The scent of men may affect results in mouse studies

researchersThe scent of men causes a unique pain-suppressing stress response in rodents that may affect outcomes in laboratory tests in ways that now are not considered in assessing findings, says UAB psychology Professor Robert Sorge, Ph.D., in study results published in Nature Methods.

His research reveals that, in the presence of a female scent, rodent stress levels remained steady. But a male scent induced a elevated stress response. The stress effect was lessened when the scent of a woman and a man both were present.

Why is that important? Increased stress makes lab animals less sensitive to pain and perhaps less likely to react naturally to procedures involving learning and performance, Sorge said.

“Our findings suggest that one major reason for lack of replication of animal studies is the gender of the experimenter,” Sorge said. “It’s a factor that’s not currently stated in the methods sections of published papers, but it should be considered based on what we’ve discovered.”

Why men? Likely, the levels of testosterone-based chemicals men secrete alert the rodents that male animals are nearby and cause their stress levels to spike.

The results of this study could have a big impact on research, given that rats and mice comprise more than 95 percent of all lab animals. The results indicate that researchers should account for these variables in their experiments.

One option is that male researchers could sit in a room with their test subjects for half an hour or more before any experiments to help ease the stress effects on the animals, which will decrease over time.

Sorge worked alongside researchers at McGill University and in his lab in the Department of Psychology at UAB.