June 16, 2020
Those who are blessed with good cheer also are apt to have good digestion. In fact, researchers from the University of Texas Southwestern Medical Center in Dallas have found evidence that serotonin—the brain chemical responsible for feelings of happiness and well–being—may stop harmful intestinal pathogens from causing deadly infections, Study Finds reports.
Serotonin is almost always thought of as a brain chemical, but about 90% of it is actually produced in the gastrointestinal tract. There also are trillions of bacteria living in the stomach and, while the vast majority of those bacteria are beneficial, some pathogenic bacteria also make their way to the gastrointestinal tract. When this happens, it can lead to serious and sometimes fatal gut infections.
Gut bacteria, like any other form of bacteria, are quite susceptible to their living environment. With this in mind, the study’s authors wondered if levels of serotonin being made in the gut affected these pathogens in any way, according to Study Finds.
To study this possible relationship, researchers focused on Escherichia coli O157, a type of bacteria known to cause semi-frequent outbreaks of sometimes deadly food-borne infections. Some samples of these bacteria were grown by the team in a lab setting and then exposed to serotonin. Notably, gene expression tests conducted after this exposure reveal that the serotonin had indeed significantly reduced the “expression” of genes within the bacteria that cause infections.
Furthermore, when human cells were exposed to the serotonin-weakened bacteria, that bacteria was no longer capable of inflicting “infection-associated lesions.” So, just add some serotonin and the bacteria loses its ability to produce an infection.
Moving forward, the researchers were eager to test their idea on living subjects. They gathered a group of mice and studied how serotonin influenced the viral capabilities of Citrobacter rodentium, which is pretty much the rodent equivalent of e.coli for humans. Some of the mice were genetically modified to produce more serotonin than usual. Others were modified to produce less than normal.
The mice that were producing more serotonin were much less likely to develop an active Citrobacter rodentium infection, and/or experience significant symptoms after being exposed to the bacterium. Conversely, mice with low levels of serotonin developed serious infections and many even died, Study Finds reports.
Mice given fluoxetine (Prozac) to raise their serotonin levels also didn’t become infected after exposure to the bacterium.
Additional experiments helped the research team pinpoint the serotonin receptor within both E. coli and C. rodentium; the protein known as CpxA. This protein is actually common among gut bacteria, so it seems likely that serotonin has a big effect on overall gut health.
The study’s authors want to continue their work on this subject, and are hopeful serotonin can be used as a legitimate treatment option for bacterial gut infections. As of now, there are very few available antibiotics that are effective against E. coli O157.
“Treating bacterial infections, especially in the gut, can be very difficult,” says study leader Vanessa Sperandio, Ph.D., a professor of microbiology and biochemistry at UT Southwestern Medical Center, in a statement. “If we could repurpose Prozac or other drugs in the same class, it could give us a new weapon to fight these challenging infections.”
Research contact: @StudyFinds