The Impact of Stress on Laboratory Animals and Variability in Research Outcome

Laboratory animal’s stress and research variability

Abstract

The laboratory environment offers an enormous amount of chronic and/or acute stress, which can be both social and physiological and require the animal to adapt to allostatic balance. Several aspects of the laboratory environment, such as confinement, cause significant and recurrent stress in laboratory animals, which is inescapable. Several factors such as transportation, handling, noise, restrictions, experimental procedures, and may cause stress which is difficult to manage. It can be even more challenging in the absence of adequate habituation/ desensitization. These may result in several physiological as well as psychological challenges, triggered by the activation of several neuroendocrine pathways, with a variety of complications such as physiological and/or psychological damage. This type of damage may result in stereotypic behaviours like pacing and circling, self-harm, and physiological consequences such as inflammatory reactions, immune dysfunction, susceptibility to diseases, and metabolic disorders. Moreover, some of the stress-mediated outcomes are epigenetic which makes the consequences transgenerational, that is the biology of animals whose immediate generations have been captured in the wild and/or have endured stress in laboratories could be epigenetically transformed compared to their wild counterparts. It is thought that lab animals have different physiological, epigenetic, and psychological differences that make it hard to extrapolate findings from animal studies to humans. These stress factors and their consequences need to be recognized sufficiently by scientists while using animal models for experiments. We have described the physiological, behavioural, and epigenetic consequences of laboratory-induced stress among animals in this review.