We all know the tickly, almost itchy feeling of building up to a sneeze. Maybe you have a cold, or it’s spring and the pollen in the air is causing allergy symptoms. Sneezes are your body’s way of trying to expel particles in your nose that should not be there, like viruses, allergens, and pretty much anything that can irritate the cells in your nasal passages. A new study from the Liu group at Washington University in St. Louis illuminates exactly how nasal irritation sends a signal to the brain that results in a sneeze.
The researchers first established that exposing mice to capsaicin, the chemical found in spicy peppers, causes them to sneeze. The researchers then used capsaicin to test mice that are missing various genes suspected to be involved in the sneeze response. If a gene is missing and the mouse no longer sneezes in response to capsaicin, then that gene likely plays a role in sneezing. The researchers found that mice missing a gene that codes for a particular protein called neuromedin B, or NMB, sneezed much less when exposed to capsaicin and even other sneeze-causing agents. Further experiments determined that when exposed to these sneeze-causing substances, sensory neurons in the nose release NMB, which activates neurons in the brainstem that then lead to sneezing.
Sneezing is an important mechanism of removing particles from our nasal passages, but it can be dangerous as well. Sneezing is a driver of infectious diseases, releasing more viral particles into the air than coughing or talking. This research is still considered what is known as basic science, meaning it does not directly translate to a medical treatment, but learning about the mechanism of sneezing opens the door to finding therapies or drugs that can help control sneezing in situations where it is not beneficial.
This study is co-authored by Fengxian Li and Haowu Jian, post-doctoral fellows in the Center for the Study of Itch & Sensory Disorders at Washington University School of Medicine in St. Louis. Corresponding author Dr. Qin Liu is an associate professor of Anesthesiology in the Center for the Study of Itch & Sensory Disorders at Washington University School of Medicine in St. Louis.
Managing Correspondent: Gemma Johnson
Press Articles: “What makes us sneeze?”, Washington University School of Medicine in St. Louis News
Original Journal Article: “Sneezing reflex is mediated by a peptidergic pathway from nose to brainstem”, Cell
Image Credit: Pixabay