Effects of repaglinide on oxidative stress in tissues of diabetic rabbits

In Vivo Evaluation of Nanoemulsion Formulations for Metformin and Repaglinide Alone and Combination

Repaglinide and Metformin are used to treat Type 2 diabetes. Repaglinide with poor water solubility has relatively low oral bioavailability (56%) and undergoes hepatic first-pass metabolism. The oral bioavailability of metformin HCl is also low (about 50-60%). The purpose of this study was to prepare nanoemulsion formulations containing metformin HCl or repaglinide alone or in combination and characterize them in vitro and in vivo. Nanoemulsion formulations containing metformin HCl and/or repaglinide were successfully prepared and in vitro characterized. In addition, in vivo efficacy of nanoemulsion formulations was evaluated in a streptozotocin-nicotinamide-induced diabetic rat model. Biochemical, histopathological, and immunohistochemical evaluations were also performed. The mean droplet size and zeta potential values of nanoemulsion formulations were in the range of 110.15±2.64-120.23±2.16 nm and -21.95 - -24.33 mV, respectively. The percent entrapment efficiency values of nanoemulsion formulations were in the range of 93.600%-96.152%. All nanoemulsion formulations had a PDI of ≤0.223. A statistically significant decrease was observed in the blood glucose values of the diabetic rats treated with nanoemulsion formulations containing active substance/substances, compared to diabetic rats (control) (p<0.05). Nanoemulsion formulations (especially nanoemulsion containing metformin HCl and repaglinide combination) have a better antidiabetic activity and are more effective in reducing oxidative stress caused by diabetes.

Anti-Alzheimer and Antioxidant Effects of Nelumbo nucifera L. Alkaloids, Nuciferine and Norcoclaurine in Alloxan-Induced Diabetic Albino Rats

The present study is aimed to determine the efficacy and dose response of the nuciferine (1), norcoclaurine (2) and crude extract of Nelumbo nucifera in managements of diabetes, Alzheimer disease and related allergies. Experimentally, alloxan (100 mg/kg body weight (b.w.))-induced diabetic rats (200−250 g) were divided into seven groups (n = 6). Group I: normal control, Group II: diabetic control, Group III: standard treated with glibenclamide and Group lV-VII: treated with methanolic crude extracts (100, 200 mg/kg), nuciferine and norcoclaurine (10 mg/kg b.w.) for 15 days. Different tests were performed, including blood glucose, body weights and antioxidant enzyme assays, i.e., superoxide dismutase (SOD), catalase test (CAT), lipid peroxidation assay (TBARS), glutathione assay (GSH) and acetylcholinesterase (AChE) assay. Nuciferine and norcoclaurine significantly reduced blood glucose (p < 0.05) and restored body weight in diabetic rats. Moreover, nuciferine and norcoclaurine (10 mg/kg) significantly recovered the antioxidant enzymes (SOD, CAT, GPx and GSH) which decreased during induced diabetes. Significant increase in TBARS was also observed in the diabetic group and nuciferine as well as norcoclaurine (10 mg/kg) inhibited the increase in TBARS in diabetic animals (p < 0.05), as compared to glibenclamide. AChE activity was significantly recovered by nuciferine and norcoclaurine (10 mg/kg) both in the blood and brain of the diabetic group (p < 0.05). Nuciferine and norcoclaurine showed potent inhibitory effects against α-glucosidase and α-amylase with IC50, 19.06 ± 0.03, 15.03 ± 0.09 μM and 24.07 ± 0.05, 18.04 ± 0.021 μM, as confirmed by molecular docking studies. This study concludes that nuciferine and norcoclaurine significantly improve memory and could be considered as an effective phytomedicine for diabetes, Alzheimer’s disease (AD) and oxidative stress.

Efficacy of ivermectin against colon cancer induced by dimethylhydrazine in male wistar rats

Colon cancer (CC) is a common form of cancer worldwide. According to growing incidence of cancer and little information about the possible protective role of Ivermectin (IVM) on colon cancer, this study aimed to investigate the chemoprotective role of IVM against colon cancer induced by Dimethylhydrazine (DMH) in Male Wistar Rats. Based on LD_50, three doses of IVM (0.25, 0.5, and 1 mg/kg) were applied before assayingthe antioxidant status, apoptotic markers, and microscopic analysis. Our result showed that glutathione (GSH) level was significantly increased in low dose of IVM-treated rats. Hight levels of oxidative stress and tissue damage consumed GSH and catalase (CAT), and dismutase (SOD) as indicated by significant drop in the treated groups. mRNA levels of Bax and caspase-3 were upregulated in rats treated with the high dose. Contrastingly, the expression of Bcl-2 was significantly downregulated with high dose. Changes in genes expression proved that IVM triggered apoptosis in treated groups compared to untreated control group. Microscopic analysis showed that rats treated with DMH exhibited high development of colorectal tumor. After induction of colorectal tumor, medium and high dose of DMH induced reduction in medullary carcinoma with great incidence of lymphoid nodules and desmoplastic reaction. In conclusion, this study demonstrates the potential of IVM as an anticancer drug against colon cancer in male Wistar rats.

Antidiabetic drugs and oxidized low-density lipoprotein: A review of anti-atherosclerotic mechanisms

Cardiovascular disease is one of the leading causes of mortality globally. Atherosclerosis is an important step towards different types of cardiovascular disease. The role of oxidized low-density lipoprotein (oxLDL) in the initiation and progression of atherosclerosis has been thoroughly investigated in recent years. Moreover, clinical trials have established that diabetic patients are at a greater risk of developing atherosclerotic plaques. Hence, we aimed to review the clinical and experimental impacts of various classes of antidiabetic drugs on the circulating levels of oxLDL. Metformin, pioglitazone, and dipeptidyl peptidase-4 inhibitors were clinically associated with a suppressive effect on oxLDL in patients with impaired glucose tolerance. However, there is an insufficient number of studies that have clinically evaluated the relationship between oxLDL and newer agents such as agonists of glucagon-like peptide 1 receptor or inhibitors of sodium-glucose transport protein 2. Next, we attempted to explore the multitude of mechanisms that antidiabetic agents exert to counter the undesirable effects of oxLDL in macrophages, endothelial cells, and vascular smooth muscle cells. In general, antidiabetic drugs decrease the uptake of oxLDL by vascular cells and reduce subsequent inflammatory signaling, which prevents macrophage adhesion and infiltration. Moreover, these agents suppress the oxLDL-induced transformation of macrophages into foam cells by either inhibiting oxLDL entrance, or by facilitating its efflux. Thus, the anti-inflammatory, anti-oxidant, and anti-apoptotic properties of antidiabetic agents abrogate changes induced by oxLDL, which can be extremely beneficial in controlling atherosclerosis in diabetic patients.

Antidiabetic and Hypolipidemic Effects of 5,7-Dimethoxyflavone in Streptozotocin-Induced Diabetic Rats

BACKGROUND The flavones are considered as competent antidiabetic molecules due to their strong antioxidant activities and higher in vivo stability. The present study evaluated the antidiabetic and hypolipidemic effects of 5,7-dimethoxyflavone in streptozotocin (STZ)-induced diabetic rat models. MATERIAL AND METHODS The antidiabetic potential of 5,7-dimethoxyflavone was evaluated in streptozotocin-induced diabetic rats. The serum levels of triglyceride, total cholesterol, and high-density lipoprotein cholesterol were measured using the Randox assay kit. Histopathological examination was carried out by hematoxylin and eosin (HE) staining. RESULTS Oral administration of 5,7-dimethoxyflavone significantly reduced STZ-induced enhancement in blood sugar and glycosylated hemoglobin, as well as significant increases in C-peptide, insulin, hemoglobin, and total protein content (p<0.05). Additionally, treatment with 5,7-dimethoxyflavone resulted in a remarkable increase in non-enzymic antioxidants. Administration of 5,7-dimethoxyflavone had a hypolipidemic effect by significantly reducing levels of serum triglycerides, total cholesterol, and low-density lipoproteins. The histopathological examination of rat pancreases revealed the beneficial effect of 5,7-dimethoxyflavone and protection of ß cell integrity in STZ-induced diabetic rats. CONCLUSIONS These findings reflect the antidiabetic and hypolipidemic effects of 5,7-dimethoxyflavone, suggesting that 5,7-dimethoxyflavone may be a promising compound for use in development of new antidiabetic drugs.

Hibiscus sabdariffa renews pancreatic β-cells in experimental type 1 diabetic model rats

This study evaluated the antidiabetic potentials of flavonoid-rich aqueous fraction of methanolic extract of Hibiscus sabdariffa calyx (HSCE) on the pancreatic β-cells of experimental type I diabetic model rats. Type 1 diabetes mellitus was induced in Wistar rats by a single intraperitoneal injection of 80mg/kg b/w streptozotocin (STZ) dissolved in 0.1M citrate buffer (pH 6.3). The rats were divided into five groups (n=12) including normal control group, test group I, diabetic negative control, test group II, and diabetic positive control. The test groups received 1.75g/kg b/w of HSCE by gavage for 15 days. Animals were sacrificed; the splenic portion of their pancreas and serum were evaluated for histopathological and biochemical parameters respectively. The regenerative effects of the extract on STZ-diabetes β-cells damage was evident from the results of the histopathological analysis and the biochemical parameters evaluated in the serum. Reduced levels of glutathione, catalase and superoxide dismutase in the serum of diabetic rats were significantly improved in the H. sabdariffa-treated rats (P<0.05). Histological examination of pancreatic islet sections revealed degenerative and necrotic changes (D) in the pancreatic islet of Langerhans, β-cell degranulation, pyknotic β-cell nuclei, decreased islet cellular density, and severe vacuolation (V) in the islet of STZ-diabetic negative control group. The morphology of the pancreas of HSCE-treated diabetic rats (test group II) revealed remarkable improvements in the islet of Langerhans. Stereological studies also revealed that HSCE-treatment remarkably improved volume of the pancreatic islets and the numerical density of β-cell (number of β-cells per unit area of islet) depleted by STZ diabetes. The study concluded that possible antidiabetic mechanism of Hibiscus sabdariffa in STZ diabetes is through induction of β-cell regeneration and its strong antioxidant potential.

Comparative evaluation of half-maximum inhibitory concentration and cytotoxicity of silver nanoparticles and multiwalled carbon nanotubes using buffalo bull spermatozoa as a cell model

There is a dearth of information regarding the safety of silver nanoparticles (Ag NPs) and multiwalled carbon nanotubes (MWCNTs) with respect to their impact on human/animal health and the environment. This study aimed to determine the half-maximum inhibitory concentration (IC50) of Ag NPs and MWCNTs by employing different doses and time interval combinations in buffalo bull spermatozoa. Semen samples containing 100 million spermatozoa each were incubated with 1, 10, 25, 50, 75 and 100 µg/mL of Ag NPs and MWCNTs at 37°C for 30, 60 and 120 min. Sperm viability was monitored by the MTT assay and eosin–nigrosin staining followed by estimation of IC50 values using correlation–regression analysis. Spermatozoa treated with IC50 doses of Ag NPs and MWCNTs were also assessed for different sperm functionality parameters including oxidative stress and membrane integrity. These parameters were observed to be significantly affected in treated spermatozoa compared with the controls. We concluded that both nanomaterials showed cytotoxicity, mediated principally via oxidative stress. This work has provided valuable toxicological information that will serve as a benchmark for future studies aimed at safe use of nanomaterials.

γ-Glutamylcysteine synthetase (γ-GCS) as a target for overcoming chemo- and radio-resistance of human hepatocellular carcinoma cells

AIMS

This study uncovered that the genetically endowed intracellular glutathione contents (iGSH) regulated by the catalytic subunit of γ‑glutamylcysteine synthetase heavy chain (γ‑GCSh) as a prime target for overcoming both the inherited and stimuli-activated chemo- and radio-resistance of hepatocellular carcinoma (HCC) cells.

MAIN METHODS

Reactive oxygen species (ROS) production and mitochondrial membrane potential (Δψm) were determined by the probe-based flow cytometry. The TUNEL assay was used as an index of radio-sensitivity and the MTT assay was used as an index of chemo-sensitivity against various anti-cancer agents. iGSH and γ‑GCSh activity were measured by HPLC methods. γ‑GCSh-overexpressing GCS30 cell line was established by tetracycline-controlled Tet-OFF gene expression system in SK-Hep-1 cells.

KEY FINDINGS

The relative radio-sensitivities of a panel of five HCC cells were found to be correlated negatively with both the contents of iGSH and their corresponding γ‑GCSh activities with an order of abundance being Hep G2 > Hep 3B > J5 > Mahlavu > SK-Hep-1, respectively. Similarly, the cytotoxicity response patterns of these HCC cells against arsenic trioxide (ATO), a ROS-producing anti-cancer drug, were exactly identical to the order of ranking instigated by the radiotherapy (RT) treatment. Next, γ‑GCSh-overexpressing GCS30 cells were found to possess excellent ability to profoundly mitigate both the drop of Δψm and apoptotic TUNEL-positive cell population engendered by ATO, cisplatin, doxorubicin, and RT treatments.

SIGNIFICANCE

Our data unequivocally demonstrate that γ‑GCSh may represent a prime target for overcoming anti-cancer drugs and RT resistance for HCC cells.

Phospholipid complex enriched micelles: A novel drug delivery approach for promoting the antidiabetic effect of repaglinide

To enhance the oral antidiabetic effect of repaglinide (RG), a newly emerging approach, based on the combination of phospholipid complexation and micelle techniques, was employed. Repaglinide-phospholipid complex (RG-PLC) was prepared by the solvent-evaporation method then characterized using Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XPRD). The results revealed obvious disappearance of the characteristic peaks of the prepared RG-PLCs confirming the formation of drug-phospholipid complex. RG-PLC enriched micelles (RG-PLC-Ms) were prepared by the solvent-evaporation technique employing poloxamer 188 as surfactant. The prepared RG-PLC-Ms showed high drug encapsulation efficiencies (93.81-99.38%), with nanometric particle diameters (500.61-665.32nm) of monodisperse distribution and high stability (Zeta potential < -29.8mV). The in vitro release of RG from RG-PLC-Ms was pH-dependant according to the release media. A higher release pattern was reported in pH=1.2 compared to a more retarded release in pH=6.8 owing to two different kinetics of drug release. Oral antidiabetic effect of two optimized RG-PLC-M formulations was evaluated in an alloxan-induced diabetic rat model for 7-day treatment protocol. The two investigated formulations depicted normal blood glucose, serum malondialdehyde and insulin levels as well as an improved lipid profile, at the end of daily oral treatment, in contrast to RG marketed tablets implying enhanced antidiabetic effect of the drug. Hence, phospholipid-complex enriched micelles approach holds a promising potential for promoting the antidiabetic effect of RG.

Rutin potentially attenuates fluoride-induced oxidative stress-mediated cardiotoxicity, blood toxicity and dyslipidemia in rats

This study was undertaken to evaluate cardio protective effect of rutin against sodium fluoride (NaF)-induced oxidative stress-mediated cardiotoxicity and blood toxicity. Cardiac injury was induced by daily administration of NaF 600 ppm in distilled water for four weeks. The animals exposed to NaF exhibited a significant increase in levels of cardiac serum markers, lipid peroxidative markers, serum total cholesterol, LDL, triglycerides and decrease in HDL levels. Decrease in hematological parameters, namely hemoglobin, red blood cells, mean corpuscular volume, mean corpuscular hemoglobin (MCH), MCH count and increase in white blood cells and erythrocyte sedimentation levels were also observed. Marked histopathological lesions and increased DNA fragmentation in cardiac tissues were observed. Activity of antioxidants-catalase, superoxide dismutase and reduced glutathione contents were decreased (p < 0.01), whereas lipid peroxidation product (malondialdehyde) was increased. A significant decrease in body and heart weight was also observed. Treatment with rutin effectively ameliorated the alterations in the studied parameters of rat through its antioxidant nature. There was also significant improvement in hematological parameters. Thus, results of this study clearly demonstrated that treatment with rutin against NaF intoxication has a significant role in protecting F-induced cardiotoxicity, blood toxicity and dyslipidemia in rats.

CCl4 induced genotoxicity and DNA oxidative damages in rats: hepatoprotective effect of Sonchus arvensis

BACKGROUND

Sonchus arvesis is traditionally reported in various human ailments including hepatotoxicity in Pakistan. Presently we designed to assess the protective effects of methanolic extract of Sonchus arvesis against carbon tetrachloride induced genotoxicity and DNA oxidative damages in hepatic tissues of experimental rats.

METHODS

36 male Sprague-Dawley rats were randomly divided into 6 groups to evaluate the hepatoprotective effects of Sonchus arvensis against CCl4 induced genotoxicity, DNA damages and antioxidant depletion. Rats of normal control group were given free access of food and water add labitum. Group II rats received 3 ml/kg of CCl4 (30% in olive oil v/v) via the intraperitoneal route twice a week for four weeks. Group III and IV received 1 ml of 100 mg/kg b.w. and 200 mg/kg b.w. SME via gavage after 48 h of CCl4 treatment whereas group V was given 1 ml of silymarin (100 mg/kg b.w.) after 48 h of CCl4 treatment. Group VI only received 200 mg/kg b.w. SME. Protective effects of SME were checked by measuring serum markers, activities of antioxidant enzymes, genotoxicity and DNA dmages.

RESULTS

Results of the present study showed that treatment of SME reversed the activities of serum marker enzymes and cholesterol profile as depleted with CCl4 treatment. Activities of endogenous antioxidant enzymes of liver tissue homogenate; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSHpx), glutathione-S-transferase (GST) and glutathione reductase (GSR) were reduced with administration of CCl4, which were returned to the control level with SME treatment. CCl4-induced hepatic cirrhosis decreased hepatic glutathione (GSH) and increased lipid peroxidative products (TBARS), were normalized by treatment with SME. Moreover, administration of CCl4 caused genotoxicity and DNA fragmentation which were significantly restored towards the normal level with SME.

CONCLUSION

These results reveal that treatment of SME may be useful in the prevention of hepatic stress.

Effect of repaglinide versus glimepiride on daily blood glucose variability and changes in blood inflammatory and oxidative stress markers

BACKGROUND

Hemoglobin A1c is the main treatment target for patients with type 2 diabetes. It has also been shown recently that postprandial glucose and daily glucose fluctuations affect the progression of diabetic complications and atherosclerotic damages.

METHODS

Continuous glucose monitoring was performed in patients with type 2 diabetes to evaluate the efficacy of repaglinide vs. glimepiride on postprandial glucose spikes and fluctuations. A total of 10 Japanese patients with type 2 diabetes treated with glimepiride monotherapy were enrolled. After observation period for 8 weeks, glimepiride was changed to repaglinide. Continuous glucose monitoring was performed whilst consuming calorie-restricted diets for two days at baseline and at the end of the 12-week trial. Blood and urine samples were collected for measurement of glucose control parameters and inflammatory and oxidative stress markers on the last day of taking either glimepiride or repaglinide.

RESULTS

Nine patients completed the trial. Although the glucose control parameters were not significantly different between glimepiride and repaglinide, the mean amplitude of glycemic excursions measured by continuous glucose monitoring was significantly reduced by changing treatment from glimepiride to repaglinide. The levels of plasminogen activator inhibitor-1, high sensitivity C-reactive protein, and urinary 8-hydoroxydeoxyguanosine were reduced significantly by repaglinide treatment.

CONCLUSION

These results suggest that repaglinide may decrease the risk of cardiovascular disease in type 2 diabetes by minimizing glucose fluctuations thereby reducing inflammation and oxidative stress.

Antioxidant Activity of Tocotrienol Rich Fraction Prevents Fenitrothion-induced Renal Damage in Rats

Fenitrothion (FNT) is an organophosphate compound widely used as pesticide in Malaysia. The present study aims to investigate effects of palm oil tocotrienol rich fraction (TRF) on the renal damage of FNT-treated rats. A total of 40 male Sprague Dawley rats were divided into 4 groups randomly, the control, TRF, FNT and FNT+TRF groups. FNT (20 mg/kg b.w.) and TRF (200 mg/kg b.w.) were given orally for 28 days continuously. Rats from the FNT+TRF group were supplemented with TRF 30 minutes prior to administration of FNT. Rats were sacrificed after 28 days, and the kidneys were removed for determination of oxidative stress and histological analysis. Plasma was collected for determination of blood creatinine and urea level. Statistical analysis showed that palm oil TRF has a protective effect against renal oxidative damage induced by FNT. In the FNT+TRF group, malondialdehyde and protein carbonyl levels were significantly lower, while the glutathione level as well as superoxide dismutase and catalase activities were significantly higher compared with the FNT-treated group (p<0.05). As for renal function, there was a markedly lower urea level (p<0.05) in the FNT+TRF group compared with the FNT-treated group, but there was no significant difference in creatinine level. Besides, total protein also showed no significant difference for all groups of rats (p>0.05). Histological evaluation also revealed that the FNT+TRF group had less glomerulus and renal tubule damage than the FNT-treated group. In conclusion, palm oil TRF was able to reduce oxidative stress and renal damage in FNT-treated rats.

Effects of mercury on glutathione and glutathione-dependent enzymes in hares (Lepus europaeus Pallas)

The aim of this study was to analyze and evaluate risks of long-term exposure to mercury in hares (Lepus europaeus Pallas), with a chemical-analytical approach evaluating median mass fraction of toxic mercury in the hares organs (liver, kidney, muscle and brain). To obtain better insight into possible effects of mercury, the study included screening of the oxidative status after long term exposure to low concentrations of mercury. Hares organs were analyzed for total mercury concentration by AAS. Glutathione and glutathione-dependent enzymes status was also investigated. The median mercury concentrations (wet weight) in the liver, kidney, muscle and brain of the hares ranged from 0.058-0.189, 0.138-0.406, 0.013-0.046 and 0.022-0.102 μg/g respectively. Concentration of the glutathione (GSH), glutathione-peroxidase (GPx), and glutathione-reductase (GR) activity increased with the mercury concentration. However, glutathione S-transferase (GST) and superoxide-dismutase (SOD) activity decreased with the mercury concentration. The results of this study show the impact of environmentally absorbed mercury on the antioxidant status of the examined hares. Further research on long-term exposure to low concentrations of mercury is needed.

Effects of Launaea procumbens on brain antioxidant enzymes and cognitive performance of rat

BACKGROUND

Launaea procumbens is used in the treatment of oxidative stress and mental disorders. The effects of Launaea procumbens methanolic extracts (LPMEs), i.e., 100 and 200 LPME mg/kg body weight (b.w.), on cognitive performance as well as on the activity of acetylcholinesterase, and antioxidant enzymes in rat brain tissue homogenates were evaluated.

METHODS

Thirty male Sprague-Dawley rats were divided equally into three groups. Rats in group I (control) were given saline (vehicle), group II received LPME (100 mg/kg b.w., p.o.), and group III were treated with LPME (200 mg/kg b.w., p.o.) in dimethyl sulfoxide (DMSO) for 7 days. Antioxidant potential was assessed by measuring the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHpx), glutathione reductase (GSR) and glutathione-S-transferase (GST) as well as lipid peroxidation and glutathione (GSH) contents in brain tissue homogenates. Activity of acetylcholinesterase (AChE) and cognitive performance were also assessed.

RESULTS

LPME administration reduced the levels of lipid peroxidation products (TBARS contents), increased GSH levels and enhanced the activities of SOD, CAT, GSHpx, GSR and GST. AChE activity was reduced by LPME treatment compared with untreated controls.

CONCLUSION

These findings suggested the significant impact of LPMEs on brain function. These effects could be through the antioxidant effects of the bioactive constituents present in LPME.

CCl4-induced hepatotoxicity: protective effect of rutin on p53, CYP2E1 and the antioxidative status in rat

BACKGROUND

Rutin is a polyphenolic natural flavonoid which possesses antioxidant and anticancer activity. In the present study the hepatoprotective effect of rutin was evaluated against carbon tetrachloride (CCl₄)-induced liver injuries in rats.

METHODS AND MATERIALS

24 Sprague-Dawley male rats were equally divided into 4 groups for the assessment of hepatoprotective potential of rutin. Rats of group I (control) received only vehicles; 1 ml/kg bw of saline (0.85%) and olive oil (3 ml/kg) and had free access to food and water. Rats of group II, III and IV were treated with CCl₄ (30% in olive oil, 3 ml/kg bw) via the intraperitoneal route twice a week for four weeks. The rutin at the doses of 50 and 70 mg/kg were administered intragastrically after 48 h of CCl₄ treatment to group III and IV, respectively. Protective effect of rutin on serum enzyme level, lipid profile, activities of antioxidant enzymes and molecular markers were calculated in CCl₄-induced hepatotoxicity in rat.

RESULTS

Rutin showed significant protection with the depletion of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma glutamyl transpeptidase (γ-GT) in serum as was raised by the induction of CCl₄. Concentration of serum triglycerides, total cholesterol and low density lipoproteins was increased while high-density lipoprotein was decreased with rutin in a dose dependent manner. Activity level of endogenous liver antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSHpx), glutathione-S-transferase (GST) and glutathione reductase (GSR) and glutathione (GSH) contents were increased while lipid peroxidation (TBARS) was decreased dose dependently with rutin. Moreover, increase in DNA fragmentation and oxo8dG damages while decrease in p53 and CYP 2E1 expression induced with CCl₄ was restored with the treatment of rutin.

CONCLUSION

From these results, it is suggested that rutin possesses hepatoprotective properties.

Quercitrin a bioflavonoid improves the antioxidant status in streptozotocin: induced diabetic rat tissues

Quercitrin, a bio flavonoid, was investigated for its antioxidant potential in streptozotocin (STZ)-induced diabetic rats. Rats were induced diabetic by a single intraperitoneal injection of streptozotocin (50 mg/kg). The levels of fasting plasma glucose and insulin were estimated. Lipid peroxidative products and antioxidants were estimated in pancreas, liver, and kidney. Histopathological studies were carried out in these tissues. A significant (P < 0.05) increase in the levels of fasting plasma glucose and lipid peroxidative products (thiobarbituric acid reactive substances and lipid hydroperoxides) and a significant (P < 0.05) decrease in plasma insulin, enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase), and nonenzymic antioxidants (reduced glutathione, vitamin C, and E) in diabetic pancreas, liver, and kidney were observed. Oral administration of quercitrin (30 mg/kg) for a period of 30 days significantly (P < 0.05) decreased fasting plasma glucose, increased insulin levels, and improved the antioxidant status of diabetic rats by decreasing lipid peroxidative products and increasing enzymic and nonenzymic antioxidants. Normal rats treated with quercitrin (30 mg/kg) showed no significant (P < 0.05) effect on any of the parameters studied. Histopathological studies of the pancreas, liver, and kidney showed the protective role of quercitrin. Thus, our study clearly shows that quercitrin has antioxidant effect in STZ-induced experimental diabetes.

Growth hormone reduces tissue damage in rat ovaries subjected to torsion and detorsion: biochemical and histopathologic evaluation

OBJECTIVE

To evaluate the effects of growth hormone (GH) as an antioxidant and tissue-protective agent and analyse the biochemical and histopathological changes in rat ovaries due to experimental ischemia and ischemia/reperfusion injury.

STUDY DESIGN

Forty-eight adult female rats were randomly divided into eight groups. In Group 1, a period of bilateral ovarian ischemia was applied. In Groups 2 and 3, 1 and 2 mg/kg of GH was administered, and 30 min later, bilateral ovarian ischemia was applied (after a 3-h period of ischemia, both ovaries were surgically removed). Group 4 received a 3-h period of ischemia followed by 3h of reperfusion. Groups 5 and 6 received 1 and 2 mg/kg of GH, respectively, 2.5 h after the induction of ischemia. At the end of a 3-h period of ischemia, bilateral vascular clips were removed, and 3h of reperfusion continued. Group 7 received a sham operation plus 2mg/kg of GH. Group 8 received a sham operation only. After the experiments, superoxide dismutase and myeloperoxidase activity and levels of glutathione and lipid peroxidation were determined, and histopathological changes were examined in all rat ovarian tissue.

RESULTS

Ischemia and ischemia/reperfusion decreased superoxide dismutase activity and glutathione levels in ovarian tissue, but increased lipid peroxidation levels and myeloperoxidase activity significantly in comparison to the sham group. The 1 and 2 mg/kg doses of GH before ischemia and ischemia/reperfusion decreased lipid peroxidation levels and myeloperoxidase activity in the experimental groups. The administration of GH before ischemia and ischemia/reperfusion treatments also increased superoxide dismutase and glutathione levels. The histopathological findings also suggested a protective role of GH in ischemia/reperfusion injury. That is, ovarian tissues in the ischemia groups showed histopathological changes, such as haemorrhage, cell degeneration, and necrotic and apoptotic cells, but these changes in the GH groups were lesser. Moreover, in the ischemia/reperfusion groups, acute inflammatory processes--such as neutrophil adhesion and migration, apoptotic and degenerative cells, stromal oedema and haemorrhage--were present. However, the ovarian tissues of the IR+GH (1 mg) group had minimal apoptotic cells, and the IR+GH (2 mg) group had no apoptotic cells. In addition, the general ovarian histological structures of these groups were similar to those of the healthy control group.

CONCLUSIONS

The administration of GH is protective against ischemia and/or ischemia/reperfusion-induced ovarian damage. This protective effect can be attributed to the antioxidant properties of GH.

Aqueous Extract from Hibiscus sabdariffa Linnaeus Ameliorate Diabetic Nephropathy via Regulating Oxidative Status and Akt/Bad/14-3-3γ in an Experimental Animal Model

Several studies point out that oxidative stress maybe a major culprit in diabetic nephropathy. Aqueous extract of Hibiscus sabdariffa L. (HSE) has been demonstrated as having beneficial effects on anti-oxidation and lipid-lowering in experimental studies. This study aimed at investigating the effects of Hibiscus sabdariffa L. on diabetic nephropathy in streptozotocin induced type 1 diabetic rats. Our results show that HSE is capable of reducing lipid peroxidation, increasing catalase and glutathione activities significantly in diabetic kidney, and decreasing the plasma levels of triglyceride, low-density lipoprotein (LDL) and increasing high-density lipoprotein (HDL) value. In histological examination, HSE improves hyperglycemia-caused osmotic diuresis in renal proximal convoluted tubules (defined as hydropic change) in diabetic rats. The study also reveals that up-regulation of Akt/Bad/14-3-3γ and NF-κB-mediated transcription might be involved. In conclusion, our results show that HSE possesses the potential effects to ameliorate diabetic nephropathy via improving oxidative status and regulating Akt/Bad/14-3-3γ signaling.

Impact of D-pinitol on the attenuation of proinflammatory cytokines, hyperglycemia-mediated oxidative stress and protection of kidney tissue ultrastructure in streptozotocin-induced diabetic rats

Oxidative stress plays a crucial role in the progression and development of diabetes and its complications due to chronic hyperglycemia. The present study was aimed to investigate the kidney tissue protective nature of d-pinitol, a cyclitol present in soybean, by assessing the key markers of hyperglycemia-mediated oxidative stress, proinflammatory cytokines and ultrastructural alterations in streptozotocin-induced diabetic rats. Oral administration of d-pinitol (50mg/kg body weight/day) for 30 days to diabetic group of rats showed a significant elevation in the level of total protein and significant decline in the levels of blood urea, serum uric acid, creatinine and advanced glycation endproducts (AGEs) and kidney proinflammatory cytokines such as TNF-alpha, IL-1beta, IL-6, NF-kappaB p65 subunit and nitrite. Further, d-pinitol administration elicited a significant attenuation in the activities of kidney enzymatic antioxidants such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) and the levels of kidney non-enzymatic antioxidants such as vitamin E, vitamin C and reduced glutathione (GSH) in the diabetic group of rats, with a concomitant decline in the levels of kidney lipid peroxides, hydroperoxides and protein carbonyls. The histological and ultrastructural observations on the kidney tissues also confirmed the renoprotective nature of d-pinitol. Thus the present study demonstrated the renoprotective nature of d-pinitol by attenuating the hyperglycemia-mediated proinflammatory cytokines and antioxidant competence in kidney tissues of streptozotocin-induced diabetic rats.

Atorvastatin reduces tissue damage in rat ovaries subjected to torsion and detorsion: biochemical and histopathologic evaluation

The aim of this study was to evaluate the effects of atorvastatin as an antioxidant and tissue protective agent and study the biochemical and histopathological changes in experimental ischemia and ischemia/reperfusion (I/R) injury in rat ovaries. The experiment used 48 adult female rats, and the experimental groups can be summarized as: group I, a sham operation; group II, a sham operation +10 mg/kg atorvastatin; group III, bilateral ovarian ischemia; and groups IV and V, bilateral ovarian ischemia +5 and 10 mg/kg atorvastatin before 30 min of ischemia, respectively (after a 3-h period of ischemia, the bilateral ovaries were surgically removed); group VI, 3-h period of ischemia followed by 3-h reperfusion; groups VII and VIII received 5 and 10 mg/kg atorvastatin, respectively, 2.5 h after the induction of ischemia, and at the end of a 3-h period of ischemia, bilateral vascular clips were removed and 3-h reperfusion continued. After the experiments, superoxide dismutase (SOD) and myeloperoxidase (MPO) activity and levels of glutathione (GSH) and lipid peroxidation (LPO) were determined, and histopathological changes were examined in all rat ovarian tissue. Ischemia and I/R increased the LPO level and MPO activity while decreasing the SOD activity and GSH level significantly in comparison to the sham group. The 5- and 10-mg/kg doses of atorvastatin before ischemia and I/R reversed the trend in LPO level and MPO activity. The levels of SOD and GSH were decreased by ischemia and I/R. The administration of atorvastatin before ischemia and I/R treatments also reversed the trend in the SOD and GSH levels. In the I/R plus atorvastatin groups, although minimal vascular dilation in the ovary stoma and some degenerative cell clusters were seen, most of the cellular structures showed no pathological changes. Administration of atorvastatin is effective in reversing tissue damage induced by ischemia and/or I/R in ovaries.

Effects of short-term therapy with different insulin secretagogues on glucose metabolism, lipid parameters and oxidative stress in newly diagnosed Type 2 Diabetes Mellitus

AIM

To compare effects of three different insulin secretagogues on early-phase insulin secretion, metabolism of glucose and lipids, and lipid peroxidation in newly diagnosed Type 2 Diabetes Mellitus (T2DM).

METHODS

Totally 60 newly diagnosed T2DM outpatients were randomized to three groups with 1-month monotherapy of repaglinide (Rg), glimepiride (Gm) or gliclazide MR (Gli), respectively. Some indexes of early-phase insulin secretion, glucose, lipids, and lipid peroxidation were inspected.

RESULTS

Fasting plasma glucose (FPG), glycosylated hemoglobin (HbA(1c)) and fructosamine (FA) were improved in all groups similarly (p>0.05). Rg group was with the highest early-phase insulin secretion index (DeltaI30/DeltaG30) (p=0.026), lower mean amplitude of glycaemic excursion (MAGE) (p<0.05), lowest mean peak value of post-lunch glucose (p=0.043), and lowest postprandial triglyceride (TG) (p=0.039). Postprandial free fatty acid (FFA) was lower after Rg and Gli treatment (p<0.05). Serum 8-iso prostaglandin F(2alpha) (8-iso PGF(2alpha)) was improved in all groups, but the improvement showed statistically significant only in Rg group (p=0.04).

CONCLUSION

Rg, Gm and Gli can all decrease blood glucose effectively in newly diagnosed T2DM patients, while Rg performs outstandingly in the aspects of improving early-phase insulin secretion, glucose excursion, postprandial lipids and 8-iso PGF(2alpha).

Modulation of nitrosative/oxidative stress in the lung of hyperglycemic rabbits by two antidiabetics, pioglitazone and repaglinide

The lungs are involved in diabetes in the cause of the complex phenomena diabetes generates. In the present study, hyperglycemia inhibited pulmonary antioxidants, including superoxide dismutase, catalase, glutathione peroxidase, and glutathione. These effects were accompanied by significant elevation of lipid peroxidation, total nitrites, and nitrotyrosine levels. The study investigated the effects of 2 oral antidiabetics, pioglitazone and repaglinide, on the mentioned parameters. It is concluded that pioglitazone exerts protective effect in the lung by inhibiting nitrosative stress and normalizing the nitrites and nitrotyrosine levels. Administration of repaglinide prevents oxidative and, to a smaller extent, nitrosative changes.

Repaglinide-loaded long-circulating biodegradable nanoparticles: rational approach for the management of type 2 diabetes mellitus

BACKGROUND

Repaglinide (RPG) is an oral hypoglycemic agent with excellent bioavailability (90-98%) and a short plasma half-life (2-6 h). A full dose of RPG is required before each meal; hence, therapy may become inconvenient. Thus, the aim of the present study was to design a novel delivery system to maintain peak plasma levels of RPG for the long-term management of diabetes mellitus.

METHODS

Two nanoparticle formulations were prepared by combining RPG with poly (lactic-co-glycolic) acid alone or as a copolymer with methoxypolyethylene glycol (RPGNP1 and RPGNP2, respectively); both formulations were subjected to in vitro and in vivo characterization. In vivo characterization was performed in a streptozotocin (STZ)-induced diabetic male albino rats.

RESULTS

The mean particle size of the RPGNP1 and RPGNP2 formulations was 387.8 ± 11.9 and 310.2 ± 12.4 nm, respectively, with a zeta potential of -27.4 ± 0.7 and -15.7 ± 0.5 mV, respectively. The entrapment efficiency and drug content of RPGNP1 (58.7 ± 1.3% and 27.4 ± 2.3%, respectively) was better than that of RPGNP2 (45.8 ± 1.2% and 24.3 ± 1.1%, respectively). Blood glucose levels of RPGNP1- and RPGNP2-treated STZ-diabetic rats were reduced significantly (to normal levels) compared with untreated STZ-diabetic rats (P < 0.05), but there was no difference between the two treatment groups (P > 0.05). However, whereas RPGNP1 was effective for a period of only 24 h, RPGNP2 was effective for up to 1 week.

CONCLUSIONS

The results of the present study show that RPGNP2 effectively manages type 2 diabetes mellitus for up to 1 week. Surface-modified NPs could be used to improve patient compliance with drug treatment as a result of decreased dosing frequency.

Rutin improves the antioxidant status in streptozotocin-induced diabetic rat tissues

Rutin, a polyphenolic flavonoid, was investigated for its antioxidant potential in streptozotocin (STZ)-induced diabetic rats. Rats were rendered diabetic by a single intraperitoneal injection of streptozotocin (50 mg/kg). The levels of fasting plasma glucose and insulin were estimated. Lipid peroxidative products and antioxidants were estimated in liver, kidney and brain. Histopathological studies were carried out in these tissues. A significant (p < 0.05) increase in the levels of fasting plasma glucose, lipid peroxidative products (thiobarbituric acid reactive substances [TBARS] and lipid hydroperoxides [HP]) and a significant (p < 0.05) decrease in plasma insulin, enzymic antioxidants (superoxide dismutase [SOD], catalase, glutathione peroxidase [GPx] and glutathione reductase [GRx]) and nonenzymic antioxidants (reduced glutathione [GSH], vitamin C and E) in diabetic liver, kidney and brain were observed. Oral administration of rutin (100 mg/kg) for a period of 45 days significantly (p < 0.05) decreased fasting plasma glucose, increased insulin levels and improved the antioxidant status of diabetic rats by decreasing lipid peroxidative products and increasing enzymic and nonenzymic antioxidants. Normal rats treated with rutin (100 mg/kg) showed no significant (p < 0.05) effect on any of the parameters studied. Histopathological studies of the liver, kidney and brain showed the protective role of rutin. Thus, our study clearly shows that rutin has antioxidant effect in STZ-induced experimental diabetes.

Antilipoperoxidative and antioxidant effects of S-allyl cysteine sulfoxide on isoproterenol-induced myocardial infarction in wistar rats

Our study evaluates the preventive effect of S-allyl cysteine sulfoxide (SACS) on lipid peroxidative products and enzymic and nonenzymic antioxidants in isoproterenol (ISO) induced myocardial infarction in rats. The male Wistar rats were rendered myocardial infarction by ISO (150 mg kg(-1), once a day for two days). The concentrations of thiobarbituric acid reactive substances and lipid hydroperoxides were increased in hearts from ISO-treated rats, whereas the content of enzymic and nonenzymic antioxidants were declined in rats administered ISO. Oral pretreatment with SACS (40 mg kg(-1) and 80 mg kg(-1) daily for a period of 35 days) significantly (p < 0.05) decreased the lipid peroxidative products and significantly (p < 0.05) increased antioxidants in ISO-induced rats. Oral administration of SACS (40 mg kg(-1) and 80 mg kg(-1)) did not show any significant effect in normal rats. Thus, the present study shows that SACS exhibits antilipoperoxidative and antioxidant effects in experimental myocardial infarction.

Antihyperglycaemic and Antioxidant Effect of Rutin, a Polyphenolic Flavonoid, in Streptozotocin-Induced Diabetic Wistar Rats

Flavonoids are non-nutritive dietary components that are widely distributed in plants. The present study investigated the antihyperglycaemic and antioxidant effect of rutin, a polyphenolic flavonoid in normal and streptozotocin-induced diabetic Wistar rats. Diabetes as induced in rats by an intraperitoneal injection of streptozotocin. Rutin was orally administered to normal and diabetic rats for a period of 45 days. Fasting plasma glucose, glycosylated haemoglobin, thiobarbituric acid reactive substances and lipid hydroperoxides were significantly (P<0.05) increased, whereas insulin, C-peptide, total haemoglobin, protein levels, non-enzymic antioxidants (glutathione, vitamin C, vitamin E and ceruloplasmin) were decreased significantly (P<0.05) in diabetic rats. Oral administration of rutin to diabetic rats significantly (P<0.05) decreased fasting plasma glucose, glycosylated haemoglobin and increased insulin, C-peptide, haemoglobin and protein levels. Administration of rutin also decreased thiobarbituric acid reactive substances and lipid hydroperoxides and increased the non-enzymic antioxidants significantly (P<0.05). Treatment of normal rats with rutin did not significantly (P<0.05) alter any of the parameters studied. These results show that rutin exhibits antihyperglycaemic and antioxidant activity in streptozotocin-induced diabetic rats.

Modification of cardiac oxidative stress in alloxan-induced diabetic rabbits with repaglinide treatment

The aim of this study was to analyze the antioxidative effect of repaglinide in the heart of alloxan-induced diabetic rabbits. The activities of superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), glutathione (GSH), ascorbic acid (AA), products of lipid peroxidation (LPO) and protein carbonyl groups (PCG) were estimated after 4 and 8 weeks of repaglinide treatment (1 mg daily). At significance level p<0.05, in diabetic heart the activities of Cu,Zn-SOD and CAT were elevated as compared to control values (by 60.7% and 55.3% for Cu,Zn-SOD, and by 89.7% and 77.4% for CAT after 4 and 8 weeks, respectively). The level of AA was diminished by 52.5% and 41.5% while GSH-Px and GSSG-R activities were decreased after 4 weeks of experiment (by 11.5% and 14.4%, respectively). GSH level was diminished by 33.2% after 8 weeks. Simultaneously, in diabetic heart the levels of LPO and PCG were elevated as compared to control values (by 51.6% and 111.3% for LPO, and by 72.0% and 132.9% for PCG after 4 and 8 weeks, respectively). In diabetic animals, repaglinide normalized GSH-Px activity and GSH level. It modified the activities of Cu,Zn-SOD, CAT and AA as compared to diabetic non-treated animals. In diabetic-treated rabbits the level of LPO was diminished as compared to diabetic non-treated animals, while the level of PCG was not affected. In the present study, repaglinide did not affect blood glucose and plasma insulin concentrations in diabetic rabbits. Nevertheless, the drug showed some beneficial antioxidative properties in the heart tissue.