Regular Aerobic Voluntary Exercise Increased Oxytocin in Female Mice: The Cause of Decreased Anxiety and Increased Empathy-Like Behaviors

Abstract

Background: It is known that regular physical activity reduces anxiety. Low anxiety levels affect mood, emotions, and empathy. Oxytocin is a powerful hormone that regulates social interaction, sexual reproduction, maternal–infant bonding, milk release, empathy, and anxiety. Empathy is an important behavior in the living community; and also important for sportsmen during sportive competition and daily living life, because sportsmen are also role model of people. Aims: To investigate the effects of voluntary physical activity on oxytocin, anxiety, and empathy levels as well as the relationship between them. Study Design: Animal experiment. Methods: Male and female mice were made to exercise in running wheel cages for 6 weeks. Their empathy and anxiety levels were evaluated by using Helping Behavior test and elevated plus maze and open field test, respectively. And then the brain and blood oxytocin levels were measured. Results: Empathy-like behavior was improved in both genders of the exercise groups (door-opening time decreased in both genders of exercise groups, p for both=0.0001). As a response to exercise, both the brain and serum oxytocin levels increased in female mice (both of p=0.0001); however, in males, oxytocin levels increased in only the brain (p<0.05). Anxiety levels decreased in all the exercise groups (increased time spent in the middle area of open field test, both genders, p=0.002; increased time spent in the open arms of elevated plus maze test, females p=0.004, males p=0.0001). There was a strong negative correlation between serum oxytocin levels and door opening time of helping behavior equipment, and moderate negative correlation was found between the brain oxytocin levels and door-opening time of helping behavior equipment in females. However, there was no correlation between both the brain and serum oxytocin levels and empathy behavior in males. But there were very strong positive correlations between low anxiety indicators and both the brain and serum oxytocin levels in both the genders. Conclusion: Voluntary physical activity decreases anxiety and increases empathy-like behavior in mice; which is associated with increased oxytocin levels in female mice but not in male mice. Further research is required to investigate the mechanisms of exercise effect on anxiety and empathic brain pathways in males.

Keywords

• Anxiety
• brain
• empathy
• exercise
• gender