Climate variability and life history impact stress, thyroid, and immune markers in California sea lions (Zalophus californianus) during El Niño conditions

DeRango, Eugene J.; Prager, Katherine C.; Greig, Denise J.; Hooper, Amanda W; Crocker, Daniel E.

doi:10.1093/conphys/coz010

Cited by 14 publications

(17 citation statements)

References 90 publications

(109 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We found no association between gene expression and aldosterone in this study. Aldosterone, a secretagogue of ACTH, was one of the most significantly altered hormones in the repeated ACTH administration experiment ( McCormley et al , 2018 ) and has been shown to be elevated in response to external stressors in several marine mammal species besides elephant seals ( Champagne et al , 2018 , DeRango et al , 2019a , DeRango et al , 2019b ). Aldosterone is primarily known for its osmoregulatory and vascular functions, but recent studies have suggested that it may have additional roles in adipogenesis and insulin sensitivity ( Marzolla et al , 2012 ).…”

Section: Discussionmentioning

confidence: 99%

“…Commonly used markers, such as circulating GCs, are extremely variable and do not fully capture the complexity of the physiological response ( MacDougall-Shackleton et al , 2019 , Romero et al , 2019). For example, marine mammal responses to various stressors can be associated with significant elevation of the mineralocorticoid aldosterone and decrease in thyroid hormone levels ( Champagne et al , 2018 , DeRango et al , 2019a , DeRango et al , 2019b , McCormley et al , 2018 , St Aubin et al , 1992 ). Furthermore, circulating hormone measurements are not practical for many marine mammal species because they are difficult to access for blood sampling (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A blubber gene expression index for evaluating stress in marine mammals

Busqueta

Crocker

Champagne

et al. 2020

Conservation Physiology

Self Cite

View full text Add to dashboard Cite

Evaluating the impacts of anthropogenic disturbance on free-ranging marine mammal populations, many of which are in decline, requires robust diagnostic markers of physiological stress and health. However, circulating levels of canonical ‘stress hormones’ such as glucocorticoids, which are commonly used to evaluate animal health, do not capture the complexity of species-specific responses and cannot be easily measured in large, fully aquatic marine mammals. Alternatively, expression of stress-responsive genes in hormone target tissues such as blubber, the specialized subcutaneous adipose tissue that can be manually or remotely sampled from many marine mammals, may be a more informative and sensitive indicator of recent (within 24 h) exposure to stressors. We previously identified genes that were upregulated in the inner blubber of juvenile northern elephant seals during experimental stimulation of the hypothalamic–pituitary–adrenal axis. In this study, we measured baseline expression levels of a subset of these genes in inner blubber of unmanipulated juvenile elephant seals of varying physiological states and correlated them with other stress markers (body condition index, corticosteroid and thyroid hormone levels). Expression of 10 genes, including those associated with lipid metabolism (ACSL1, HMGCS2, CDO1), redox homeostasis (GPX3), adipokine signaling (ADIPOQ), lipid droplet formation (PLIN1, CIDEA) and adipogenesis (DKK1, AZGP1, TGFBI), was described by three principal components and was associated with cortisol and thyroid hormone levels. Significantly, baseline gene expression levels were predictive of circulating hormone levels, suggesting that these markers may be potential indicators of exposure to stressors in marine mammal species that are inaccessible for blood sampling. A similar approach may be used to identify species-specific stress markers in other tissues that can be sampled by remote biopsy dart from free-ranging marine mammals, such as outer blubber and skin.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A blubber gene expression index for evaluating stress in marine mammals

Busqueta

Crocker

Champagne

et al. 2020

Conservation Physiology

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, mothers were captured only twice during the season, whereas pups were captured on average five times, so we would expect to observe greater habituation in pups than mothers. Alternatively, exposure to chronic stress has been shown to downregulate cortisol responses to an acute stressor (Rich and Romero 2005;DeRango et al 2019). Maternal provisioning is costly, with offspring survival and growth often being traded off against parental condition (Smiseth et al 2013).…”

Section: Cortisol Responsivenessmentioning

confidence: 99%

Low heritability and high phenotypic plasticity of salivary cortisol in response to environmental heterogeneity in a wild pinniped

Nagel

Kaiser

Stainfield

et al. 2021

Preprint

View full text Add to dashboard Cite

Individuals are unique in how they interact with and respond to their environment. Correspondingly, unpredictable challenges or stressors often produce an individualized response of the hypothalamic-pituitary-adrenal axis and its downstream effector cortisol. We used a fully crossed, repeated measures design to investigate the factors shaping individual variation in baseline cortisol and cortisol responsiveness in Antarctic fur seal pups and their mothers. Saliva samples were collected from focal individuals at two breeding colonies, one with low and the other with high population density, during two consecutive years of contrasting food availability. Mothers and pups were sampled concurrently at birth and shortly before weaning, while pups were additionally sampled every 20 days. We found that heritability was low for both baseline cortisol and cortisol responsiveness, while within-individual repeatability and among-individual variability were high. A substantial proportion of the variation in baseline cortisol could be explained in pups and mothers by a combination of intrinsic and extrinsic factors including sex, weight, day, season, and colony of birth. However, the same variables explained little of the variation in cortisol responsiveness. Our findings provide detailed insights into the individualization of endocrine phenotypes in a wild pinniped.

show abstract

“…Research suggests that extreme temperatures, infections, resource scarcity, as well as psychological or social stresses, alter the thyroid function in humans and other animals. For example, thyroid hormones are upregulated in male California sea lions during the breeding season, enhancing energetic investment into costly reproductive behaviour [ 99 ], whereas by contrast, fasting reduces T4 levels in juvenile Northern Elephant Seals [ 100 ]. Although the HPT axis is stimulated by some (anticipated) acute energy-demanding situations including cold or exercise, bodily states of overall negative energy balance such as chronic stress, inflammation, or fasting, suppress the HPT axis ’ activity [ 39 , 101 ].…”

Section: Introductionmentioning

confidence: 99%

Reinterpreting patterns of variation in human thyroid function

Keestra

Tabor²,

Alvergne

2020

Evolution, Medicine, and Public Health

View full text Add to dashboard Cite

Two hundred million people worldwide experience some form of thyroid disorder, with women being especially at risk. However, why human thyroid function varies between populations, individuals and across the lifespan has attracted little research to date. This limits our ability to evaluate the conditions under which patterns of variation in thyroid function are best understood as ‘normal’ or ‘pathological’. In this review, we aim to spark interest in research aimed at understanding the causes of variation in thyroid phenotypes. We start by assessing the biomedical literature on thyroid imbalance to discuss the validity of existing reference intervals for diagnosis and treatment across individuals and populations. We then propose an evolutionary ecological framework for understanding the phylogenetic, genetic, ecological, developmental and physiological causes of normal variation in thyroid function. We build on this approach to suggest testable predictions for how environmental challenges interact with individual circumstances to influence the onset of thyroid disorders. We propose that dietary changes, ecological disruptions of co-evolutionary processes during pregnancy and with pathogens, emerging infections and exacerbated stress responses can contribute to explaining the onset of thyroid diseases. For patients to receive the best personalised care, research into the causes of thyroid variation at multiple levels is needed.

show abstract

Climate variability and life history impact stress, thyroid, and immune markers in California sea lions (Zalophus californianus) during El Niño conditions

Cited by 14 publications

References 90 publications

A blubber gene expression index for evaluating stress in marine mammals

A blubber gene expression index for evaluating stress in marine mammals

Low heritability and high phenotypic plasticity of salivary cortisol in response to environmental heterogeneity in a wild pinniped

Reinterpreting patterns of variation in human thyroid function

Contact Info

Product

Resources

About