The combination of atorvastatin with silymarin enhances hypolipidemic, antioxidant and anti-inflammatory effects in a rat model of metabolic syndrome.

Hypolipidemic and cardioprotective effects of statins can be associated with the development of myopathies and new-onset type 2 diabetes. These adverse effects may be related to increased oxidative stress. The plant extract silymarin (SM) is known for its antioxidant and anti-inflammatory actions. We tested the hypothesis that the combination of atorvastatin (ATV) with SM could improve therapy efficacy and eliminate some negative effects of statin on hypertriglyceridemia-induced metabolic disorders. Hereditary hypertriglyceridemic rats were fed a standard diet for four weeks without supplementation; supplemented with ATV (5 mg/kg b. wt./day) or a combination of ATV with 1 % micronized SM (ATV+SM). ATV treatment elevated plasma levels of HDL-cholesterol (p<0.01), glucose and insulin and decreased triglycerides (p<0.001). The combination of ATV+SM led to a significant reduction in insulin, an improvement of glucose tolerance, and the hypolipidemic effect was enhanced compared to ATV alone. Furthermore, ATV supplementation increased skeletal muscle triglycerides but its combination with SM decreased triglycerides accumulation in the muscle (p<0.05) and the liver (p<0.01). In the liver, ATV+SM treatment increased the activities of antioxidant enzymes, glutathione and reduced lipid peroxidation (p<0.001). The combined administration of ATV with SM potentiated the hypolipidemic effect, reduced ectopic lipid accumulation, improved glucose metabolism, and increased antioxidant and anti-inflammatory actions. Our results show that SM increased the effectiveness of statin therapy in a hypertriglyceridemic rat model of metabolic syndrome.

The effect of combined diet containing n-3 polyunsaturated fatty acids and silymarin on metabolic syndrome in rats.

The risk of development of metabolic syndrome can be increased by hypertriglyceridemia. A search for effective therapy is a subject of considerable attention. Therefore, our hypothesis is that the fish oil (containing polyunsaturated fatty acids; n-3 PUFA) in a combination with silymarin can more effectively protect against hypertriglyceridemia-induced metabolic disturbances. The study was conducted using a unique non-obese strain of rats with hereditary hypertriglyceridemia an accepted model of metabolic syndrome. Adult male rats were treated with n-3 PUFA (300 mg/kg/day) without or with 1 % micronized silymarin in a diet for 4 weeks. The treatment with the diet containing n-3 PUFA and silymarin significantly reduced concentrations of serum triglycerides (-45 %), total cholesterol (-18 %), non-esterified fatty acids (-33 %), and ectopic lipid accumulation in skeletal muscle (-35 %) compared to controls. In addition, an increase in Abcg5 and Abcg8 mRNA expression (as genes affecting lipid homeostasis) as well as in protein content of ABCG5 (+78 %) and ABCG8 (+232 %) transporters have been determined in the liver of treated rats. Our findings suggest that this combined diet could be used in the prevention of hypertriglyceridemia-induced metabolic disorders.

Positive effects of different drug forms of silybin in the treatment of metabolic syndrome.

Silymarin and silybin are widely used for their hepatoprotective properties. Our previous studies confirm positive effect of silymarin on lipoprotein profile and lipid homeostasis. Advanced drug forms may improve the bioavailability of these compounds. In this study, we investigate the effects of silybin in different drug forms (standardized silybin, micronized silybin, and silybin in form of phytosomes) on dyslipidemia and glucose metabolism in hereditary hypertriglyceridemic (HHTg) rats. Male HHTg rats were divided into four groups of seven animals and were fed by experimental diets. Silybin significantly decreased serum level of triglycerides in groups of rats fed by standardized silybin and silybin in form of phytosomes compared to control group. Results show that silybin did not affect the total cholesterol level, but significantly increased the levels of HDL cholesterol in all groups of animals. Silybin in a standardized form had the highest hypotriglyceridemic effect. On the other hand, the micronized form has caused the highest increase of protective HDL and most significantly decreased glucose and insulin levels. Our results suggest that silybin is probably responsible for some positive properties of silymarin. Subsequent dose-dependent studies of silybin action may reveal the intensity of its positive effects on lipid and glucose parameters.

Differences in hepatic expression of genes involved in lipid homeostasis between hereditary hypertriglyceridemic rats and healthy Wistar rats and in their response to dietary cholesterol.

UNLABELLED: Differences in expression of mRNA of genes regulating lipid and drug metabolism between hereditary hypertriglyceridemic rats (HHTg, accepted model of metabolic syndrome) and healthy Wistar-Kyoto (WKY) rats were studied. Also, differences in expression due to intake of high cholesterol diet (1% w/w) were determined to investigate possible differences in response of the WKY and HHTg rats to increased intake of dietary cholesterol. Levels of ATP-binding cassette transporters (ABCG5, ABCG8), fatty acid synthase (FAS) and cytochrome P450 (CYP2C11) mRNA were significantly lower in HHTg rats on standard laboratory diet; in contrary, CYP7A1, CYP2C6 and CYP2B2 gene expression was significantly higher. The WKY rats responded to high cholesterol diet by an increase in expression of mRNAs for sterol regulatory element binding protein (SREBP1c), CYP2B2 and CYP7A1; lower expression was found in the FAS, ABCG5, ABCG8, CYP4A1, CYP4A2 and acyl-CoA oxidase. HHTg rats responded to cholesterol intake in a similar manner, however, differences were found in expression of the FAS and CYP4A1 mRNA (decrease was not observed), CYP2B2 (decrease instead of an increase). CONCLUSIONS: (i) dietary cholesterol significantly influences expression of genes involved in lipid homeostasis and drug metabolism, and (ii) the HHTg rats responded to dietary cholesterol in a different way.

Hypolipidemic effects of silymarin are not mediated by the peroxisome proliferator-activated receptor alpha.

Silymarin is widely used in supportive therapy of liver diseases. It has been shown lately that silymarin has beneficial effects on some risk factors of atherosclerosis owing to its hypolipidemic properties. PPARalpha plays a key role in lipid metabolism and homeostasis as its target genes are involved in catabolism of fatty acids by beta-oxidation (e.g. acyl-CoA oxidase) and by omega-oxidation (e.g. cytochrome P4504A). Here we studied the possibility that hypolipidemic effects of silymarin may be mediated by PPARalpha. Rats fed with a high-cholesterol diet with either silymarin or fenofibrate (as a positive control both for PPARalpha expression as well as for lipid determination) were used. The effects of silymarin on expression of PPARalpha both at the mRNA (including selected target genes) as well as the protein level were determined. In parallel, the levels of cholesterol and triacylglycerols were determined. Our results confirmed the hypolipidemic effects of silymarin and demonstrated that these effects are probably not mediated by PPARalpha because of unchanged mRNA levels of PPARalpha target genes. Furthermore, this work shows for the first time that cholesterol itself inhibits expression of CYP4A mRNA.

Disposition of sanguinarine in the rat.

Sanguinarine is an alkaloid with known antibiotic and anti-inflammatory activity and its pharmacokinetics have been studied in the rat after a single oral dose (10 mg kg(-1) body weight). Alkaloid determination in the plasma and liver was carried out by high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC/ESI-MS). The pharmacokinetic parameters (t(max), c(max), AUC(0-->t) and AUC(0-->infinity)) were determined for sanguinarine and dihydrosanguinarine, the major components detected in plasma. The first step in sanguinarine metabolism in the rat was the reduction of the iminium bond resulting in formation of the less toxic dihydrosanguinarine. Both compounds were completely eliminated from the plasma and liver after 24 h and not detected in urine. After a single oral dose of (3)H-sanguinarine, more than 42% of the ingested radioactivity was present in gastrointestinal tract. Benz[c]acridine, up to date the only sanguinarine metabolite referred to in the literature, was not detected in the plasma, liver or urine.

Antioxidant status, lipoprotein profile and liver lipids in rats fed on high-cholesterol diet containing currant oil rich in n-3 and n-6 polyunsaturated fatty acids.

Plant-based n-3 polyunsaturated fatty acids (PUFA) possess a prospective antiatherogenic potential. Currant oil from Ribes nigrum L. is one of the few plant oils containing PUFAn-3 (15.3 mol%) in addition to PUFAn-6 (60.5 mol%). This study was aimed at comparing the effects of currant oil with those of lard fat, rich in saturated (43.8 mol%) and monounsaturated (47.0 mol%) fatty acids, on antioxidant parameters, the lipoprotein profile and liver lipids in rats fed on 1 % (w/w) cholesterol diets containing either 10 % of currant oil (COD) or lard fat (LFD). After 3 weeks of feeding, the COD induced a significant decrease in blood glutathione (GSH) and an increase in Cu(2+) induced oxidizability of serum lipids, but did not affect liver GSH and t-butyl hydroperoxide-induced lipoperoxidation of liver microsomes. Although the COD did not cause accumulation of liver triacylglycerols as LFD, the lipoprotein profile (VLDL, LDL, HDL) was not significantly improved after COD. The consumption of PUFAn-3 was reflected in LDL as an increase in eicosapentaenoic and docosahexaenoic acid. These results suggest that currant oil affects positively the lipid metabolism in the liver, above all it does not cause the development of a fatty liver. However, adverse effects of currant oil on the antioxidant status in the blood still remain of concern.

Pharmacokinetic study of iodine-labeled silibinins in rat.

The very low bioavailability of silibinin (silybin, SB), the main antioxidant flavonolignan of silymarin from Silybum marianum L. (Asteraceae), requires sensitive methods to study the modulation of silibinin bioavailability. To evaluate the potential for use of radiolabeled silibinin, two silibinin derivatives, separated by HPLC after iodination ((125)I-SB(1) and (125)I-SB(2)) and their complexes 1 : 1 with phosphatidylcholine ((125)I-SPC(1) and (125)I-SPC(2)) were administered concurrently with a single intragastric dose of 5.0 mg or 50 mg of unlabeled silibinin (alone or as a constituent of the complex) per kg of body weight in a comparative study of bioavailability in the rat. Pharmacokinetic parameters as well as organ uptake of (125)I-SB(1)-derived radioactivity showed a dose-response pattern. The parameters of bioavailability after (125)I-SPC(1) intake were not influenced by unlabeled silibinin (complexed with phosphatidylcholine), since maximal levels were achieved by the lower dose of unlabeled compound. The superior bioavailability of (125)I-SPC(1) was obvious at the lower dose of unlabeled compound as elevated AUC and RA(max) (maximal percentage of administered radioactivity), and increased radioactivity in liver, kidney, spleen and heart. An absence of these characteristics with (125)I-SB(2) and (125)I-SPC(2) suggests the use of(125)I-SB(1) for studies of modulation of its bioavailability in vivo in rat.

Serum lipoprotein fatty acid patterns in various types of familiar combined hyperlipidemia.

The relative content of various fatty acids in serum lipoproteins was determined in patients with type IIa (38), IIb (49) and IV (77) of hyperlipoproteinemia and compared with 52 controls. Significant changes were found in hyperlipoproteinemia associated with hypertriglyceridemia (type IV) but not in "pure" hypercholesterolemia (type IIa). In all lipoprotein fractions (VLDL, LDL, HDL) in type IV of hyperlipoproteinemia the increased oleic and linolenic acid proportions were found, while proportions of linoleic, arachidonic and docosahexaenoic acids were decreased. The saturated fatty acids (myristic, palmitic and stearic) were found increased in LDL. Linear regression analysis has shown positive correlation between the content of arachidonic and docosahexaenoic acids in HDL and LDL and the serum levels of total HDL-cholesterol, HDL2-cholesterol, HDL3-cholesterol and ApoA1, while a negative correlation between these fatty acids and serum triglycerides level appeared. These findings can be explained partly by increased content of triglycerides and free fatty acids in lipoproteins. Possible differences concerning mechanisms of accelaration of atherogenesis in various types of hyperlipidemia are discussed.

Unsaturated fatty acids incorporated in HDL in hypo- and hyperalphalipoproteinemia--relation to the HDL-cholesterol level.

Proportions of unsaturated fatty acids of high density lipoprotein (HDL) lipids and their relationships to the HDL-cholesterol level were compared in hypo- and hyperalphalipoproteinemic subjects. Both groups did not differ in the level of serum cholesterol. However, hypoalphalipoproteinemia was associated with hypertriglyceridemia, higher HDL-triacylglycerol level, and higher proportion of HDL-18:1 (oleic acid) and lower proportions of HDL-18:2 (linoleic acid) and 20:4 (arachidonic acid) than hyperalphalipoproteinemia. The HDL-20:4 was the only fatty acid correlating (negatively) with HDL-cholesterol. However, HDL-18:1 correlated positively and HDL-18:2 negatively with HDL-triacylglycerols, lipids related to the fall of HDL-cholesterol. These results suggest 1) an antagonism of 20:4 and 18:2 as structural components of HDL lipids in relation to the HDL-cholesterol level, and 2) an association of replacement of HDL 18:2 by 18:1 with the disorder of plasma triacylglycerol metabolism.

The effect of N-deacetylcolchiceine on serum lipoproteins in rats.

N-Deacetylcolchiceine (DAC) administered i.p. to rats decreased the level of serum cholesterol and apoB. It was accompanied by the fall of HDL-C due to the decrease of both HDL subfractions HDLa and HDLb, and by a rather weaker decrease of LDL-C. The levels of serum and lipoprotein triacylglycerols were not significantly affected. The "clearing reaction" to heparin in DAC rats differed from controls with regard to plasma cholesterol resulting in its accumulation in HDLa and LDL simultaneously with an increased activity of post-heparin lipoprotein lipase. These results suggest that the DAC accelerates the lipoprotein cholesterol metabolism.

The preheparin and postheparin lipids of high density lipoprotein subfractions: relation to the serum insulin and postheparin plasma lipase activities in normal human.

The preheparin and postheparin lipoprotein lipids (cholesterol C and triacylglycerols TAG) were related to the serum insulin and to the postheparin plasma activities of lipoprotein lipase (LPL) and hepatic lipase (HL) in normolipemic human. The positive correlation, although not statistically significant, of insulin level of the LPL activity was found, while no correlation to the HL activity was seen. Under preheparin conditions: 1) both insulin level and LPL activity were negatively related to the VLDL-C/TAG ratio indicating an enrichment of VLDL with TAG, 2) moreover, the LPL activity was positively related to the HDL-C and HDL3-C, 3) the HL activity predominated in relation to the HDL, and particularly to the HDL3, as indicated by negative correlations to the both lipids and to the lipid/apoA-I ratios of HDL and HDL3. This lipid depletion of HDL3 was more expressive due to the TAG, while HDL2 appeared to be relatively enriched with TAG, as suggested by correlations of C/TAG ratios with HL activity. The in vivo acceleration of lipoprotein metabolism by heparin resulted in: 1) the reduction of VLDL-TAG and HDL2-TAG, and in the increase of HDL3-TAG, 2) the appearance of positive relation of HDL2-C to the LPL activity and of opposite relation to the HL activity, 3) the lack of HL correlation to the TAG of HDL and HDL3. Even under these conditions no relation of insulin level to any HDL lipid was revealed. The results suggest that in normal human the HL affects more considerably than LPL the lipid metabolism of HDL subfractions and it does not seem to be under insulin control.