Male, but not female, experimenters induce intense stress in rodents that can dampen pain responses, according to a paper published today in Nature Methods. Such reactions affect the rodents’ behaviour and potentially confound the results of animal studies, the study suggests.
The authors discovered this surprising gender disparity while investigating whether the presence of experimenters affects rodent pain studies. For years, anecdotal reports have suggested that rodents show a diminished pain response when a handler remains in the room.
This apparent effect is “something that people have been whispering about at meetings for years,” says lead author Jeffrey Mogil, a pain researcher at McGill University in Montreal, Canada. “But no one had bothered to look at this systematically.”
