Indirubin-3'-monoxime prevents aberrant activation of GSK-3ß/NF-κB and alleviates high fat-high fructose induced Aß-aggregation, gliosis and apoptosis in mice brain.

Deciphering the molecular mechanisms of amyloid pathology and glial cell-mediated neuroinflammation, offers a novel avenue for therapeutic intervention against neurodegeneration. Recent findings demonstrate a crucial link between activation of glycogen synthase kinase-3ß (GSK-3ß), amyloid deposition and a neuroinflammatory state. However, studies demonstrating the pharmacological effects of GSK-3ß inhibition and the interlinked molecular mechanisms still remain elusive. The present study explores whether high fat-high fructose diet (HFFD)-induced neuropathological changes could be alleviated by indirubin-3'-monoxime (IMX), a GSK-3ß inhibitor. Male Swiss albino mice (8 weeks old) were fed with normal pellet or HFFD for 60 days. HFFD mice were treated with IMX once daily for last 7 days of the experimental period. HFFD fed-mice had significant amyloid deposits in cerebral cortex and hippocampus, and protein expression analyses showed activation of GSK-3ß, nuclear translocation of NF-κB p65 and upregulation of inflammatory (TNF-α, IL-6, COX-2), astrocytic (GFAP), glial surface (CD-68) and pro-apoptotic markers (Bax and caspase-3). IMX treatment promotes the inhibitory phosphorylation of GSK-3ß at Ser9 and moreover, a marked reduction in the phosphorylation of IKK-ß, which prevents translocation and activation of NF-κB. Protein expression studies in IMX-treated brain tissues positively correlate with the anti-neuroinflammatory effects of GSK-3ß inhibition. Taken together, our results provide substantial evidence that IMX could potentially attenuate neuroinflammation in coordination with the master transcription factor-NF-κB.

Nitric oxide mediates the insulin sensitizing effects of ß-sitosterol in high fat diet-fed rats.

ß-Sitosterol has been shown to have antidiabetic and antioxidant effects in animal models. The objective of the study is to investigate the effects of ß-sitosterol on insulin sensitivity, oxidative and nitrosative stress and lipid abnormalities in liver of high fat-fed rat model of insulin resistance (IR) and to assess whether nitric oxide (NO) is involved in its action. Adult male albino Wistar rats of body weight 150-180g were fed either control diet (CON) or high fat diet (HFD). Each dietary group was divided into two and treated or untreated with ß-sitosterol (10mg/kgb.w.(-1)day(-1)) for 4weeks. Inhibition of total nitric oxide synthase (NOS) by administration of nitro-l-arginine methyl ester (L-NAME) and inducible NOS (iNOS) by aminoguanidine (AG) in HFD and HFD+ ß-sitosterol groups were accomplished to identify the role of NO. After 28days, assays were performed in plasma and liver. HFD-fed rats showed hyperglycemia, hyperinsulinemia, IR, oxidative damage, nitrosative stress, lipid accumulation and elevated serum aminotransferases. Increased expression of iNOS and decreased expression of endothelial NOS (eNOS) were observed in them. Hepatic fat accumulation was further confirmed by histology. The biochemical and histological abnormalities associated with HFD feeding were significantly reduced by ß-sitosterol administration. Administration of L-NAME to HFD-fed rats caused decrease in insulin sensitivity and increase in oxidative stress. Co-administration of L-NAME for the last seven days to ß-sitosterol-treated HFD rats abolished the glucose lowering effect of ß-sitosterol, but the ability to decrease oxidative stress remained unaltered. On the other hand, administration of AG resulted in improved glucose homeostasis and antioxidant levels but decreased oxidative stress and enhanced antioxidant potential in both HFD and HFD+ ß-sitosterol treated groups. Thus, ß-sitosterol promotes insulin sensitivity in rats fed HFD possibly by improving NO levels. With additional studies, ß-sitosterol might be used as a functional drug or as an adjuvant in the management of IR and associated fatty liver disease.

Antioxidant potential of Coriandrum sativum L. seed extract.

The seeds of C. sativum are used as a traditional drug for the treatment of diabetes. The antioxidant and free-radical-scavenging property of seeds in vitro was studied and also investigated whether the administration of seeds curtails oxidative stress in the kidney of streptozotocin-induced diabetic rats. Incorporation of seed powder in the diet led to marked lowering of blood glucose and a rise in the levels of insulin in diabetic rats. A parallel beneficial effect was observed on oxidant -antioxidant balance in the kidney. Addition of coriander seed powder not only inhibited the process of peroxidative damage but also significantly reactivated the antioxidant enzymes and antioxidant levels in diabetic rats. The total polyphenolic content of the seeds was found to be 12.2 gallic acid equivalents (GAE)/g while total flavanoid content was found to be 12.6 quercetin equivalents/g. The seeds also showed scavenging activity against superoxides and hydroxyl radicals in a concentration-dependent manner. Maximum free radical-scavenging action and free radical reducing power of coriander seed extract was observed at a concentration of 50 microg GAE. Islet histology structures showed degeneration of pancreatic islets in diabetic rats which was also reduced in diabetic rats treated with seed powder. These results show that C. sativum seeds not only possess antihyperglycemic properties but antioxidative properties also. Increased dietary intake of coriander seeds decrease the oxidative burden in diabetes mellitus.

Insulin resistance induced by a high-fructose diet potentiates thioacetamide hepatotoxicity.

INTRODUCTION: Insulin resistance (IR) is recognised as an aetiopathogenic factor for a variety of liver diseases. This study investigated the susceptibility of the liver to the toxic actions of thioacetamide (TA) in a rat model of IR, induced by feeding the rats a high-fructose diet (60 g/100 g) for 30 days. METHODS: Hepatic function and damage were assessed at 0 hour and at 6, 12, 24 and 36 hours after a sublethal dose of TA (300 mg/kg intraperitoneally) was administered. RESULTS: After 30 days of fructose feeding, the rats showed IR, a decline in their liver antioxidant status and a rise in lipid peroxidation. Liver dysfunction in fructose-fed rats was evident from a rise in transaminase and total bilirubin, a decrease in the albumin/globulin ratio in plasma, a decrease in nitrite and arginase, and an increase in protein carbonyl and nitrosothiol content in the liver. Increased staining for the 3-nitrotyrosine antibody was observed in the fructose-fed rat livers as compared to the controls. TA (300 mg/kg) caused 80 percent mortality in fructose-fed rats within 48 hours, while no death occurred among the controls. CONCLUSION: Fructose-fed rats suffered from liver dysfunction and damage. TA caused liver injury in both control and fructose-fed rats. Time-based studies showed that progressive liver injury occurred only in rats that were fructose-fed from 6, 12 and 24 hours after TA administration, with a peak at 36 hours. In control diet-fed rats, the extent of damage was maximal at 24 hours, and declined at 36 hours. Thus, the toxic effects of TA are potentiated due to compromised liver function in the setting of IR.

Insulin resistance induced by high-fructose diet potentiates carbon tetrachloride hepatotoxicity.

Insulin resistance (IR) is recognized as a contributory factor for a variety of liver diseases. The present study investigates the susceptibility of liver to the toxic actions of carbon tetrachloride (CCl(4)) in a rat model of IR, induced by feeding a high-fructose diet (60 g/100 g) for 30 days. A sub-lethal dose of CCl(4) (2 mL/kg intraperitoneally [i.p.], in corn oil) was administered and the outcome of hepatotoxicity was assessed at 0 hour and at 6, 12, 24 and 36 hours after CCl(4) administration. After 30 days of fructose feeding, the rats showed IR, decline in liver antioxidant status and rise in lipid peroxidation. Liver dysfunction in fructose-fed rats was evident from a rise in transaminases, total bilirubin and a decrease in albumin/globulin ratio in plasma and decreases in nitrite, arginase and increase in protein carbonyl and nitrosothiol content in liver. Increased staining for 3-nitro tyrosine (3-NT) antibody was observed in fructose-fed rat liver as compared to control. CCl(4) (2 mL/kg) caused 100% mortality in fructose-fed rats within 48 hours, while no death of animals occurred in control. CCl(4) caused liver damage in both control and fructose-fed rats. Time-based studies showed that progressive liver injury occurred only in fructose-fed rats from 0, 6, 12, 24 hours, with a peak at 36 hours. In control diet-fed rats, the extent of damage was maximum at 24 hours, which declined at 36 hours. Thus, the toxic effects of CCl(4) are potentiated due to compromised liver function in the setting of IR.

Mitochondrial damage, cytotoxicity and apoptosis in iron-potentiated alcoholic liver fibrosis: amelioration by taurine.

Taurine effectively prevents ischemia-induced apoptosis in the cardiomyocytes and hypothalamic nuclei. The present study explores the influence of taurine on mitochondrial damage, oxidative stress and apoptosis in experimental liver fibrosis. Male albino Wistar rats were divided into six groups and maintained for a period of 60 days as follows: Group I, control; Group II, ethanol treatment [6 g/(kg/day)]; Group III, fibrosis induced by ethanol and iron (0.5% w/w); Group IV, ethanol + iron + taurine (2% w/v); Group V, ethanol + taurine treatment and Group VI, control + taurine treatment. Hepatocytes isolated from ethanol plus iron-treated rats showed decreased cell viability and redox ratio, increased reactive oxygen species formation, lipid peroxidation, DNA fragmentation, and formation of apoptotic bodies. Liver mitochondria showed increased susceptibility to swell, diminished activities of mitochondrial respiratory chain complexes and antioxidants. Taurine administration to fibrotic rats restored mitochondrial function, reduced reactive oxygen species formation, prevented DNA damage, and apoptosis. Thus taurine might contribute to the amelioration of the disease process.

Induction of alcohol-metabolizing enzymes and heat shock protein expression by ethanol and modulation by fenugreek seed polyphenols in Chang liver cells.

The present study investigated the effect of fenugreek seed polyphenolic extract (FPEt) on ethanol-induced protein expression in Chang liver cells. Cells were incubated with either 30 mM EtOH alone or together in the presence of FPEt for 24 h. Cells were harvested and assessed for expression of alcohol metabolizing enzymes-alcohol dehydrogenase (ADH(2) isoform), aldehyde dehydrogenase (ALDH(2) isoform), cytochrome P450 (CYP2E1), the electron transport component (cytochrome-c), and the heat shock proteins. The expression of ADH(2), ALDH(2), and CYP2E1 were upregulated, whereas the expression of cytochrome-c was downregulated in the ethanol-treated cells. The expression of cellular heat shock proteins-HSP70, HSC70, HSC92, and mitochondrial protein mtHSP70 were induced in ethanol-treated Chang liver cells. FPEt modulated the protein expression changes induced by ethanol and had no effect when incubated with normal Chang liver cells. FPEt might exert cytoprotective action on ethanol-induced liver cell damage, possibly by enhancing cellular redox status.

Insulin sensitizing actions of fenugreek seed polyphenols, quercetin & metformin in a rat model.

BACKGROUND & OBJECTIVE: Plant polyphenols have been known to exert anti-diabetic action and promote insulin action. The present study was carried out to compare the effects of administration of fenugreek seed polyphenolic extract (FPEt), quercetin and metformin (a positive control) in an acquired model of insulin resistance (IR). METHODS: Adult male Wistar rats divided into seven groups (n=12). IR was induced in groups (groups 2, 3, 4 and 5) by feeding a high fructose diet (FRU) (60 g/100 g diet) for 60 days. From day 16, FRU rats were administered either FPEt (200 mg/kg bw) (group 3), quercetin (50mg/kg bw) (group 4) or metformin (50 mg/kg bw) (group 5) for the next 45 days. Group 1 served as normal control while groups 6 and 7 served as FPEt and quercetin controls respectively. Oral glucose tolerance test (OGTT) was done on day 59 to assess glucose tolerance. At the end of 60 days, the levels of glucose, insulin, triglycerides (TG) and free fatty acids (FFA) were measured in the blood and the activities of insulin-inducible and suppressible enzymes in cytosolic and mitochondrial fractions of liver and skeletal muscle. The extent of tyrosine phosphorylation of proteins in response to insulin was determined by assaying protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) in liver. RESULTS: Fructose caused increased levels of glucose, insulin, TG and FFA, alterations in insulin sensitivity indices, enzyme activities and reduced glycogen content. Higher PTP activity and lower PTK activity suggest reduced tyrosine phosphorylation status. Administration of FPEt or quercetin improved insulin sensitivity and tyrosine phosphorylation in fructose-fed animals and the effect was comparable with that of metformin. INTERPRETATION & CONCLUSION: Our findings indicated that FPEt and quercetin improved insulin signaling and sensitivity and thereby promoted the cellular actions of insulin in this model.

Impact of Essentiale L on ethanol-induced changes in rat brain and erythrocytes.

INTRODUCTION: The present study was designed to investigate the effect of Essentiale L, a mixture of polyenylphospholipids from soybeans, on oxidative stress in various brain regions, on erythrocytes (RBC) and on RBC membrane composition in ethanol-administered rats. METHODS: Adult male albino rats of body weight 150-170 g were divided into four groups and administered either isocaloric glucose (5 g/kg body weight/day) or ethanol (6 g/kg body weight/day) through oral gavage. Essentiale L was administered to a set of ethanol-fed rats and the control rats at a dosage of 300 mg/kg body weight/day through oral gavage. The treatment protocol was carried out for 45 days. At the end of the experimental period, the animals were sacrificed, and the biochemical parameters related to the lipid profile, oxidative stress and thiol status were assayed in the brain regions, RBC and RBC membrane. RESULTS: Ethanol administration resulted in increased levels of lipid peroxidation products in RBC and different brain regions, such as the cortex, cerebellum, striatum, hippocampus and hypothalamus, and depletion of enzymatic and nonenzymatic antioxidants and alterations in oxidised glutathione/glutathione (GSSG/GSH) ratio and thiol groups (protein-bound and total), signifying oxidative stress. Ethanol-treated rats also showed significant alterations in protein content and lipid composition in RBC membranes. Significant differences in the relative proportions of hexose, hexosamine and sialic acid of the membranes were observed. Administration of Essentiale L prevented all the alterations induced by ethanol and returned their levels to near-normal. CONCLUSION: These findings suggest that Essentiale L, a therapeutic adjunct for liver diseases, also has bioprotective effects on nonhepatic tissues and cells.

Protective action of fenugreek (Trigonella foenum graecum) seed polyphenols against alcohol-induced protein and lipid damage in rat liver.

The study investigates the effect of fenugreek seed polyphenol extract (FPEt) on ethanol-induced damage in rat liver. Chronic ethanol administration (6 g kg(-1) day(-1) x 60 days) caused liver damage that was manifested by excessive formation of thiobarbituric-acid-reactive substances, lipid hydroperoxides, and conjugated dienes, the end products of lipid peroxidation, and significant elevation of protein carbonyl groups and diminution of sulfhydryl groups, a marker of protein oxidation. Decreased activities of enzymic and non-enzymic antioxidant levels and decreased levels of thiol groups (both non-protein and protein) were observed in ethanol-treated rats. Further, ethanol significantly increased the accumulation of 4-hydroxynonenal protein adducts, nitrated and oxidized proteins in liver which was evidenced by immunohistochemistry. Administration of FPEt to ethanol-fed rats (200 mg kg(-1) day(-1)) significantly reduced the levels of lipid peroxidation products and protein carbonyl content, increased the activities of antioxidant enzymes, and restored the levels of thiol groups. The effects of FPEt were comparable with those of a positive control, silymarin. These findings show that FPEt ameliorates the pathological liver changes induced by chronic ethanol feeding.

Renoprotective action of L-carnitine in fructose-induced metabolic syndrome.

AIM: Rats fed high dosage of fructose that form a well-known experimental model of the metabolic syndrome also display progressive renal disturbances. The present study evaluates the influence of l-carnitine (CA) administration on oxidant-antioxidant balance, protein damage and lipid levels in kidney of rats administered high dose of fructose. METHODS: Adult male Wistar rats were divided into four groups of 10 rats each. Groups I and IV animals received starch-based control diet, while groups II and III rats were fed a high-fructose diet (60 g/100 g). Groups III and IV animals additionally received CA (300 mg/kg/day) for 60 days. The extent of lipid peroxidation, enzymatic and non-enzymatic antioxidants and lipid levels were measured after 60 days. The accumulation of nitrated and oxidatively modified proteins in kidney was also measured by immunohistochemical study with specific antibodies. RESULTS: Fructose-fed rats exhibited increased levels of peroxidation end products, diminished antioxidant status, increased staining for the presence of 4-hydroxy-2-nonenal, 2,4-dinitrophenol and 3-nitrotyrosine protein adducts and lipid accumulation in kidney. CA administration attenuated these pathological renal alterations. CONCLUSIONS: The benefits of CA in this model suggest the therapeutic use of CA to counter the kidney changes associated with metabolic syndrome.

Epigallocatechin gallate, a green tea phytochemical, attenuates alcohol-induced hepatic protein and lipid damage.

ABSTRACT Oxidative damage to cellular constituents is one of the major mechanisms of alcoholic liver injury, and administration of antioxidants ameliorates alcoholic liver disease. The present study investigated the influence of (-) epigallocatechin gallate (EGCG), a major polyphenol component of green tea, on oxidant-antioxidant balance, protein, and lipid damage in liver of rats fed ethanol. Chronic ethanol administration (6 g/kg/day x 60 days) caused liver damage that was manifested by excessive formation of lipid peroxidation end products such as thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides (LHP), and conjugated dienes (CD) accompanied by a reduction in enzymic and non-enzymic antioxidant levels. Further, ethanol caused a rise in protein carbonyl formation and loss of protein thiol groups. Ethanol-fed rats exhibited increased staining for the presence of 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT), and 2,4-dinitrophenol (DNP) protein adducts in liver. The detrimental effects of ethanol were alleviated upon simultaneous treatment with EGCG (100 mg/kg/day) for the last 30 days of alcohol feeding. These findings show that EGCG ameliorates protein and lipid damage induced by the hepatotoxin, ethanol.

(-) Epigallocatechin Gallate (EGCG) Prevents Lipid Changes and Collagen Abnormalities in Chronic Ethanol-Fed Rats.

ABSTRACT The objective of the study is to examine the influence of (-) epigallocatechin gallate (EGCG), a green tea component, on lipid and collagen abnormalities in chronic ethanol-fed rats. Solubility properties, aldehyde content, fluorescence, and peroxidation were analyzed in collagen samples isolated from liver. Chronic alcoholism (6 g/kg/day x 60 days) was associated with fatty liver and collagen accumulation. Significant alterations in the levels of lipids (cholesterol, phospholipids, free fatty acids, and triglycerides) and total collagen were observed in liver. Collagen obtained from ethanol-fed rats showed alterations in solubility properties, increased fluorescence, peroxidation, and aldehyde content. Coadministration of EGCG along with ethanol significantly reduced the levels of liver lipids and collagen, improved the solubility properties of collagen, and caused a reduction in cross-linking as evidenced by a decrease in fluorescence, peroxidation, and aldehyde content. Histology of liver sections of ethanol-fed rats showed accumulation of fat and collagen, which were largely prevented by EGCG administration. The possible mechanisms in the protective action of EGCG in alcoholic liver disease are suggested and discussed.

Beneficial impact of L-carnitine in liver: a study in a rat model of syndrome X.

The present study was designed to explore whether L-carnitine (CA) regulates insulin signaling and modulates the changes in liver in a well-characterized insulin resistant rat model. Adult male Wistar rats were divided into 4 groups. Groups I and IV animals received starch-based control diet, while groups II and III rats were fed a high fructose-diet (60 g/100 g). Groups III and IV animals additionally received CA (300 mg/kg/day i.p). After a period of 60 days hepatic tyrosine phosphorylation status was determined by assaying protein tyrosine phosphatase (PTP) and protein tyrosine kinase (PTK) activities. Oxidative damage was monitored by immunohistochemical localization of 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT) and dinitrophenol (DNP)-protein adducts. In addition protein kinase C beta II (PKC beta II) expression, propidium iodide staining of isolated hepatocytes and histology of liver tissue were determined to examine liver integrity. Fructose-fed rats displayed reduced insulin action, increased expression of PKC beta II, altered histology, fragmentation of hepatocyte nuclear DNA, and accumulation of oxidatively modified proteins. Simultaneous treatment with CA alleviated the abnormalities associated with fructose feeding. In summary the data suggest that elevated oxidative damage and PKC expression could in part induce insulin resistance and CA has beneficial impact on liver during insulin resistance with modulatory effects at the post-receptor level.

Changes in redox ratio and protein glycation in precataractous lens from fructose-fed rats: effects of exogenous L-carnitine.

1. Rats fed high dietary fructose are documented to form an acquired model of insulin resistance. The present study measured the effects of administration of L-carnitine (CA) on lens protein glycation, oxidative stress and redox homeostasis in rats fed a high-fructose diet. 2. Animals were divided into four groups: (i) an untreated control group (fed starch diet); (ii) an untreated fructose-group (fed a high-fructose diet); (iii) a CA-treated (300 mg/kg per day), fructose-fed group; and (iv) a CA-treated, starch-fed group. After 60 days treatment, lenses were dissected and multiple oxidative stress markers, glycation of proteins and the ratio of oxidized to reduced glutathione (GSSG/GSH) were determined. 3. A significant decline in enzyme and non-enzyme anti-oxidants and an increase in lipid peroxidation products, protein oxidation, protein glycation, GSSG/GSH ratio and aldehyde formation were observed in lens samples obtained from fructose-fed rats. Administration of CA to fructose-fed rats significantly attenuated oxidative damage and protein glycation and returned levels of anti-oxidants to near those seen in the control group. 4. The results of the present study indicate that dietary fructose disturbs lens integrity and exogenous CA may safeguard the lens by preventing glycation and oxidative stress.

Increase in nitric oxide and reductions in blood pressure, protein kinase C beta II and oxidative stress by L-carnitine: a study in the fructose-fed hypertensive rat.

Recently we showed that the administration of intraperitoneal L-carnitine (CA) has insulin-sensitizing effects in the high fructose-fed Wistar rat, a widely used model of metabolic syndrome. The present study was conducted to examine the regulatory effects of CA on blood pressure (BP) and related pressor mechanisms. Fructose-fed rats (FFR) showed elevated BP, cardiac hypertrophy, glucose intolerance, and increases in plasma glucose, insulin, free fatty acids (FFA), and angiotensin-converting enzyme (ACE) activity. They also showed increased protein kinase C betaII (PKC betaII) expression and oxidative stress in cardiac tissue. In plasma, decreased kallikrein enzyme activity and nitric oxide metabolites were observed, compared to control. Simultaneous treatment with CA (300 mg/Kg) mitigated these alterations. PKC betaII expression was similar to that of control; the rats displayed normal BP and ACE activity, enhanced antioxidant protection, and close to normal values of metabolic parameters. The BP-lowering effect of CA was abolished when CA-treated rats were administered L-nitroarginyl methyl ester (L-NAME 6g/Kg). These observations suggest that the BP-lowering action of CA in this model could be attributed to multiple and interrelated mechanisms, such as an increase in NO and kinin availability, reduction in PKC action, and antioxidant protection.

Evaluation of in vitro antioxidant activity of Indian bay leaf, Cinnamomum tamala (Buch. -Ham.) T. Nees & Eberm using rat brain synaptosomes as model system.

The study investigated the perturbation of oxidant-antioxidant balance in brain synaptosomes of diabetic rats and determined the antioxidant and free radical-scavenging property of the Indian bay leaf. Brain synaptosomes were isolated from control and streptozotocin-induced diabetic animals and oxidative stress parameters were assayed. A methanolic extract of bay leaf (BLE) was tested for the polyphenolic content and antioxidant activity by in vitro assays. A significant increase in the levels of lipids and lipid peroxidation products and a decline in antioxidant potential were observed in diabetic rat brain synaptosomes. The total polyphenolic content of BLE was found to be 6.7 mg gallic acid equivalents (GAE)/100g. BLE displayed scavenging activity against superoxide and hydroxyl radicals in a concentration-dependent manner. Further, BLE showed inhibition of Fe(2+)-ascorbate induced lipid peroxidation in both control and diabetic rat brain synaptosomes. Maximum inhibition of lipid peroxidation, radical scavenging action and reducing power of BLE were observed at a concentration of 220 microg GAE. These effects of BLE in vitro were comparable with that of butylated hydroxyl toluene (BHT), a synthetic antioxidant. It can be concluded that synaptosomes from diabetic rats are susceptible to oxidative damage and the positive effects of bay leaf in vitro, could be attributed to the presence of antioxidant phytochemicals.

Fenugreek (Trigonella foenum graecum) seed polyphenols protect liver from alcohol toxicity: a role on hepatic detoxification system and apoptosis.

The present study investigates the hepatoprotective effect of fenugreek seed polyphenolic extract (FPEt) against ethanol-induced hepatic injury and apoptosis in rats. Chronic ethanol administration (6 g/kg/day x 60 days) caused liver damage that was manifested by the elevation of markers of liver dysfunction--aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), bilirubin and gamma-glutamyl transferase (GGT) in plasma and reduction in liver glycogen. The effects on alcohol metabolizing enzymes such as alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) were studied and found to be altered in the alcohol-treated group. Ethanol administration resulted in adaptive induction of the activities of cytochrome p450 (cyt-p-450) and cytochrome-b5 (cyt-b5) and reduction in cytochrome-c-reductase (cyt-c-red) and glutathione-S-tranferase (GST), a phase II enzyme. Further, ethanol reduced the viability of isolated hepatocytes (ex vivo) as assessed by the trypan blue exclusion test and increased hepatocyte apoptosis as assessed by propidium iodide staining (PI). Treatment with FPEt restored the levels of markers of liver injury and mitigated the alterations in alcohol metabolizing and detoxification enzymes and the electron transport component cytochrome-c reductase. Increased hepatocyte viability and reduced apoptotic nuclei were observed in FPEt-treated rats. These findings demonstrate that FPEt acts as a protective agent against ethanol-induced abnormalities in the liver. The effects of FPEt are comparable with those of a known hepatoprotective agent, silymarin.

Effects of L-carnitine on RBC membrane composition and function in hyperinsulinemic rats.

The purpose of the study was to investigate the effects of L-carnitine (CA) on the susceptibility of erythrocyte (RBC) to peroxide-induced lipid oxidation, RBC membrane composition, ATPases activity and oxidative stress in fructose-fed hyperinsulinemic rats. The rats were subjected to experimental hyperinsulinemia and hyperglycemia by feeding a high fructose diet (60 g/100 g) for 6 weeks. The rats showed significant alterations in the RBC membrane composition. The protein content was lower than control animals, while cholesterol, phospholipids and free fatty acids were higher in fructose-fed animals. Significant differences in the total carbohydrate and relative proportions of hexose, hexosamine, sialic acid and fucose of membranes were observed. In these rats, membrane-bound ATPases (total ATPase, Na+, K+ ATPase, Mg2+ and Ca2+ ATPases) were significantly lower while thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LHP) in RBC membrane were significantly higher than those of control rats. The red cells were more susceptible to peroxide-induced oxidative stress that correlated with reduced levels of vitamin E found RBC membrane. When fructose-diet fed rats were treated simultaneously with CA (300 mg/kg b.w/day, i.p.), such alterations in membrane composition and enzyme activities did not occur. Effects of fructose loading on lipid peroxidation was also alleviated by CA. These findings suggest that high levels of dietary fructose is detrimental to RBC membrane integrity and that CA may have membrane stabilizing effects in this diet-induced model of type 2-diabetes.

L-Carnitine inhibits protein glycation in vitro and in vivo: evidence for a role in diabetic management.

Glycation-initiated changes in tissue proteins are suggested to play an important role in the development of diabetes-related pathological changes. The purpose of this study was to examine the anti-glycating effect of L-carnitine (CA) in vivo in the high-fructose diet-fed rat and to determine the potential of CA to inhibit in vitro glycation. Additionally the glucose-disposal efficiency of CA in the rat diaphragm was investigated. High-fructose diet (60 g/100 g diet)-fed rats were treated with CA (300 mg/kg/day i.p.) for 60 days. The effect of CA on glucose, fructose and fructosamine in plasma, methyl glyoxal and glycated haemoglobin in whole blood and skin and tail tendon collagen glycation were determined. The inhibitory effect of CA on the glycation of bovine serum albumin in vitro was compared with that of aminoguanidine (AG), a known antiglycation agent. Glucose utilisation induced by insulin in the control rat diaphragm was monitored in the presence and absence of CA. High-fructose feeding induced hyperglycaemia and glycation of haemoglobin and skin and tail tendon collagen. In CA-administered fructose-fed rats glycation was significantly reduced. In vitro glycation and accumulation of advanced glycation end products were mitigated by CA. CA was more effective than AG in inhibiting glycation in vitro. CA also enhanced the utilisation of glucose in the rat diaphragm. The findings of the study reveal that CA not only has antiglycation effect but also enhances glucose disposal in the rat diaphragm. These findings provide evidence for the therapeutic utility of CA in diabetes and associated complications.