scholarly journals Litter characteristics and helping context during early life shape the responsiveness of the stress axis in a wild cooperative breeder

2021 ◽  
Author(s):  
Aurelie Cohas ◽  
Coraline Bichet ◽  
Rebecca Garcia ◽  
Sylvia Pardonnet ◽  
Sophie Lardy ◽  
...  

Stress responses have evolved to quickly and appropriately deal with environmental stressors in order to secure or restore homeostasis. Since the regulation of stress hormones plays a key adaptive role, the regulatory processes controlling stress hormones levels may be under high selective pressure. The social environment during early life (parents and litter characteristics) strongly affects ontogeny of the hypothalamic-pituitary-adrenal (HPA) axis. In cooperative breeders, offspring are also confronted with helpers but whether and how variation in the helping context can affect HPA axis responsiveness of offspring remains unanswered. Combining dexamethasone suppression and adrenocorticotropic hormone stimulation tests, we investigated the link between the social environment and the characteristics of the HPA axis at the early stages of life in wild Alpine marmots. We show that when raised in the presence of helpers, marmot pups exhibit a greater capacity not only to mount, but also to turn off a stress response. The capacity to mount a stress response was also higher as the pups were raised in large litters. Determining impacts of such social modulation of the HPA axis functioning on individual fitness would make an important contribution to our understanding of the evolution of cooperative breeding.

2015 ◽  
Vol 112 (18) ◽  
pp. 5637-5642 ◽  
Author(s):  
Katie A. McLaughlin ◽  
Margaret A. Sheridan ◽  
Florin Tibu ◽  
Nathan A. Fox ◽  
Charles H. Zeanah ◽  
...  

Disruptions in stress response system functioning are thought to be a central mechanism by which exposure to adverse early-life environments influences human development. Although early-life adversity results in hyperreactivity of the sympathetic nervous system (SNS) and hypothalamic–pituitary–adrenal (HPA) axis in rodents, evidence from human studies is inconsistent. We present results from the Bucharest Early Intervention Project examining whether randomized placement into a family caregiving environment alters development of the autonomic nervous system and HPA axis in children exposed to early-life deprivation associated with institutional rearing. Electrocardiogram, impedance cardiograph, and neuroendocrine data were collected during laboratory-based challenge tasks from children (mean age = 12.9 y) raised in deprived institutional settings in Romania randomized to a high-quality foster care intervention (n = 48) or to remain in care as usual (n = 43) and a sample of typically developing Romanian children (n = 47). Children who remained in institutional care exhibited significantly blunted SNS and HPA axis responses to psychosocial stress compared with children randomized to foster care, whose stress responses approximated those of typically developing children. Intervention effects were evident for cortisol and parasympathetic nervous system reactivity only among children placed in foster care before age 24 and 18 months, respectively, providing experimental evidence of a sensitive period in humans during which the environment is particularly likely to alter stress response system development. We provide evidence for a causal link between the early caregiving environment and stress response system reactivity in humans with effects that differ markedly from those observed in rodent models.


2021 ◽  
Vol 12 ◽  
Author(s):  
Van A. Ortega ◽  
Emily M. Mercer ◽  
Gerald F. Giesbrecht ◽  
Marie-Claire Arrieta

Stress is broadly defined as the non-specific biological response to changes in homeostatic demands and is mediated by the evolutionarily conserved neuroendocrine networks of the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Activation of these networks results in transient release of glucocorticoids (cortisol) and catecholamines (epinephrine) into circulation, as well as activation of sympathetic fibers innervating end organs. These interventions thus regulate numerous physiological processes, including energy metabolism, cardiovascular physiology, and immunity, thereby adapting to cope with the perceived stressors. The developmental trajectory of the stress-axis is influenced by a number of factors, including the gut microbiome, which is the community of microbes that colonizes the gastrointestinal tract immediately following birth. The gut microbiome communicates with the brain through the production of metabolites and microbially derived signals, which are essential to human stress response network development. Ecological perturbations to the gut microbiome during early life may result in the alteration of signals implicated in developmental programming during this critical window, predisposing individuals to numerous diseases later in life. The vulnerability of stress response networks to maladaptive development has been exemplified through animal models determining a causal role for gut microbial ecosystems in HPA axis activity, stress reactivity, and brain development. In this review, we explore the evolutionary significance of the stress-axis system for health maintenance and review recent findings that connect early-life microbiome disturbances to alterations in the development of stress response networks.


2013 ◽  
Vol 368 (1618) ◽  
pp. 20120345 ◽  
Author(s):  
Daniel E. Runcie ◽  
Ralph T. Wiedmann ◽  
Elizabeth A. Archie ◽  
Jeanne Altmann ◽  
Gregory A. Wray ◽  
...  

Variation in the social environment can have profound effects on survival and reproduction in wild social mammals. However, we know little about the degree to which these effects are influenced by genetic differences among individuals, and conversely, the degree to which social environmental variation mediates genetic reaction norms. To better understand these relationships, we investigated the potential for dominance rank, social connectedness and group size to modify the effects of genetic variation on gene expression in the wild baboons of the Amboseli basin. We found evidence for a number of gene–environment interactions (GEIs) associated with variation in the social environment, encompassing social environments experienced in adulthood as well as persistent effects of early life social environment. Social connectedness, maternal dominance rank and group size all interacted with genotype to influence gene expression in at least one sex, and either in early life or in adulthood. These results suggest that social and behavioural variation, akin to other factors such as age and sex, can impact the genotype–phenotype relationship. We conclude that GEIs mediated by the social environment are important in the evolution and maintenance of individual differences in wild social mammals, including individual differences in responses to social stressors.


2015 ◽  
Vol 282 (1813) ◽  
pp. 20151167 ◽  
Author(s):  
Vérane Berger ◽  
Jean-François Lemaître ◽  
Dominique Allainé ◽  
Jean-Michel Gaillard ◽  
Aurélie Cohas

Evidence that the social environment at critical stages of life-history shapes individual trajectories is accumulating. Previous studies have identified either current or delayed effects of social environments on fitness components, but no study has yet analysed fitness consequences of social environments at different life stages simultaneously. To fill the gap, we use an extensive dataset collected during a 24-year intensive monitoring of a population of Alpine marmots ( Marmota marmota ), a long-lived social rodent. We test whether the number of helpers in early life and over the dominance tenure length has an impact on litter size at weaning, juvenile survival, longevity and lifetime reproductive success (LRS) of dominant females. Dominant females, who were born into a group containing many helpers and experiencing a high number of accumulated helpers over dominance tenure length showed an increased LRS through an increased longevity. We provide evidence that in a wild vertebrate, both early and adult social environments influence individual fitness, acting additionally and independently. These findings demonstrate that helpers have both short- and long-term effects on dominant female Alpine marmots and that the social environment at the time of birth can play a key role in shaping individual fitness in social vertebrates.


Author(s):  
James P. Herman

Appropriate control of the HPA (hypothalamo-pituitary-adrenocortical axis) is required for adaptation to physiological and environmental challenges. Inadequate control is linked to numerous stress-related pathologies, including PTSD, highlighting its importance in linking physiological stress responses with behavioral coping strategies. This chapter highlights neurocircuit mechanisms underlying HPA axis adaptation and pathology. Control of the HPA stress response is mediated by the coordinated activity of numerous limbic brain regions, including the prefrontal cortex, hippocampus, and amygdala. In general, hippocampal output inhibits anticipatory HPA axis responses, whereas amygdala subnuclei participate in stress activation. The prefrontal cortex plays an important role in inhibition of context-dependent stress responses. These regions converge on subcortical structures that relay information to paraventricular nucleus corticotropin-releasing hormone neurons, controlling the magnitude and duration of HPA axis stress responses. The output of these neural networks determines the net effect on glucocorticoid secretion, both within the normal adaptive range and in pathological circumstances.


2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Isa Kolbe ◽  
Rebecca Dumbell ◽  
Henrik Oster

Many physiological processes and most endocrine functions show fluctuations over the course of the day. These so-called circadian rhythms are governed by an endogenous network of cellular clocks and serve as an adaptation to daily and, thus, predictable changes in the organism’s environment. Circadian clocks have been described in several tissues of the stress axis and in adipose cells where they regulate the rhythmic and stimulated release of stress hormones, such as glucocorticoids, and various adipokine factors. Recent work suggests that both adipose and stress axis clock systems reciprocally influence each other and adrenal-adipose rhythms may be key players in the development and therapy of metabolic disorders. In this review, we summarize our current understanding of adrenal and adipose tissue rhythms and clocks and how they might interact to regulate energy homoeostasis and stress responses under physiological conditions. Potential chronotherapeutic strategies for the treatment of metabolic and stress disorders are discussed.


2015 ◽  
Vol 144 ◽  
pp. 116-123 ◽  
Author(s):  
R.G. Gulevich ◽  
S.G. Shikhevich ◽  
M.Yu. Konoshenko ◽  
R.V. Kozhemyakina ◽  
Yu.E. Herbeck ◽  
...  

2015 ◽  
Vol 282 (1817) ◽  
pp. 20150920 ◽  
Author(s):  
Antica Culina ◽  
Camilla A. Hinde ◽  
Ben C. Sheldon

Initial mate choice and re-mating strategies (infidelity and divorce) influence individual fitness. Both of these should be influenced by the social environment, which determines the number and availability of potential partners. While most studies looking at this relationship take a population-level approach, individual-level responses to variation in the social environment remain largely unstudied. Here, we explore carry-over effects on future mating decisions of the social environment in which the initial mating decision occurred. Using detailed data on the winter social networks of great tits, we tested whether the probability of subsequent divorce, a year later, could be predicted by measures of the social environment at the time of pairing. We found that males that had a lower proportion of female associates, and whose partner ranked lower among these, as well as inexperienced breeders, were more likely to divorce after breeding. We found no evidence that a female's social environment influenced the probability of divorce. Our findings highlight the importance of the social environment that individuals experience during initial pair formation on later pairing outcomes, and demonstrate that such effects can be delayed. Exploring these extended effects of the social environment can yield valuable insights into processes and selective pressures acting upon the mating strategies that individuals adopt.


2021 ◽  
Vol 12 ◽  
Author(s):  
Qian Liu ◽  
Jianhui Wu ◽  
Liang Zhang ◽  
Xiaofang Sun ◽  
Qing Guan ◽  
...  

Psychological factors can modulate the hypothalamic–pituitary–adrenal (HPA) axis activity toward stressors. Animal studies demonstrated that uncontrollability was one critical factor associated with HPA axis stress response, but the results in human studies were inconsistent. The current study adopted a standardized laboratory stress induction procedure, the Trier Social Stress Test (the TSST), as the stressor to regulate the objective controllability level, and young adult participants were asked to rate their subjectively perceived control level toward the stressor and measured their cortisol stress responses (N=54; 19 females and 35 males) to address this concern. Results showed that participants’ perceived control on the TSST was related to the cortisol stress response. In other words, under the stress of a certain objective controllability level, the lower the subjectively perceived control level, the greater the HPA axis response. This finding suggested that, in addition to objective controllability, subjectively perceived control is a psychological factor that regulates activation of the HPA axis in young adults.


Author(s):  
Jan Abel Olsen

This chapter explores three main issues related to the analyses of the social gradient in health: correlations, causations, and interventions. Observed correlations between indicators of socioeconomic position and health do not imply that there are causations. The usefulness of various indicators is discussed, such as education, income, occupation categories, and social class. A causal pathway is presented that suggests a chain from early life circumstances, via education, occupation, income, and perceived status onto health. The chapter ends with a discussion of various policy options to reduce inequalities in health that are caused by social determinants.


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