Five taste sensations and just three types of taste cells make up the world of taste – or so we think. A new discovery suggests this equation may be more complex than we initially imagined.
Researchers working with rodents have identified a new population of taste cells and they appear to be more capable of evaluating flavor than previously thought. Instead of being as selective as other taste cells, this ‘broad reactive’ cell can react to all known tastes except salt.
Taste cells are receptors that group together to form taste buds, shaped like tiny garlic bulbs on the tongue. Some of the tastes can also be found on the soft palate (the palate of a person) and on the back of the throat.
Taste cells can be ruthless, for good reason. If they sense an unpleasant or potentially harmful taste, our taste buds will tell us to refuse and push the food out. But taste something sweet, and they̵7;ll ask us for more.
As you probably know, there are 5 flavors: sour, salty, bitter, sweet and salty. But fat can be another substance, and it can be starches. Just as people argue about whether cilantro is a godsend or tastes like soap, scientists are continuing to debate and study about different types of taste and taste cells.
Type I taste cells represent about half of the cells in taste buds. They can react with saccharides and amino acids to create a sweet sensation and umami flavor (umami is a pleasant salty taste related to the amino acids in protein and food additive MSG). But their main job is to act as a rack for other neighboring nerve cells.
Type II cells can detect a bitter, sweet or umami taste, while type III cells have a similar selectivity, but make up less than a fifth of taste cells in taste buds. They may detect a sour or salty taste.
Now scientists from Buffalo University in New York have discovered and characterized a previously unknown type III subset of cells isolated from transgenic mice.
These newly found cells are also sensitive to acidity, but lack their forte for conventional salt detection. In its place, these widely responsive type III cells use a single signaling pathway to detect bitterness, umami, and sweetness.
“Our study describes a new population of taste cells that can detect a wide variety of stimuli, including chemicals from different taste qualities,” the authors explained in the article. their.
The flexibility of this new population of taste cells mirrors the neurons in the brain, where both general and more specialized neurons are used to process information about taste.
Although not every single cell tested will be stimulated by all of the tastes in the experiments, 100% of the ‘broadly responsive’ (BR) cells react to more than one odor quality. flavors and about 80% detect three or four flavors.
“Having the cells extensively modulated will allow the taste system to better differentiate between chemicals with similar characteristics,” the authors said of their findings, which would be widely applicable. more widely available to other mammals with the same taste system.
Having identified and characterized the new taste cells, further experiments were set up to see how well the taste buds really depend on them. It involved testing the taste-stimulating behavior of mice that were engineered to live without the major component of the signaling pathway used by BR cells.
Both genetically modified and wild rats were given oral monosodium glutamate fluids to stimulate the sensation of umami, a sweetener, a bitter compound called denatonium, or salt. An ingeniously named device called a hygrometer measures their response to each solution relative to water.
The genetically modified mice drank sweet, bitter, and umami liquids like water; for them there was no difference in taste until they reached the highest concentrations on the face. Without the BR cell signaling pathway, the rats lost their sense of these flavors.
“Although BR cells are just a subset of cells in the bud, our data show that these cells do make a significant contribution to taste,” concluded the authors.
Scientists questioned their presence for a while after previous research found that multiple receptor cells, sampled as intact taste buds from mice, react to a variety of taste qualities. sense. But so far, no one has isolated and identified the responsible multi-function taste cells.
Again, we have mice to thank for this latest discovery. Now, to design a lick-measuring device for humans …
Research is published in Heredity of PLOS.