Sex-specific Relationship Between Maternal and Neonate Cortisol in Fallow Deer

Keskeiset käsitteet

Maternal glucocorticoid levels influence foetal glucocorticoid levels, impacting offspring phenotype, with sex-specific differences observed in fallow deer.

Tiivistelmä

The study explores the relationship between maternal and neonate cortisol levels in free-ranging fallow deer. Maternal glucocorticoid levels positively correlate with foetal cortisol levels, particularly in female offspring. Sex-specific mechanisms may optimize male growth at the expense of survival.
The research conducted in Phoenix Park, Dublin, involved collecting faecal samples from pregnant does to quantify maternal cortisol metabolites. Neonate hair samples were collected post-parturition for cortisol level analysis. Results indicated a positive association between maternal and female offspring cortisol levels but not in males.
The study suggests that male offspring may prioritize growth over survival due to evolutionary adaptations. Sex-specific placental mechanisms may regulate the transfer of maternal glucocorticoids to foetuses differently based on sex. The findings provide insights into sex-specific maternal effects on offspring phenotype.

Tilastot

Faecal samples collected from 99 pregnant does revealed a range of maternal faecal cortisol metabolite levels (91-608 ng/g).
Neonate hair cortisol levels ranged from 6.50-18.30 pg/mg, with an outlier value of 29.5 pg/mg.
Final sample size consisted of 40 fawns (18 females and 22 males) paired with their mothers.

Lainaukset

"We found that female hair cortisol was positively associated with maternal FCMs."
"Male hair cortisol levels were not associated with maternal FCMs."
"Our findings suggest that there are sex differences in the underlying evolutionary processes."

Tärkeimmät oivallukset

Sex differences in the relationship between maternal and foetal glucocorticoids in a free-ranging large mammal

by Amin,B., Fis... klo www.biorxiv.org 05-05-2023

https://www.biorxiv.org/content/10.1101/2023.05.04.538920v4

Syvällisempiä Kysymyksiä

How do sex-specific placental mechanisms influence the transfer of maternal glucocorticoids to male and female foetuses?

Sex-specific placental mechanisms play a crucial role in determining how maternal glucocorticoids are transferred to male and female foetuses. Studies have shown that there are differences in the structure and activity of the placenta between sexes, which can impact the transport of maternal hormones. For example, males may have higher expression or activity of enzymes like 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in response to maternal glucocorticoid surges. This enzyme helps inactivating cortisol to cortisone, thereby regulating the levels of active cortisol reaching the foetus.
In addition, ATP-binding cassette transporters that mediate glucocorticoid efflux towards maternal circulation may be more pronounced in male placentas compared to females. These differences suggest that males may have evolved mechanisms to limit exposure to high levels of maternal glucocorticoids during gestation, potentially prioritizing growth over survival. On the other hand, females might allow for greater transfer of these hormones due to different placental structures or activities.

Could variations in placental structure and activity explain the observed sex differences in the relationship between maternal and foetal cortisol levels?

Variations in placental structure and activity indeed offer a plausible explanation for the observed sex differences in how maternal and foetal cortisol levels relate differently between male and female offspring. The differential expression or activity of enzymes like 11β-HSD2 within the placenta can lead to varying degrees of regulation on cortisol metabolism between sexes.
For instance, if male placentas exhibit higher expression or efficiency of 11β-HSD2 compared to female placentas, this could result in more effective conversion of active cortisol into inactive cortisone before it reaches male foetuses. As a consequence, lower levels of circulating cortisol would be available for males compared to females during gestation.
Moreover, potential disparities in ATP-binding cassette transporter function could also contribute by influencing how efficiently glucocorticoids are transported across membranes within different sexes' placentas. These variations likely play a significant role in shaping sex-specific responses to maternal hormonal influences during development.

How might these findings impact conservation efforts for free-ranging large mammal populations?

The findings regarding sex-specific relationships between maternal and neonate cortisol levels provide valuable insights that can inform conservation strategies for free-ranging large mammal populations:

Population Management: Understanding how prenatal stress affects offspring differently based on their sex can help wildlife managers tailor conservation interventions more effectively.

Reproductive Success: By recognizing potential trade-offs between growth rates and survival linked with prenatal stress exposure through maternally derived hormones like glucocorticoids, conservationists can work towards promoting better reproductive outcomes.

Health Monitoring: Monitoring stress hormone levels non-invasively provides a tool for assessing population health status without direct interference with individuals.

Long-term Viability: Considering sex-specific responses when evaluating population dynamics ensures comprehensive management practices aimed at sustaining healthy genetic diversity over generations while accounting for individual variability influenced by early-life experiences.

Overall, integrating knowledge about how prenatal environments shape offspring phenotypes differently based on their sex enhances our ability to implement targeted conservation measures that support optimal reproductive success and long-term viability within free-ranging large mammal populations.