, bypassing the taste receptors entirely.
This is because you will find a well-known connection between the gut and the brain, called the gut-brain axis. Seeing and smelling food, for example, causes the gut to secrete digestive fluids.
It seems that a similar connection exists for sugar. When the researchers gave the mice sugar directly to their guts, a region of their brains lit up with activity.
This region, called the caudal nucleus of the solitary tract, is the main brain stem, among the brain’s most primitive parts, which regulates fundamental processes such as for example breathing and heart rate.
“Something was transmitting a sign, indicating the presence of sugar, from the gut to the mind,” explains Alexander Sisti, Ph.D., a joint first writer of the paper.
Sugar-sensing neurons
Next, they wished to find the receptor in the gut and shifted their attention to the vagus nerve. That is one of the longest nerves within the body, running from the mind stem to the colon, in fact it is a major approach to communication between the gut and the brain.
The researchers watched the activity of cells in the vagus nerve when sugar was delivered to the gut, finding - for the first time - several sugar-sensing neurons in the pathway from the gut to the brain.
“By recording brain-cell activity in the vagus nerve, we pinpointed a cluster of cells in the vagus nerve that react to sugar,” Sisti explains.
These receptors in the gut were activated by sugar - but not artificial sweeteners, which may clarify why sweeteners have not significantly reduced sugar consumption given that they were widely introduced 40 years back.
Source: www.medicalnewstoday.com
