Temporal differences in the responses of the pituitary adrenocortical axis, the sympathoadrenomedullar axis, heart rate, and behaviour to a daily repeated stressor in domestic pigs.
In this study we examined responses of domestic pigs (Sus scrofa domestica) to a daily repeated stressor. In particular, we focused on differences in temporal changes across treatment repetition between the pituitary adrenocortical axis, the sympathoadrenomedullar axis, heart rate, and behaviour. To induce a stress response, we separated eight castrated male pigs from their group mates visually and auditorily for 1 h on 10 successive days. Overall, enhanced plasma levels of cortisol, ACTH, and adrenaline indicated a clear stress response. Levels of cortisol and ACTH decreased continuously with repetition of exposures to the stressor. In contrast, levels of adrenaline, behavioural activity, and heart rate did not change consistently across repetition of exposures. Interestingly, therefore, hormones of the pituitary adrenocortical axis showed a process of adaptation whereas subjects did not adapt to the stressor with respect to titres of adrenaline, heart rate, and particular behaviours (e.g., grid pressing, vocalisation, locomotion). Instead, they continued to react actively towards the social separation. Our results suggest that different stress systems can differ in temporal pattern of their response towards a repeated stressor. Such temporal differences should be considered when studying the effects of repeated stress.
Schrader
L
L
Institut für Verhaltensbiologie, FU Berlin, Germany. lars.schrader@inw.agrl.ethz.ch
Ladewig
J
J
D000222:Adaptation, Physiological / Q000502:physiology*; D000313:Adrenal Medulla / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D004924:Escape Reaction / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D008297:Male; D010913:Pituitary-Adrenal System / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology; D012934:Social Isolation; D013315:Stress, Psychological / Q000503:physiopathology*; D013552:Swine; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors