The physiological significance of the circadian dynamics of the HPA axis: Interplay between circadian rhythms, allostasis and stress resilience

Circadian time-keeping mechanisms preserve homeostasis by synchronizing internal physiology with predictable variations in the environment and temporally organize the activation of physiological signaling mechanisms to promote survival and optimize the allocation of energetic resources. In this paper, we highlight the importance of the robust circadian dynamics of allostatic mediators, with a focus on the hypothalamic-pituitary-adrenal […]

Central nervous regulation of the hypothalamic-pituitary-adrenal axis and its impact on fertility, immunity, metabolism and animal welfare – a review

The paper reviews mechanisms of neuronal control of the hypothalamic-pituitary-adrenal (HPA) axis with a view on its impact on performance and welfare. The limbic hippocampal and amygdaloid input to the paraventricular hypothalamic nucleus constitutes the basic intracerebral axis by which emotional stimuli affect the stress response. This axis is the backbone of the HPA feedback […]

Paradoxical sleep deprivation activates hypothalamic nuclei that regulate food intake and stress response

A large body of evidence has shown that prolonged paradoxical sleep deprivation (PSD) results in hypothalamic–pituitary–adrenal (HPA) axis activation, and in loss of body weight despite an apparent increase of food intake, reflecting increased energy expenditure. The flowerpot technique for PSD is an efficient paradigm for investigating the relationships among metabolic regulation and stress response. […]

Effects of sleep deprivation on cardiac autonomic and pituitary-adrenocortical stress reactivity in rats

A demanding life style, often associated with restricted time for sleep, is a growing problem in our society and may become a major health issue in the near future. Since the physiological stress system plays a critical role in coping with a challenge, it is important to know whether this system is affected by sleep […]

A single exposure to an acute stressor has lasting consequences for the hypothalamo–pituitary–adrenal response to stress in free-living birds

In vertebrates, activation of the hypothalamo–pituitary–adrenal (HPA) axis in response to unpredictable events results in elevated glucocorticoid secretion. Repeated exposure to stressors alters subsequent glucocorticoid secretion, either by inducing chronic stress or as a result of habituation. However, most studies of repeated stress focus on the impacts of multiple and frequent exposures to acute stressors, […]

Stress and welfare: Two complementary concepts that are intrinsically related to the animal’s point of view

The closely associated concepts of welfare and stress may be considered as opposites since welfare cannot be achieved under stress and vice versa. Stress was first considered as an unspecific response to any challenge taxing the organism’s resources where the HPA axis plays a central role [Selye H. A syndrome produced by diverse nocuous agents. […]

Stress revisited: A critical evaluation of the stress concept

With the steadily increasing number of publications in the field of stress research it has become evident that the conventional usage of the stress concept bears considerable problems. The use of the term ‘stress’ to conditions ranging from even the mildest challenging stimulation to severely aversive conditions, is in our view inappropriate. Review of the […]

Exploration of the hypothalamic-pituitary-adrenal function as a tool to evaluate animal welfare

Measuring HPA axis activity is the standard approach to the study of stress and welfare in farm animals. Although the reference technique is the use of blood plasma to measure glucocorticoid hormones (cortisol or corticosterone), several alternative methods such as the measurement of corticosteroids in saliva, urine or faeces have been developed to overcome the […]

A single exposure to social isolation in domestic piglets activates behavioural arousal, neuroendocrine stress hormones, and stress-related gene expression in the brain

Stressful early life events can have short- and long-term effects on neuroendocrine and behavioural mechanisms of adaptation. Here, we investigated the effects of a single social isolation (4 h) of domestic piglets on both behavioural alterations in open-field tests and modifications in the expression of genes regulating glucocorticoid response in stress-related brain regions at 7, 21 […]

Variations in the postnatal maternal environment in mice: Effects on maternal behaviour and behavioural and endocrine responses in the adult offspring

According to the maternal mediation hypothesis, brain and behavioural development in rodents is affected by environment-dependent variations in maternal care. Thus, it has been shown that early handling results in reduced behavioural and neuroendocrine responses to stressors and that these effects are associated with increased maternal care received during infancy. To investigate this further in […]