| Objective:To establish a model of NAFLD in rats,study the earlyintervention effect of Pu-erh tea water extract (PTE) on NAFLD and explore the mechanisms that effect of PTE on NAFLD.Methods:Establishment of rat model of NAFLD:16male SD rats were divided into two groups with8rats in each group:normal diet group, high-fat diet group. The normal diet group fed a normal diet and the high-fat diet group fed a high-fat diet. At the end of4th weeks,all rats were killed,and several datas were examinedincluding rat body weight, liver weight and liver index, serumTC、TG、HDL-C、LDL-C, ALT、AST、ALP, histopathological changes.The intervention trial:32male SD rats were divided into four groups with8rats in each group:normal group (ND),high-fat diet model group(HFDG), pu-erh tea group (PTG),Dietary intervention group(DIG).ND fed a normal diet for12weeks; HFDGfed a high-fat diet for12weeks; PTG fedHFD for4weeks and then followed by feeding HFD as well asbeing gavaged PTE at the dose of1.58g/(kg.d) for8weeks; DIG fed normal diet instead for8weeks,after feedingHFD for4weeks. At the end of12thweeks, we killed all rats and examined rat body weight, liver weight and liver index, serum TC、TG、HDL-C、LDL-C, ALT、 AST、ALP, liver TG、 TC contents, histopathological changes, and the gene expressions of liver SREBP-1c、FAS、ACC, PPAR-γ, PPAR-αHSL by RT-PCR.Results:(1) Establishment of rat model of NAFLD:Compared with the normal diet group, the rat body weight, wet liver weight,and liver index increased significantly in high-fat diet group (p<0.01,p<0.001, p<0.01, respectively); meanwhile,serum TG, TC,LDL-C level also elevated significantly(p<0.001,p＜0.001,p<0.001, respectively).There was no significant change of HDL-C level observed in HFG (p>0.05); ALT. AST and ALP levels were higher than the ND(p＜0.01,p＜0.01, p<0.001, respectively); hepatic steatosis was obvious in the high-fat group, which suggested that rats could be established as a model of NAFLD by fed a HFD for4weeks.(2) Effects of PTE on rat body weight, liver weight and liver index:Compared with HFDG, rats body weight, wet liver weight and liver index decreased significantly (P＜0.001, P＜0.001, P＜0.001, respectively) in PTG; the change of body weight was not significant (p>0.05) whilethe wet liver weightand liver index of rats decreased significantly (P＜0.001, P<0.001, respectively) in the DIG.Compared with the DIG, body weight decreased significantly (p<0.001), but wet liver weight and liver index were higher than the DIG (p<0.001, p<0.001, respectively) in the PTG. Compared with the ND, the body weight was significantly decreased (p＜0.001),while wet liver weight and liver index were higher than the ND(p＜0.001,p＜0.01, respectively)in the PTG; regarding the DIG, there is no significant change of body weight, liver weight and liver index(p>0.05). (3)Effects of PTE on rat hepatic pathology:Compared with HFDG, hepatic steatosis was significantly improved, liver lipids decreased significantly in the PTG; hepatic steatosis was markedly improvedin the DIG.Compared with DIG, the rat liver has a small amount of lipid droplets inthe PTG. Compared with ND, the rat liver has a small amount of lipid droplets inthe PTG; and the liver tissue structure in DIG was similar to which in the ND.(4) Effects of PTE on rat liver TG,TCcontent:Compared with HFDG, liver TG,TC decreased significantly (p<0.001,p<0.001, respectively) in the PTG; liver TG,TC decreased significantly(,p＜0.001,p＜0.001, respectively) in the DIG. Compared with DIG, The liver TC elevated markedly (p<0.001),the change of lier TG was not significant (p>0.05) in the PTG. Compared with ND, the content of TG was not significant (p>0.05), the content of TC elevated obviously (p<0.001) in the PTG; the contents of TG. TC were not significant (p＜0.05) in the DIG.(5)Effects of PTE on the serum TG、TC、LDL-C、HDL-C levels:Compared with HFDG, serum TG, LDL-C decreased significantly (p<0.001,p<0.01) in PTG, and serum TC,HDL-C increased significantly(p<0.05,p<0.001, respectively) in the PTG; in the DIG, serum TC, LDL-C decreased significantly(p<0.01,p<0.001), respectively), but the change of serum TG,HDL-C was not significant (p>0.05,, p>0.05, respectively). Compared with DIG, the serum TG decreased markedly (p＜0.01),but serum TC. HDL-C were higher than the DIG (p＜0.001,p＜0.001, respectively), while the LDL-C difference was not significant (p>0.05) in the PTG. Compared with ND, the serum TC,HDL-C level was higher than the ND (p<0.001,p＜0.001, respectively), while the level of serum TG、LDL-C was not significant (p＜0.05) in the PTG; the level of serumTG、TC、HDL-C、LDL-C was not significant (p>0.05) in the DIG.(6)Effects of PTE on the serum ALT,AST,ALP levels:Compared with the HFDG, the serum ALT,AST level was reduced obviously (p<0.01, p<0.01, respectively),while there was no significant difference in ALP (p>0.05) in the PTG; the levels of serum ALT,AST,ALP were decreased markedly (, p＜0.001, p＜0.001,p＜0.001, respectively) in the DIG. There was higher (p＜0.001,p＜0.001, respectively) in ALT, ALP in PTG than the ones in DIG, however, the change of AST was not significant (p>0.05) in PTG, when compared with the DIG. Compared with the ND, ALT, ALP levels were still higher than the ND (p＜0.001, p＜0.001, respectively), AST level was not significant (p>0.05); in the DIG, there was not obvious difference in ALT, AST, ALP levels (p>0.05).(7)Effects of PTE on the gene expressionof hepatic SREBP-lc、FAS、ACC、PPAR-γ PPARa, HSL:Compared with HFDG, in the PTG, the expression of hepatic SREBP-1c. FAS. ACC, PPAR-γ decreased obviously (p<0.01, p<0.001,p<0.05, p<0.05, respectively), the expression of hepatic PPARa. HSL increased significantly(p＜0.05, p<0.01, respectively); in the DIG, the expression of hepatic SREBP-1c. FASdecreased markedly (p<0.01, p<0.001, respectively), HSL expression increasedobviously (p<0.01), but the expression difference of hepatic ACC. PPAR-γ、PPARawas not significant (p>0.05). Compared with the DIG, The expression difference of liver SREBP-1c, FAS. ACC, PPAR-γ, PPARa. HSL was not significant (p>0.05) in the PTG. Compared with ND, the expression difference of hepatic SREBP-1c. FAS. ACC, PPAR-γ, PPARa, HSL was not significant (p>0.05) in the PTG, the expression difference of hepatic SREBP-1c. FAS. ACC, PPAR-γ, PPARa, HSL was not significant (p>0.05) in the DIG.Conclusions:(1) We successed in replicating the rat NAFLD model by feeding a HFD for4weeks, the model was similar to human NAFLD, and was suitable for experimental researchfor prevention and treatment of NAFLD(2) PTE can improve liver function, hepatic steatosis, with the effect of regulating blood fat, and reducing weight, which has a good therapeutic effect on NAFLD. (3) PTE could improve liver steatosis in NAFLD rats by reducing expressions of hepatic PPAR-y, SREBP-lc and its target genes FAS, ACC to inhibit hepatic fatty acid uptake and fat synthesis, and increasing hepatic PPAR-a, HSL expression to promote fatty acid oxidation and liver lipolysis.(4) Diet control reducing the intake of high-calorie diet can be used as the basis for NAFLD treatment. |
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