An intricate relationship exists between gene activity and social experience. Looking at mice being challenged by other mice in staged interaction experiments, researchers from the University of Illinois at Urbana-Champaign illustrate changes occurring in the brain when an animal’s experiences influence its behavior.
Study leader Lisa Stubbs and her research team designed a series of experiments where one mouse intruded upon the habitat of a second mouse, looking at gene activity across interacting brain regions in response to the challenge. They calculated the activity of genes from different parts of the brain, including the frontal cortex, hypothalamus, and amygdala. This wide range of quantification is based on gene interactions changing over time, interactions differing among tissue types, and genes being defined, in part, by how they interact with other genes.
While analyzing gene interactions, researchers looked for the involvement of specific transcription factors, as well as any links between gene responses to social experience and their “epigenetic state,” or their gene expression. Epigenetic modification to the chromatin structure - the way DNA is packaged in a cell - affects the way a particular gene is expressed.
From their controlled gene network study, they found a significant amount of gene activity related to metabolism and neurochemical signaling, indicating that social stress may change the way brain cells “consume energy and communicate with one another.”
"We found that the chromatin landscape is profoundly remodeled over a very short time in the brain regions responding to social challenge," said Stubbs. "This is surprising because chromatin profiles are thought to be relatively stable in adult tissues over time."
The findings from the mouse experiments also resembled findings from a similar study in honey bees. "As we examined the regulatory networks active in the mouse brain over time, we could see that some of the same pathways already explicated in honey bees... were also dysregulated similarly by social challenge in mice," Stubbs explained. "That cross-species concordance is extremely exciting and opens new doors to experimentation that is not being pursued actively by other research groups."
The recent study is a strong example of the kind of findings that can be gleaned from genetic models in animals like mice, providing scientists with dependable data that can be applied to studies of more complex animal models and - eventually - human studies. Mice are not by far the only animals who experience social stress and social behavior disorders, and researchers have a lot left to uncover about how genetic activity in the brain changes in response to these social challenges.
The present study was published in the journal Genome Research.