Alterations in Lipid Metabolism and Hepatopancreatic Lipidomics Induced by Microcystin-LR Exposure in Common Carp (Cyprinus carpio)

Microcystin-LR (MC-LR) is a hepatotoxin produced by toxic cyanobacteria such as <i>Microcystis aeruginosa</i> and it poses significant risks to aquatic organisms and human health. However, research on the long-term effects of environmental MC-LR exposure on lipid metabolism in fish is relatively scarce. This research investigates the effects and underlying mechanisms of chronic (one month) low-dose (3.5 μg/kg) MC-LR exposure in common carp (<i>Cyprinus carpio</i>) by using biochemical assays, histopathology, molecular analyses, and lipidomics. In this study, MC-LR exposure significantly altered serum enzyme activities and lipid profiles, induced hepatic inflammation and lipid accumulation, and disrupted hepatopancreatic structure. Meanwhile, key regulators of lipogenesis, fatty acid β-oxidation, and cholesterol metabolism were dysregulated, indicating enhanced lipid synthesis and impaired catabolism. Elevated oxidative stress and pro-inflammatory cytokines likely contributed to lipid metabolic disturbances, exacerbating the hepatotoxicity of MC-LR. Lipidomics profiling revealed significant disruptions in glycerophospholipids, glycerolipids, and sphingolipids, highlighting impaired lipid homeostasis. This study provides novel insights into the hepatic lipid metabolic disorders induced by MC-LR in fish.