Effects And Mechanisms Of Sea Buckthorn Pomace On Browning Of White Adipocytes In Lambs

Sea Buckthorn（Hippophae rhamnoides L.）is rich in isoflavones and flavonoids bioactive substances with antioxidant,anti-inflammatory,wound healing and lowering blood lipids.At the same time,because of the high content of antioxidant substances in the plant.Sea buckthorn seed oil,berries,leaves and bark are known for their medicinal properties.Adipose tissue includes white fat,beige fat and brown fat.White adipose tissue（WAT）mainly stores lipids,whereas beige fat cells are present in WAT,consuming energy in the form of calories similar to brown fat,and have the effect of resisting metabolic diseases and obesity.Model animal studies showed that sea buckthorn can improve blood sugar,hypotriglyceridemia and antioxidant effects in diabetic rats,and can prevent hyperlipidemia and oxidative stress-related diabetic complications.In addition,sea buckthorn has the function of improving obesity and obesity-related lipid metabolism disorders caused by high-fat diet,but its effects and mechanisms on browning of iWAT in lambs are unclear.The aims of this study was to investigate the epigenetic effect of active ingredients in sea buckthorn on browning of iWAT in lambs and its effects and mechanisms on insulin sensitivity.The objective of this study was to investigate the effects of dietary sea buckthorn pomace（SBP）on sheep beige adipocyte formation.A control group（0% SBP）and a test group with concentrations of 7.8% and 16% SBP were studied with WAT in the groin of lambs.Effects of SBP on size distribution of iWAT adipocytes by H&E staining;the effects of SBP on the expression of key genes and proteins in differentiation of beige adipocytes and their effects on mitochondrial biosynthesis related genes and glucose uptake related genes and proteins were examined by qRT-PCR and western blotting.The effects of different concentrations of sea buckthorn oil（SBO）on the browning of 3T3-L1 pre-adipocytes was studied using 3T3-L1 preadipocytes as a model.The effects of the size and accumulation of fat cell lipid droplets were investigated by Oil-red-O staining;the effects on the expression of key genes and proteins in differentiation of beige adipocytes were detected by qRT-PCR and western blotting;and the effects of SBO on glucose uptake during differentiation of 3T3-L1 cells were investigated using 2-NDBG.The test results are as follows:1.The data showed that adding 7.8% and 16% of the SBP significantly reduced the size and average crosssectional area of lipid droplets in iWAT,accelerating the browning of iWAT.2.The contents of UCP1 and Cidea mRNA and UCP1,PPARγ and C/EBPβ proteins were significantly increased compared with the control group（P < 0.05）.Therefore,SBP may contribute to the increase of beige adipocytes in iWAT.3.The treatment group of 7.8% and 16% SBP promoted mitochondrial copy number,while the group with 16% SBP increased the expression of PGC-1α,NRF-1and TFAM genes（P < 0.05）,suggesting that SBP may regulate PGC-1α content to drive mitochondrial biogenesis in lambs.4.The levels of IRS and Akt phosphorylation and Glut4 protein and mRNA in the 16% SBP group were significantly higher than those in control group（P < 0.05）,and the AMPK signaling pathway was activated.5.The contents of beige fats related genes PGC-1α,PPARγ,C/EBPβ（P < 0.05）and related proteins UCP1,PPARγ and C/EBPβ were promoted by adding 10^-4 SBO（P < 0.05）.6.SBO promotes mitochondrial biogenesis.The expression of mitochondrial related genes NRF-1,TFAM and COX2 increased in the SBO addition group（P < 0.05）to promote mitochondrial biogenesis.7.The addition of SBO in cell differentiation solution significantly increased the protein contents of IRS1,Akt,AMPK and Glut4（P < 0.05）and increased the content of Glut4 mRNA（P < 0.05）.In conclusion,sea buckthorn has the function of browning WAT of sheep,which may be realized by activating AMPK,enhancing the insulin sensitivity of adipocyte and promoting mitochondrial synthesis.16% SBP treatment group has the most obvious effect on the formation of beige fats in lamb iWAT,and the 10^-4 SBO treatment group has a more significant effect on the browning of 3T3-L1 pre-adipocytes.