Specific bacteria in the gut encourage mother mice to neglect their young

Specific bacteria in the gut encourage mother mice to neglect their young

Escherichia coli (E. coli) bacteria, pictured here, is a common intestinal bacterium in humans and animals. There are many different strains, some of which cause disease. Credit: fusebulb / Shutterstock.com

As scientists learn more about the microorganisms that colonize the body – collectively called the microbiota – one effect of great importance is the effect that these microbes can have on the brain. A new study led by scientists from Salk Institute found a strain of E coli bacteria that, when they live in the intestines of female mice, cause them to neglect their offspring.

The findings, published January 29, 2021, in the journal Scientific progress, shows a direct link between a particular microbe and maternal behavior. Although research has been done in mice, it contributes to the growing amount of science that shows that microbes in the gut are important for the health of the brain and that they can influence development and behavior.

“To our knowledge, this is the first evidence that the gut microbiota is important for promoting healthy maternal behavior and bonding between mother and offspring in an animal model,” said Professor Janelle Ayres, head of Salk’s Molecular and Systems Physiology Laboratory. senior author of the paper. “This contributes to the ever-growing evidence that there is an intestinal-brain connection, and that microbes are important in regulating the behavior of the host they inhabit.”

The ways in which the microbiota can affect mental health and neurological disorders is a growing area of ​​research. The composition of the intestinal microbiota in humans is linked to depression, anxiety, autism and other conditions. But it was difficult to study how individual bacterial strains exert their influence on human behavior, a connection often called the axis of the microbiota-intestinal brain.

In her lab, Ayres uses mice to investigate how body systems and the brain communicate with each other to promote health. These include focusing on how body processes are regulated by microbes, and on the ways in which microbes influence growth and behavior. In the current experiments, she and her team investigated groups of mice that each had a single strain E coli in their intestines. Mice with a specific species E coli, named O16: H48 MG1655, maternal offspring that delayed growth. Further investigation showed that the mice were smaller because they were malnourished.

“We found that the behavior of the pups was normal and that the milk made by mothers had a normal, healthy composition and was produced in normal quantities,” says Ayres. “Eventually we found out that colonization with this particular bacterium led to poor maternal behavior. The mice neglected their young.”

Additional experiments revealed that the mice could be rescued from stunted growth, either by giving a growth factor called IGF-1, or by giving it to mouse mothers who could take proper care of them. It confirmed that the cause of stunted growth is the result of the behavior of the mothers rather than of something in the little ones themselves.

“Our study provides an unprecedented understanding of how the gut microbiota can disrupt maternal behavior and how it can negatively affect the development of offspring,” says first author Yujung Michelle Lee, a former graduate student in the laboratory of Ayres and now a doctor at Genentech. . “It is very interesting to me that the establishment of a healthy mother-baby relationship is driven by factors outside hormones, and that the microorganisms that live in our bodies play an important role in it.”

Ayres and her team plan to investigate how these microbes cause changes in mouse behavior. Early findings suggest that the bacteria may affect the levels of serotonin, the hormone associated with feelings of happiness and well-being, but more work is needed.

“It’s very difficult to study these relationships in humans because the human microbiota contains hundreds of different species of microorganisms,” says Ayres, who holds the Helen McLoraine Development Chair. “But once we understand more about the mechanisms in animal models, we may be able to translate our findings to humans to determine if the microbes and their effects may be the same.”

The U16: H48 MG1655 strain has been found in human gut and was previously believed to have no positive or negative effects.


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More information:
Microbiota control of maternal behavior regulates the early growth of offspring, Scientific progress (2021). DOI: 10.1126 / sciadv.abe6563, advances.sciencemag.org/content/7/5/eabe6563

Provided by Salk Institute

Quotation: Specific bacteria in the gut encourage mother mice to neglect their young (2021, 29 January) obtained on 30 January 2021 from https://phys.org/news/2021-01-specific-bacteria-gut-prompt-mother. html

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