Scientists at McMaster University have uncovered new insights into the complex interactions between different kinds of brain cells and their responses to social and stress stimuli.  

In a study involving mice, researchers compared the real-time activity of oxytocin neurons and astrocytes, using a technique called dual-color fiber photometry. The mice were exposed to familiar and unfamiliar mice or were placed under a stress-inducing stimulus – a looming shadow that mimicked a threat of an aerial predator. 

They found in female mice that neurons responsible for producing the social bonding-related hormone oxytocin exhibit a significant increase in activity during friendly interactions with unfamiliar mice, suggesting a strong neural response to meeting and learning about a new social partner. Notably, no such increase was seen in male mice. Astrocytes – brain cells that support neurons – did not show measurable changes in activity during social interactions, regardless of the familiarity of the social partner or the sex of the experimental mice. 

“Our findings highlight the importance of understanding how different brain cell types respond to social stimuli, which could have significant implications for developing strategies to enhance social experiences,” explains Katrina Choe, an assistant professor in the Department of Psychology, Neuroscience and Behaviour, who led the study together with current and former graduate students Katy Celina Sandoval and Joshua Rychlik. “This difference in how male and female mice process social novelty could have broader implications for understanding gender differences in social interactions.” 

Oxytocin is known for its role in social bonding, trust, and emotional regulation. It is often referred to as the “love hormone” because it enhances trust, empathy, and social interactions. Beyond physiological roles, oxytocin influences various social behaviors, including forming relationships and social learning.  

But the study also revealed that oxytocin neurons continued to be extra active even after the stress stimulus, the looming shadow, had disappeared.  

“We found that oxytocin neurons not only respond to stress but continue to stay active after the threat is gone, suggesting a potential role in extended stress-buffering effect,” says Choe.  

Astrocytes, meanwhile, responded strongly to the looming shadow, but their activity returned to baseline levels once the stressor was removed.  

“While oxytocin neurons and astrocytes are located near each other in the brain, they responded differently to the same stressor,” explains Choe. “Astrocytes seem to be more sensitive to immediate threats, while oxytocin neurons are potentially involved in maintaining resilience after the threat has disappeared.”  

Choe says the distinct reactions open the door for further research into how these brain cells interact.  

“We’re interested in exploring how these changes in oxytocin neuronal activity arise, both in social and stress contexts. Understanding what sensory inputs trigger these patterns in the brain will be a key focus of our future research,” she says.  

“By advancing our understanding of these neural mechanisms, the research opens new avenues for enhancing social experiences and resilience to stress.”