Sex-specific stress and biobehavioral responses to human experimenters in rats

Jamshid Faraji; Mirela Ambeskovic; Nevyn Sauter; Jaxson Toly; Kera Whitten; Nayara Antunes Lopes; David M Olson; Gerlinde A S Metz

doi:10.3389/fnins.2022.965500

Sex-specific stress and biobehavioral responses to human experimenters in rats

Front Neurosci. 2022 Jul 22:16:965500. doi: 10.3389/fnins.2022.965500. eCollection 2022.

Authors

Jamshid Faraji¹, Mirela Ambeskovic¹, Nevyn Sauter¹, Jaxson Toly¹, Kera Whitten¹, Nayara Antunes Lopes², David M Olson², Gerlinde A S Metz^{1

2

3}

Affiliations

¹ Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
² Department of Obstetrics and Gynecology, University of Alberta, Edmonton, AB, Canada.
³ Southern Alberta Genome Sciences Centre, University of Lethbridge, Lethbridge, AB, Canada.

Abstract

Important factors influencing the outcome of animal experiments in preclinical research are often overlooked. In the current study, the reaction of female and male rats toward the biological sex of a human experimenter was investigated in terms of anxiety-like behaviors and physiological stress responses, as measured by infrared (IR) thermography, circulating corticosterone (CORT) and oxytocin levels. Female rats displayed consistently exacerbated anxiety-related behaviors along with elevated body surface temperature during repeated exposure to male experimenters. Experimental stress further intensified thermal responses to a male experimenter, especially in female rats. The behavioral responses to a male experimenter in females were associated with higher circulating CORT and lower oxytocin levels. Similar responses were induced by a T-shirt worn by a human male. The findings suggest that psychophysiological responses of female rats to a male experimenter are influenced by both visual and olfactory cues. The results emphasize the need to not only consider sex differences in experimental animals, but also standardize and report the experimenter's biological sex to avoid ambiguity in the generation and interpretation of results.

Keywords: corticosterone (CORT); cutaneous temperature; experimenter sex; hypothalamic-pituitary-adrenal (HPA) axis; infrared thermography; oxytocin; sex differences; stress response.