Mice and rats play a key role in the development of new drugs and other medical advances. In fact, 95 percent of all lab animals are rodents, according to the Foundation for Biomedical Research. But for years, researchers have had trouble replicating the findings of research involving rodents, causing some to question the validity of results. In 2014, scientists at McGill University uncovered something that may explain why. They determined that male researchers trigger a stress response in mice and rats, making them less sensitive to pain -- and thereby affecting experiment outcomes. Female researchers had no such effect on the rodents.
Scent of a woman, or a man:
- The McGill team found that rodents pick up chemo-signals from male researchers. Pheromones secreted by men from their armpits -- from apocrine glands -- apparently alert rodents to the presence of nearby male animals, including humans.
- All mammals share the same chemo-signals, but male and female pheromones differ. The researchers were able to use cotton T-shirts, worn by both men and women, to test the rodents' responses.
- The mice and rats used in medical trials are inbred so that, except for sex differences, they are almost identical genetically. This helps make experiment results more uniform.
