Olfactory receptors are views as docking stations for airborne chemical compounds responsible for smell of food and other substances.
Specific odors are registered with the brain through the chain of biochemical events when molecules connect with the receptors.
“Our team recently discovered that blood cells — not only cells in the nose — have odorant receptors,” said Schieberle. “In the nose, these so-called receptors sense substances called odorants and translate them into an aroma that we interpret as pleasing or not pleasing in the brain. But surprisingly, there is growing evidence that also the heart, the lungs and many other non-olfactory organs have these receptors. And once a food is eaten, its components move from the stomach into the bloodstream. But does this mean that, for instance, the heart ‘smells’ the steak you just ate? We don’t know the answer to that question.”
Schieberle’s team found that blood cells isolated from human blood samples are attracted to odorant molecules responsible for producing a certain aroma. Schieberle described one experiment in which scientists put an attractant odorant compound on one side of a partitioned multi-well chamber, and blood cells on the other side. The blood cells moved toward the odor.
“Once odor components are inside the body, however, it is unclear whether they are functioning in the same way as they do in the nose,” he stated. “But we would like to find out.”
“Receptors help us sense flavors and aromas in the mouth and nose,” said Schieberle. “These receptors are called G-protein-coupled receptors, and they were the topic of the Nobel Prize in Chemistry in 2012. They translate these sensations into a perception in the brain telling us about the qualities of a food.” Odorant receptors and the organization of the olfactory system also were the topic of the 2004 Nobel Prize in Medicine.
Of the total of around 1,000 receptors in the human body, about 800 of these are G-protein-coupled receptors, he said. Half of these G-protein-coupled receptors sense and translate aromas. But only 27 taste receptors exist.