Even low-doses of penicillin in mice in late pregnancy and their offspring can create long-term behavioral changes in the young rodents, including higher levels of aggression and lower levels of anxiety, along with neurochemical changes in the brain and an imbalance in their gut microbes.
An international group of researchers that included Dr. Omry Koren of the Bar-Ilan University School of Medicine in the Galilee learned this in what they called a “landmark study” just published in Nature Communications and funded by the US Office of Naval Research.
The study, led by researchers at St. Joseph’s Healthcare Hamilton and McMaster University in Hamilton, Ontario, found that providing clinical (low) doses of the antibiotic to pregnant mice and their offspring caused the long-term behavioral changes. However, giving these mice a probiotic lactobacillus strain of bacteria (such as that in bio yogurt) helped to prevent these effects.
The researchers found that while the study was performed in mice, they point to popular increasing concerns about the long-term effects of antibiotics on humans, said senior author Dr. John Bienenstock, director of the Brain-Body Institute at St.
Joseph’s and a distinguished professor at McMaster. “Furthermore,” he says, “our results suggest that a probiotic might be effective in preventing the detrimental effects of the penicillin.”
Koren’s lab at the medical school in Safed was in charge of characterizing the microbial changes. Using next-generation sequencing techniques and bioinformatics, Koren and his team analyzed the microbiomes of mice infants and mothers.
Other studies have shown that large doses of broad-spectrum antibiotics in adult animals can affect behavior.
But there haven’t been previous studies that have tested the effects of clinical doses of a commonly-used, narrow- spectrum antibiotic such as penicillin on gut bacteria and behavior.
“There are almost no babies in North America that haven’t received a course of antibiotics in their first year of life,” said Bienenstock. “Antibiotics aren’t only prescribed, but they’re also found in meat and dairy products. If mothers are passing along the effects of these drugs to their as yet unborn children or children after birth, this raises further questions about the long-term effects of our society’s consumption of antibiotics.”
A previous study in 2014 raised similar concerns after finding that giving clinical doses of penicillin to mice in late pregnancy and early life led to a state of vulnerability to dietary induction of obesity.
The research team will follow up their studies by analyzing the effects of penicillin on the offspring when given only to the pregnant mothers. They also plan on investigating the efficacy of different types of potentially beneficial bacteria in protecting offspring against the behavioral changes that result from antibiotic usage.
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