Distinct responses from triglyceride and cholesterol metabolism in common carp (Cyprinus carpio) upon environmental cadmium exposure

Mechanisms insights into bisphenol S-induced oxidative stress, lipid metabolism disruption, and autophagy dysfunction in freshwater crayfish

Bisphenol S (BPS) is widely used in plastic products, food packaging, electronic products, and other applications. In recent years, BPS emissions have increasingly impacted aquatic ecosystems. The effects of BPS exposure on aquatic animal health have been documented; however, our understanding of its toxicology remains limited. This study aimed to explore the mechanisms of lipid metabolism disorders, oxidative stress, and autophagy dysfunction induced in freshwater crayfish (Procambarus clarkii) by exposure to different concentrations of BPS (0 µg/L, 1 µg/L, 10 µg/L, and 100 µg/L) over 14 d. The results indicated that BPS exposure led to oxidative stress by inducing elevated levels of reactive oxygen species (ROS) and inhibiting the activity of antioxidant-related enzymes. Additionally, BPS exposure led to increased lipid content in the serum and hepatopancreas, which was associated with elevated lipid-related enzyme activity and increased expression of related genes. Furthermore, BPS exposure decreased levels of phosphatidylcholine (PC) and phosphatidylinositol (PI), disrupted glycerophospholipid (GPI) metabolism, and caused lipid deposition in the hepatopancreatic. These phenomena may have occurred because BPS exposure reduced the transport of fatty acids and led to hepatopancreatic lipid deposition by inhibiting the transport and synthesis of PC and PI in the hepatopancreas, thereby inhibiting the PI3K-AMPK pathway. In conclusion, BPS exposure induced oxidative stress, promoted lipid accumulation, and led to autophagy dysfunction in the hepatopancreas of freshwater crayfish. Collectively, our findings provide the first evidence that environmentally relevant levels of BPS exposure can induce hepatopancreatic lipid deposition through multiple pathways, raising concerns about the potential population-level harm of BPS and other bisphenol analogues.

Environmental cadmium exposure perturbs systemic iron homeostasis via hemolysis and inflammation, leading to hepatic ferroptosis in common carp (Cyprinus carpio L.)

Cadmium (Cd) pollution is considered a pressing challenge to eco-environment and public health worldwide. Although it has been well-documented that Cd exhibits various adverse effects on aquatic animals, it is still largely unknown whether and how Cd at environmentally relevant concentrations affects iron metabolism. Here, we studied the effects of environmental Cd exposure (5 and 50 μg/L) on iron homeostasis and possible mechanisms in common carp. The data revealed that Cd elevated serum iron, transferrin saturation and iron deposition in livers and spleens, leading to the disruption of systemic iron homeostasis. Mechanistic investigations substantiated that Cd drove hemolysis by compromising the osmotic fragility and inducing defective morphology of erythrocytes. Cd concurrently exacerbated hepatic inflammatory responses, resulting in the activation of IL6-Stat3 signaling and subsequent hepcidin transcription. Notably, Cd elicited ferroptosis through increased iron burden and oxidative stress in livers. Taken together, our findings provide evidence and mechanistic insight that environmental Cd exposure could undermine iron homeostasis via erythrotoxicity and hepatotoxicity. Further investigation and ecological risk assessment of Cd and other pollutants on metabolism-related effects is warranted, especially under the realistic exposure scenarios.

Role of Mitochondrial Reactive Oxygen Species-Mediated Chaperone-Mediated Autophagy and Lipophagy in Baicalin and N-Acetylcysteine Mitigation of Cadmium-Induced Lipid Accumulation in Liver

Cadmium (Cd) is a major health concern globally and can accumulate and cause damage in the liver for which there is no approved treatment. Baicalin and N-acetylcysteine (NAC) have been found to have protective effects against a variety of liver injuries, but it is not clear whether their combined use is effective in preventing and treating Cd-induced lipid accumulation. The study found that Cd increased the production of mitochondrial reactive oxygen species (mROS) and elevated the level of chaperone-mediated autophagy (CMA). Interestingly, mROS-mediated CMA exacerbates the Cd-induced inhibition of lipophagy. Baicalin and NAC counteracted inhibition of lipophagy by attenuating Cd-induced CMA, suggesting an interplay between CMA elevation, mitochondrial destruction, and mROS formation. Maintaining the stability of mitochondrial structure and function is essential for alleviating Cd-induced lipid accumulation in the liver. Choline is an essential component of the mitochondrial membrane and is responsible for maintaining its structure and function. Mitochondrial transcriptional factor A (TFAM) is involved in mitochondrial DNA transcriptional activation and replication. Our study revealed that the combination of baicalin and NAC can regulate choline metabolism through TFAM and thereby maintain mitochondrial structure and functionality. In summary, the combination of baicalin and NAC plays a more beneficial role in alleviating Cd-induced lipid accumulation than the drug alone, and the combination of baicalin and NAC can stabilize mitochondrial structure and function and inhibit mROS-mediated CMA through TFAM-choline, thereby promoting lipophagy to alleviate Cd-induced lipid accumulation.

Effects of stocking density on the growth performance, mitophagy, endocytosis and metabolism of Cherax quadricarinatus in integrated rice-crayfish farming systems

Red claw crayfish (Cherax quadricarinatus) is an economic freshwater shrimp with great commercial potential. However, the suitable stocking density of C. quadricarinatus is still unclear in integrated rice-crayfish farming system. Thus, this study aimed to investigate the effects of stocking density on growth performance, mitophagy, endocytosis and metabolism of C. quadricarinatus. The C. quadricarinatus was reared at low density (LD, 35.73 g/m²), middle density (MD, 71.46 g/m²) and high density (HD, 107.19 g/m²) in an integrated rice-crayfish farming system. After 90 days of farming, the growth performance of C. quadricarinatus significantly decreased in the MD and HD groups relative to that in the LD group. The HD treatment caused oxidative stress and lipid peroxidation at the end of the experiment in hepatopancreas. Transcriptome analysis showed that there were 1,531 DEGs (differently expressed genes) between the LD group and HD group, including 1,028 upregulated genes and 503 downregulated genes. KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis indicated that the DEGs were significantly enriched in endocytosis and mitophagy pathways. Meanwhile, four lipid metabolism pathways, including biosynthesis of unsaturated fatty acids, fatty acid biosynthesis, glycerolipid metabolism and glycerophospholipid metabolism, exhibited an upregulated tendency in the HD group. In conclusion, our data showed that when the stocking density reached up to 207.15 g/m² in HD group, the growth performance of C. quadricarinatus was significantly inhibited in this system. Meanwhile, the data indicated that C. quadricarinatus may respond to the stressful condition via activating antioxidant defense system, endocytosis, mitophagy and metabolism-related pathways in hepatopancreas.