Black rice bran improved lipid metabolism in hyperlipidemia mice via steroid hormone biosynthesis and PPAR signaling pathway

This study was aimed to explore the alleviating effect of black rice (BR), black peeled rice (BPR), and black rice bran (BRB) on lipid metabolism disorders in hyperlipidemia mice caused by high fat and cholesterol diet (HFCD). Combined untargeted metabolomics and RNA-seq transcriptomics analysis was used to demonstrate the potential mechanism regulated by BR, BPR and BRB. The untargeted metabolomics analysis indicated that BR especially BRB significantly increased Deoxycholic acid, 5-Dehydroavenasterol, scyllo-Inositol, Phloretin, 5-KETE, Lipoxin B4, 3,4-Dihydroxybenzeneacetic acid levels, while BRB significantly regulated PPAR signaling pathway, Arachidonic acid metabolism, Regulation of lipolysis in adipocytes, Steroid biosynthesis, and Sphingolipid signaling pathway, which closely linked to lipid metabolism. Furthermore, RNA-seq transcriptomics analysis showed that BRB obviously regulated Steroid hormone biosynthesis (Cyp2b9, Cyp2b13 and Cyp2c38) and PPAR signaling pathway (Pparg, Fabp4, Cd36 and Plin4), which were closely associated with inflammation and lipid metabolism. Moreover, quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) analysis validated this. The obtaining results were hoping to reveal the detailed mechanism of BRB in alleviating hyperlipidemia and provide some insights for developing a new kind of natural anti-hyperlipidemia drug.