By Mike Foster
Debate over whether man flu is real — or whether men are just big babies — is as inevitable as the dreaded flu season itself.
A new joint study by University of Ottawa researchers scores one for the dudes. Strong, silent types that turn into shivering, grouchy wrecks as they binge-watch The Wire can now blame basic physiology. Experiments found that flu-infected male mice displayed more sickness behaviour and greater fluctuations in body temperature than female mice, and took longer to recover.
The research, conducted at uOttawa’s NISE (NeuroImmunology, Stress and Endocrinology) Laboratory, was recently published online in Brain, Behaviour and Immunity, a peer-reviewed journal.
“Age and sex differences in immune response following LPS treatment in mice” adds to previous research that has found that dissimilarities in male and female immune responses could be linked to sex hormones. Testosterone is generally seen as an immune suppressor and estrogen as an immune enhancer.
As part of broader research on how puberty remodels the brain, researchers from uOttawa’s School of Psychology (Faculty of Social Sciences) and the School of Nutrition Sciences (Faculty of Health Sciences) examined age and sex differences in acute immune response.
Psychology professor Nafissa Ismail, director of the NISE lab, said: “My data supports the idea that the man flu isn’t just a myth.”
The researchers injected male and female adult mice and pubescent male and female mice with the same bacterial infection that induces the symptoms seen in human flu.
“We don’t see the mice curl up with a blanket, but they huddle together, lose their appetite, become lethargic, and their eyelids become droopy,” Ismail said.
The experiments involved infecting groups of mice with LPS (Lipopolysaccharide) and then observing sickness behaviour and body temperature, taking measurements of pro- and anti-inflammatory cytokines (small proteins) in their blood following LPS treatment, and removing gonadal hormones to see if this affected outcomes.
The physical symptoms among the adult male mice were visibly worse than for adult female mice and pubescent mice of both sexes. The physiological measures of their immune responses — body temperatures, fever and signs of inflammation — were also more severe.
Ismail says the study stands out because it includes comparisons between males and females as well as adult and pubescent mice. Her wider research examines how stressful events during puberty appear to have a long-term effect on reproductive and other behaviours.
Pubescent mice recover much faster from illness as their developing immune systems under-react to infections. However, it appears that exposure to stressors during puberty predisposes them to long-term changes in the brain and in behaviour, including behaviours that are symptoms of depression, anxiety and cognitive function problems, Ismail said.
In further studies, Ismail and her graduate students, Rupali Sharma, Emma Murray and Daria Kolmogorova, plan to measure how mononucleosis affects adolescents and adults. Also, Ismail and her graduate students will use an NSERC Engage grant to examine whether exposure to probiotics during puberty can prevent mental health issues later on.
In the meantime, men can cite the science as they hog the duvet the next time they come down with the flu.