Anyone who has eaten a fishy oyster or mushroom soup that hasn’t rested well remembers the ominous nausea that heralds impending bad times. The bacteria release toxins which trigger the process of rapid emptying of stomach contents. It’s kind of a protective mechanism – getting rid of invaders en masse is probably helpful in the long run, even if it’s unpleasant in the short term. But how the brain receives the alarm signal and then sends another to tell the stomach to initiate a Technicolor yawn has remained a mystery.
Your next food poisoning isn’t the only reason to understand this particular neural pathway. Understanding how to counter it could be helpful for people who develop nausea from chemotherapy drugs and other medications. As if battling cancer wasn’t painful and scary enough, patients are often so discouraged by food that maintaining their weight becomes a major struggle.
In a new study, researchers report that bacteria and chemotherapy drugs appear to trigger the same molecular pathways in the gut. The findings, based on mouse experiments and published Tuesday in the journal Cell, showed that a bacterial toxin and a chemotherapy drug both triggered a cascade of similar neural messages that cause nausea.
The choice of mice for the study was unusual. It turns out that the mice can’t vomit – a small weakness that generally makes it difficult to use them to study nausea. Researchers have used cats and dogs in the past, but the biology of mice in general is so much better understood, with much better tools available to scientists to do so.
Cao Peng, a professor at Tsinghua University in Beijing, and his colleagues wondered if the mice were still able to feel sick like people do after ingesting chemo drug or a bad salad – or close enough, to anyway, so researchers can use the creatures to understand the origins of the sensation.
“If we want to get better drugs,” Dr. Cao said, “we need to know the detailed mechanism.”
The researchers gave the mice a bacterial toxin and watched them closely with high-speed cameras, and found that the rodents started opening their mouths oddly after the treatment. Other tests showed that their abdominal muscles move in the same way as human stomachs when they are about to be sick. Indeed, the scientists think that the mice had retches or dry vomiting. A chemo drug made the mice behave similarly, so scientists looked deeper into which cells reacted to these triggers and how.
They traced the effect on certain brain neurons that released neurotransmitters when the drug or toxin reached the gut. Following these messages, they discovered cells in the small intestine that reacted to the presence of these harmful substances. A central player in the nausea and retching pathway was an immune system molecule called interleukin 33, or IL33. Preventing the mice from making IL33 significantly reduced their symptoms.
It’s possible that drugs that interfere with IL33 or other players in this pathway could help alleviate the suffering of people undergoing chemotherapy, Dr. Cao said. This paper – identifying behavior in mice that can override vomiting and laying bare the pathway taken by signals from the gut – is a first step to potentially improving the quality of life of chemotherapy patients, if the results hold. in man.
Yet mice tasked with mimicking food poisoning are unwell for about 24 hours after receiving bacterial toxins, Dr. Cao said. After that, they are back to their active selves. If only we could get rid of a turkey sandwich that sat out too long so fast.
#brains #send #signal #time #vomit