The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in enabling organisms to respond to environmental challenges. In vertebrates, programming of the responsiveness of an individual’s HPA axis occurs during development, where early exposure to stressors can determine an individual’s responses to future environmental stress. This research aims to explore the mechanisms by which early developmental conditions translate into changes in the HPA axis.
Epigenetic mediation of the HPA axis
Epigenetic modifications occur during development, can be influenced by early life experiences and environment, and can persist throughout life, providing heritable variation in gene expression. They are therefore likely candidates for mediating development of the stress response. By manipulating both pre-natal maternal stress and post-natal environmental stress in a combined study, this research aims to determine how these life history stage stressors individually and synergistically impact epigenetic regulation throughout the HPA axis, and subsequently program the offspring stress response in an altricial avian species.
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Maternal hormonal effects on offspring development
Maternal effects, particularly maternal hormonal exposure, can shape an offspring's development and produce long-lasting effects on an offspring’s brain and behavior. Because bird embryos develop in eggs outside of the mother’s body, eggs present the potential for a deeper understanding of the mechanistic relationships between maternal hormones and offspring. The aim of this research is to gain a better understanding of the transmission, regulation, and impact of stress hormones (glucocorticoids) passed between mothers and offspring via the egg.
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Blood as a biomarker for the brain
Understanding the mechanisms involved in how stress impacts HPA axis reactivity in the early developmental environment requires assessing changes in parts of the brain, specifically the hypothalamus and hippocampus. However, this means euthanizing the organism, which eliminates the potential for long-term study. This research aims to determine if blood can be used a quantitative or qualitative biomarker, or molecular signature, to study inaccessible tissues of interest.
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