Defensive responses of Brandt's voles (Lasiopodomys brandtii) to chronic predatory stress

Abstract

Predator odors are non-intrusive natural stressors of high ethological relevance. The objective of this study was to investigate the processing of a chronic, life-threatening stimulus during repeated prolonged presentation to Brandt's voles. One hundred and twenty voles were tested by repeated presentation of cat feces in a defensive withdrawal apparatus. Voles exposed to feces for short periods showed more avoidance, more concealment in the hide box, less contact time with the odor source, more freezing behavior, less grooming, more jumping, and more vigilant rearing than did non-exposed voles, and those exposed for longer periods. Serum levels of adrenocorticotropic hormone and corticosterone increased significantly when animals were repeatedly exposed to cat feces for short periods. The behavioral and endocrine responses habituated during prolonged presentation of cat feces. ΔfosB mRNA expression level was highest in voles exposed to cat feces for 6 and 12 consecutive days, and subsequently declined in animals exposed to cat feces for 24 days. We therefore conclude that the behavioral and endocrine responses to repeated exposure to cat feces undergo a process of habituation, while ΔfosB changes in the medial hypothalamic region exhibit sensitization. We propose that habituation and sensitization are complementary rather than contradictory processes that occur in the same individual upon repeated presentation of the same stressor.

Parameters That Affect Fear Responses in Rodents and How to Use Them for Management

“…Each component within this complex mixture react to environmental conditions (e.g., bacterial decomposition, UV light) at different rates and in different manners (Rasmussen, 1988;Muller-Schwarze, 2006), ultimately modifying the chemical profile of the cue over time. Even handling and storage of the chemical cues can alter the way animals perceive them (Hoffmann et al, 2009;Hegab et al, 2014). It is therefore possible that changes in chemical structure of the signal may also change its information over time (Parsons and Blumstein, 2010).…”

Prenatal predatory stress in a wild species of subterranean rodent: Do ecological stressors always have a negative effect on the offspring?

“…In mammal species, the exposure to ecological and environmental stressors, such as the presence of predators or their odors, can cause severe changes in the physiology and behavior of individuals (Apfelbach, Blanchard, Blanchard, Hayes, & McGregor, ; Hegab et al, ; Hegab, Kong, Yang, Mohamaden, & Wei, ; Kavaliers & Choleris, ; Takahashi, Nakashima, Hong, & Watanabe, ). Prey species exposed to predator‐derived odors have shown alterations in foraging, feeding, general activity, and, mainly in females, reproduction (Apfelbach et al, ), although negative results were also described depending upon prey life history (Orrock, ) These changes may be accompanied by an impact on the regulation of the hypothalamic–pituitary–adrenal (HPA) axis, with increased levels of stress hormones such as glucocorticoids (GCs) and adrenocorticotrophic hormone (ACTH) (Apfelbach et al, ; Figueiredo, Bodie, Tauchi, Dolgas, & Herman, ; File, Zangrossi, Sanders, & Mabbutt, ).…”

Source Odor, Intensity, and Exposure Pattern Affect Antipredatory Responses in the Subterranean Rodent Ctenomys talarum

“…These behavioral adaptations, like predator avoidance and the development of antipredator behaviors, are fundamental for survival (Hegab et al. ). In many cases, antipredator defense involves the detection and response to specific chemical cues that predators produce.…”