Biomedical Research and the Male Scientist

Mouse behavior in a study may depend greatly on the sex of the researcher.
Courtesy: http://www.allaboutvision.com/conditions/amd_news.htm

           Many scientific fields focus on disease studies in order to develop effective therapies. Before potential remedies are supplied to human subjects, their efficacy and safety must first be tested on animals. Mice have served as suitable subjects for new drugs and treatment options that may potentially alleviate or eradicate human disease; thus, an overwhelming majority of biomedical research projects utilize mice. In these studies, variables need to be considered in order to accurately assess whether the experimental group is truly responding to the administered treatment. Such variables may include the health of the mice, the time of day that the treatment is administered, and the treatment dosage.

            Nevertheless, there may be an additional factor that biomedical researchers are not considering: the sex of the researcher. A report in Nature Methods details this discovery. Jeffrey Mogil's lab specializes in projects relating to pain perception in mice at McGill University in Canada. Interestingly, Mogil noticed that something was amiss with the recent set of experiments done by his students.  A pain-inducing agent was injected into the hind paws of mice, and facial grimaces were measured post-treatment. However, mice showed a significant reduction in facial grimaces in the presence of male researchers compared to that of no researcher, and the number of facial grimaces was not affected by the presence of female researchers. It was hypothesized that the smell of males influence this trend because placing a male's shirt in close proximity to a cage was able to exert this same effect, and surprisingly, this effect was nullified by the placement of a female's shirt nearby. Upon further analysis, the scent of male researchers and males of other species increased the levels of corticosterone, a stress-related hormone, in the blood of mice. This revelation led Mogil's group to postulate that the male scent induces a stress response in mice, which can alter the outcome of administered treatments.

             Though the idea that mice behavior exhibits a sex bias can be comical, this possibility raises a number of concerns. For example, some people wonder whether all past biomedical experiments employing mice are now invalidated. This finding does not necessarily prove this notion for a number of reasons. First, this set of experiments was done solely to measure pain responses; this study does not address sex bias in other types of mouse studies, such as those involving drug responses. Also, some physical characteristics of mice are known to be dependent on genetic background. This means that a particular stimulus may elicit a different behavior in a mouse with brown coat color compared to one with black coat color. Mouse behavior may also exhibit a more pronounced sex bias in response to pain versus other stimuli. Furthermore, we are reminded that there are subtle aspects of scientific studies that may influence their outcome, and we should identify and consider these factors more heavily when evaluating the data of future experiments.