Transcriptomic analysis of hydrogen peroxide-induced liver dysfunction in Cyprinus carpio: Insights into protein synthesis and metabolism

Hydrogen peroxide (H2O2), a prevalent reactive oxygen species (ROS) found in natural aquatic environments, has garnered significant attention for its potential toxicity in fish. However, the molecular mechanisms underlying this toxicity are not yet comprehensively understood. This study aimed to assess H2O2-induced liver dysfunction in common carp (Cyprinus carpio) and elucidate the underlying molecular mechanisms via biochemical and transcriptomic analyses. Common carp were divided into normal control (NC) and H2O2-treated groups (1 mM H2O2), the latter of which was exposed to H2O2 for 1 h per day over a period of 14 days. Serum biochemical analyses indicated that exposure to H2O2 resulted in moderate liver damage, characterized by elevated alanine aminotransferase (ALT) activity and lowered albumin (Alb) level. Concurrently, H2O2 exposure induced oxidative stress and modified the hepatic metabolic enzyme levels. Transcriptome analysis highlighted that 1358 and 1188 genes were significantly downregulated and upregulated, respectively, in the H2O2-treated group. These differentially expressed genes (DEGs) were significantly enriched in protein synthesis and a variety of metabolic functions such as peptide biosynthetic processes, protein transport, ribonucleoprotein complex biogenesis, oxoacid metabolic processes, and tricarboxylic acid metabolic processes. Dysregulation of protein synthesis is principally associated with the downregulation of three specific pathways: ribosome biogenesis, protein export, and protein processing in the endoplasmic reticulum (ER). Furthermore, metabolic abnormalities were primarily characterized by inhibition of the citrate cycle (TCA) and fatty acid biosynthesis. Significantly, anomalies in both protein synthesis and metabolic function may be linked to aberrant regulation of the insulin signaling pathway. These findings offer innovative insights into the mechanisms underlying H2O2 toxicity in aquatic animals, contributing to the assessment of ecological risks.