| Hyperlipidemia is defined as one or several lipids which are higher than normal levels in plasma because the metabolism and transport of fats are abnormal. Dyslipidemia is nearly associated with cardiovascular diseases, which is one of the primary dangerous factors to atherosclerosis and coronary heart disease. Based on the elevation of various plasma lipoprotein, hyperlipidemia is classified into six types in clinic: TypeⅠ, plasma TG levels are very high, but TC concentrations are normal or little increase; typeⅡa, plasma TC is elevated while TG may be normal; TypeⅡb, both TC and TG are high; TypeⅢ, both TC and TG levels are very high; TypeⅣ, TG levels are significantly elevated and TC levels are normal or little elevation; TypeⅤ, both TG and TC are increased, but the increase of TG is primary. At present, the animal models of hyperlipidemia and atherosclerosis are induced by means of breeding, injection, stress, and immunity. In Europe and America, the transgenic animal model of hyperlipidemia has been developed using molecular biology and gene engineering technology. However, there are some disadvantages in these animal models, for example the period is longer, the process is more complicated, and the TG concentrations can not be raised obviously.Non-alcoholic fatty liver disease represents a spectrum of liver diseases characterized mainly by macrovesicular steatosis in the absence of significant alcohol ingestion. Although a non-alcoholic fatty liver rarely leads to more serious liver problems, this condition may interfere with normal liver function or cause inflammation and/or fibrosis secondary to hepatocyte injury, with resultant liver failure, hepatocirrhosis, or hepatocellular carcinoma. The incidence of fatty liver is 15–30 % in the general population, but rises to 50–90 % in obese people. At present, orthodox medicine offers no specific drug to reverse the condition of fatty liver, although antioxidants, insulin sensitizers, hepatoprotectants, and general lipid-lowering agents are used. Some hypocholesterolaemic drugs have been shown to cause disorders in liver function resulting from non-specific actions.The present work attempted to establish a new model of acute hyperlipoproteinemia using schisandrin B (Sch B) for studying the blood lipid-lowering drugs and the lipid metabolism.At the same time, the effects of Sch B on serum and hepatic lipids were observed in experimentally-induced hypercholesterolaemic mice. 1 Influences of schisandrin B on serum and hepatic lipid levels in normal miceObjective: To establish an animal model of acute hyperlipoproteinemia using schisandrin B. Method: Mice were intragastrically treated with single doses of schisandrin B (0.05-0.8 g/kg, suspended in olive oil). Normal animals received the vehicle (olive oil) at 10 ml/kg. Serum and liver tissue samples were obtained 24 h after schisandrin B administration.. Result: The serum triglyceride level was increased by 10-235 % in a dose-dependent manner. However, the serum low density lipoprotein cholesterol level was significantly decreased by 28 % at a dose of 0.8 g/kg. Kinetics parameters estimated by Scott's plot analysis of schisandrin B-induced changes in serum and hepatic triglyceride levels were determined: serum- Emax (maximal effect) = 6 mmol/L (384 % increase, P<0.001); KD (affinity) = 0.59 mmol/kg; pD2 (an index of affinity) = 6.62; liver- Emax = 21μmol/g (43 % increase, P< 0.001); KD = 0.37 mmol/kg; pD2 = 6.83. Conclusion: The schisandrin B-induced elevation in serum triglyceride level, which resembles typeⅠorⅣhyperlipidemia in humans, can be used as mouse model for screening candidate lipid-lowing drugs.2 Influences of schisandrin B and fenofibrate combination on serum/hepatic lipid levels in miceObjective: To observe the effect of combination of schisandrin B and fenofibrate on serum and hepatic lipids in normal mice. Method:(1)Mice were orally administered with fenofibrate (0.1 g/kg in 0.5 % CMC) with or without schisandrin B (0.4 g/kg in olive oil). Drug untreated animals received the vehicle (0.5 % CMC and olive oil 10 ml/kg) only. (2)Mice were intragastrically treated with schisandrin B at increasing single doses (0.2-1.6 g/kg in olive oil) and/or fenofibrate (0.1 g/kg in 0.5 % CMC) for 4 days. Drug-untreated animals received the vehicle (i.e. 0.5 % CMC 10 ml/kg/day×4 and olive oil 10 ml/kg at the d 4). and liver tissue samples were obtained 24 h after schisandrin B administration. Result: Schisandrin B-treated mice the serum and hepatic TG level was respectively increased by 140-795 % and 36-148 %, but hepatic TC content was decreased by 18-43 % in a dose-dependent manner. Fenofibrate treatment at single dose of 0.1 g/kg did not affect the serum and hepatic TC level in both vehicle- and schisandrin B-treated mice but inhibited the increase in hepatic TG content caused by schisandrin B. Fenofibrate pretreatment (0.1 g/kg/day×4) markedly lowered hepatic TG contents, when compared with the vehicle-treated mice, and notably increased the hepatic TC-lowering effect of schisandrin B. Conclusion: The results implicate a competitive/synergic interaction between schisandrin B and fenofibrate in heaptrophic action in mice.3 Influences of schisandrin B on serum and hepatic lipid levels in hypercholesterolaemic mice3.1 Effects of schisandrin B on serum and liver lipid levels in mice treatedwith cholesterol and bile saltObjective: To observe the effect of schisandrin B on serum and hepatic lipid levels in hypercholesterolaemic mice . Method: Hypercholesterolaemia was induced by oral administration of a cholesterol/bile salts mixture (3/0.5 g/kg daily) for successive 4 days, which is suspended in olive oil. In drug treatment groups, Schisandrin B and fenofibrate suspended in olive oil were intragastrically administered at doses of 0.1,0.2 g/kg and 0.1 g/kg, respectively. Normal animals received the vehicle (olive oil) at 10 ml/kg. Result: In mice treated with cholesterol/bile salts for 4 days, the hepatic TC levels were prominently increased, but the serum TG contents were notable reduced. Although schisandrin B treatment did not produce any detectable effect on serum TC levels, Sch B treatment significantly elevated serum TG contents when compared with the level seen in hypercholesterolaemic mice receiving no drug treatment. Conclusion: Schisandrin B has the effect of counterworking with the hypercholesterolaemia induced by cholesterol and bile salt.3.2 Effects of schisandrin B on serum and hepatic lipid levels in mice with fed high-fat dietObjective: To observe the effect of schisandrin B on serum and hepatic lipid levels in hypercholesterolaemic mice. Method: Hypercholesterolaemia was induced by feeding a high fat/cholesterol (10/1 %, w/w) diet for successive 5 days. In drug treatment groups, Schisandrin B and fenofibrate suspended in olive oil were intragastrically administered at doses of 0.05,0.1,0.2 g/kg and 0.1 g/kg, respectively. Normal animals received the vehicle (olive oil) at 10 ml/kg. Result: In mice fed with a high fat diet for 5 days, the hepatic TC and TG levels were prominently increased, but the serum TG contents were notable reduced. Sch B treatment significantly elevated serum TG contents and made a remarkable decrease of hepatic TC and TG levels, when compared with the level seen in hypercholesterolaemic mice receiving no drug treatment. Conclusion: Schisandrin B has the effect of counterworking with the hypercholesterolaemia induced by feeding a high fat diet.3.3 Effects of schisandrin B on serum and hapetic lipid levels in mice fed a high-fat diet containing bile saltObjective: To observe the effect of schisandrin B on serum and hepatic lipid levels in hypercholesterolaemic mice. Method: Hypercholesterolaemia was induced by feeding a high fat/cholesterol/bile salts (10/1/0.3 %, w/w) diet for successive 7 days. In drug treatment groups, Schisandrin B and fenofibrate suspended in olive oil were intragastrically administered at doses of 0.05,0.1,0.2 g/kg and 0.1 g/kg, respectively. Normal animals received the vehicle (olive oil) at 10 ml/kg. Result: In mice fed with a high fat diet containing bile salts for 7 days, the hepatic TC and TG levels were prominently increased, but the serum TG contents were notable reduced. Sch B treatment significantly elevated serum TG contents and made a remarkable decrease of hepatic TC and TG levels, when compared with the level seen in hypercholesterolaemic mice receiving no drug treatment. Conclusion: Schisandrin B has the effect of counterworking with the hypercholesterolaemia induced by feeding a high fat diet containing bile salts.4 Influenceof schisandrin B on the hepatic index in mice4.1 Effects of schisandrin B with/without fenofibrate on the hepatic index in normal miceObjective: To observe the effect of schisandrin B with/without fenofibrate on the hepatic weight of normal mice. Method: Method is the same as described in 1.2.. Result: Effective kinetics of schisandrin B on liver weight were analyzed in the absence and presence of fenofibrate pretreatment hepatic index (Emax = 62.27 %, KD = 0.64 mmol/kg, pD2 = 6.59) in mice. Fenofibrate treatment at multiple doses (0.1 g/kg×4, p.o.) increased the hepatic index in mice. The combined treatment with schisandrin B and fenofibrate increase the hepatic index in semi-additive manner. Conclusion: The results indicate that schisandrin B and fenofibrate interact synergistically and competitively on liver weight in mice. 4.2 Effects of schisandrin B on the hepatic indices in hypercholesterolaemic miceObjective: To observe the effect of schisandrin B on the liver weight of hypercholesterolaemic mice. Method: It has been described as 2.3.. Result: The hepatic index was increased in hypercholestetolaemic mice, compared with that of mice received the vehicle (olive oil) or fed normal diets only. Sch B or benofibrate treatment further increased the hepatic index, when compared with that of hypercholestetolaemic mice receiving no drug treatment, with the effect of fenofibrate being more prominent. Conclusion: Schisandrin B was found to cause a lesser degree of liver hypertrophy than did fenofibrate.5 Influences of schisandrin B on lipids in hepatic cell lines5.1 Effect of schisandrin B on lipid metabolism in normal hepatic cellsObjective: To observe the influences of Sch B on normal hepatic cells. Method: HepG2 and LO2 cells at 80 % confluency were exposed to Schisandrin B. Stock solutions of 100 mM Schisandrin B prepared in DMSO were conveniently diluted in culture medium containing 1 % (w/v) bovine serum albumin (BSA) to abtain the desired final concentrations. The Schisandrin B was added to HepG2 cells 24 h after seeding. For 24 h culture with Sch B, the cells were stained with Sudan black B saturated in ethanol for 15 min at 37°C. Result: MTT statistics demonstrated that 100 and 120μM Sch B have the obviously inhibitory effect to growth of HepG2 and LO2 cells (P<0.001); the staining results showed that lipid accumulation in the cells was induced by the addition of Sch B at a dose of 80μM. Conclusion: 80μM schisandrin B could induce lipid accumulation in HepG2 and LO2 cells without causing any toxicity.5.2 Effect of schisandrin B on vitro fatty liver model of hepatic cellsObjective: To observe the effect of Sch B on vitro fatty liver model of hepatic cells. Method: To induce fat-overloading of cells, HepG2 and LO2 cells at 80 % confluency were exposed to a long-chain mixture of FFAs (oleate and palmitate) at the ratio of 3:1. The FFAs mixture and SchB was added to HepG2 and LO2 cells 24 h after seeding. For the 24 h culture, the cells were stained with Sudan black B saturated in ethanol for 15 min at 37°C. Result: The study showed that after 24 h culture with 1 mmol/ml FFAs mixture, it has not any inhibitory effect and has successfully induced fat accumulation in HepG2 cells. With the Sch B co-culturing to HepG2 and LO2 cellS, the extent of fat accumenlation has been attenuated at a minuse dose-dependent manner. Conclusion: Schisandrin B could attenuate the FFAs-induced fat accumulation in vitro fatty liver model. |
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