Seasonal Plasticity in Tryptophan Metabolism Provides New Insights Into Physiological Adaptation in Snake Hibernation

Hibernation is a common behavioral strategy for snakes to cope with extreme environments. This phenomenon has raised important scientific questions regarding its physiological adaptation mechanisms. Although tryptophan and its metabolites have been widel y studied for their roles in various physiological processes in animals-including immune regulation, metabolic homeostasis, and circadian rhythms-the impact of snake hibernation on tryptophan metabolism remains unexplored. In the present study, an integrated multi-omics approach that combines targeted metabolomics, transcriptomics, and microbiome was used to reveal the tryptophan metabolism mechanisms in active and hibernating snakes. Our results revealed that the higher gut indole concentrations observed in active snakes indicate a greater reliance on microbial pathways in their tryptophan metabolism. Correlation analyses between gut microbiota and indole levels further identified specific bacterial genera-Paeniclostridium, Romboutsia, and Clostridium sensu stricto 1-as potential key contributors to tryptophan conversion into indole. Additionally, the higher serum concentrations of metabolites such as kynurenic acid and 5-hydroxytryptophol, along with the upregulated expression of key genes, indicate that hibernating snakes exhibit an increased reliance on the kynurenine and 5-hydroxytryptamine pathways for tryptophan metabolism. These findings collectively suggested that the seasonal plasticity of tryptophan metabolism may mediate physiological adaptations during snake hibernation, thereby providing deeper cognition into the mechanisms underlying reptilian hibernation strategies.