Inhibition of Protein Kinase C Restores Na+, K+-ATPase Activity in Sciatic Nerve of Diabetic Mice

We have tested if inhibition of protein kinase C is able to prevent and/or to restore the decrease of Na+,K(+)-ATPase activity in the sciatic nerve of alloxan-induced diabetic mice. Mice were made diabetic by subcutaneous injection of 200 mg of alloxan/kg of body weight. The activity of Na+,K(+)-ATPase decreased rapidly (43% after 3 days) and slightly thereafter (58% at 11 days). We show that intraperitoneal injection of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), an inhibitor of protein kinase C, prevents completely the loss of Na+,K(+)-ATPase activity produced by alloxan. Also, H7 injected into diabetic mice, 4-9 days after the injection of alloxan, restores the activity of the enzyme. The amount of activity recovered depends on the dose of H7 administered; complete recovery was reached with injection of 15 mg of H7/kg of body weight. The effect of H7 is transient, with a half-life of approximately 1 h.     

In vitro and in vivo protective effect of Ganoderma lucidum polysaccharides on alloxan-induced pancreatic islets damage

This study was undertaken to investigate the protective effect against alloxan-induced pancreatic islets damage by Ganoderma lucidum Polysaccharides (Gl-PS) isolated from the fruiting body of Ganoderma lucidum (Leyss. ex Fr.) Karst. In vitro, alloxan caused dose-dependent toxicity on the isolated pancreatic islets. Pre-treatment of islets with Gl-PS for 12 h and 24 h significantly reversed alloxan-induced islets viability loss. Gl-PS was also found to inhibit the free radicals production induced by alloxan in the isolated pancreatic islets using confocal microscopy. Gl-PS dose-dependently increased serum insulin and reduced serum glucose levels when pretreated intragastrically for 10 days in alloxan-induced diabetic mice. It was found that the pancreas homogenates had higher lipid peroxidation products in alloxan-treated mice than in the Gl-PS-treated animals. Aldehyde fuchsin staining revealed that alloxan caused nearly all the beta cells disappearing from the pancreatic islets, while Gl-PS partly protected the beta cells from necrosis. Alloxan (60 mg/kg) induced NF-kappa B activation in the pancreas at 30 min after injection, pretreatment with Gl-PS inhibited alloxan-induced activation of NF-kappa B. These results suggest that Gl-PS was useful in protecting against alloxan-induced pancreatic islets damage in vitro and in vivo; one of the mechanisms is through its scavenging ability to protect the pancreatic islets from free radicals-damage induced by alloxan.     

Protection against alloxan-induced diabetes in mice by stimulation of alpha 2-adrenergic receptors

A single intravenous injection of alloxan in mice induced hyperglycemia in a dose dependent fashion. This diabetogenic action of alloxan was prevented by a single intraperitoneal injection of the alpha 2-adrenergic agonists, i.e. oxymetazoline, clonidine or epinephrine 40 min prior to the injection of alloxan. The alpha 1-adrenergic agonists, i.e. methoxamine and phenylephrine, and a beta-adrenergic agonist, isoproterenol, failed to prevent the diabetogenic action of alloxan. The inhibitory effect of clonidine on alloxan-induced diabetes was antagonized by yohimbine or phentolamine, but not by prazosin. Although alpha 2-adrenergic agonists caused a transient hyperglycemia at the time of alloxan administration (40 min after the administration of alpha 2-adrenergic agonists), the plasma glucose level at the time of alloxan injection did not correlate with the anti-diabetogenic effect of alpha 2-adrenergic agents. These results clearly demonstrate that the alpha 2-adrenergic mechanism which inhibits insulin release from pancreatic B cells prevented the diabetogenic action of alloxan in mice.     

Protective effect of diltiazem hydrochloride on the occurrence of alloxan- or streptozotocin-induced diabetes in rats.

This study demonstrated that 20 mg/kg of the Ca2+ channel blocker, diltiazem hydrochloride, administered by intraperitoneal injection 15 min before 200 mg/kg of alloxan given by the same route to induce diabetes, served to suppress disease onset completely in rats. Even though 48-h fasting promoted the onset of alloxan diabetes, 40 mg/kg of diltiazem hydrochloride completely prevented the occurrence of diabetes induced by intraperitoneal injection of 200 mg/kg of alloxan. Forty mg/kg of the same agent, however, failed to prevent the onset of diabetes induced by the intravenous injection of streptozotocin (50 mg/kg). From the fact that Ca2+ channel blockers such as nicardipine, verapamil and bepridil have a similar suppressive effect on the occurrence of alloxan diabetes, one may readily infer that this action is characteristic of Ca2+ channel blockers. Moreover, the results suggest the close connection of Ca2+ in the occurrence of alloxan diabetes in rats.     

Effect of the Zinc Oxide Nanoparticles and Thiamine for the Management of Diabetes in Alloxan-Induced Mice: a Stereological and Biochemical Study

This research was carried out to evaluate the antidiabetic effects of zinc oxide nanoparticles (ZnO NPs) and thiamine following experimental diabetes. Fifty-six 6-week-old female mice were used and divided into seven groups of eight animals. Diabetes was induced in fasted mice by using intraperitoneal (IP) injection of alloxan (180 mg/kg). Groups included (I) non-diabetic control, (II) thiamine (30 mg/l, IP), (III) alloxan-induced diabetic mice, (IV) diabetes + ZnO NPs (0.1 mg/kg IP), (V) diabetes + ZnO NPs (0.5 mg/kg IP), (VI) diabetes + ZnO NPs (0.1 mg/kg IP) + thiamine (30 mg/l, IP), and (VII) diabetes + ZnO NPs (0.5 mg/kg IP) + thiamine (30 mg/l, IP). Coincident with pancreas recovery, in diabetic treated mice (groups IV to VII), the mean islet volume, islets per square micrometer, and volume density of the pancreas had increased than in alloxan-induced diabetic mice. ZnO NPs and thiamine induced a decreasing blood glucose, lower serum triglyceride (TG), LDL, and total cholesterol (TC) levels in alloxan-induced diabetic mice treated with ZnO NPs and thiamine, simultaneously increasing HDL as well. In conclusion, ZnO NPs and thiamine are potent antidiabetic factors, and that, these compound supplementation possesses hypoglycemic properties and have effect on serum lipid parameters in diabetes mice.     

Antidiabetic potential of Caralluma europaea against alloxan-induced diabetes in mice

Medicinal plants play an important role in the management of diabetes mellitus especially in developing countries where resources are lacking. Herbal of natural origin, unlike the synthetic compounds, are more effective, safer and have less side effects. For continuing research on biological properties of Moroccan medicinal plants, the present work was undertaken to evaluate the potential and mechanism of the antidiabetic activity of the Caralluma europaea methanolic extract in alloxan-induced diabetic mice. A high-performance liquid chromatography technique (HPLC) was used to identify and quantify the major phenolic compounds in the methanolic extract. The in vitro antioxidant property was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging method, reducing power and ß-carotene-linoleic acid assays. The acute toxicity of the extract was evaluated by giving it orally to mice at single doses of 200, 500, 1000, 2000 mg/kg body weight. The antidiabetic effect was conducted on Swiss albino mice. Diabetes was induced with single intraperitonial injection of alloxan monohydrate (200 mg/kg body weight) and animals were treated with methanol extract at a dose of 250 mg/kg and 500 mg/kg body weight. The blood glucose levels were measured and histopathological analysis of pancreas was performed to evaluate alloxan-induced tissue injuries. The main phenols identified and quantified in the extract were ferulic acid, quercetine, 3,4 dihydroxybenzoic acid, rutin, epigallocatechin, and catechin. Ferulic acid was found to be the main phenolic compound ant its proportion was up to 52% of total phenolic compounds, followed by quercetin (36%). The result showed that methanol extract exhibited an antioxidant effect. Acute toxicity studies revealed that C. europaea extract was safe up 2000 mg/kg body weight and approximate LD₅₀ is more than 2000 mg/kg. Moreover, the methanol extract prevented the diabetogenic effect of alloxan and decreased significantly the blood glucose level (P < 0.001) in treated mice. Morphometric study of pancreas revealed that C. europaea extract protected significantly the islets of Langerhans against alloxan-induced tissue alterations.     

Effects of Se-enriched polysaccharides produced by Enterobacter cloacae Z0206 on alloxan-induced diabetic mice

In this study, the water-soluble selenium-enriched exopolysaccharides (Se-ECZ-EPS) were isolated from submerged culture broth of Enterobacter cloacae Z0206 through fermentation, ethanol precipitation and deproteinization. The protective effects of Se-ECZ-EPS on alloxan-induced diabetic mice were investigated. Diabetes was induced in ICR (Institute of Cancer Research) mice by administration of single doses of alloxan intraperitoneally (190 mg/kg body weight). Se-ECZ-EPS at a dose of 200 mg/kg body weight were administered per os (p.o.) as single dose per day to diabetes-induced mice for a period of 42 days. The decrease in body weight, serum insulin level, and the increase in blood glucose level, glycosylated serum protein (GSP), total cholesterol (TC) and triglycerides (TG) in liver were observed in diabetic mice. On the other hand, oral administration of Se-ECZ-EPS resulted in a significant reduction in fasting blood glucose levels, GSP, TC and TG contents in liver coupled with improvement of body weight and serum insulin level in comparison with diabetic control group. These results suggest that Se-ECZ-EPS possess significant protective and anti-diabetic effects in alloxan-induced diabetic mice.     

Alloxan-induced diabetes in the rat - protective action of (-) epicatechin?

Administration of alloxan (150 mg/kg body weight, i.p.) to male Wistar rats induced a reproducible and persistent diabetes mellitus as evidenced by elevated serum glucose and low serum insulin concentrations. Administration of either (-)epicatechin or (+)catechin (250 mg/kg, i.p. on each occasion) at 36, 24, 12 and 1 hour before and at 12 and 24 hours after alloxan administration did not prevent the induction of the diabetes. Similarly, treatment of animals with (-)epicatechin or (+)catechin (125 mg/kg i.p. twice daily) for 21 days commencing 24 hours after alloxan administration did not reverse the peristing elevated serum glucose and low serum insulin concentrations. Moreover, administration of these compounds did not relieve any of the symptoms of the alloxan-induced diabetes such as poor weight gain, polyuria or polydipsia.     

链脲佐菌素诱导C57小鼠1型糖尿病模型的研究

目的:通过小剂量多次腹腔注射链脲佐菌素(STZ)诱导建立与人类1型糖尿病相似的C57小鼠糖尿病模型,研究建模剂量和成模率。方法:将32只C57小鼠随机分为正常对照组(A)和实验组(B)。实验组(B)可分为低、中、高剂量组(50 mg/kg、70mg/kg、90 mg/kg)(n=8)。两组都喂普通饲料1周后,B组连续5天腹腔注射不同剂量STZ,测定注射前、注射后1周、2周、3周、4周、5周的空腹血糖和体重,观察小鼠饮食、饮水和排尿情况。STZ注射第3周进行口服糖耐量实验(OGTT)。结果:给药前A、B组体重和血糖无显著差异,给药1周后,B组饮水量和进食量明显增加,体重减轻。C57小鼠用药2周后,中剂量组达到建模标准,成模率75%。各剂量组均出现了糖耐量异常。结论:诱导建立C57小鼠1型糖尿病模型方法是连续5日腹腔注注射STZ,适宜剂量为70 mg/kg。     

The streptozotocin-induced diabetic nude mouse model: differences between animals from different sources

Diabetes is induced in mice by using streptozotocin (STZ), a compound that has a preferential toxicity toward pancreatic β cells. We evaluated nude male mice from various sources for their sensitivity to a single high dose (160 to 240 mg/kg) of STZ. Diabetes was induced in male mice (age: median, 12 wk; interquartile range, 11 to 14 wk; body weight, about 30 g) from Taconic Farms (TAC), Jackson Laboratories (JAX), and Charles River Laboratories (CRL). Mice were monitored for 30 d for adverse side effects, blood glucose, and insulin requirements. In CRL mice given 240 mg/kg STZ, more than 95% developed diabetes within 4 to 5 d, and loss of body weight was relatively low (mean, 0.4 g). In comparison, both TAC and JAX mice were more sensitive to STZ, as evidenced by faster development of diabetes (even at a lower STZ dose), greater need for insulin after STZ, greater body weight loss (mean: TAC, 3.5 g; JAX, 3.7 g), and greater mortality. We recommend conducting exploratory safety assessments when selecting a nude mouse source, with the aim of limiting morbidity and mortality to less than 10%.     

虎眼万年青多糖降血糖作用的研究

目的:研究虎眼万年青多糖对四氧嘧啶诱导的糖尿病小鼠的降糖作用以及对糖尿病相关特征的影响。方法:采用腹腔注射四氧嘧啶致糖尿病小鼠模型;分成阳性药物组、模型对照组、空白对照组、虎眼万年青多糖高、中、低剂量组,连续给药14d,观察糖尿病小鼠的体重、血糖水平、总胆固醇(TG)和甘油三脂(TC)的变化。结果:经灌胃给药14d后,与空白对照组比较,模型组小鼠体质量呈下降趋势(P0.01),血糖值(P0.01)、总胆固醇TG(P0.01)、甘油三酯TC(P0.01)均明显上升;与模型组比较,虎眼万年青多糖高、中剂量组能有效降低糖尿病小鼠的血糖水平(P0.01),总胆固醇TG(P0.01),甘油三脂TC(P0.01),并且虎眼万年青多糖高剂量组可缓解糖尿病小鼠体重减轻症状(P0.01),而低剂量组作用效果不明显(P0.05)。结论:虎眼万年青多糖能够降低四氧嘧啶致糖尿病小鼠血糖水平,改善血脂代谢紊乱。     

Features of the morphofunctional state of the endocrine part of the pancreas during the development of experimental diabetes in the presence of regulatory peptides

The multiple 7-day intranasal introduction of PGArg and GPArg peptides at a dose of 1 mg per kg body weight before the injection of the diabetogenic dose of alloxan provided the maintenance of normoglycemia in rats. The similar introduction of PGPArg peptide did not provide any protection against the development of diabetes mellitus. The quantity of pancreatic islets in the animals from this group remained quite comparable to the norm, but the total number of cells per islet was below the norm, as well as in the control group. The GPArg peptide showed the best results as a preventive anti-diabetic agent.     

Arginine rich coconut kernel protein modulates diabetes in alloxan treated rats

Diabetes mellitus is a syndrome characterized by the loss of glucose homeostasis due to several reasons. In spite of the presence of known anti-diabetic medicines in the pharmaceutical market, remedies from natural resources are used with success to treat this disease. The present study was undertaken to investigate the effect of coconut kernel protein (CKP) on alloxan induced diabetes in Sprague-Dawley rats. Diabetes was induced by injecting a single dose of alloxan (150mg/kg body weight) intraperitoneally. After inducing diabetes, purified CKP isolated from dried coconut kernel was administered to rats along with a semi synthetic diet for 45 days. After the experimental period, serum glucose, insulin, activities of different key enzymes involved in glucose metabolism, liver glycogen levels and the histopathology of the pancreas were evaluated. The amount of individual amino acids of CKP was also determined using HPLC. Results showed that CKP has significant amount of arginine. CKP feeding attenuated the increase in the glucose and insulin levels in diabetic rats. Glycogen levels in the liver and the activities of carbohydrate metabolizing enzymes in the serum of treated diabetic rats were reverted back to the normal levels compared to that of control. Histopathology revealed that CKP feeding reduced the diabetes related pancreatic damage in treated rats compared to the control. These results clearly demonstrated the potent anti-diabetic activity of CKP which may be probably due to its effect on pancreatic β cell regeneration through arginine.     

Supplementation of N-acetylcysteine inhibits NFkappaB activation and protects against alloxan-induced diabetes in CD-1 mice.

Reactive oxygen species (ROS) are involved in the destruction of pancreatic beta cells and the development of insulin-dependent diabetes mellitus (IDDM). However, the cellular mechanism responsible for beta cell death is still unclear. We hypothesize that activation of NFkappaB by ROS is the key cellular signal in initiating a cascade of events leading to beta cell death. Thus, enhancement of pancreatic GSH, a known antioxidant and key regulator of NF-kappaB, should protect against IDDM. Weanling CD1 mice (n=5) were injected with alloxan (50 mg/kg i.v.) to induce IDDM. Using EPR spin trapping techniques, we demonstrated that alloxan generated ROS in the pancreas 15 min after administration. Activation of NFkappaB in pancreatic nuclear extracts was observed 30 min after alloxan injection, as assessed by an electrophoretic mobility shift assay. Fasting blood glucose levels were monitored for 14 days. Supplementation with N-acetylcysteine (NAC, 500 mg/kg), a GSH precursor, inhibited alloxan-induced NFkappaB activation and reduced hyperglycemia. Thus, NFkappaB activation by ROS may initiate a sequence of events leading to IDDM. Inhibition of NF-kappaB activation by NAC attenuated the severity of IDDM. This research will contribute to the understanding of the etiology of IDDM and may lead to the development of better strategies for disease prevention.     

Hypoglycemic Effects of a Polysaccharide from Tetrastigma hemsleyanum Diels & Gilg in Alloxan‐Induced Diabetic Mice

Tetrastigma hemsleyanum Diels & Gilg , a well‐known traditional Chinese medicine, possesses antitumor and anti‐inflammatory activity, etc. However, the anti‐diabetic effect has not been determined. In our present study, a water‐soluble polysaccharide, named THP with molecular weight of 93 307 Da, was isolated from T. hemsleyanum by DEAE‐52 ion‐exchange and Sephadex G‐100 chromatography. It contains rhamnose, arabinose, mannose, glucose, and galactose in the molar ratio of 0.07:0.14:0.38:0.21:0.31. Then anti‐diabetic effects of THP were examined by treating alloxan‐induced diabetic mice with different doses (100, 200, and 300 mg/kg) of THP orally. The results showed that THP could decrease the blood glucose, TC, TG, LDL‐C levels, increase the body weight, HDL‐C, insulin levels, and enhance the activities of antioxidant enzyme system in alloxan‐induced diabetic mice. Furthermore, the histopathological examination of pancreas, liver, and kidney indicated that THP could protect and reverse β‐cells in diabetic mice with low damage to liver and kidney, which suggests that THP may stimulate pancreatic release of insulin and can be an effectively potential candidate for diabetes mellitus.     

Therapeutic effects of stem cell on hyperglycemia,hyperlipidemia, and oxidative stress in alloxan-treated rats

Diabetes mellitus is the most common endocrine disorder that affects more than 285 million people worldwide. The purpose of this study was to investigate the effect of mesenchymal stem cells (MSCs) from the bone marrow of albino rats, on hyperglycemia, hyperlipidemia, and oxidative stress induced by intraperitoneal injection (i.p.) of alloxan at a dose of 150 mg/kg in rats. Injection of alloxan into rats resulted in a significant increase in serum glucose, total cholesterol, triglyceride, low density lipoprotein cholesterol, and sialic acid level and a significant decrease in serum insulin, high density lipoprotein-cholesterol, vitamin E, and liver glycogen as compared to their corresponding controls. Also, oxidative stress was noticed in pancreatic tissue as evidenced by a significant decrease in glutathione level, superoxide dismutase, glutathione-S-transferase activities, also a significant increase in malondialdehyde and nitric oxide levels when compared to control group. Treatment of diabetic rats with MSCs stem cells significantly prevented these alterations and attenuated alloxan-induced oxidative stress. In conclusion, rat bone marrow harbors cells that have the capacity to differentiate into functional insulin-producing cells capable of controlling hyperglycemia, hyperlipidemia, and oxidative stress in diabetic rats. This may be helpful in the prevention of diabetic complications associated with oxidative stress.     

Pretreatment with catalase or dimethyl sulfoxide protects alloxan-induced acute lung edema in dogs.

We tested the preventive effects of catalase, an enzymatic scavenger of hydrogen peroxide, or dimethyl sulfoxide (DMSO), a hydroxyl radical scavenger, on intravenous alloxan-induced lung edema in four groups of pentobarbital sodium-anesthetized, ventilated dogs for 3 h: saline (20 ml.kg-1.h-1) infusion alone (n = 5), alloxan (75 mg/kg) + saline infusion (n = 5), catalase (150,000 U/kg) + alloxan + saline infusion (n = 5), or DMSO (4 mg/kg) + alloxan + saline infusion (n = 5). Catalase or DMSO significantly prevented the increase in plasma thromboxane B2 and 6-keto-prostaglandin F1 alpha over 3 h after alloxan and the accumulation of extravascular lung water after 3 h [3.95 +/- 0.52 (SE) g/g with catalase, 3.06 +/- 0.42 g/g with DMSO] but not early pulmonary arterial pressor response. An electron microscopic study indicated that catalase or DMSO significantly reduced the endothelial cellular damages after alloxan. These findings strongly suggest that hydrogen peroxide and hydroxyl radical are major mediators responsible for intravenous alloxan-induced edematous lung injury in anesthetized ventilated dogs.     

Chromium picolinate attenuates hyperglycemia-induced oxidative stress in streptozotocin-induced diabetic rats

Chromium picolinate is advocated as an anti-diabetic agent for impaired glycemic control. It is a transition metal that exists in various oxidation states and may thereby act as a pro-oxidant. The present study has been designed to examine the effect of chromium picolinate supplementation on hyperglycemia-induced oxidative stress. Diabetes was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (50 mg/kg body weight) and chromium was administered orally as chromium picolinate (1 mg/kg body weight) daily for a period of four weeks after the induction of diabetes. As is characteristic of diabetic condition, hyperglycemia was associated with an increase in oxidative stress in liver in terms of increased lipid peroxidation and decreased glutathione levels. The activity of antioxidant enzymes like superoxide dismutase, catalase and glutathione reductase were significantly reduced in liver of diabetic animals. Levels of α-tocopherol and ascorbic acid were found to be considerably lower in plasma of diabetic rats. Chromium picolinate administration on the other hand was found to have beneficial effect in normalizing glucose levels, lipid peroxidation and antioxidant status. The results from the present study demonstrate potential of chromium picolinate to attenuate hyperglycemia-induced oxidative stress in experimental diabetes.     

Induction of type-1 diabetes mellitus in laboratory rats by use of alloxan: route of administration, pitfalls, and insulin treatment

Uncertainties have existed regarding the systematic induction and management of drug-induced diabetes mellitus (DM). Issues have included the optimal route of administration of the drug, methods of reducing drug toxicosis and mortality, how to induce type-1 versus type-2 DM, and how to manage labile DM in rats. In attempting to induce type-1 DM in Sprague-Dawley rats, we classified hyperglycemic animals as having type-1 DM only if their post-treatment blood ketone concentration was high. We found that multiple doses of alloxan led to significantly higher mortality than did a single dose. A single high dose (200 mg/kg of body weight given intraperitoneally) was the best treatment and led to 70% incidence of type-1 DM and only 10% mortality. In contrast, intravenous administration of similar doses was toxic. Assiduous management of alloxan-induced DM is crucial to avoid severe hypoglycemia from massive insulin release and to avoid diabetic ketoacidosis. Frequent glucose monitoring and appropriate administration of carbohydrate and fluids is necessary during this stage. For long-term management, daily administration of long-acting insulin (glargine) appears to be safe and effective. Rapid-acting insulins reduce glucose concentration rapidly, and must be used with caution. If specific precautions are observed, intraperitoneal administration of high-dose alloxan to laboratory rats leads to a condition that closely resembles human type-1 DM.     

Effect of carboxymethyl-chitin-glucan on cyclophosphamide induced mutagenicity

The effect of high molecular carboxymethyl-chitin-glucan (CMCG), administered either intraperitoneally, intravenously or orally prior to cyclophosphamide injection, on the frequency of micronucleated reticulocytes was evaluated in peripheral blood of female ICR mice. Both intraperitoneal and intravenous administration of CMCG decreased the clastogenic effect of cyclophosphamide. The protective effect of CMCG was concentration dependent, with a higher decrease achieved by 100 mg/kg than by 50 mg/kg body weight. On the other hand, not even five peroral pretreatments with CMCG in the dose of 200 mg/kg body weight during the week prior to simultaneous administration of CMCG and cyclophosphamide induced a decrease of micronucleated reticulocytes in peripheral blood. It is therefore conceivable that CMCG failed to pass through the gastrointestinal tract, probably due to its high molecular weight. The antimutagenic effect of CMCG against cyclophosphamide was manifested by its intraperitoneal and intravenous administration to female ICR mice.