Anabolic Effect of Insulin Therapy on the Bone: Osteoprotegerin and Osteocalcin Up‐Regulation in Streptozotocin‐Induced Diabetic Rats

Type 1 diabetes mellitus (T1DM) is associated with several skeletal alterations, particularly in conditions of poor glycaemic control. Insulin therapy is the major conservative treatment for T1DM; however, the effects of this hormone on bone markers of T1DM rats are limited, and the regulatory mechanisms remain elusive. Therefore, the evaluation of molecular and non‐molecular parameters in a chronic animal model of T1DM‐induced bone loss, treated with and without insulin, may help in elucidating the insulin mechanisms. Male Wistar rats were assigned into three groups: control, T1DM (T1DM rats induced with streptozotocin [STZ] at 40 mg/kg intravenously) and T1DM plus insulin therapy (T1DMI). After 8 weeks, we evaluated the serum biochemical, tibia histomorphometric and biomechanical parameters, as well as the gene expression of the receptor activator of nuclear factor kappa‐B ligand (RANKL), osteoprotegerin (OPG) and osteocalcin (OC) of femur mRNA. Compared with T1DM, the T1DMI group showed less bone loss, which was revealed by the increased trabecular width (TbWi, p < 0.001) and trabecular bone area (BAr, p < 0.01), reduced trabecular separation (TbSp, p < 0.01) and increased Young's modulus (p < 0.05). Moreover, molecular analyses indicated that the expression of OPG and OC was up‐regulated (p < 0.001 and p < 0.05, respectively). In summary, the up‐regulation of OPG and OC in the T1DMI group supports an anabolic effect of insulin, which was demonstrated by the maintenance of bone architecture and flexibility. These results suggest that insulin therapy may prevent T1DM‐induced bone loss via the effects on the bone formation.     

Effect of Helicteres isora. Bark Extracts on Brain Antioxidant Status and Lipid Peroxidation in Streptozotocin Diabetic Rats

Abstract

The current study investigated the effect of the aqueous extract of Helicteres isora. L (Sterculiaceae) bark on oxidative stress in the brains of rats during diabetes. The aqueous extract of H. isora. bark was administered orally (100, 200 mg/kg b.w.) and the effect of the extract on blood glucose, plasma insulin, and the levels of thiobarbituric acid reactive substances (TBARS), hydroperoxides, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S.-transferase (GST), and reduced glutathione (GSH) were estimated in streptozotocin (STZ) diabetic rats. Tolbutamide was used as the standard reference drug. A significant increase in the activities of plasma insulin, SOD, CAT, GPx, GST, and GSH were observed in the brain on treatment with 100 and 200 mg/kg b.w. of H. isora. bark extract (HIBe) and tolbutamide for 5 weeks. Both treated groups (bark extract and drug) showed a significant decrease in TBARS and hydroperoxides formation in brain, suggesting its role in protection against lipid peroxidation–induced membrane damage. These findings suggest a possible antiperoxidative role of H. isora. bark extract that may be used for therapeutic purposes.     

Effects of Resveratrol Supplementation on Oxidative Damage and Lipid Peroxidation Induced by Strenuous Exercise in Rats

The purpose of the present study was to investigate the effects of resveratrol supplementation on oxidative damage and lipid peroxidation induced by strenuous exercise in rats. The rats were randomly divided into five groups: a sedentary control group, an exercise control group, and three treatment exercise groups administered increasing doses of resveratrol (25, 50, and 100 mg/kg body weight). Resveratrol was administered by oral gavage once daily for four weeks. At the end of the four-week period, the rats performed a strenuous exercise on the treadmill, and the levels of lactate dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) were measured. The results showed that resveratrol supplementation had protective effects against strenuous exercise-induced oxidative damage and lipid peroxidation by lowering the levels of LDH, CK, MDA, 4-HNE, and 8-OHdG in the serum or muscle of rats. These beneficial effects are probably owing to the inherent antioxidant activities of resveratrol.     

Effects of Airborne Fine Particulate Matter on Antioxidant Capacity and Lipid Peroxidation in Multiple Organs of Rats

The purpose of this research was to determine whether airborne fine particulate matter (PM_2.5) could increase levels of lipid peroxidation and alter intracellular redox status in multiple organs of rats. Thirty-two male Wistar rats were randomly divided into the treated groups using PM_2.5 at different dosages (1.5, 7.5, 37.5 mg/kg) and with a control group using saline. Rats were sacrificed 24 h after one-time intratracheal instillation. Then we investigated the activities of Cu, Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and the levels of glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) in hearts, livers, spleens, lungs, kidneys, brains, and testicles. It was found that PM_2.5 at dosages of 7.5 and 37.5 mg/kg significantly increased lipid peroxidation levels in the hearts, livers, lungs, and testicles, decreased SOD, CAT, and GPx activities in the lungs, livers, kidneys, and brains, and depleted GSH levels in all the measured organs compared to the control. There were also differences in the changes of antioxidative enzymes activities and lipid peroxidation levels in seven organs. These results led to a conclusion that airborne PM_2.5 was a systemic toxic agent, not only to respiratory and cardiovascular systems. Its toxic effects might be attributed to oxidative damage mediated by prooxidant/antioxidant imbalance or excess free radicals. Further work is required to explain the toxicity role of PM_2.5 on multiple organs of mammals.     

Protective Effects of Glycyrrhizin on Gentamicin‐Induced Acute Renal Failure in Rats

Abstract: The aim of this study was to investigate the effects of glycyrrhizin (200 mg/kg/day) on renal function in association with the regulation of aquaporin 2 water channel in rats with gentamicin (100 mg/kg/day)‐induced acute renal failure. Polyuria in rats with gentamicin‐induced acute renal failure was associated with down‐regulation of renal aquaporin 2 in the inner and outer renal medulla, and cortex. Glycyrrhizin administration restored the expression of aquaporin 2 with paralleled changes in urine output. Changes in renal functional parameters, such as creatinine clearance, urinary osmolality, and solute‐free reabsorption, accompanying acute renal failure were also partially restored after administration of glycyrrhizin. Histological changes in rats with gentamicin‐induced acute renal failure were also abrogated by glycyrrhizin treatment. The above results suggest that glycyrrhizin treatment could ameliorate renal defects in rats with acute renal failure induced by gentamicin.     

茶多酚对脑缺血再灌注损伤的保护作用及在体外抗脂质过氧化和清除自由基作用

目的 :研究茶多酚对脑缺血再灌注损伤的保护作用及抗脂质过氧化和清除自由基的作用。方法 :结扎大鼠双侧颈总动脉及迷走神经后 ,再灌注 4 5min ,建立脑缺血再灌注模型。由自由基诱导的脑线粒体脂质过氧化 ,用硫代巴比妥酸法测定。由Xan XO诱导的O 2 and由Fe2 + H2 O2 诱导的·OH ,用紫外分光光度仪测定。结果 :在脑缺血再灌注损伤时 ,茶多酚能改善SOD、GSH Px、CAT活性 (P <0 0 1) ,同时降低脑水肿和MDA含量 (P <0 0 1和P <0 0 5 )。茶多酚具有明显的清除·OH和O 2 的作用 (IC50 分别为 2 2mmol·L-1和 1 9mmol·L-1) ,茶多酚明显抑制由·OH诱导脑线粒体脂质过氧化 ,并呈浓度依赖性。结论 :结果提示茶多酚能保护脑缺血再灌注损伤 ,与其清除自由基和抗脂质过氧化作用有关     

Effects on Lipid Peroxidation and Antioxidative Enzymes of Euonymus alatus in Cultured Rat Hepatocytes

Abstract: The Euonymus alatus (Thunb.) Sieb. has long been used as a crude drug. In this paper, we investigate the effects of E. alatus on cultured hepatocyte cell system and lipid peroxidation in hydrogen peroxide (H₂O₂) treatment conditions. The study covers the physiological activity (the antioxidative activity and the nitrite‐scavenging effect) of E. alatus. H₂O₂ that can produce intracellular free radical was used for inducer of the peroxidation of cellular lipids. Treatment of E. alatus attenuated in cell killing enhanced by increasing concentrations of H₂O₂. The increased malondialdehyde level induced by H₂O₂ treatment was reduced by pre‐treatment of E. alatus. Furthermore, addition of E. alatus in cell culture medium significantly reduced cell killing and content of intracellular antioxidants. Changes in nitrite‐scavenging effect of E. alatus at various concentrations (5–25 mg/ml) and various pH levels (pH 1.2, 4.2 and 6.0) were also observed. The present study was also done to investigate the effects of E. alatus on cultured hepatocyte cell system, H₂O₂‐induced cytotoxicity and antioxidative enzyme activities, including catalase, superoxide dismutase, glutathione peroxidase and glutathione S‐transferase in H₂O₂ treatment conditions. E. alatus treatment had significant protective or elevating activities on these antioxidative enzyme activities compared to a normal group. The results indicate that E. alatus provides a strong antioxidant protection of cells against H₂O₂‐induced oxidative stress.     

Inhibitory Effect of Melatonin on Homocysteine‐Induced Lipid Peroxidation in Rat Brain Homogenates

Abstract: Oxidative damage is implicated in several pathologies including cardiovascular disease. As a model system to study the response of cells to oxidative insults, homocysteine toxicity was examined since it is an independent risk factor for atherosclerotic disease. The levels of malondialdehyde and 4‐hydroxyalkenals were assayed as an index of oxidatively damaged lipid. In in vitro experiments, the increase of lipid peroxidation products induced by homocysteine were concentration‐ and time‐dependent. To study the protective effect of melatonin on homocystine induced lipid peroxidation, brain homogenates were treated with different concentrations of melatonin. The accumulation of malondialdehyde and 4‐hydroxyalkenals induced by homocysteine was significantly reduced by melatonin in a concentration‐dependent manner. Additionally, a melatonin concentration of 1.5 mM reduced the levels of oxidatively damaged lipid products below those measured in control homogenates (no homocysteine, no melatonin). These data suggest that melatonin, an endogenous antioxidant may have a role in protecting cells from oxidative damage due to homocysteine and they support the idea that pharmacological concentrations could be used as a therapeutic agent in reducing cardiovascular disease where homocysteine may be a causative or contributing agent.     

Lipid Peroxidation and Copper Toxicity in Rats

ABSTRACT

Pentane production was used as an index of lipid peroxidation in male rats fed either 0 or 1000 ppm copper in diets with and without vitamin E. Pentane production by vitamin E-deficient rats not fed copper was greater than that by vitamin E-supplemented rats not fed copper. Pentane production was low by all groups of rats. Copper-fed, vitamin E-deficient and vitamin E-supplemented rats produced more pentane than did respective controls not fed copper. After 9 weeks of feeding the diets, more pentane was produced by vitamin E-deficient than by vitamin E-supplemented rats following intraperitoneal injection of 5 mg of copper/kg of body weight, and vitamin E-deficient rats fed copper produced 5-fold more pentane than did those not fed copper. Thiobarbituric acid-reactants were highest in blood, kidney and liver from copper-fed rats. Lipid-soluble fluorophores in spleen were lowest In vitamin E-supplemented rats not fed copper and highest in copper-fed, vitamin E-deficient rats.     

A Possible Mechanism of Naproxen‐Induced Lipid Peroxidation in Rat Liver Microsomes

Abstract: Previous papers from our laboratory report that naproxen and salicylic acid induced lipid peroxidation in rat liver microsomes, however, the mechanism is still unclear. In the present paper, ferrous iron release, nicotinamide‐adenine dinucleotide phosphate reduced form (NADPH) oxidation and hydrogen peroxide (H₂O₂) formation have been measured to find out which mechanisms are involved in naproxen‐ and salicylic acid‐induced lipid peroxidation. While the increase of ferrous iron release was observed with high concentrations of naproxen, salicylic acid did not stimulate ferrous iron release. Neither of these drugs stimulated NADPH oxidation and H₂O₂ formation. However hexobarbital and perfluorohexane, known as uncouplers of cytochrome P450, stimulated microsomal NADPH oxidation, O₂ consumption, H₂O₂ formation and water (H₂O) formation involving four‐electron oxidase reaction. These results suggest that ferrous iron release contributes to naproxen‐induced microsomal lipid peroxidation and that naproxen and salicylic acid are not uncouplers of cytochrome P450. Apparently H₂O₂ does not play an important role in naproxen‐ and salicylic acid‐induced microsomal lipid peroxidation.     

The Role of Rac1 on Carbachol‐induced Contractile Activity in Detrusor Smooth Muscle from Streptozotocin‐induced Diabetic Rats

This study was designed to determine the role of the small GTPase Rac1 on carbachol‐induced contractile activity in detrusor smooth muscle using small inhibitor NSC 23766 in diabetic rats. Rac1 expression in bladder tissue was also evaluated. In the streptozotocin (STZ)‐induced diabetic rat model, three study groups were composed of control, diabetic and insulin‐treated diabetic subjects. The detrusor muscle strips were suspended in organ baths at the end of 8–12 weeks after STZ injection. Carbachol (CCh) (10^?9–10^?4 M) concentration–response curves were obtained both in the absence and in the presence of Rac1 inhibitor NSC 23766 (0.1, 1 and 10 μM). Diabetes‐related histopathological changes and Rac1 expressions were assessed by haematoxylin and eosin staining and immunohistochemical staining, respectively. CCh caused dose‐dependent contractile responses in all the study groups. Rac1 inhibitor NSC 23766 inhibited CCh‐induced contractile responses in all groups, but this inhibition seen in both diabetes groups was greater than in the control group. Histological examination revealed an increased bladder wall thickness both in the diabetes and in the insulin‐treated diabetes groups compared to the control group. In immunohistochemical staining, expression of Rac1 was observed to be increased in all layers of bladder in both diabetic groups compared to the control group. In the diabetic bladders, increased expression of Rac1 and considerable inhibition of CCh‐induced responses in the presence of NSC 23766 compared to those of the control group may indicate a specific role of Rac1 in diabetes‐related bladder dysfunction, especially associated with cholinergic mediated detrusor overactivity.     

Halothane Induced Hepatic Necrosis in Rats: The Role of in Vivo Lipid Peroxidation

Abstract: Hepatic damage was induced in phenobarbitone pretreated male Fischer 344 rats by the administration of 1 % halothane in 14% oxygen for either 1 or 2 hours. Ethane production during the exposure period was not significantly different between the halothane and non-halothane exposed groups. Animals were sacrificed 1, 2, 6 and 24 hrs from commencement of anaesthesia and the hepatic microsomal fraction analyzed for diene conjugates, lipid hydroperoxides, total lipid content and fatty acid composition. Animals exposed to halothane and sacrificed at 2 and 24 hrs had significantly elevated levels of diene conjugates (P < 0.05), while lipid hydroperoxide concentration and serum alanine aminotransferase increased in only those animals sacrificed at 24 hrs. Alterations in total lipid content and hepatic microsomal fatty acid composition were not observed in animals sacrificed after 1 and 2 hrs. A significant reduction in total lipid and arachidonic acid content occurred only in those animals sacrificed 24 hrs after exposure, however a concomitant increase in the saturated fatty acid fraction was not observed. It is proposed that alterations in fatty acid composition in vivo and evidence of lipid peroxidation occur as a result of cell death rather than an initiating event in halothane induced hepatic necrosis in rats.     

太子参多糖对糖尿病大鼠糖、脂代谢的影响

目的观察太子参多糖对糖尿病大鼠糖、脂代谢的影响。方法大鼠腹腔注射四氧嘧啶200mg／kg制作糖尿病模型,观察太子参多糖不同剂量（1．2,0．6,0．3g／kg）对实验性糖尿病大鼠空腹血糖、血脂、胰岛素水平的影响。结果太子参多糖能改善糖尿病大鼠的一般状况,延缓体重下降,降低空腹血糖,降低甘油三酯（TG）和总胆回醇（TC）水平,但不影响胰岛素水平。结论太子参多糖对糖尿病大鼠有显著治疗作用。     

Exendin-4对糖尿病大鼠糖脂代谢的影响

目的:观察Exendin-4对2型糖尿病(T2DM)大鼠糖脂代谢及胃排空的影响。方法:高脂高糖饲料加小剂量链脲佐菌素制备T2DM大鼠模型,随机分为正常对照组(NC组)、正常干预组(NE组)、糖尿病对照组(DC组)和糖尿病干预组(DE组);Exendin-4(2ng/g,2次/d)干预50d。核素法测定各组大鼠胃半排时间、排空速率,留取血清测定空腹血糖(FBG)、糖化血清蛋白(GSP)、游离脂肪酸(FFA)、总胆固醇(TC)和三酰甘油(TG)的含量。结果:DC组较NC组FBG、GSP、FFA、TC和TG水平升高,胃半排时间缩短、排空速率加快,差异有统计学意义(P<0.05或P<0.01)。DE组较DC组FBG、GSP和FFA浓度降低,胃半排时间加长、而排空速率减慢,差异有统计学意义(P<0.05或P<0.01)。多因素逐步回归分析示影响胃半排时间的因素是FBG。结论:Exendin-4可以改善同期糖尿病大鼠的血糖、FFA及胃排空异常。     

Protective Effect of Berberine on Cyclophosphamide‐Induced Haemorrhagic Cystitis in Rats

Abstract: The urotoxicity of cyclophosphamide and the protective effect of the herb berberine were investigated in this study. Administration of 150 mg/kg cyclophosphamide intraperitoneally caused a serious haemorrhagic cystitis in rats after 12 hr, including bladder oedema, haemorrhage, and dramatic elevation of nitric oxide metabolites (nitrite+nitrate) in urine and in plasma. To explore whether cyclophosphamide‐induced cystitis could be prevented by berberine, rats were pretreated with a single dose or two doses of berberine at 50, 100, or 200 mg/kg intraperitoneally then challenged with cyclophosphamide (150 mg/kg, intraperitoneally). The results indicated that pretreatment of rats with berberine could reduce cyclophosphamide‐induced cystitis in a dose‐dependent manner. Furthermore, we found that two doses of berberine showed greater protection against cyclophosphamide urotoxicity than when given a single dose. In addition, our data shows that a single dose of 200 mg/kg berberine, or two doses of 100, and 200 mg/kg berberine could completely block cyclophosphamide‐induced bladder oedema and haemorrhage, as well as nitric oxide metabolites increase in rat urine and plasma. In conclusion, our findings suggest that berberine could be a potential effective drug in the treatment of cyclophosphamide‐induced cystitis, and provides us with the bright hope in the prevention and treatment of cyclophosphamide urotoxicity.     

Protective Effects of Antioxidants Against Uraemia-Induced Lipid Peroxidation and Glutathione Depletion in Humans

Abstract: The effects of uraemias and antioxidant therapy for 40 days with vitamin A, vitamin C and vitamin E on blood and erythrocyte sulfhydryl (glutathione, GSH) content and on erythrocyte glutathione-S transferase (GST), glutathione reductase (GSR) and glutathione peroxidase activities were studied in six uraemic patients maintained on haemodialysis. In addition, the effect of antioxidant therapy on erythrocyte lipid peroxidation was determined, and erythrocyte haemoglobin content was measured. Uraemic patients in dialysis exhibited significant decreases in blood and erythrocyte GSH content as well as significant decreases in the activities of GST, GSR and GSH-peroxidase relative to control subjects. Furthermore, the uraemic patients had elevated erythrocyte malondialdehyde levels. Blood and erythrocyte GSH content from uraemic patients was significantly elevated after 20 days of antioxidant treatment and remained elevated thereafter throughout the remaining 20 days of the study (130% and 173%, respectively). Antioxidant therapy also produced significant increases in GSR and GSH-peroxidase activities after 20 days of treatment which remained relatively constant thereafter. No significant change in GST activity was observed. Erythrocyte malondialdehyde levels, as an index of oxidative tissue damage, exhibited a significant decrease (70%) in the patients after 40 days of antioxidant therapy. A gradual increase in erythrocyte haemoglobin content was observed following treatment of the uraemic subjects (45% at day 40). The results suggest that antioxidant therapy may protect against oxidative stress associated with uraemia.     

Protective Effects of Salicylic Acid and Vitamin C on Sulfur Dioxide-Induced Lipid Peroxidation in Mice

The antioxidant effects of exogenous salicylic acid (SA) and vitamin C (Vit C) on the oxidative stress induced by 56 mg/m³ of sulfur dioxide (SO₂) in mouse livers and brains were investigated. The exposure of SO₂ caused significant elevation of thiobarbituric acid-reactive substance (TBARS) levels and reduction of enzyme activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in brain and liver, accompanied by a decrease in relative growth rate, when compared with controls. Application of moderate concentrations of SA and Vit C markedly reduced the SO₂-induced elevation of TBARS levels, with 5.5 mg/kg SA or 200 mg/kg Vit C being most effective. In contrast to the decrease of TBARS levels, the levels of SOD, POD, and CAT in liver and brain were significantly increased in comparison with controls. The polyacrylamide gel electrophoresis (PAGE) of total liver proteins showed that the SO₂ inhalation caused a 30-kD protein band disappearance compared with the control. However, the band remained unchanged in the samples treated with 5.5 and 8.25 mg/kg SA or 100, 200, and 400 mg/kg Vit C. Therefore, this protein band may serve as a marker for the damage induced by SO₂ and an additional basis for drug screening and selection.     

槲皮素对糖尿病大鼠肾脏的保护作用

观察了槲皮素对糖尿病大鼠肾组织山梨醇、肾重／体重、肾小球滤过率及尿白蛋白排泄的影响。结果发现,槲皮素治疗后糖尿病大鼠肾组织山梨醇含量、肾小球滤过率、尿白蛋白排泄较对照组糖尿病大鼠明显下降,P＜0．01。提示槲皮素对糖尿病肾脏醛糖还原酶有较强的抑制作用,早期应用有助于防止或延缓糖尿病肾病的发生。