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Abstract Enhanced production of dehydroepiandrosterone (DHEA) by the foetal hypothalamic‐pituitary‐adrenal (HPA) axis enables maturational events critical for labour induction and neonatal adaptation. Despite knowledge of the interconnected nature of maternal and foetal physiology and dramatic changes in DHEA production after birth, few studies have examined DHEA levels in newborns and none have examined DHEA’s response to acute stress. Understanding normative patterns of early DHEA activity is needed to accurately assess functioning of the biological stress system with relevance for health and development. The present study analysed DHEA concentrations and change after stress among 93 newborns and associations with pregnancy, delivery and demographic risk factors. Three saliva samples, collected prior to and following a blood draw stressor, were used to determine baseline and stress reactive DHEA levels. Mothers self‐reported on health behaviours during pregnancy. Data on obstetric factors were obtained from medical records. DHEA levels declined from pre‐ to post‐stressor assessments. Results also showed that post‐stressor DHEA change was significantly associated with administration of medications used to treat pain and accelerate labour. However, there was no significant variation in DHEA pre‐stress levels or change after stress as a function of time after birth. By capturing DHEA levels after birth, the present study provides a window into prenatal health of the HPA system. The study also advances knowledge of DHEA in newborns by providing data on reference levels and important covariates. This information on basic adrenal physiology provides a foundation that can be expanded on to enhance understanding of early hypothalamic‐pituitary‐adrenal axis activity.
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Maternal glucocorticoids have minimal effects on HPA axis activity and behavior of juvenile wild North American red squirrels
ABSTRACT As a response to environmental cues, maternal glucocorticoids (GCs) may trigger adaptive developmental plasticity in the physiology and behavior of offspring. In North American red squirrels (Tamiasciurus hudsonicus), mothers exhibit increased GCs when conspecific density is elevated, and selection favors more aggressive and perhaps more active mothers under these conditions. We tested the hypothesis that elevated maternal GCs cause shifts in offspring behavior that may prepare them for high-density conditions. We experimentally elevated maternal GCs during gestation or early lactation. We measured two behavioral traits (activity and aggression) in weaned offspring using standardized behavioral assays. Because maternal GCs may influence offspring hypothalamic–pituitary–adrenal (HPA) axis dynamics, which may in turn affect behavior, we also measured the impact of our treatments on offspring HPA axis dynamics (adrenal reactivity and negative feedback), and the association between offspring HPA axis dynamics and behavior. Increased maternal GCs during lactation, but not gestation, slightly elevated activity levels in offspring. Offspring aggression and adrenal reactivity did not differ between treatment groups. Male, but not female, offspring from mothers treated with GCs during pregnancy exhibited stronger negative feedback compared with those from control mothers, but there were no differences in negative feedback between lactation treatment groups. Offspring with higher adrenal reactivity from mothers treated during pregnancy (both controls and GC-treated) exhibited lower aggression and activity. These results suggest that maternal GCs during gestation or early lactation alone may not be a sufficient cue to produce substantial changes in behavioral and physiological stress responses in offspring in natural populations.
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- Award ID(s):
- 1749627
- PAR ID:
- 10327896
- Date Published:
- Journal Name:
- Journal of Experimental Biology
- Volume:
- 224
- Issue:
- 10
- ISSN:
- 0022-0949
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1242/jeb.236620
