| Objective: To investigate the lipid-lowering effect and the influence on hepatic oxidative stress indicators and nuclear erythroid-2 related factor 2/antioxidant response element(Nrf2/HO-1) signaling pathway of curcumin by using acute hyperlipidemia rats model through preventive drug administration,and to compare with atorvastatin and fenofibrate.Methods: 80 healthy male SD rats were divided randomly into eight groups: the blank control group(NC group, Xiwang corn oil 2.5ml/kg for 10days), hyperlipidemia model group(MODEL group, Xiwang corn oil 2.5ml/kg for 10 days), low concentration of curcumin group(LC group, curcuminoids125mg/kg.d for 10 days), middle concentration of curcumin group(MC group,curcuminoids 250mg/kg.d for 10 days), high concentration of curcumin group(HC group, curcuminoids 500mg/kg.d for 10 days), atorvastatin group(ATV group, atorvastatin 2.1mg/kg.d for 10 days), fenofibrate group(FNFB group,fenofibrate 30mg/kg.d for 10 days), combined drugs group[CD group,(atorvastatin 2.1mg+ fenofibrate 30mg)/kg.d for 10 days]. 1 hour after given drugs in the tenth day, the MODEL and medication groups were given disposable intraperitoneal injection of 75% yolk emulsion(25ml/kg), while the NC group was given disposable intraperitoneal injection of saline(25ml/kg). 24 hours later, the rats tails’ blood was collected to determine the level of total cholesterol(TC), triglyceride(TG), high-density lipoprotein(HDL), low-density lipoprotein(LDL), alanine transaminase(ALT) and aspartate aminotransferase(AST) by using automatic biochemical analyzer.After taking the blood of the rats, all of them were given 4% chloral hydrate intraperitoneal injection(10ml/kg) anesthesia, quickly opened the abdominal cavity, removed the liver. Part of the liver sample was stained with HE toobserve the morphological changes and lipid deposition, and part of the liver sample was frozen in-80℃ liquid nitrogen to determine the content of MDA and the activity of SOD, CAT and GSH-PX by corresponding methods. The contents of Nrf2 and HO-1 mRNA in liver tissue were measured by RT-PCR,and the expressions of Nrf2 in liver cell nucleus and HO-1 protein were determined by Western blot. Data analysis was performed by SPSS 23.0, the data were described by the mean and standard deviation((?)±s). Groups were compared using one way ANOVA of completely random design. Multiple comparisons were analyzed using LSD and SNK-q test. Statistically significant difference was set at P<0.05.Results:1 The changes of serum lipids among the groups(Table 1, Fig.1)TC and LDL: The levels of TC and LDL in MODEL group were significantly increased when compared with NC group(P<0.05). The levels of TC and LDL of all the medication groups were decreased when compared with MODEL group(P<0.05). Among the medication groups, the ATV, HC and CD group decreased the most significantly(P<0.05), and there was no significant difference between any two among the three groups(P>0.05). The decline in FNFB and MC group was less when compared with the three groups above(P<0.05), and there was no significant difference between the two groups(P>0.05). The decline of TC and LDL levels in LC group was the most non-obvious(P<0.05).TG: The TG level in MODEL group was significantly increased when compared with NC group(P<0.05). Compared with MODEL group, the TG levels of all the medication groups were decreased(P<0.05), among which HC and CD group decreased the most significantly(there was no significant difference between the two groups, P>0.05), second was FNFB group(P<0.05), third was MC and ATV group(the two had no significant difference,P>0.05). The TG level in LC group was higher than MC group(P<0.05), but when compared with ATV group, there was no significant difference(P>0.05).HDL: The HDL level in MODEL group was significantly decreasedwhen compared with NC group(P<0.05). All the medication groups were higher than MODEL group, but there was no significant difference between medication groups and MODEL group(P>0.05).2 The outcome of liver function(Table 2)There was no statistically difference among the 8 groups on serum ALT and AST levels(P>0.05).3 The changes of oxidative stress parameters in liver tissue(Table 3,Fig.2)MDA: The MDA level in MODEL group was higher than NC group(P<0.05). The MDA levels in medication groups were deceased when compared with MODEL group(P<0.05). The levels of MDA in HC, CD and ATV group decreased the most significantly, which showed no significant difference when compared with NC group(P>0.05), and each was lower than MC, FNFB and LC group(P<0.05). There was no significant difference between any two among HC, CD and ATV group(P>0.05), and there was no significant difference between any two among MC, FNFB and LC group(P>0.05).The activity of SOD: The activity of SOD in MODEL group was lower than NC group(P<0.05). The activity of SOD in medication groups were higher than MODEL group(P<0.05). HC group was higher than any other medication group and NC group(P<0.05). Each of CD, MC and ATV group was higher than FNFB and LC group(P<0.05). There was no significant difference between any two among CD, MC and ATV group(P>0.05), and there was no significant difference between FNFB and LC group(P>0.05).CAT: The activity of CAT in MODEL group was lower than NC group(P<0.05). The activity of CAT in medication group was higher than MODEL group(P<0.05). HC group was the highest in the medication groups(P<0.05),second was CD group(P<0.05), third were MC and ATV group(P<0.05). The lowest were LC and FNFB group(P<0.05). There was no significant difference between MC and ATV group(P>0.05), and there was no significant difference between LC and FNFB group(P>0.05).GSH-PX: The activity of GSH-PX in MODEL group was lower than NC group and medication group except LC and FNFB group(P<0.05). HC group was higher than any other group except NC(P<0.05). The activity of GSH-PX in HC group was the highest compared with other medication groups(P<0.05),but no statistical difference compared with NC group(P>0.05). Second were ATV and CD group(the two had no statistically difference, P>0.05), third were MC group(P<0.05). The lowest were LC and FNFB group(the two had no statistically difference, P>0.05).4 The histopathological changes of liver tissue(Fig.6)The liver tissue structure in NC group was clear and complete, hepatic cord rowed in an orderly manner. No vacuolar degeneration was found in NC group. Compared with NC group, the hepatic cells in MODEL group were bigger and slightly swollen, and were arranged in disorder. HE staining showed some small circular lipid droplets in liver cells. Compared with MODEL group, the performance on pathology of liver tissue in the treatment group was better in different degree. No inflammation, necrosis, fibrosis and other pathological changes occurred in the liver tissues of the rats in the eight groups.5 The expression of Nrf2/HO-1 signaling pathway(Table 4, Fig.3-5)Nrf2 mRNA in liver tissue: Compared with NC group, the Nrf2 mRNA levels in all the other groups were increased(P<0.05); CD, HC, ATV and MC group were higher than FNFB and LC group(P<0.05). There was no significant difference between any two among CD, HC, ATV and MC group(P>0.05), and there was no significant difference between FNFB and LC group(P>0.05).Nrf2 protein in hepatic nuclear: All the medication groups and MODEL group were increased when compared with NC group(P<0.05). HC and CD group were the highest in medication groups(P<0.05), second were ATV and MC group(P<0.05), third were LC and FNFB group(P<0.05). MODEL group was the lowest except NC group(P<0.05).HO-1 mRNA: All the medication groups and MODEL group wereincreased when compared with NC group(P<0.05). CD and HC group were the highest in medication groups and MODEL group(P<0.05), second were MC and ATV group(P<0.05), the lowest were FNFB and LC group(P<0.05).There was no significant difference between any two among FNFB, LC and MODEL group(P>0.05).HO-1 protein: All the medication groups and MODEL group were increased when compared with NC group(P<0.05). HC and CD group were the highest in medication groups and MODEL group(P<0.05), second were MC and ATV group(P<0.05), the lowest were FNFB and LC group(P<0.05).There was no significant difference between any two among FNFB, LC and MODEL group(P>0.05).Conclusions:1 Prophylactic use of curcumin can reduce the TC, TG, LDL levels in acute hyperlipidemia rats, but the HDL rise is not significant. The lipid-lowering effect of curcumin is in a dose-dependent manner, the lipid-lowering effect of high-dose curcumin group is the strongest.2 Prophylactic use of curcumin can improve the liver’s ability of anti-oxidative stress in rats with acute hyperlipidemia, the antioxidant ability of high-dose curcumin group is the strongest.3 The antioxidant effect of curcumin may be attributed to the induction of Nrf2/HO-1 signaling pathway. |
