Identification of Senkyunolide I as a novel modulator of hepatic steatosis and PPARα signaling in zebrafish and hamster models.

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of liver-related morbidity and mortality, with hepatic steatosis being the hallmark symptom. Salvia miltiorrhiza Bunge (Smil, Dan-Shen) and Ligusticum striatum DC (Lstr, Chuan-Xiong) are commonly used to treat cardiovascular diseases and have the potential to regulate lipid metabolism. However, whether Smil/Lstr combo can be used to treat NAFLD and the mechanisms underlying its lipid-regulating properties remain unclear.

PURPOSE

To assess the feasibility and reliability of a short-term high-fat diet (HFD) induced zebrafish model for evaluating hepatic steatosis phenotype and to investigate the liver lipid-lowering effects of Smil/Lstr, as well as its active components.

METHODS

The phenotypic alterations of liver and multiple other organ systems were examined in the HFD zebrafish model using fluorescence imaging and histochemistry. The liver-specific lipid-lowering effects of Smil/Lstr combo were evaluated endogenously. The active molecules and functional mechanisms were further explored in zebrafish, human hepatocytes, and hamster models.

RESULTS

In 5-day HFD zebrafish, significant lipid accumulation was detected in the blood vessels and the liver, as evidenced by increased staining with Oil Red O and fluorescent lipid probes. Hepatic hypertrophy was observed in the model, along with macrovesicular steatosis. Smil/Lstr combo administration effectively restored the lipid profile and alleviated hepatic hypertrophy in the HFD zebrafish. In oleic-acid stimulated hepatocytes, Smil/Lstr combo markedly reduced lipid accumulation and cell damage. Subsequently, based on zebrafish phenotypic screening, the natural phthalide senkyunolide I (SEI) was identified as a major molecule mediating the lipid-lowering activities of Smil/Lstr combo in the liver. Moreover, SEI upregulated the expression of the lipid metabolism regulator PPARα and downregulated fatty acid translocase CD36, while a PPARα antagonist sufficiently blocked the regulatory effect of SEI on hepatic steatosis. Finally, the roles of SEI on hepatic lipid accumulation and PPARα signaling were further verified in the hamster model.

CONCLUSIONS

We proposed a zebrafish-based screening strategy for modulators of hepatic steatosis and discovered the regulatory roles of Smil/Lstr combo and its component SEI on liver lipid accumulation and PPARα signaling, suggesting their potential value as novel candidates for NAFLD treatment.