American scientists have identified the neural mechanism of sneezing. It turned out that this process is responsible for areas of the brain that are not associated with breathing. The results of the study are published in the journal Cell.
Scientists first identified the area in the central nervous system that causes sneezing more than twenty years ago, but until now little was known about how the sneezing reflex works at the cellular and molecular level.
Researchers from Washington University School of Medicine in St. Louis and the Perelman School of Medicine at the University of Pennsylvania have identified for the first time certain cells and proteins that control sneezing.
“Sneezing is the strongest and most common way to spread droplets from respiratory infections,” study leader Dr. Qin Liu, an assistant professor of anesthesiology at the University of Washington School of Medicine, said in a press release. “A better understanding of what makes us sneeze, in particular how neurons behave in response to allergens and viruses, will help create treatments that can slow the spread of infectious respiratory diseases.”
In a laboratory study, the authors exposed mice to aerosol droplets containing histamine or capsaicin — sharp compounds derived from chili peppers that cause both mice and humans to sneeze. By observing the response of nerve cells to capsaicin, the scientists first identified a small group of neurons associated with sneezing and then identified the molecules, neuropeptides, which transmit sneezing signals to these nerve cells.
It turned out that the neuromedin B (NMB) molecule is necessary for the occurrence of sneezing. By removing NMD-sensitive neurons in the part of the nervous system responsible for sneezing in mice, the researchers blocked this reflex.
“Interestingly, the neurons that cause sneezing are not located in any of the known areas of the brain associated with breathing, but they are connected to these areas through their axons,” says Dr. Liu.
The authors also found that they could stimulate the sneezing reflex by targeting a specific area of the mouse brain with the NMB peptide. At the same time, the animals began to sneeze in the absence of any external stimuli.
“We are studying the neural mechanism behind sneezing, as many people, including my family members, suffer from problems such as seasonal allergies and viral infections. Our goal is to find out how neurons behave in response to allergies and viral infections, causing itchy eyes, sneezing, and other symptoms,” explains the scientist.
Since many viruses, including the new coronavirus SARS-CoV-2, spread mainly by aerosol, the authors propose to develop a drug that suppresses the production of the NMB molecule, which can be used by infected people to protect others.
“When sneezing, about twenty thousand drops containing the virus are released, which remain in the air for up to ten minutes. To prevent future viral outbreaks and help treat allergic sneezing, it is important to understand the pathways that trigger this reflex to block them,” Liu notes.