Effects and Possible Mechanisms of Dietary Bile Acids on the Liver of Spotted Sea Bass (Lateolabrax maculatus)

The application of bile acids (BA) in aquafeeds offers potential to mitigate hepatic lipid deposition caused by excessive diets. This study evaluated the effects of different quantities of dietary BA supplementation (0, 500, 1000, 1500 mg/kg) on spotted sea bass (Lateolabrax maculatus). The results showed that 500–1000 mg/kg BA supplementation enhanced growth performance (weight gain, feed conversion ratio), and reduced serum lipids (TG, TC) and liver injury markers (ALT, AST) in Lateolabrax maculatus. Hepatic lipid vacuolization was alleviated at optimal doses (500–1000 mg/kg), while excessive BA (1500 mg/kg) induced hepatocyte swelling. RNA-seq results showed that a total of 5124 differentially expressed genes (DEGs) were enriched in apelin, FoxO, PPAR signaling pathways and in fatty acid metabolism. Weighted gene co-expression analysis identified hub genes SLC25A5 and UCP1 linked to mitochondrial function and lipid oxidation. Moreover, at the transcriptional regulatory level, differential alternative splicing (DAS) analysis further inferred that bile acids could effectively alleviate fat accumulation in the liver through the aforementioned pathways. These findings elucidate BAs’ role in mitigating hepatic lipid accumulation via transcription and splicing-mediated metabolic modulation and provide new insight to the balances between BA supplementation and liver health of spotted sea bass.