Dietary sea buckthorn polysaccharide reduced lipid accumulation, alleviated inflammation and oxidative stress, and normalized imbalance of intestinal microbiota that was induced by high-fat diet in zebrafish Danio rerio.

The purpose of this study was to explore the beneficial effects of sea buckthorn polysaccharide (SP) on lipid metabolism, liver, and intestinal health in zebrafish fed with high-fat diet (HFD). The zebrafish were fed with regular diet (RD), HFD, and HFD supplemented with 2 g/kg (HFD_2SP) and 4 g/kg (HFD_4SP) of SP, respectively. Growth, serum biochemistry, histopathology, expression of genes involved in lipid metabolism, inflammation, oxidative stress and tight junction, and changes in intestinal microbiota were detected. Results showed that adding 2 and 4 g/kg of SP in the HFD significantly improved the survival rate of zebrafish; reduced the levels of serum triglyceride (TG), total cholesterol (TC), aspartate aminotransferase (AST), and alanine transaminase (ALT); and alleviated the lipid accumulation in the liver of zebrafish. Furthermore, SP significantly enhanced the antioxidant capacity of liver and intestine by up-regulating the expression of Nrf2 and Cu/Zn-SOD and alleviated liver and intestinal inflammation induced by HFD through up-regulating the expression of TGF-β1 and suppressing the expression of P38MAPK, IL-8, and IL-1β. Especially, dietary SP normalized intestinal microbiota imbalance caused by HFD and inhibited the proliferation of harmful bacteria, i.e., Mycobacterium, but promoted the proliferation of intestinal beneficial bacteria, i.e., Cetobacterium. In summary, 2 and 4 g/kg of dietary SP significantly reduced lipid accumulation, alleviated inflammation and oxidative stress, and normalized the imbalance of intestinal microbiota induced by HFD and consequently improved the survival rate of zebrafish.