Mechanism of MWCNTs induced hepatotoxicity in Cyprinus carpio: New perspective from a Lipidomic study.

Carbon nanotubes (CNTs), an extensively applied nanomaterial, can cause damage to the liver in fish. However, the underlying lipotoxic modes of CNTs exposure have not been studied. In the present study, juvenile Cyprinus carpio was exposed via water to various doses of multi-walled CNTs (MWCNTs) (0, 0.25, and 2.5 mg L-1) for a consecutive 28-day period. Our results showed elevated hepatosomatic index (HSI) and aspartate aminotransferase (AST) activities in plasma in all exposure groups, indicating that MWCNTs exposure induced liver dysfunction. Significantly increased low-density lipoprotein (LDL) and total cholesterol (CHO) levels along with significantly decreased triglyceride (TG) levels were observed in fish of HSC (2.5 mg L-1 MWCNTs), indicating abnormal lipid metabolism. Subsequently, the livers of fish in the HSC group were harvested for LC-MS/MS-based targeted lipidomic analysis. Changes in the lipid profiles showed 87 and 92 lipids significant up-regulated and down-regulated, respectively. These significantly altered lipids were classed into 20 lipid classes. Among them, Cer, Hex1Cer, CerG2GNAc1, SM, SPH, and phSM belong to sphingolipid. Taken together with our previous findings, these results suggested that the dysregulation of sphingolipid metabolism may be associated with oxidative stress and apoptosis induced by MWCNTs exposure in C. carpio. This study provides new insights into the potential mechanism of MWCNTs in fish, especially from the aspect of lipid metabolism.