According to a study published on November 1st in the journal Cell Host & Microbe, common gut bacteria can amplify the effects of cocaine on mice. Their research shows how cocaine use promotes the development of bacteria, which then consume a substance called glycine that is necessary for healthy brain function. Mice respond to drugs more strongly as glycine levels drop, and these responses include aberrant behaviors such as markedly increased motility and desire.
Additionally, the mice’s sensitivity to cocaine returns to normal levels when glycine is added back into the system or when a genetically altered bacteria is used; this shows that this amino acid can function as a mediator of addiction-like behavior in animal models.
According to the first author, Santiago Cuesta, a neurologist at the University of Wisconsin School of Medicine and Public Health, “I was interested in the gut-brain axis, and I found it really unique and intriguing.”
Cuesta and colleagues discovered that cocaine activates the QseC protein, which promotes the growth of proteobacteria like E. coli in mice’s guts. These glycine-fueled bacteria outcompete the healthy gut bacteria that already reside in our digestive systems, occupying the majority of the available resources.
According to senior author Vanessa Sperandio, a microbiologist at the University of Wisconsin School of Medicine and Public Health, “the gut bacteria are absorbing all of the glycine, and the levels are falling both systemically and in the brain.” It appears that altering glycine in general has an effect on the glutamatergic synapses that make animals more likely to become addicted.
According to Cuesta, “Usually, when discussing neurological habits, people do not consider regulating the microbiota, and microbiota studies do not often evaluate behaviors, but here we show they are connected.” Our microbiome can truly influence brain-related or psychiatric behaviors.
The science will advance, Sperandio believes, “by linking these communities and moving beyond correlations towards causations for the various sorts of psychiatric diseases.”
