Cell subjournal: How gut bacteria affect the role of cocaine in mice

Researchers report Nov.
1 in the journal Cell Host and Microbes that common gut bacteria can enhance the effects of
cocaine in mice.
Their research demonstrates how cocaine promotes bacterial growth, which in turn depletes glycine
, a chemical that contributes to normal brain function.
When glycine levels were depleted, the mice showed a higher response to the drug and exhibited behavioral abnormalities such as a significant increase in
drug-induced motor and seeking behavior.

In addition, by systematically supplementing with glycine or using a genetically modified bacterium that could not use glycine, the mice's response to cocaine decreased to normal levels, suggesting that this amino acid can act as an intermediary
of addiction-like behavior in animal models.

Lead author Santiago Cuesta, a neuroscientist and first author at the University of Wisconsin School of Medicine and Public Health, said, "I was interested in the gut-brain axis and I found it very novel and exciting
.
"

Cuesta and his colleagues found that when cocaine entered the gut of mice, it triggered activation of the QseC protein, which helps the growth
of γ-proteobacteria such as E.
coli.
These glycine-fueled bacteria, which compete with the normal gut bacteria already present in our digestive system, take up most of the space and resources
.

Senior author Vanessa Sperandio, a microbiologist and senior author at the University of Wisconsin School of Medicine and Public Health, said: "Gut bacteria are consuming all of glycine, and levels of glycine in the system and brain are declining
.
" "Overall, altering glycine appears to be affecting glutamate synapses, making animals more addictive
.
"

"Normally, for neuroscience behavior, people don't think about controlling the microbiota, and microbiota studies don't usually measure behavior, but here we show that they are interrelated
," Cuesta said.
"Our microbiome can actually regulate mental or brain-related behaviors
.
"

"I think the connections between these communities will move the field forward, beyond interrelationships and toward the causes of different types of mental disorders
," Sperandio said.

Journal Reference:

1. Santiago Cuesta, Paula Burdisso, Amir Segev, Saï d Kourrich, Vanessa Sperandio.
   Gut colonization by Proteobacteria alters host metabolism and modulates cocaine neurobehavioral responses.
   Cell Host & Microbe, 2022; DOI: 10.
   1016/j.
   chom.
   2022.
   09.
   014