When we eat food that has been contaminated with potentially harmful bacteria, vomiting is a crucial way for the body to eliminate toxins. To find out exactly what happens when we vomit, a team of researchers followed a similar process in mice, from the gut to the brain.

“The neural mechanism of vomiting is similar to that of vomiting,” says neurobiologist Peng Cao of the National Institute of Biological Sciences in Beijing.

“In this experiment, we were able to successfully construct a paradigm for studying toxin-induced vomiting in mice, with which we can examine the brain’s defensive responses to toxins at the molecular and cellular level.”

After giving mice a sample of the bacterial toxin Staphylococcal Enterotoxin A (SEA) – which is produced by Staphylococcus aureus and also causes foodborne illness in humans – the researchers observed unusual mouth-opening actions in the animals , as well as contractions of the diaphragm and abdominal muscles (something we also see in dogs when they vomit).

Vomiting, the brain’s defensive responses to toxins

Through a fluorescent labeling process, it was shown that SEA in the gut activated the release of the neurotransmitter serotonin, writes ScienceAlert.

This serotonin then triggers a chemical process that sends a message along the vagus nerves—the main connectors between the gut and the brain—to specific cells known as Tac1+DVC neurons in the brainstem.

When these Tac1+DVC neurons were artificially disabled by the researchers, the vomiting decreased.

The same thing happened with nausea induced by doxorubicin, a common chemotherapy drug: when the Tac1+DVC neurons were disabled or when serotonin production was stopped, the mice had significantly less regurgitation compared to a control group .

The research could pave the way to anti-nausea drugs

The researchers found that intestinal tissues made up of so-called enterochromaffin cells are responsible for releasing serotonin in the gut, and future studies could look at how toxins interact with these cells specifically to trigger the vomiting process.

The detailed map resulting from the study could teach us more about both food poisoning and chemotherapy.

The results would suggest that the body produces similar defensive responses to both, although further studies in humans would be needed to determine the relevance of the results to our own biology.

Ultimately, the research could lead to better anti-nausea drugs for people undergoing chemotherapy, allowing prescription drugs to fight cancer with fewer unpleasant side effects.

The research was published in the journal Cell.

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