Elevated maternal corticosterone alters offspring development, physiology, and behavior in quail
Within the last decade, a large body of literature has accumulated documenting the deposition of maternal androgens into egg yolk and their consequences for offspring. However, little is known about the transfer of maternal glucocorticoids into yolk and their effects on offspring. Here I show that high plasma corticosterone in a laying bird corresponds to high corticosterone in the yolk of her eggs. I then demonstrate that elevated yolk corticosterone has a range of effects on offspring development and adult phenotype.Female quail from selected for heightened plasma corticosterone response to capture and restraint lay eggs with higher yolk corticosterone than quail selected for a low plasma corticosterone response. This difference in yolk corticosterone concentration is particularly interesting given that baseline corticosterone levels do not differ between the two lines.Experimentally elevating plasma corticosterone in laying quail increased corticosterone concentration in the yolk of their eggs. Chicks that hatched from eggs laid by females implanted with corticosterone grew more slowly than controls, and showed higher plasma corticosterone response to capture and restraint as adults.To determine whether the effects of elevated maternal corticosterone were mediated by transfer of the steroid itself to yolk, yolk corticosterone concentration was manipulated directly. Male, but not female, chicks that hatched from eggs injected with corticosterone grew more slowly than controls, and female, but not male, offspring showed a decreased corticosterone response as adults.Finally, eggs were injected with corticosterone and chick performance in a maze, and adult expression of anxiety behavior were quantified to investigate the effects of elevated yolk corticosterone on cognitive ability and behavior. Chicks from eggs injected with corticosterone completed the maze faster than controls on the first trial. However, control chicks improved in their second trial to become as fast at completing the maze as the corticosterone chicks. There was no effect of corticosterone treatment on anxiety behavior in adults.Thus, I show that high maternal corticosterone is transferred to avian egg yolk and that it has lasting effects on offspring development and adult phenotype. Future studies are needed to understand the role of maternal corticosterone in yolk within an ecological context.
- Biology