Meeting Abstract
Stress exposure affects many aspects of host physiology, and increases in glucocorticoid stress hormones may affect the gut microbiota. Previous studies have shown connections between stress hormones and the gut microbiome, but have only used correlation in the wild or single treatments of stress hormones. Here, we tested whether the gut microbiome responds to the stress hormone corticosterone (CORT) in a dose-dependent manner. Twenty captive European Starlings were randomly divided into four groups (n = 5): Control group (Con, placebo), low-level CORT group (LC, 0.25mg), middle-level CORT group (MC, 1.5mg), high-level CORT group (HC, 7.5mg). Feces were collected before implantation, and 2, 7, 21, 27 days after implantation to understand the temporal changes associated with stress hormones. CORT implantation changed the composition and structure of gut microbiota in birds. We found that birds implanted with the low-level concentration of CORT had increased alpha diversity at the 2 and 7 day (ASV richness and Shannon index). Birds in HC groups exhibited the most distinct microbial communities compared to their starting point, though this effect disappeared within 21 days (unweighted and weighted UniFrac distances). At the phylum level, CORT treatment caused an increase in the abundance of Firmicutes and decrease in Cyanobacteria. These changes were temporary, as the abundances of bacteria partially recovered. Our findings clearly demonstrate a close link between glucocorticoid levels and gut microbiota in captive birds. Furthermore, we demonstrate that the gut microbiome responds to CORT in a dose-dependent manner, and so variation in environmental stress may have variable effects on the gut microbiome in natural populations.
