Effects Of (-)-Epigallocatechin-3-gallate On White Adipose Tissue Angiogenesis In High Fat Diet Rats

?Objectives? Previous studies showed that the development of obesity was closely related with angiogenesis in the adipose tissue.Vascular endothelial growth factor(VEGF)is the most studied factor among factors that regulate the angiogenesis of adipose tissue,and it is considered to be the most critical angiogenic factor.It was found that angiogenesis inhibitors can reduce obese animal's body weight.Thus,regulation of angiogenesis in the adipose tissue may be a potetional treatment strategy for obesity.(-)-Epigallocatechin-3-gallate(EGCG)is the most abundant and biologically active ingredient in green tea catechins.The benefits of EGCG for obesity and related metabolic abnormalities have been confirmed by extensive studies.In addition,the anti-angiogenic effect of EGCG on the inhibition of tumor tissue angiogenesis has also commonly reported.But it has not been reported whether EGCG can inhibit adipose tissue angiogenesis.Based on previous studies,we hypothesized that EGCG can suppress obesity by inhibiting adipose tissue angiogenesis with reducing of adipose tissue growth and expansion.In this study,we aimed to study the effect of EGCG on the angiogenesis of white adipose tissue in high fat diet feed rats.Based on the strong antioxidant and antiinflammatory properties of EGCG,we will also explore the possible mechanism of EGCG on white adipose tissue angiogenesis from the perspective of oxidative stress and inflammation,and to provide evidence for the treatment of obesity and related chronic disease by regulation of angiogenesis.?Methods? Forty male SD rats were randomly divided into five groups: normal control group,high fat diet group,EGCG low,medium and high dose intervention group,8 rats in each group.Normal control group were fed with normal diet(calories 343.92 kcal/100 g,fat 13.8%),high-fat diet group were fed with high-fat diet(calories 401.8 kcal/100 g,fat 36.3%),EGCG intervention groups were fed with high-fat diet along with intragastric administration of EGCG.The low dose group was 100mg/(kg · d),the middle dose group was 200mg/(kg · d),the high dose group 400mg/(kg · d).After 8 weeks,the rats were killed.(1)Detect the obesity index(weight,visceral fat weight),glucose metabolism and lipid metabolism [fasting blood glucose(FBG),triglyceride(TG),cholesterol(TC)],liver oxidative stress level [total superoxide dismutase(T-SOD)activity,glutathione peroxidase enzyme(GPx)activity and malondialdehyde(MDA)content] and compared with similar studies to determine the optimal dose of EGCG intervention.(2)The group of EGCG with the optimal dose was used as EGCG intervention group.Compared EGCG intervention group with the normal control group and the high fat diet group.The adipocyte size and vascular density of the adipose tissue in rats were observed under the microscope;The serum VEGF concentration was detected by Elisa Kit;Detect the expression of VEGF m RNA in adipose tissue and to study the effect of EGCG on the angiogenesis of white adipose tissue in rats.(3)RT-PCR was used to detect the expression of nuclear factor E2(Nrf2),heme oxygenase-1(HO-1),catalase(CAT),SOD,GPx,interleukin-6(IL-6)and monocyte chemoattractant protein-1(MCP-1)m RNA,and to explore the possible mechanism of EGCG on the angiogenesis of adipose tissue.?Results? 1.The body weight,liver weight and serum FBG of the high fat diet group were significantly higher than those of the normal control group(all P<0.05).Each EGCG group could effectively reduce body weight,liver weight,serum FBG and TG levels in high fat diet rats(all P<0.05).The low dose EGCG could increase liver GPx activity (P<0.05).The middle dose of EGCG could decrease the content of MDA in the liver(P<0.05).Compared with similar studies,the optimal dose of EGCG [200mg/(kg·d)] was used to improve the body weight,glucose metabolism,lipid metabolism and liver oxidative stress in high fat diet rats.2.The adipocyte size,number of vascular/each adipocyte,serum VEGF concentration and VEGF m RNA expression in adipose tissue of high fat diet group were significantly higher than those of normal control group(all P<0.05).EGCG can significantly reduce the above indicators of high fat diet group(all P<0.05).3.The expression of Nrf2,HO-1,SOD,GPx and CAT m RNA in adipose tissue of EGCG group was significantly higher than that in high fat diet group and normal control group(all P <0.05).The expression of MCP-1 and IL-6 m RNA in adipose tissue of EGCG group was significantly lower than that in high fat diet group(all P <0.05).?Conclusions? 1.The optimal dose of EGCG that improved obesity-related metabolic abnormalities and oxidative stress level in high-fat diet rats is 200mg/(kg · d).2.EGCG can decrease the production of serum VEGF,vascular density and the expression of VEGF m RNA in white adipose tissue of high fat diet rats,inhibiting the angiogenesis in white adipose tissue.3.The effect that EGCG inhibit angiogenesis in white adipose tissue may be associated with the up-regulation of Nrf2/HO-1 pathway to increase the expression of antioxidant enzymes(SOD,CAT,GPx),reduce ROS production and decrease the inflammatory response.