Abstract: This study aims to evaluate the effects of astaxanthin on lipid metabolism in HepG2 cells treated with oleic acid and in C57BL/6J mice fed with a high-fat diet. A HepG2 cell model of oleic acid-induced steatosis in vitro was established. Furthermore, cellular lipid accumulation was determined using Oil red O staining assay and cholesterol (TC), triglyceride (TG) contents were determined in the normal, model and astaxanthin treatment groups. Serum total TC, TG and high-density-lipoprotein-cholesterol (HDL-C) of mice in the normal diet, high-fat and astaxanthin intervention groups were detected as well. Liver histomorphology was observed by hematoxylin and eosin (HE) staining. The mRNA expression levels of the genes related to lipid regulation were determined using quantitative real-time polymerase chain reaction (qRT-PCR). The fecal excretion of short chain fatty acids was detected by gas chromatography (GC). Astaxanthin could significantly alleviate oleic acid-induced steatosis in HepG2 cells, and cellular TC and TG contents decreased significantly in the astaxanthin intervention group compared with the model group (P < 0.05). Furthermore, the SREBP-1C and FAS mRNA expression levels were significantly down-regulated in the astaxanthin intervention group, the degree of steatosis in the astaxanthin intervention group was significantly decreased and the content of total short-chain fatty acids increased significantly, and serum TG and TC levels decreased significantly relative to those in the high-fat diet group (P < 0.05). Therefore, Astaxanthin can regulate lipid metabolism by reducing the content of lipid droplets in HepG2 cells, and by regulating blood lipid levels, increasing the content of short-chain fatty acids in feces, improving liver pathology, and regulating the expression of the genes related to lipid synthesis in the liver of mice.

Key words: high-fat diet; astaxanthin; gene expression; short-chain fatty acids; HepG2 cells