The influence of chronic cadmium exposure on the activity of adult Pelophylax nigromaculatus revealed by brain transcriptomics and metabolomics.

Cadmium (Cd), a common environmental pollutant, has potentially negative effects on the behavior of aquatic animals. This study investigated the effects of exposure to Cd (0 mg/L, 1 mg/L and 10 mg/L) on movement behavior, brain metabolites, and brain gene expression of adult Pelophylax nigromaculatus. Treatments with 1 mg/L and 10 mg/L Cd resulted in a significant increase in movement frequency, movement time, average speed of movement, and movement distance. It was evident that Cd treatments had a significant impact on brain metabolic pathways, including the purine metabolism, glycerophospholipid metabolism and the mTOR signaling pathway. Cd treatments significantly altered the relative abundance of brain metabolites, including phosphatidylserine, phosphatidylethanolamine and adenosine monophosphate. In addition, Cd treatments altered the KEGG pathways, including the TNF signaling, IL-17 signaling and tuberculosis, as well as the gene expression of PI3K and AKt. The results indicated that heavy metal pollutants could affect the brain metabolism and transcription in amphibians of amphibians, leading to active movement behaviors.