The influence of the smell of men and women on the behavior of laboratory rats

Abstract

The results of behavioral tests of laboratory animals are highly variable. Even within the same laboratory the results of the same test can differ significantly. We tested the effect of the experimenter’s smell — male and female — on the behavior of male Wistar rats. The smell donors were clinically healthy non-smoking, low-alcohol-consuming volunteers aged 20–21: four men, and four women in the luteal phase of the menstrual cycle. They wore cotton socks and T-shirts at night, which, in the morning, were sealed in plastic bags. The animals were tested on the same day. In the first experiment (n = 20), smell samples were placed in the center of the elevated zero maze. First, we tested naive animals, after 20 days in the presence of a male smell, and after another 20 days in the presence of a female smell. The presence of human body smells during testing increased the rats’ anxiety. A male smell had a greater effect than a female smell. In the second experiment (n = 29), the delayed effect of exposure to human smells was studied. The home cages were equipped with perforated plastic containers with fabric inside. They remained in the cages for one hour. During exposure to the smell, the animals were aroused, which was manifested in an intensive examination of containers and multiple agonistic contacts. Four hours later, increased anxiety was noted only after exposure to a female smell. The obtained data show that the results of behavioral tests on laboratory rats may depend, inter alia, on the sex of the experimenter.