When we eat food contaminated with potentially harmful bacteria, vomiting is an important way the body eliminates the toxins. To get a closer look at the process from launch to throw, a team of researchers followed a similar process in mice, from their gut to their brain.
Curiously, mice don’t actually vomit, perhaps because their esophagus is too long compared to their body size and muscle strength is too weak.
However, they do choke, which bodes well for investigating the biological signals behind food poisoning.
“The neural mechanism of gagging is similar to that of vomiting,” says neurobiologist Peng Caofrom the National Institute of Biological Sciences in Beijing.
“In this experiment, we successfully build a paradigm for studying toxin-induced gagging in mice, which allows us to study the brain’s defense responses to toxins at the molecular and cellular level.”
After mice are given a sample of the bacterial toxin staph enterotoxin A (SEA) — which is produced by Staphylococcus aureus and also leads to foodborne illness in humans – the researchers observed the animals have an unusually wide mouth opening, as well as contractions of the diaphragm and abdominal muscles (something we also see in dogs when they vomit).
Through a fluorescent labeling process, SEA has been shown to activate the release of the neurotransmitter serotonin in the gut. This serotonin then triggers a chemical process that sends a message down the vagus nerves — the main connections between the gut and the brain — to specific cells known as Tac1+DVC neurons in the brainstem.
When these Tac1+DVC neurons were artificially deactivated by the researchers, the gagging subsided. The same happened with nausea induced by doxorubicin, a common chemotherapy drug: when the Tac1+DVC neurons were turned off or serotonin production stopped, the mice gagged much less compared to a control group.
“With this study, we can now better understand the molecular and cellular mechanisms of nausea and vomiting, which will help us design better drugs,” says Cao.
Gut tissue, made up of cells called enterochromaffin cells, is responsible for releasing serotonin in the gut, the researchers found, and future studies could examine how toxins interact with these cells in particular to trigger the process of vomiting.
The detailed map resulting from the study could potentially have taught us more about food poisoning and chemotherapy. The results suggest that the body triggers similar defenses to both, although further human studies would be needed to determine the relevance of the results to our own biology.
Ultimately, the research could point the way to better anti-nausea drugs for people undergoing chemotherapy, allowing the prescribed drugs to work Cancer with fewer unpleasant side effects.
“Besides food germs, humans encounter many pathogens, and our bodies are equipped with similar mechanisms to eliminate these toxins,” says Cao.
“For example, coughing is our body’s attempt to die Coronavirus. It’s a new and exciting area of research into how the brain senses the existence of pathogens and initiates responses to get rid of them.”
The research was published in cell.
