Alterations in antioxidant enzymes and oxidative damage in experimental diabetic rat tissues: Effect of vanadate and fenugreek (Trigonella foenum graecum)

With the premise that oxygen free radicals may be responsible for the severity and complications of diabetes, the level of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) as well as the oxidative damage were examined in the tissues of control, diabetic and treated rats. After three weeks of diabetes, the activity of CAT was significantly increased in heart in diabetes (about 6-fold) but decreased in liver. The SOD activity decreased significantly in liver but increased in brain. The activity of GPx decreased significantly in liver and increased in kidney. A significant increase was observed in oxidative damage in heart and kidney and a small increase in brain with decrease in liver and muscle. Vanadate and fenugreek (Trigonella foenum graecum) administration to diabetic animals showed a reversal of the disturbed antioxidant levels and peroxidative damage. Results suggest that oxidative stress play a key role in the complications of diabetes. Vanadate and fenugreek seeds showed an encouraging antioxidant property and can be valuable candidates in the treatment of the reversal of the complications of diabetes.     

Carvacrol partially reverses symptoms of diabetes in STZ-induced diabetic rats

Little is known about the protective effects of carvacrol on the symptoms of streptozotocin induced diabetes in rats. Hence, this present study was designed to evaluate the protective effect of the strong antioxidant, carvacrol, on the symptoms of streptozotocin induced diabetes in rats. Carvacrol at the doses of 25 and 50 mg/kg body weight were orally administered to diabetic rats for a period of 7 days after the onset of diabetes. Food-water intake and body weight changes were daily recorded. Biochemical parameters such as serum glucose, insulin, total cholesterol, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were measured. Although treatment of diabetic rats with oral administration of carvacrol resulted in a slight reduction in serum glucose level and significant reduction in serum total cholesterol, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase in comparison with diabetic control rats, there were no significant differences in serum insulin levels, food-water intake values and body weight changes. Despite the inadequacy of carvacrol on diabetes treatments, it was determined to have at least a partially protective role on liver enzymes.     

秋茄枝乙醇提取物减轻链脲佐菌素诱导的大鼠肝脏和胰腺病理损伤

目的:研究秋茄枝乙醇提取物(EEK)对链脲佐菌素(STZ)诱导的2型糖尿病(T2DM)大鼠肝脏和胰腺组织病理结构的影响。方法:以高脂饲料喂养联合STZ建立T2DM大鼠模型。大鼠分为为正常对照组、T2DM模型组、二甲双胍组、EEK低、中、高剂量组。大鼠给药4周后处死,取肝脏和胰腺进行组织病理学检查。结果:随着EEK剂量的增加,大鼠肝脏和胰岛组织的病理损伤逐步减轻。结论:EEK有助于修复STZ诱导的T2DM大鼠受损的肝脏和胰岛组织。     

Differential effects of acetaminophen on enzymatic and non-enzymatic antioxidant factors and plasma total antioxidant capacity in developing and adult rats

Recently we reported that ferric reducing ability of plasma (FRAP) assay, as an index of total antioxidant activity, increases in growing rats in response to high dose of vitamin K. In this study, it was found that acetaminophen (APAP) can cause elevation in FRAP in suckling and adult rats. This study was initiated to assess the contribution of individual antioxidant factors on elevation in FRAP. A surge in FRAP, 1 h after high dose APAP (250 or 450 mg/kg BW) administration was recorded in both young as well as adults. Whereas, low dose drug (25 mg/kg) failed to alter FRAP in both the age groups. Time-course studies show that drug-dependent elevation in FRAP begin rapidly, reaching a maximum at 1 h (> 500%). Increased FRAP was associated with a marked increase (∼14-fold) in plasma bilirubin, 6 h after drug administration at 450 mg/kg only in suckling rats. Similarly, APAP-related increase in superoxide dismutase activity in erythrocytes was limited to young rats of both the age groups. Other factors measured during this period viz., plasma uric acid, bilirubin and total protein together with catalase activity of erythrocytes remained unchanged in treated rats. Under these circumstances, APAP-related depletion in liver glutathione was almost similar in both the age groups. During a 12 h study, the concentration of lipid peroxidation products, in liver of treated groups remained within the levels of respective controls. The endpoint hepatotoxic effects of APAP was almost similar in both the age groups, suggesting that like adults, immature rats can cope with toxic effects of APAP owing to their drug-dependent induction in certain antioxidant factors.     

In vitro toxicity and antidiabetic activity of a newly developed polyherbal formulation (MAC-ST/001) in streptozotocin-induced diabetic Wistar rats

The present study was designed to investigate the hypoglycemic effect of an aqueous extract of MAC-ST/001 (a new polyherbal formulation) which was given once daily to rats at different doses. The animals were divided into diabetic and nondiabetic control groups. The duration of each experiment lasted from 1 week to 1 month, and the results were compared with that of the standard hypoglycemic drug glibenclamide (10 mg/kg), which was given once daily. In this study, biochemical and histopathological parameters were studied in streptozotacin (STZ) (single intraperitoneal injection of 55 mg/kg)-induced diabetic rats. The diabetic rats showed a significant (p?<?0.05 and p?<?0.01) decrease in their body weight and serum amylase with marked elevation in blood glucose, serum cholesterol, blood urea nitrogen, creatinine, alkaline phosphatase, and serum transaminases (AST and ALT) after 1 week till the 28th day of diabetes. Cytotoxicity of MAC-ST/001 formulation was also studied on C2C12, 3T3-L1, and HepG2 cells through MTT assay. Histological examination of the liver and pancreas of normal control, diabetic control, and drug-treated rats revealed significant results. Finally, it was concluded that administration of this MAC-ST/001 extract reversed most blood and tissue changes caused by STZ-induced diabetes in rats.     

Fenugreek seed (<Emphasis Type="Italic">Trigonella foenum graecum</Emphasis>) polyphenols inhibit ethanol-induced collagen and lipid accumulation in rat liver

Chronic alcoholism is associated with fatty liver and fibrosis characterized by collagen accumulation. Seeds of fenugreek, an annual herb, are reported to possess hepatoprotective activity. The study aims to investigate the effects of fenugreek seed polyphenol extract (FPEt) on liver lipids and collagen in experimental hepatotoxic rats. Hepatotoxicity was induced in male albino Wistar rats by administrating ethanol (6 g/kg per day) for 30 days. Control rats were given isocaloric glucose solution. FPEt was co-administered with ethanol at a dose of 200 mg/kg per day for the next 30 days. Silymarin was used as a positive control. Ethanol treatment caused increase in plasma and liver lipids, together with alterations in collagen content and properties. Administration of FPEt to alcohol-fed rats significantly improved lipid profile and reduced collagen content, crosslinking, aldehyde content and peroxidation. The effects were comparable with that of silymarin. FPEt administration had a positive influence on both lipid profile and on the quantitative and qualitative properties of collagen in alcoholic liver disease. The protective effect is presumably due to the bioactive phytochemicals in fenugreek seeds.     

Protective effect of Lawsonia alba Lam., against CCl4 induced hepatic damage in albino rats

The oral administration in varying doses of aqueous suspension of extract of L. alba, bark extract to rats for 10 days afforded good hepatoprotection against CCl4 induced elevation in serum marker enzymes, serum bilirubin, liver lipid peroxidation and reduction in total serum protein, liver glutathione, glutathione peroxidase, glutathione-s-transferase, glycogen, superoxide dismutase and catalase activity. The results suggest hepatoprotective and antioxidant activity of extract of L. alba bark.     

Increased DNase I activity in diabetes might be associated with injury of pancreas

DNase I is an endonuclease responsible to destruction of chromatin during apoptosis. However, its role in diabetes is still unclear. With blood samples from our previous study related to type 2 diabetes, we examined the DNase I activity in the serum of these patients and the role of DNase I in the injury of pancreas was further investigated in rats and INS-1 cells. Serum and pancreatic tissues from human and rats were used for the study. Insulin resistance and diabetes were induced by high fat diet and STZ injection, respectively. DNase I activity was determined by radial enzyme-diffusion method. Expressions of DNase I and caspase-3 in pancreas were determined in rat pancreatic tissues and INS-1 cells. Apoptosis of INS-1 cells was determined by both TUNEL assay and Flow Cytometry. There was a significant elevation of DNase I activity in serum of patients with type 2 diabetes and rats with STZ injection. Moreover, increase in DNase I expression was observed in the pancreas of diabetic person and rats. Furthermore, high glucose induced both DNase I and caspase-3 expression and at the same time increased apoptosis rate of INS-1 cells. In conclusion, elevated DNase I in diabetes may be related to pancreatic injury and could be one of the causes that induce diabetes.     

Gender- and age-related changes in 6-phosphogluconate dehydrogenase gene expression in white adipose tissue of rats (Rattus norvegicus) are not related to serum testosterone concentration

Previously, we have shown that the age-related changes in 6-phosphogluconate dehydrogenase (6PGDH) activity depend on sex, and that oestradiol is playing a crucial role in the regulation of 6PGDH gene expression in rat liver, but not in other tissues [Pankiewicz, A., Sledzinski, T., Nogalska, A., Swierczynski, J., 2003. Tissue specific, sex and age-related differences in the 6-phosphogluconate dehydrogenase gene expression. Int. J. Biochem. Cell Biol. 35, 235-245.]. To complete the knowledge on the influence of sex hormones on 6PGDH activity, experiments have been performed on the effect of testosterone on 6PGDH gene expression in rat white adipose tissue and liver. The results presented here disclosed that in young male rats high serum testosterone concentration was associated with high white adipose tissue 6PGDH activity. After orchidectomy, a decrease in serum testosterone concentration (both in young and old rats) was observed. In contrast, no changes in white adipose tissue and liver 6PGDH activity were found. In female rats, both young and old, serum testosterone concentration was below the limit of detection, whereas 6PGDH activity was much higher in young than in old animals. Moreover, the testosterone administration to 9-month old male rats (which displayed much lower serum testosterone concentration that young animals) resulted in no effect on 6PGDH activity either in WAT or in the liver. In conclusion, the results presented in this paper indicate that testosterone does not play any role in the age- and gender-related differences in 6PGDH gene expression in white adipose tissue.     

Evaluation of antidiabetic activity of Pleurotus pulmonarius against streptozotocin-nicotinamide induced diabetic wistar albino rats

The current research aims to evaluate the antidiabetic properties of Pleurotus pulmonarius, an edible basidiomycetes mushroom fungi in diabetic induced wistar albino rats. Mycelial Hot Water Extracts (HWE) and Acetone Extracts (AE) of Pleurotus pulmonarius was orally administrated to STZ-NA induced (55 mg/kilogram body weight) diabetic wistar albino rats at a concentration of 200 and 400 mg/kg for 4 weeks. The outcomes revealed that the HWE of Pleurotus pulmonarius resulted in a significant (p < 0.001) reduction in blood glucose level. A noteworthy (p < 0.001) reduction in serum lipid profile and elevation in High-Density Lipoprotein Cholesterol (HDL-C) after administration with HWE, also demonstrating the protective effects of HWE in diabetes-related complications. Besides all antidiabetic parameters, pathological morphology of the pancreas, liver and kidney are regularised. This observation indicated that HWE of Pleurotus pulmonarius possessed higher antidiabetic activity than AE. Besides, HWE also promoted a significant control of alpha amylase enzyme in a concentration-dependent manner with a maximum activity of 99.23% inhibition at 1000 µg/ml. The outcomes of the present study indicated that the HWE possesses a potential antidiabetic activity both in vitro and in vivo. Thus, it can be used as a nontoxic complementary drug in the controlling of diabetes and related complications, thus providing scientific authentication of its use as an antidiabetic agent.     

Role of pectin from cucumber (Cucumis sativus) in modulation of protein kinase C activity and regulation of glycogen metabolism in rats

The regulatory role of protein kinase C (PKC) in glycogen metabolism in pectin fed rats was investigated. Administration of pectin (5 g/kg body wt/day) from cucumber (Cucumis sativius L.) led to inhibitory effects on PKC activity in the liver of rats. In the brain and pancreas, PKC activity was significantly higher in pectin-treated rats as compared to the control group. Level of blood glucose was significantly lowered and the level of glycogen in the liver was significantly increased in pectin-administered rats. Glycogen synthase activity was enhanced, while glycogen phosphorylase enzyme showed inhibition in pectin-treated rats. Results indicated that pectin administration might have caused an increase in the secretion of the insulin, which, in turn, had a stimulatory effect on the PKC activity in the pancreas. The decreased PKC activity in the liver and increased PKC activity in the brain and pancreas on pectin administration indicated enhanced glycogenesis and reduced glycogenolysis.     

Postnatal maturation patterns of serum corticosterone and growth hormone in rats: effect of chronic thyroxine administration.

The effects of chronic neonatal hyperthyroidism in rats on the ontogenic pattern of serum corticosterone and growth hormone (GH) were studied. Thyroxine (T4) treated and saline injected rat pups were sacrificed under basal and stress conditions. In comparison to saline control animals, daily T4 administration (0.4 micrograms/gram body weight) produced a sustained elevation in basal corticosterone levels by day 12 and a significant elevation of serum corticosterone in response to stress by day 4. The serum GH levels in non-stressed animals were moderately decreased in response to T4 administration as compared to saline injected animals with a greater reduction in GH measured in samples obtained from stressed animals. The results indicate that chronic T4 administration influences the developmental pattern of serum corticosterone and GH under both non-stress and stress conditions.     

Elevated body fat in rats by the dietary nitric oxide synthase inhibitor, L-N omega nitroarginine.

The influence of the dietary nitric oxide (NO) synthase inhibitor, L-N omega nitroarginine (L-NNA) on body fat was examined in rats. In experiment 1, all rats were fed with the same amount of diet with or without 0.02% L-NNA for 8 wk. L-NNA intake caused elevations in serum triglyceride and body fat, and reduction in serum nitrate (a metabolite of nitric oxide). The activity of hepatic carnitine palmitoyltransferase was reduced by L-NNA. In experiment 2, rats were fed for 8 wk with the same amount of diets with or without 0.02% L-NNA supplemented or not with 4% L-arginine. The elevation in body fat, and the reductions in serum nitrate and in the activity of hepatic carnitine palmitoyltransferase by L-NNA were all suppressed by supplemental L-arginine. The results suggest that lower NO generation elevated not only serum triglyceride, but also body fat by reduced fatty acid oxidation.     

Decreased activity and impaired induction of nitric oxide synthase by lipopolysaccharides in streptozotocin-induced diabetic rats

The effect of diabetes was determined on nitric oxide synthase (NOS) activity in rat heart and liver. The diabetes was induced by streptozotocin (STZ) and NOS activity was determined after 1 or 12 weeks post-STZ injection. In both tissues, the majority of NOS activity was associated with endothelial constitutive calcium-sensitive NOS (ecNOS) isoform and found in the particulate (100,000xg pellet) fraction in young rats. The diabetes as well as age reduced this activity significantly in heart, whereas only the age caused a decrease in ecNOS activity in liver tissue. Lipopolysaccharides (LPS) induced calcium-insensitive iNOS activity in both young and old rats. The induction was significantly higher (up to 10-fold) in liver as compared to heart. Although the maximum induction of iNOS in young rats was almost similar in diabetic tissues as compared to control animals, there was a lag period for induction of iNOS in diabetic tissues. In old diabetic rats, the induction by LPS was almost completely abolished. These results suggest that diabetes causes either no change or a decrease in ecNOS activity and impairment in the induction of iNOS by LPS in rat heart and liver.     

Monocytes and platelets share the glycoproteins IIb and IIIa that are absent from both cells in Glanzmann's thrombasthenia type I.

The possibility that thyroxine (T4) itself exerts the hormonal effect in vivo on the rat liver nuclear receptor was studied with the aid of iopanoic acid (IOP), an inhibitor of the conversion of T4 into tri-iodothyronine (T3). After administration of 2.4 micrograms of T4/100 g body weight to hypothyroid rats for 7 days, T4 and T3 concentrations in serum and in the liver nuclear non-histone protein (NHP) were all increased to the hyperthyroid range. Hepatic mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) activity and DNA content increased significantly. The equilibrium association constant (Ka) of the nuclear T3 receptor was unchanged and the maximal binding capacity (Cmax.) increased 1.4-fold. Simultaneous administration of IOP (5 mg/100 g body weight) to the rats given 2.4 micrograms of T4/100 g body weight completely blocked the conversion into T3. The serum T4 was even more increased, whereas the serum T3 decreased to the hypothyroid range. Although the NHP-bound T4 was at a concentration comparable with the rats given T4 alone, no NHP-bound T3 was detected. Yet the alpha-GPD activity was elevated 2.8-fold and the DNA content increased to the same extent as observed in the rats given T4 alone. The Ka and Cmax. of the nuclear receptor were significantly decreased. After administration of 48 or 480 micrograms of T4/100 g body weight for 3 days, serum T4 and T3 were markedly increased. The NHP-bound T3 was also increased, but no NHP-bound T4 was detected. The alpha-GPD activity was markedly elevated, but the DNA content was unchanged. The Cmax. per g of liver was increased, whereas the Ka remained unchanged. Simultaneous administration of IOP to these animals could not completely block the T4 conversion. The observed hormonal effects in the absence of nuclear T3 indicate that T4 possesses the intrinsic hormonal activities on the rat liver. T4 is less potent in induction of alpha-GPD activity but as potent in increment of hepatic DNA as T3. Although the binding site for T4 is not fully characterized, it appears to be acidic NHP. T4 is an active hormone, yet is also a prohormone of T3, offering the closest analogy with testosterone.     

Hepatic and intestinal gamma-glutamyltranspeptidase activity: its activation by chronic ethanol administration.

To study the effect of chronic ethanol administration on the activity of gamma-glutamyltranspeptidase (GGTP) in various tissues, female rats were pair-fed liquid diets with 36% of total calories either as ethanol or isocaloric carbohydrate (controls). Six weeks of ethanol feeding in an increase of cytochrome P450 content by 70%. Hepatic microsomal GGTP activity was more than doubled after ethanol feeding whether expressed per gram of liver or per mg of microsomal protein. Furthermore intestinal GGTP activity was significantly enhanced after ethanol, whereas there was no change in the enzyme activity in either kidney or pancreas. Phenobarbital administration to rats also resulted in an enahancement of GGTP activity in the liver but not in the intestine. These results suggest that enhanced hepatic and intestinal GGTP activities may contribute, at least partly, to increased serum GGTP activity frequently seen in alcoholics.     

Mechanism of bromocriptine-induced hyperglycaemia

Results reveal that bromocriptine at a dose of 6 mg/kg. I.P. in mice caused a significant hyperglycaemic effect which was accompanied by a marked increase in liver glycogen. After adrenalectomy, the effect of bromocriptine on serum glucose level was reduced whereas its effect on liver glycogen content was abolished. In rats, administration of bromocriptine (17.5 mg/kg I.P.) induced a significant rise in serum glucose level which was associated with marked reduction in serum insulin activity and increase in serum corticosterone level with no effect on serum triiodothyronine (T3) or thyroxine (T4) levels. It could be concluded that bromocriptine-induced hyperglycaemia might be attributed at least partially to inhibition of insulin release and stimulation of corticosterone secretion.     

The influence of N-stearoylethanolamine on the activity of antioxidant enzymes and on the level of stable NO metabolites in the rat testes and blood plasma at the early stages of streptozotocine-induced diabetes

The influence of N-stearoylethanolamine was investigated on the activity of enzymes of antioxidant protection and content of stable metabolites of nitric oxide (NO) in the testes and plasma of rats at the early stages of development of streptozotocine-induced diabetes mellitus. It was shown that the activity of superoxide dismutase, catalase is reduced in the plasma and testes of animals with streptozotocin-induced (50 mg/kg) diabetes (blood glucose 8-10 mmol/L). A significant increase in the amount of nitrite and nitrate anions was revealed in the plasma of rats, while only the level of nitrite was significantly changed in the testes of animals. The per os administration of the NSE aqueous suspension in a dose of 50 mg/kg during 10 days to the rats with induced diabetes contributed to the normalization of catalase activity in the testis, which correlated with a decrease in the amount of TBA-reacting products and activity of superoxide dismutase and catalase in the blood plasma of animals; the use of NSE also contributed to the reduction of nitrite content in the gonads and to normalization of both nitrite and nitrate in the blood plasma of rats. The NSE administration to intact animals caused an increase in superoxide dismutase activity and significantly reduced the content of stable NO metabolites in the blood plasma of animals.     

Modulatory effect of fenugreek saponins on the activities of intestinal and hepatic disaccharidase and glycogen and liver function of diabetic rats

Diabetes mellitus is a serious health concern throughout the world and is often associated with a variety of bodily disorders such as liver toxicity and dysfunction. This study elucidates the effect of fenugreek saponin administration on disaccharidase and glycogen activities in the intestine and liver of surviving diabetic rats. It also evaluates the effect of saponin feeding using a number of liver toxicity indices, namely stress oxidant, liver dysfunction markers and metabolism. Our findings indicate that the fenugreek saponin fraction significantly modulated the disaccharidase and glycogen enzyme activities in the intestine and liver of rats, increased the hepatic glycogen content, suppressed the increase of blood glucose level and improved results in the oral glucose tolerance test (OGTT). The fenugreek saponin extract also efficiently protected the hepatic function, which was evidenced by the significant increases of superoxide dismutase (SOD), catalase (CAT), gluthation peroxidase (GPX), aspartate transaminase (AST), alanine transaminase (ALT) and lactate deshydrogenase (LDH) enzyme activities. Fenugreek saponin also induced a notable delay in the absorption of LDL-cholesterol and triglycerides and a remarkable increase in levels of HDL-cholesterol. A histological analysis of the hepatic tissues further established the positive effect of fenugreek saponin. Overall, the findings of the current study indicate that fenugreek saponins exhibit attractive properties and can be considered as promising candidates for future application as therapeutic agents in biotechnological and bioprocess-based technologies, particularly those related to the development of anti-diabetic, hepatoprotective and hypolipidemic drugs.     

Streptozotocin-induced diabetes increases (Ca2+-Mg2+)-ATPase activity in hepatic plasma membranes of rats: Involvement of protein kinase C

The alteration in calcium transport in the liver of rats with streptozocin(STZ)-diabetic state was investigated. STZ (6 mg/100 g body weight) was subcutaneously administered in rats, and 1 or 2 weeks later they were sacrificed by bleeding. STZ administration caused a remarkable elevation of serum glucose concentration. Liver calcium content was significantly increased by STZ administration. Hepatic plasma membrane (Ca²⁺-Mg²⁺)-ATPase activity was markedly elevated by STZ administration. This increase was completely abolished by the presence of staurosporine (10^-7-10^-5 M), an inhibitor of protein kinase C, in the enzyme reaction mixture, suggesting an involvement of protein kinase C signalling. Moreover, the STZ-induced increase in liver plasma membrane (Ca²⁺-Mg²⁺)-ATPase activity was significantly raised by the presence of okadaic acid (10^-5 and 10^-4 M). Meanwhile, the STZ-increased (Ca²⁺-Mg²⁺)-ATPase activity was not appreciably altered by the presence of anti-regucalcin IgG in the reaction mixture, indicating that the activatory protein regucalcin does not participate in the elevation of the enzyme activity. The present study demonstrates that STZ-induced diabetes causes the increase in hepatic plasma membrane (Ca²⁺-Mg²⁺)-ATPase activity of rats.