Exposure To Males Causes Stress In Rodents
This study measured the effect of the gender of human experimenters on animals in research. The presence of male experimenters produced stress that increased anxiety and suppressed pain in rats and mice. Female rodents were more stressed. The effect was reproduced with human hormones and sweat factors, and with bedding from other non-neutered male animals. There was no effect with female experimenters, hormones or bedding. The simultaneous presence of a woman nullified the stressful impact of a male experimenter. Archived data sets from other experiments were reviewed and showed the same effect.
[Abstract excerpted from original source.]
“We found that exposure of mice and rats to male but not female experimenters produces pain inhibition. Male-related stimuli induced a robust physiological stress response that results in stress-induced analgesia. This effect could be replicated with T-shirts worn by men, bedding material from gonadally intact and unfamiliar male mammals, and presentation of compounds secreted from the human axilla. Experimenter sex can thus affect apparent baseline responses in behavioral testing.”