Lipid peroxidation in the pancreas and other organs in streptozotocin diabetic rats

Selenium supplementation via modulation of selenoproteins ameliorates binge drinking-induced oxidative, energetic, metabolic, and endocrine imbalance in adolescent rats' skeletal muscle

Adolescence is characterized by increased vulnerability to addiction and ethanol (EtOH) toxicity, particularly through binge drinking (BD), a favored acute EtOH-ingestion pattern among teenagers. BD, highly pro-oxidant, induces oxidative stress (OS), affecting skeletal muscle (SKM), where selenium (Se), an antioxidant element and catalytic center of selenoproteins, is stored, among other tissues. Investigating the effects of Se supplementation on SKM after BD exposure holds therapeutic promise. For this, we randomised 32 adolescent Wistar rats into 4 groups, exposed or not to intermittent i.p. BD [BD and control (C)] (3 g EtOH per kg per day), and supplemented with selenite [BDSe and CSe] (0.4 ppm). In SKM, we examined the oxidative balance, energy status (AMPK, SIRT-1), protein turnover (IRS-1, Akt1, mTOR, IGF-1, NF-κB p65, MAFbx, ULK1, pelF2α), serum myokines (myostatin, IL-6, FGF21, irisin, BDNF, IL-15, fractalkine, FSTL-1, FABP-3), and selenoproteins (GPx1, GPx4, SelM, SelP). In the pancreas, we studied the oxidative balance and SIRT-1 expression. Selenite supplementation mitigated BD-induced OS by enhancing the expression of selenoproteins, which restored oxidative balance, notably stimulating protein synthesis and normalizing the myokine profile, leading to improved SKM mass growth and metabolism, and reduced inflammation and apoptosis (caspase-3). Selenite restoration of SelP's receptor LRP1 expression, reduced by BD, outlines the crucial role of SKM in the SelP cycle, linking Se levels to SKM development. Furthermore, Se attenuated pancreatic OS, preserving insulin secretion. Se supplementation shows potential for alleviating SKM damage from BD, with additional beneficial endocrine effects on the pancreas, adipose tissue, liver, heart and brain that position it as a broad-spectrum treatment for adolescent alcohol consumption, preventing metabolic diseases in adulthood.

In vivo antidiabetic effects of phenolic compounds of spinach, mustard, and cabbage leaves in mice

Leafy vegetables are considered to have health-promoting potentials, mainly attributed to bioactive phenolic compounds. The antidiabetic effects of spinach, mustard, and cabbage were studied by feeding their phenolic-rich aqueous extracts to alloxan-induced diabetic mice. The antioxidant, biochemical, histopathological, and hematological indices of the control, diabetic, and treated mice were studied. Phenolic compounds present in the extracts were identified and quantified using HPLC-DAD. Results showed ten, nineteen, and eleven phenolic compounds in spinach, mustard, and cabbage leave aqueous extracts, respectively. The body weight, tissue total glutathione (GSH) contents, fasting blood sugar, liver function tests, renal function tests, and lipid profile of the mice were affected by diabetes and were significantly improved by the extract treatments. Likewise, hematological indices and tissues histological studies also showed recovery from diabetic stress in treated mice. The study's findings highlight that the selected leafy vegetables potentially mitigate diabetic complications. Among the studied vegetables, cabbage extract was comparatively more active in ameliorating diabetic stress.

Effects of antioxidants on diabetic kidney diseases: mechanistic interpretations and clinical assessment

Diabetic kidney disease (DKD) is more prevalent with an increase in diabetes mellitus. Oxidative stress is a major factor in the occurrence and progression of DKD. Defending against oxidative stress and restoring antioxidant defense might be key to preventing and treating DKD. The purpose of this article is to provide an explanation of how oxidative stress affects DKD, conduct a systematic review and meta-analysis on DKD, and examine the effect of antioxidants on the disease. An analysis of 19 randomized controlled trials showed that the use of antioxidants could reduce UAE (albumin excretion rate) in patients with DKD (SMD: - 0.31; 95% CI [- 0.47, - 0.14], I² = 0%), UACR (urine albumin/creatinine ratio) (SMD: - 0.60; 95% CI [- 1.15, - 0.06], I² = 89%), glycosylated hemoglobin (hbA1c) (MD: - 0.61; 95% CI [- 1.00, - 0.21], I² = 93%) and MDA (malonaldehyde) (SMD:-1.05; 95% CI [- 1.87, - 0.23], I² = 94%), suggesting that antioxidants seemed to have therapeutic effects in patients with DKD, especially in reducing proteinuria and hbA1c. The purpose of this study is to provide new targets and ideas for drug research and clinical treatment of DKD.

Saccharomyces boulardii exerts renoprotection by modulating oxidative stress, renin angiotensin system and uropathogenic microbiota in a murine model of diabetes

AIMS

We aimed to investigate whether Saccharomyces boulardii strain might exert renoprotective effects by modulating renal renin angiotensin system, oxidative stress and intestinal microbiota in streptozotocin-diabetic mice.

MAIN METHODS

Thirty-six C57BL/6 male mice were divided into four groups: control (C), control + probiotic (CP), diabetes (D), diabetes + probiotic (DP). Diabetes was induced by one intraperitoneal injection of streptozotocin and Saccharomyces boulardii was administered by oral gavage for 8 weeks. Blood glucose, albuminuria and urinary volume were measured. Renal levels of angiotensin peptides (angiotensin I, II and 1-7) and the activities of angiotensin-converting enzyme (ACE) and ACE2 were determined, besides that, renal morphology, serotonin and dopamine levels and also microbiota composition were analyzed.

KEY FINDINGS

Probiotics significantly increased C-peptide secretion and reduced blood glucose of diabetic animals. Saccharomyces boulardii also improved renal antioxidant defense, restored serotonin and dopamine concentration, and activated the renin-angiotensin system (RAS) vasodilator and antifibrotic axis. The modulation of these markers was associated with a beneficial impact on glomerular structure and renal function of diabetic treated animals. The phenotypic changes induced by Saccharomyces boulardii were also related to modulation of intestinal microbiota, evidenced by the decreased abundance of Proteus and Escherichia-Shigella, considered diabetic nephropathy biomarkers.

SIGNIFICANCE

Therefore, probiotic administration to streptozotocin-induced diabetic mice improves kidney structure and function in a murine model and might represent a reasonable strategy to counteract nephropathy-associated maladaptive responses in diabetes.

Dexpanthenol reduces diabetic nephropathy and renal oxidative stress in rats

Hyperglycemia increases reactive oxygen species (ROS) and the resulting oxidative stress contributes to the development of diabetic complications. Dexpanthenol (Dxp) is the biological active form of pantothenic acid. We investigated whether Dxp administration could decrease oxidative stress as a way to treat renal complications of diabetes mellitus (DM). Thirty-two male Wistar albino rats were divided into four groups: control, Dxp, DM and DM + Dxp. Experimental diabetes was induced by a single dose of streptozotocin (STZ). After administration of STZ, the DM + Dxp group was administered 500 mg/kg Dxp intraperitoneally every day for 6 weeks. At the end of the study, blood glucose levels were measured and rats were sacrificed. Kidneys were embedded in paraffin, sectioned and stained with hematoxylin and eosin, and periodic acid-Schiff. The mean malondialdehyde levels, glutathione peroxidase, superoxide dismutase and catalase activities, and total antioxidant and total oxidant status also were measured. The control group was normal in histological appearance. We observed congestion, inflammation, glomerulosclerosis, tubular desquamation, loss of villi and hydropic degeneration in tubule cells in the DM group. Indicators of oxidative stress were elevated and antioxidant activity was reduced in the DM group compared to controls. In the DM + Dxp group, oxidative stress was decreased, antioxidant activity was increased and histopathological changes were reduced compared to the DM group. We found that Dxp exhibited ameliorative effects on STZ induced diabetic nephropathy by increasing antioxidant activity.

Melatonin, quercetin and resveratrol attenuates oxidative hepatocellular injury in streptozotocin-induced diabetic rats

In this study, effects of melatonin, quercetin and resveratrol on hepatocellular injury in streptozotocin (STZ)-induced experimental diabetes were aimed to be investigated by histological and biochemical methods. Thirty-five male Wistar albino rats were divided into five groups, namely, control, diabetes (STZ 45 mg/kg/single dose/intraperitoneally (ip)), diabetes + melatonin (10 mg/kg/30 days/ip), diabetes + quercetin (25 mg/kg/30 days/ip) and diabetes + resveratrol (10 mg/kg/30 days/ip). Initial and final blood glucose levels and body weights (BWs) were measured. At the end of the experimentation, following routine tissue processing procedure, sections were stained with haematoxylin-eosin (H-E), periodic acid Schiff and Masson's trichrome. Tissue malondialdehyde (MDA) and glutathione (GSH) levels and superoxide dismutase (SOD) and catalase (CAT) activities were examined. The diabetic rats had significantly higher blood glucose levels than those of control rats (p = 0.0001). Mean BWs of diabetic rats were significantly decreased when compared with the control rats (p = 0.0013). Histopathological alterations including cellular glycogen depletion, congestion, sinusoidal dilatation, inflammation and fibrosis were detected in diabetes group. On the other hand, histopathological changes markedly reduced in all of the treatment groups (p = 0.001). Mean tissue MDA level was increased but mean tissue CAT and SOD activities and GSH levels were decreased in the diabetes group. Melatonin, quercetin and resveratrol administered diabetic rats showed an increase in CAT activities and GSH levels and a decrease in MDA levels (p < 0.05, for all). Melatonin, quercetin and resveratrol administrations markedly reduced hepatocellular injury in STZ-induced experimental diabetes.

Protective effects of saffron (its active constituent, crocin) on nephropathy in streptozotocin-induced diabetic rats

The reactive oxygen species take role in pathogenesis of many diseases including hypoxia, hypercholesterolemia, atherosclerosis, nephropathy, hypertension, ischemia–reperfusion damage, and heart defects. The aim of this study was to evaluate whether crocin administration could protect kidney injury from oxidative stress in streptozotocin-induced diabetic rats. The rats were randomly divided into 3 groups each containing 10 animals as follows: group 1, control group; group 2, diabetes mellitus (DM) group; and group 3, DM + crocin group. At the end of the study, trunk blood was collected to determine the plasma levels of blood urea nitrogen (BUN) and creatinine (Cr). The kidney tissue was removed, and biochemical and histological changes were examined. Diabetes caused a significant increase in malondialdehyde (MDA) and xanthine oxidase (XO) activities and a decrease in glutathione (GSH) contents (  p < 0.01) when compared with control group in the rat kidneys. Crocin given to DM rats significantly decreased MDA (  p < 0.01) and XO (  p < 0.05) activities and elevated GSH (  p < 0.05) contents when compared with DM group. Plasma levels of BUN and Cr were significantly higher in the DM group when compared with the control group (  p < 0.01). Pretreatment of the DM animals with crocin decreased the high level of serum Cr and BUN. Control group was normal in histological appearance, but congestion, severe inflammation, tubular desquamation, tubular necrosis, and hydropic degeneration in tubular cells were observed in the DM group. Histopathological changes markedly reduced, and appearance of kidney was nearly similar to control group in DM + crocin group. Our results show that crocin could be beneficial in reducing diabetes-induced renal injury.

Symplocos cochinchinensis attenuates streptozotocin-diabetes induced pathophysiological alterations of liver, kidney, pancreas and eye lens in rats

The beneficial effects of hydroethanol extract of Symplocos cochinchinensis (SCE) has been explored against hyperglycemia associated secondary complications in streptozotocin induced diabetic rat model. The experimental groups consist of normal control (NC), diabetic control (DC), DC + metformin 100 mg kg(-1) bwd, DC + SCE 250 and DC + SCE 500. SCEs and metformin were administered daily for 21 days and sacrificed on day 22. Oral glucose tolerance test, plasma insulin, % HbA1c, urea, creatinine, aspartate aminotransferase, alanine aminotransferase, albumin, total protein etc. were analysed. Aldose reductase (AR) activity in the eye lens was also checked. On day 21, DC rats showed significantly abnormal glucose response, HOMA-IR, % HbA1c, decreased activity of antioxidant enzymes and GSH, elevated AR activity, hepatic and renal oxidative stress markers like malondialdehyde, protein carbonyls compared to NC. DC rats also exhibited increased level of plasma urea and creatinine. Treatment with SCE protected from the deleterious alterations of biochemical parameters in a dose dependent manner including histopathological alterations in pancreas. SCE 500 exhibited 46.28% of glucose lowering effect and decreased HOMA-IR (2.47), % HbA1c (6.61), lens AR activity (15.99%), and hepatic, renal oxidative stress and function markers compared to DC group. Considerable amount of liver and muscle glycogen was replenished by SCE treatment in diabetic animals. Although metformin showed better effect, the activity of SCE was very much comparable with this drug.

Antidiabetic effect of flavonoids from Malus toringoides (Rehd.) Hughes leaves in diabetic mice and rats

ETHNOPHARMACOLOGICAL RELEVANCE

The leaf of Malus toringoides (Rehd.) Hughes is a traditional folk medicine in Tibet, China, which is called "E Se" in Tibetan language. This original plant grows on snow mountains at an attitude of 3000 to 3700 m. It is primarily used to treat hypertension, hyperlipidemia, hyperglycemia, indigestion and other diseases. This study aimed to evaluate the antidiabetic effect of flavonoids extracted from E Se (ESF) and to explore the potential mechanism in streptozotocin (STZ) or alloxan (ALX) induced diabetic mice and STZ-induced diabetic rats.

MATERIALS AND METHODS

72 h after the establishment of a diabetic model, STZ or ALX induced diabetic mice and STZ-induced diabetic rats were treated daily with ESF at doses of 45, 90, 180 mg/kg and 37.5, 75, 150 mg/kg, respectively. Both mice and rats were fasted for 5h before administration and the blood glucose (BG) levels were tested 1h after treatment. Body weight was determined every other day. For STZ-induced rats, glycosylated hemoglobin (Hb1Ac), serum insulin and c-peptide, hepatic glycogen, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels in liver were assessed on the fourth day after BG level detection.

RESULTS

Compared with the model group, the general behavior of mice treated with ESF (90, 180 mg/kg) and rats treated with ESF (75, 150 mg/kg) became better and BG levels were significantly reduced (P<0.05). Significant decrease (P<0.05) in Hb1Ac level was observed in ESF-treated rats compared with diabetic rats. Significant increase (P<0.05 ) in serum insulin and c-peptide were detected in ESF-treated rats. The treatment also significantly (P<0.05) elevated SOD activity and reduced MDA level in the liver of diabetic rats. Besides, ESF 150 mg/kg had a trend of rising hepatic glycogen content of diabetic rats.

CONCLUSIONS

The findings of this study suggest that flavonoids from the Malus toringoides (Rehd.) Hughes leaves may possess an antidiabetic activity in animals with established diabetes.

Amelioration of streptozotocin-induced diabetic nephropathy by melatonin, quercetin, and resveratrol in rats

The role of oxygen radicals are known for the pathogenesis of kidney damage. The aim of the present study was to investigate the antioxidative effects of melatonin, quercetin, and resveratrol on streptozotocin (STZ)-induced diabetic nephropathy in rats. A total of 35 male Wistar rats were divided into 5 groups as follows: control, diabetes mellitus (DM), DM + melatonin, DM + quercetin, and DM + resveratrol. All the injections started on the same day of single-dose STZ injection and continued for 30 days. At the end of this period, kidneys were removed and processed for routine histological procedures. Biochemical parameters and morphological changes were examined. In DM group, blood glucose levels were significantly increased, whereas body weights were decreased compared with the control group. Significant increases in blood urea nitrogen and tissue malondialdehyde (MDA) levels and decreases in superoxide dismutase and catalase activities were detected in DM group. Administration of melatonin, quercetin, and resveratrol significantly reduced these values. Melatonin was more efficient in reducing MDA levels than other antioxidants ( p < 0.05). STZ-induced histopathological alterations including epithelial desquamation, swelling, intracytoplasmic vacuolization, brush border loss and peritubular infiltration. Additionally, basement membrane thickening and sclerotic changes were observed in glomerulus. Transforming growth factor-β1 positive cells were also increased. Melatonin, quercetin, and resveratrol significantly reduced these histopathological changes. Our results indicate that melatonin, quercetin, and resveratrol might be helpful in reducing diabetes-induced renal damage

Synergistic antidiabetic activity of Vernonia amygdalina and Azadirachta indica: biochemical effects and possible mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

A decoction from a combination of herbs is commonly used in Traditional African Medicine for the management of chronic ailments. In Nigeria, the leaves of Vernonia amygdalina Del. (VA) and Azadirachta indica A. Juss (AI) are used traditionally as a remedy against diabetes mellitus for which empirical evidence attests to its efficacy.

AIM OF THE STUDY

To evaluate the synergistic antidiabetic action of VA and AI, the biochemical effects and possible mechanism in streptozotocin-induced diabetic rat (SDR) models.

MATERIALS AND METHODS

Ethanolic extracts of VA and AI were co-administered (200 mg/kg, 50:50) to non-diabetic rats (NDRs) and SDRs for 28 days. Blood glucose and body weight were monitored during this period, and at end of treatment, serum glucose, insulin, triiodothyronine (T3), tetraiodothyronine (T4) and α-amylase activity were studied. Glucose and activities of antioxidant enzymes, e.g., catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), were estimated in hepatocytes, along with the impact on the histology of the liver and pancreas. Medium acting insulin, HU (5 IU/kg, s.c.) was used as a positive control.

RESULTS

The study reveals that compared with single extracts, the combined extract (VA/AI) promptly lowered blood glucose and maintained a relatively steady level over the study period, in tandem with HU. During this period, body weight gain successively increased. In SDRs, fasting blood glucose at days 0 and 28 was raised by 4.33 and 3.16 fold, respectively, and the serum glucose was raised by 7.70 fold vs. normal control (P<0.05). The discrepancies in the individual effects of VA and AI on hepatic glucose and α-amylase activity were also restored. In NDRs, VA/AI lowered blood and serum glucose (1.14 and 1.94 fold, respectively), although to a lesser extent when compared with HU. Furthermore, VA/AI was found to lower serum insulin, T3 and T4 by 1.66, 1.57 and 2.16 fold, respectively, in SDR (P<0.05). This was similar to HU, which demonstrated 1.79 and 1.68 fold reduction of insulin and T3, respectively (P<0.05), but had no effect on T4. Conversely, in NDRs, VA/AI caused 1.32, 4.93 and 1.04 fold increase in insulin, T3 and T4, respectively, reciprocal to its effect on blood and serum glucose. Oxidative stress in SDR, characterised by decreased GPx and CAT activities, was ameliorated, as the activities of the enzymes and SOD increased following a 28-day treatment with VA/AI (P<0.05). The features of diabetic pathology, indicated in the histology of the liver and pancreas, were reversed. However, the extent of recovery was partial with VA, better with AI, and distinct and total with VA/AI, compared with a null effect by HU.

CONCLUSION

Taken together, our results contribute towards validation of enhanced antidiabetic efficacy of VA and AI when combined. This synergy may be exerted by oxidative stress attenuation, insulin mimetic action and β-cell regeneration.

Methoxy VO-salen stimulates pancreatic β cell survival by upregulation of eNOS and downregulation of apoptosis in STZ-induced diabetic rats

The present study was designed to investigate the effect of MetVO-salen in ameliorating diabetes and oxidative stress in the pancreas of diabetic rats. Streptozotocin (STZ)-induced diabetic rats were treated with MetVO-salen complex intraperitonially (0.3 and 0.6 mg/kg) thrice a week and continued for 8 weeks. Total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides in serum, and blood glucose were estimated. Furthermore, oxidative stress in rats was also investigated in terms of superoxide dismutase (SOD), catalase, lipid peroxidation, and glutathione (GSH). In addition, the anti-diabetic activity of MetVO-salen was also investigated by assessing histopathological, immunohistochemical in terms of endothelial nitric oxide synthase expression, and apoptotic events in pancreas. Treatment with MetVO-salen complex reduced the blood glucose level and significantly altered the serum biochemical parameters of diabetic rats. Treatment with above complex decreased the lipid peroxidation and the antioxidant enzymes such as SOD, CAT, and GSH to near-control levels. Histopathological, immunohistochemical, and apoptotic studies also revealed that MetVO-salen-induced amelioration of the diabetic state appears to be significant to the preservation of a functional portion of the pancreatic β cells which initially prevent STZ toxicity. This study provides new direction for the management of diabetes but needs further clinical evaluation.

Aloe vera gel alleviates cardiotoxicity in streptozocin-induced diabetes in rats

Objectives

Persistent hyperglycaemia results in oxidative stress along with the generation of oxygen free radicals and appears to be an important factor in the production of secondary complications in diabetes. The aim of this work was to evaluate markers of oxidative stress in heart tissue along with the protective, antioxidant and antidiabetic activity of 30% Aloe vera gel in diabetic rats.

Methods

Streptozocin was given as a single intravenous injection and 30% Aloe vera gel was given in two doses for 20 days, orally. Blood glucose, glycosylated haemoglobin, blood reduced glutathione, serum lactate dehydrogenase and serum creatine kinase levels were measured on day 21 after drug treatment. Heart rate and mean blood pressure were recorded at the end of the study. Different biochemical variables were evaluated in the heart tissue, including thiobarbituric acid reactive substance (TBARS), reduced glutathione, superoxide dismutase and catalase in diabetic and in Aloe vera-treated diabetic rats.

Key findings

In streptozocin diabetic rats, the TBARS level was increased significantly, superoxide dismutase and reduced glutathione significantly decreased, and the catalase level was significantly increased. Aloe vera 30% gel (200 mg/kg) treatment in diabetic rats reduced the increased TBARS and maintained the superoxide dismutase and catalase activity up to the normal level. Aloe vera gel increased reduced glutathione by four times in diabetic rats.

Conclusions

Aloe vera gel at 200 mg/kg had significant antidiabetic and cardioprotective activity.

Cardioprotective effect of vitamin E: rescues of diabetes-induced cardiac malfunction, oxidative stress, and apoptosis in rat

AIM

This study was designed to assess the effect of vitamin E on cardiac autonomic neuropathy, cardiomyocyte apoptosis, and the status of oxidative stress in the heart under hyperglycemic conditions, in vivo.

METHODS

Wistar male rats (n=16) were made hyperglycemic by streptozotocin at 6 months of age. Normal Wistar rats (n=8) of the same age were used as the control group. Diabetic rats were divided into two groups, nontreated and those treated with vitamin E (300 mg/day). Stable hyperglycemic status was proved by levels of blood sugar and HbA(1c). Lipid peroxidation, protein oxidation, and cellular antioxidant defense were measured by 8-isoprotane, protein carbonyl content, and superoxide dismutase (SOD) activity, respectively.

RESULTS

Cardiac complications such as autonomic neuropathy as prolonged QT interval along with significant increases in level of 8-isoprotane, protein carbonyl content, and SOD activity were observed after 6 weeks. Structural abnormality was also observed as severe induction of apoptosis in cardiomyocytes.

CONCLUSION

Significant decline in apoptosis, lipid peroxidation, protein oxidation, and QT interval resulted from vitamin E administration, which strongly implies that this radical scavenger may promote a convalescing effect on diabetic cardiomyopathy through the attenuation of oxidative stress and abrogation of apoptotic signals, which was verified by restoring normal QT interval.

Antioxidative and anti-diabetic effects of amaranth (Amaranthus esculantus) in streptozotocin-induced diabetic rats

The anti-diabetic and antioxidative effect of amaranth grain (AG) and its oil fraction (AO) was studied in streptozotocin-induced diabetic rats. Male Sprague-Dawley rats were divided into four groups after induction of STZ-diabetes: normal control; diabetic control; diabetic-AG supplement (500 g kg(-1) diet); diabetic-AO supplement (100 g kg(-1) diet) and fed experimental diets for 3 weeks. Serum glucose, insulin, activities of serum marker enzymes of liver function and liver cytosolic antioxidant enzymes were measured. The AG and AO supplement significantly decreased the serum glucose and increased serum insulin level in diabetic rats. Serum concentration of liver function marker enzymes, GOT and GPT, were also normalized by AG and AO treatment in diabetic rats. Liver cytosolic SOD and GSH-reductase activities were significantly increased, and catalase, peroxidase and GSH-Px activities were decreased in diabetic rats. AG and AO supplement reverted the antioxidant enzyme activities to near normal values. Hepatic lipid peroxide product was significantly higher, and GSH content was decreased in diabetic rats. However, AG and AO supplement normalized these values. Our data suggest that AG and AO supplement, as an antioxidant therapy, may be beneficial for correcting hyperglycaemia and preventing diabetic complications.

Experimental diabetes model in chick embryos treated with streptozotocin

The aim of the present study was to investigate whether diabetes model can be made by treatment of streptozotocin (STZ) in chick embryos and this model can be used to predict the effect of drug. When STZ (0.3 mg/egg) was injected into the albumen of fertile eggs on the 14th day of incubation, level of blood glucose significantly increased than that of the control on the 17th day of incubation, and level of serum insulin significantly decreased. In addition, the enhanced level of blood glucose in STZ-treated embryos reduced by injection of human insulin. In conclusion, STZ-treated embryos may be applicable to evaluate human insulin and anti-diabetes drugs as an experimental diabetes model.

Effects of melatonin on plasma oxidative stress in rats with streptozotocin induced diabetes

The aim of this study was to evaluate the effect of single melatonin injection on plasma oxidative stress in rats with streptozotocin induced diabetes. Diabetes was induced after a single intraperitoneal dose of streptozotocin (60 mg/kg), while hyperglycemia was determined 10 days upon injection. Diabetic rats were divided into two groups. In the first group the injection of melatonin was applied intraperitoneally (20 mg/kg), while the second group received physiological solution. Twenty-four hours later the rats were killed and their blood was centrifuged. In the rat plasma the following parameters were evaluated: the glucose level, superoxide radical, lipid peroxidation, reduced glutathione, total antioxidant capacity, antioxidant enzymes and the aldose reductase activity. The injected melatonin decreased the superoxide radical in the rat plasma. Moreover, melatonin increased the total antioxidative capacity and the activity of antioxidative enzymes superoxide dismutase and glutathione peroxidase. These results indicate that melatonin is a strong scavenger, which may diminish negative effects of oxidative stress in diabetic rats 24 hours after its application The findings suggest that melatonin is also a strong antioxidant. It increases the antioxidant enzymes activity, inhibiting the release of superoxide radicals. A high total antioxidative capacity and the lower activity of aldose reductase enlarge melatonin scavenger capacity against reactive oxygen species in diabetic rats.

Anti-diabetic activity of the semi-purified fractions of Averrhoa bilimbi in high fat diet fed-streptozotocin-induced diabetic rats

The present study was designed to investigate the hypoglycemic and hypolipidemic activities of the semi-purified fractions of an ethanolic leaf extract of Averrhoa bilimbi (ABe) in high fat diet (HFD)-streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats aged 10 weeks (200-250 g) were fed with a high fat diet obtained from Glen Forrest stock feeders (Western Australia) for 2 weeks prior to intraperitoneal injection with streptozotocin (STZ, 50 mg/kg). The leaves of A.bilimbi were exhaustively extracted with 80% ethanol, concentrated at 40 degrees C using a rotavapor and partitioned successively with butanol, ethylacetate and hexane to get aqueous (AF), butanol (BuF), ethylacetate (EF), and hexane fractions (HF). The fractions were freeze-dried to obtain powders of each. To investigate the effect of long term administration of the hypoglycemic fractions, diabetic animals were treated with vehicle (distilled water), AF (125 mg/kg), or BuF (125 mg/kg), twice a day for 14 days. The long term administration of AF and BuF at a dose of 125 mg/kg significantly (P < 0.05) lowered blood glucose and triglyceride concentrations when compared to the vehicle. The hepatic glycogen content was significantly higher (P < 0.05) in AF-treated rats when compared to diabetic control, however no change was found in the BuF-treated rats. Moreover, AF as well as BuF did not cause any significant change in the total cholesterol and HDL-cholesterol. There was also no difference in liver thiobarbituric acid reactive substances (TBARS) and cytochrome P450 values between AF, BuF and vehicle-treated control rats. In conclusion, the results indicate that AF is more potent than BuF in the amelioration of hyperglycemia and hyperlipidemia in HFD fed-STZ diabetic rats. Hence, AF is a potential source for the isolation of active principle(s) for oral anti-diabetic therapy.

Effect of ethanolic extract of Zingiber officinale on dyslipidaemia in diabetic rats

The lipid lowering and antioxidant potential of ethanolic extract of Zingiber officinale Roscoe (family, Zingiberaceae) was evaluated in streptozotocin (STZ)-induced diabetes in rats. Ethanolic extract of Zingiber officinale (200 mg/kg) fed orally for 20 days produced, significant antihyperglycaemic effect (P < 0.01) in diabetic rats. Further, the extract treatment also lowered serum total cholesterol, triglycerides and increased the HDL-cholesterol levels when compared with pathogenic diabetic rats (P < 0.01). STZ-treatment also induced a statistically significant increase in liver and pancreas lipid peroxide levels (P < 0.01) as compared to normal healthy control rats. Zingiber officinale extract treatment lowered the liver and pancreas thiobarbituric acid reactive substances (TBARS) values (P < 0.01) as compared to pathogenic diabetic rats. The results of test drug were comparable to gliclazide (25 mg/kg, orally), a standard antihyperglycaemic agent. The results indicate that ethanolic extract of Zingiber officinale Roscoe can protect the tissues from lipid peroxidation. The extract also exhibit significant lipid lowering activity in diabetic rats. The present study is the first pilot study to assess the potential of Zingiber officinale in diabetic dyslipidaemia.

Protective effect of caffeic acid phenethyl ester (CAPE) on lipid peroxidation and antioxidant enzymes in diabetic rat liver

The aim of this study was to examine the effect of caffeic acid phenethyl ester (CAPE) on lipid peroxidation (LPO) and the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the liver of streptozotocin (STZ)-induced diabetic rats. Twenty-seven rats were randomly divided into three groups: group I, control non-diabetic rats (n = 9); group II, STZ-induced, untreated diabetic rats (n = 8); group III, STZ-induced, CAPE-treated diabetic rats (n = 10), which were intraperitoneally injected with CAPE (10 microM kg(-1) day(-1)) after 3 days followed by STZ treatment. The liver was excised after 8 weeks of CAPE treatment, the levels of malondialdehyde (MDA) and the activities of SOD, CAT, and GSH-Px in the hepatic tissues of all groups were analyzed. In the untreated diabetic rats, MDA markedly increased in the hepatic tissue compared with the control rats (p < 0.0001). However, MDA levels were reduced to the control level by CAPE. The activities of SOD, CAT, and GSH-Px in the untreated diabetic group were higher than that in the control group (p < 0.0001). The activities of SOD and GSH-Px in the CAPE-treated diabetic group were higher than that in the control group (respectively, p < 0.0001, p < 0.035). There were no significant differences in the activity of CAT between the rats of CAPE-treated diabetic and control groups. Rats in the CAPE-treated diabetic group had reduced activities of SOD and CAT in comparison with the rats of untreated diabetic group (p < 0.0001). There were no significant differences in the activity of GSH-Px between the rats of untreated diabetic and CAPE-treated groups. It is likely that STZ-induced diabetes caused liver damage. In addition, LPO may be one of the molecular mechanisms involved in STZ-induced diabetic damage. CAPE can reduce LPO caused by STZ-induced diabetes.

Effects of atorvastatin and pravastatin on glucose tolerance in diabetic rats mildly induced by streptozotocin

Effects of atorvastatin and pravastatin on glucose tolerance in mildly induced diabetic rats by streptozotocin at 24 mg/kg, i.v. were studied. Non-diabetic and diabetic rats were given orally 0.5% carboxymethylcellulose (control), 8 mg/kg atorvastatin or 8 mg/kg pravastatin once a day for 6 weeks. An oral glucose tolerance test (OGTT) was carried out 1, 2, 3, and 6 weeks after the administration. The blood glucose and plasma insulin levels measured before OGTT in the diabetic rats were not different from those in the non-diabetic rats. However, the hyperglycemic response to OGTT in the diabetic rats significantly exceeded that in the non-diabetic rats. The plasma insulin increased by OGTT in the diabetic rats appeared to be lower than that in the non-diabetic rats. Statin treatments for 1 week did not modify the OGTT-induced hyperglycemia appreciably, although there were some significant differences. More than 2 weeks after administration, the blood glucose levels at several time points after a glucose intake in the atorvastatin-treated diabetic rats were significantly higher than the respective levels in the control diabetic rats. Neither atorvastatin nor pravastatin modified the OGTT-induced insulin secretion. Statins, especially atorvastatin, may influence the glucose tolerance in mildly induced diabetic rats without alterations of insulin secretion.

Ultrastructural, immunohistochemical and biochemical investigations of the rat liver exposed to experimental diabetes und acute hypoxia with and without application of Ginkgo extract

The aim of this paper was to investigate the effect of streptozotocin-induced diabetes by i.p. bolus injection of streptozotocin at 60 mg per kg bodyweight over four months and additional acute respiratory hypoxia (20 min. duration, 5% oxygen v/v), and also the protective effect of Ginkgo biloba extract (EGb 761) on Wistar rat liver under these experimental conditions. Diabetic and additional hypoxic alterations in histology and ultrastructure were subjected to qualitative and quantitative analysis, collagen was investigated by immunohistochemistry, and some biochemical parameters of oxidative stress were determined. Diabetes caused an increase in the size of the hepatocytes and their nuclei with a decrease in nucleus-to-plasma ratio and glycogen content. Connective tissue was variably increased in individual cases as shown by routine histological staining. EGb did not influence these data. Ultrastructural morphometry revealed a significant reduction in rough endoplasmic reticulum (rER) and a significant increase in smooth endoplasmic reticulum (sER) through diabetes, an increase under EGb protection, with no significant alteration under hypoxia. The volume fraction of mitochondria was significantly increased after induction of diabetes but less increased in the protected group. Additional hypoxia reduced this parameter. The mean cross-section area of mitochondria was significantly elevated in all diabetic groups compared to controls. Volume density of mitochondrial cristae was significantly diminished in all diabetic groups; EGb could only improve this parameter in the diabetic-hypoxic group.

Alterations in antioxidant enzymes and oxidative damage in experimental diabetic rat tissues: effect of vanadate and fenugreek (Trigonellafoenum 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 3 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.

Alternation of hepatic antioxidant enzyme activities and lipid profile in streptozotocin-induced diabetic rats by supplementation of dandelion water extract

BACKGROUND

Dandelion water extract (DWE), an herbal medication, may have an effect on the activity and mRNA expression of hepatic antioxidant enzymes and lipid profile in streptozotocin (STZ)-induced diabetic rats.

METHODS

Male Sprague-Dawley rats were divided into nondiabetic (control), diabetic, and diabetic-DWE-supplemented groups. Diabetes was induced by injecting streptozotocin (55 mg/kg BW, i.p.) in a citrate buffer. The extract was supplemented in 2.4 g of a DWE/kg diet.

RESULTS

The DWE supplement significantly decreased the serum glucose concentration in the diabetic rats. The hepatic superoxide dismutase and catalase activities significantly increased and the GSH-Px activity decreased in the diabetic rats, compared with the control group. When the DWE supplement was given to the diabetic rats, the antioxidant enzyme activity reverted to near-control values. However, there was no difference in the mRNA expression concentrations of these enzymes between the groups. With regard to the hepatic lipid peroxidation product, the malondialdehyde (MDA) content was significantly higher in the diabetic group than in the nondiabetic group. However, the DWE supplement lowered the hepatic MDA concentration in the diabetic-induced rats. The DWE supplement also lowered the total cholesterol and triglyceride concentrations in the serum and hepatic tissue, while increasing the serum HDL-cholesterol in the diabetic rats.

CONCLUSIONS

A DWE supplement can improve the lipid metabolism and is beneficial in preventing diabetic complications from lipid peroxidation and free radicals in diabetic rats.

Differences in antioxidant status in skeletal muscle tissue in experimental diabetes

BACKGROUND

It has been suggested that oxidative stress may play an important role in pathogenesis of diabetic complications. The present study was designed to evaluate the oxidative stress-related parameters in alloxan (A)-induced long-term diabetes in rabbits.

METHODS

After 3, 6 and 12 weeks of diabetes, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R) and concentrations of ascorbic acid (AA) and free sulfhydryl compounds (SH) were measured in skeletal muscle of diabetic rabbits and the normal control subjects. The products of lipid peroxidation (MDA) were also estimated.

RESULTS

In our tests, the muscle SOD activity, SH and AA concentrations were significantly reduced. CAT activity increased significantly at all time intervals. GSH-Px activity decreased after 3 weeks and then remained at the control level. GSSG-R activity decreased progressively at 3rd and 6th week and then significantly increased. MDA level increased initially, dropped below baseline after 6 weeks and then remained at the level of the control group.

CONCLUSIONS

The changes observed in the present experiment suggest a significant imbalance in antioxidative system in the skeletal muscle of rabbits with alloxan-induced diabetes. Such study may lead to therapeutic approaches for limiting the damage from oxidation reactions and preventing the diabetic complications.

Radical scavenging properties of novel benzopyran derivatives, TA248 and TA276, and effects of the compounds on ischemic/reperfused myocardium in dogs

Characteristics of novel benzopyran derivatives, TA248 and TA276, and their effects on myocardial contraction in ischemic/reperfused hearts in dogs were examined. TA248 and TA276 inhibited NADPH-dependent lipid peroxidation induced by Fe(3+) in the rat brain homogenate. Both compounds reduced *O(2-) produced by xanthine-xanthine oxidase system in a dose-dependent manner. TA276 scavenged.OH generated by Fenton reaction in a dose-dependent manner. TA248 also inhibited the.OH production, but the effect was neither complete nor dose dependent. Myocardial contraction was assessed as segment shortening of the left ventricular wall in pentobarbital-anesthetized open-chest dogs. The segment shortening was decreased by the left anterior descending coronary artery ligation (ischemia) and returned by release of the ligated artery (reperfusion). The segment shortening did not recover fully during reperfusion. Either TA248 or TA276 injected 10 min before ischemia improved the recovery of myocardial contraction during reperfusion. Both compounds preserved the level of ATP in the 60-min reperfused myocardium. However, the level of lipid peroxides was not changed by TA248 and TA276. TA248 and TA276 may protect myocardium against ischemic/reperfusion insult, partly because of their free radical scavenging activity, but no significant change in myocardial lipid peroxide level was observed.

Activity of lysosomal apparatus in rat myocardium during experimental coronary and noncoronary myocardial damage

Cardiac and plasma activities of marker lysosomal enzymes were studied in Wistar rats with metabolic (epinephrine) and occlusion (ligation of coronary arteries) myocardial infarction. Activity of all examined lysosomal enzymes significantly increased in the myocardium and blood plasma starting from the first day after ligation of the coronary arteries and was accompanied by leukocytic infiltration of the myocardium. Enzyme activity gradually decreased to postoperation day 14. In metabolic infarction leukocytic infiltration and specific activity of lysosomal enzymes rose gradually and attained maximum to postoperation day 14, while the signs of labilization of lysosomal membranes appeared from the first postoperation day. Plasma activity of lysosomal enzymes in metabolic infarction increased smoothly and peaked on day 14.

Modulation of xenobiotic metabolism and oxidative stress in chronic streptozotocin-induced diabetic rats fed with Momordica charantia fruit extract

We studied the long-term effects of streptozotocin-induced diabetes on tissue-specific cytochrome P450 (CYP) and glutathione-dependent (GSH-dependent) xenobiotic metabolism in rats. In addition, we also studied the effect of antidiabetic Momordica charantia (karela) fruit-extract feeding on the modulation of xenobiotic metabolism and oxidative stress in rats with diabetes. Our results have indicated an increase (35-50%) in CYP4A-dependent lauric acid hydroxylation in liver, kidney, and brain of diabetic rats. About a two-fold increase in CYP2E-dependent hepatic aniline hydroxylation and a 90-100% increase in CYP1A-dependent ethoxycoumarin-O-deethylase activities in kidney and brain were also observed. A significant increase (80%) in aminopyrene N-demethylase activity was observed only in rat kidney, and a decrease was observed in the liver and brain of diabetic rats. A significant increase (77%) in NADPH-dependent lipid peroxidation (LPO) in kidney of diabetic rats was also observed. On the other hand, a decrease in hepatic LPO was seen during chronic diabetes. During diabetes an increased expression of CYP1A1, CYP2E1, and CYP4A1 isoenzymes was also seen by Western blot analysis. Karela-juice feeding modulates the enzyme expression and catalytic activities in a tissue- and isoenzyme-specific manner. A marked decrease (65%) in hepatic GSH content and glutathione S-transferase (GST) activity and an increase (about two-fold) in brain GSH and GST activity was observed in diabetic rats. On the other hand, renal GST was markedly reduced, and GSH content was moderately higher than that of control rats. Western blot analyses using specific antibodies have confirmed the tissue-specific alterations in the expression of GST isoenzymes. Karela-juice feeding, in general, reversed the effect of chronic diabetes on the modulation of both P450-dependent monooxygenase activities and GSH-dependent oxidative stress related LPO and GST activities. These results have suggested that the modulation of xenobiotic metabolism and oxidative stress in various tissues may be related to altered metabolism of endogenous substrates and hormonal status during diabetes. The findings may have significant implications in elucidating the therapeutic use of antidiabetic drugs and management of Type 1 diabetes in chronic diabetic patients.

Influence of streptozotocin-induced diabetes in rats on the lithium content of tissue and the effect of dietary lithium supplements on this diabetic condition

To study the effects of lithium supplementation on the diabetic condition, we measured the lithium concentration in the liver, kidney, and muscle from streptozotocin (STZ)-induced diabetic male Sprague-Dawley (SD) rats that were either treated or untreated with peroral lithium carbonate (0.3 mg/mL). The data showed that the lithium content of the liver and muscle was significantly lower in STZ rats than in normal control rats (0.22 +/- 0.05 v 1.30 +/- 0.15, P < .01, and 0.79 +/- 0.30 v 2.48 +/- 2.00 microg/g, respectively). After 4 weeks of lithium carbonate supplementation, we found that (1) the lithium content of the liver and muscle returned to the normal range, (2) the extent of STZ-mediated destruction of beta cells in the pancreas decreased, (3) fasting blood glucose (FBG) and 2-hour postprandial blood glucose (PBG) decreased (P < .05), (4) among the indicators of oxidative stress and antioxidant defenses, blood lipid peroxidate (LPO) decreased and erythrocyte superoxide dismutase (RBC-SOD) and glutathione (GSH) returned to normal, and (5) hepatic LPO decreased and glutathione peroxidase (GSH-Px) increased. These results suggest that the restoration of lithium to control levels in the liver and muscle of diabetic animals is associated not only with decreased blood glucose but also with reduced oxidative stress, and consequently with the protection of insulin-secreting pancreatic islet cells.