New investigation shows interface between intestinal microbiota and maternal behavior

Overview

• Post By : Kumar Jeetendra


• Source: Salk Institute


• Date: 30 Jan,2021

As scientists learn more about the microorganisms that colonize the human anatomy –collectively referred to as the microbiota–one area of extreme interest is the effect that these microbes can have on the mind. A new study headed by Salk Institute scientists has identified a strain of E. coli bacteria that, when living in the guts of female mice, causes them to neglect their offspring.

The findings, published January 29, 2021, in the journal Science Advances, show a direct link between a particular microbe and maternal behaviour.

Even though the study was done in mice, it adds to the growing body of science demonstrating that microbes in the gut are important for brain health and may affect development and behavior.

To our knowledge, this is the first demonstration that the intestinal microbiota is important for promoting healthy maternal behavior and bonding between mom and offspring in an animal model. It adds to the ever-growing evidence that there’s a gut-brain connection, and that microbes are important for regulating the behavior of the host that they’re inhabiting.”

Janelle Ayres, Study Senior Author and Professor, Laboratory Head of Molecular and Systems Physiology Laboratory, Salk Institute

The ways the microbiota can affect mental health and neurological disorders is a developing area of research. The makeup of the gut microbiota in people has been associated with depression, anxiety, autism and other conditions. But it has been difficult to study how different strains of bacteria exert their influence on human behavior, a connection often called the microbiota-gut-brain axis.

In her laboratory, Ayres uses mice to examine how body systems and the brain interact with each other to promote wellbeing. This includes focusing on how body processes are controlled by microbes as well as the ways that microbes affect growth and behavior. In the present experiments, she and her team had been investigating groups of mice which each had a single strain of E. coli in their gut. Mice with one specific breed of E. coli, known as O16:H48 MG1655, mothered offspring that had stunted growth.

“We discovered that the pups’ behaviour was normal, and the milk made by the mothers was of normal, healthful composition and was being produced in normal amounts,” Ayres says. “We finally figured out that being colonized with this bacteria led to poor maternal behavior. The mice were failing their pups.”

Further experiments revealed that the mice could be rescued from stunted growth, either by providing them a growth factor called IGF-1 or handing them off to foster mouse mothers that could take care of them properly. This confirmed that the cause of stunted growth was coming from the mothers’ behavior rather than something in the pups themselves.

“Our study offers an unprecedented understanding of how the intestinal microbiota can interrupt maternal behaviour and how this can negatively affect growth of an offspring,” says first author Yujung Michelle Lee, a former graduate student at Ayres’ laboratory and now a postdoctoral fellow at Genentech. “it’s quite interesting to me that establishment of a healthier mother-infant relationship is driven by factors beyond hormones, which the germs living in our own bodies play a major part in it.”

Early findings suggest the bacteria may be affecting levels of serotonin, the hormone associated with feelings of happiness and well-being, but more work is necessary.

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