Long-term effects of insulin therapy, islet transplantation, and pancreas transplantation in the prevention of glomerular changes in kidneys of alloxan-induced diabetic rats

Groups of inbred alloxan-induced diabetic rats were treated with insulin (I), islets (IT), or pancreas transplantation (PT). Nondiabetic (N) and untreated diabetic (D) control groups were concurrently included. Each group was divided into five subgroups of 10 rats and killed after follow-up of 1, 3, 6, 9, and 12 months. Clinical and laboratory parameters were recorded, and kidney ultrastructural and morphometric analyses performed in each 12-month subgroup, namely glomerular basement membrane (GM) thickening, podocyte number, and number/extension of slit diaphragms (S). Rats from the I group showed poor metabolic control of diabetes compared with N group control rats. However, successfully transplanted rats (IT and PT) had complete restoration to normal levels for all metabolic parameters. GM thickening was significantly higher in diabetic compared with control rats. In contrast, the numbers of podocytes and slits as well as slit extensions were significantly decreased. Insulin therapy did not prevent any alterations upon comparison of diabetic vs control rats. Despite good metabolic control in IT rats, the degree of kidney lesion control never compared with that achieved in PT rats. In this group all glomerular changes were similar to the age-dependent lesions observed in control rats. We conclude that either IT or PT may be a good option for diabetes treatment, although pancreas transplantation seems to be the most effective treatment to control chronic complications.     

Diltiazem attenuates oxidative stress in diabetic rats

Diabetic nephropathy is the main cause of end stage renal damage. Oxidative stress is involved in the etiology of diabetic nephropathy and intracellular calcium is reported to play a considerable role in the development of renal damage in the diabetic kidney. Calcium antagonism can slow the progression of renal impairment in diabetes. The present study was thus designed to examine the effect of a nondihydropyridine calcium channel blocker, diltiazem, on renal function, oxidative stress, and nitric oxide (NO) release in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced by a single intraperitoneal injection of STZ (65 mg/kg) in rats. After 4 weeks of STZ injection, the rats were divided in to four groups: control rats, diabetic rats treated with saline, and two groups of diabetic rats treated with diltiazem (5 and 10 mg/kg, i.p, respectively) for 8 weeks starting from 4 weeks after STZ injection. Renal function was assessed by creatinine, blood urea nitrogen, creatinine clearance, and urea clearance. Oxidative stress was measured by renal malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and catalase. We also measured renal nitrite levels. At the end of the 8 weeks, diabetic rats exhibited renal dysfunction as evidenced by reduced creatinine and urea clearance along with enhanced albumin excretion rate as compared with control rats. Biochemical analysis of kidneys revealed a marked increase in oxidative stress demonstrated by increased lipid peroxidation and decreased activities of key antioxidant enzymes, GSH, SOD, and catalase in diabetic rats. Release of NO also significantly higher in diabetic rats than controls. Chronic treatment with diltiazem in diabetic rats significantly attenuated both renal dysfunction and oxidative stress along with increased NO levels as compared with untreated diabetic rats. The kidneys of diabetic rats showed morphological changes such as hyaline casts, glomerular thickening, and moderate interstitial fibrosis and arteriolopathy, whereas diltiazem administration markedly prevented diabetic-induced renal morphological alterations. The present study suggests that oxidative stress/nitrosative stress is increased in the diabetic kidney and calcium channel blockage can prevent these changes. The results also suggest that in STZ-induced diabetic rats, the protective action of diltiazem might be mediated, at least in part, by its effect on tissue oxidant/antioxidant status.     

Temporal relationship between successful pancreas transplantation and control of ocular complications in alloxan-induced diabetic rats

PURPOSE: The impact of pancreas transplantation (PT) on the progression of eye disease is still controversial. This study evaluated the course of retinopathy in transplanted rats in two different diabetic stages. METHODS: Sixty inbred male Lewis rats were assigned to four experimental groups: NC-15 nondiabetic control rats; DC-15 untreated diabetic control rats; PT1-15 diabetic rats that received syngeneic pancreas transplants 2 weeks after alloxan diabetes induction; PT2-15 diabetic rats that received pancreas transplants 12 weeks after diabetes onset. Clinical and laboratory parameters and lens opacity were examined in all rats prior to treatment and at 1-, 6-, and 12-months follow-up. Nucleated eyes from five rats in each group processed for ultrastructural study of the retinal at 6 and 12 months after PT or at follow-up. RESULTS: Cataracts were observed in 20%, 60%, and 100% of DC rats at 1-, 6-, and 12-months follow-up, respectively. Early PT (2 weeks) significantly reduced the prevalence of this complication but not late (12 weeks) PT. PT1 rats also showed improved ultrastructure of the superficial and deep capillary plexuses of the retina, and of Müller cells, compared with DC and PT2. In the last group, retinopathy continued to evolve despite successful PT. CONCLUSION: Our results suggested that prevention of diabetic ocular lesions by PT was closely dependent on earlier performance of the procedure.     

Melatonin prevents gentamicin‐induced testicular toxicity and oxidative stress in rats

This study investigated the protective effects of melatonin (MT) against gentamicin (GM)‐induced testicular toxicity and oxidative damage in rats. GM (100 mg kg^?1) was injected intraperitoneally (i.p.) to rats for 6 days. MT (15 mg kg^?1) was administered i.p. to rats for 6 days at 1 hr after the GM treatment. GM caused a decrease in prostate and seminal vesicle weights, sperm count and sperm motility. Histopathological examination showed various morphological alterations in the testis, characterised by degeneration of spermatogonia/spermatocytes, decrease in the number of early spermatogenic cells and vacuolisation. In addition, an increased malondialdehyde concentration and decreased glutathione content and glutathione reductase, catalase and glutathione‐S‐transferase activities were found in the testis. In contrast, MT treatment significantly attenuated the testicular toxicity of GM, including decreased reproductive organ weights, sperm count, and sperm motility and increased histopathological alterations. MT also had an antioxidant benefit by decreasing the lipid peroxidative product malondialdehyde and increasing the level of the antioxidant glutathione and the activities of antioxidant enzymes in the testis. These results indicate that MT prevents testicular toxicity induced by GM in rats, presumably due to its potent antioxidant activity, and its ability to inhibit lipid peroxidation, and restore antioxidant enzyme activity.     

Pancreas transplantation in nonuremic, type I diabetic recipients

Between July 1978 and January 1988, 111 of 210 pancreas transplants were in nonuremic, nonkidney (NUNK) recipients in whom complications of diabetes were judged more serious than the potential side effects of antirejection therapy. In all NUNK cases, the 1-year patient survival rate (PSR) and graft survival rate (GSR) were 90% and 39%. Since November 1984, 1-year PSR and GSR for 62 NUNK recipients of pancreas transplants alone (PTA) were 93% and 48%, compared to 89% and 37% for 28 pancreas transplants after (PAK) and 89% and 73% for 20 simultaneous (SPK) with a kidney transplant. The 1-year GSR for 1984-88 technically successful (TS) PTA cases (n = 47) was 63%, versus 75% for PAK (n = 13) and 86% for SPK (n = 17) cases. The 1-year GSRs, by technique and source for 1984-88 PTA cases, were 58% for bladder-drained cadaver (n = 30), 51% for enteric-drained related (n = 32), and 29% for enteric-drained cadaver (n = 17) donor transplants, and 75% (n = 24), 77% (n = 16), and 38% (n = 13) for the corresponding TS cases. Of NUNK recipients, 35 have had grafts function for more than 1 year and all but 3 were treated with cyclosporine (CsA). In the CsA-treated recipients, serum creatinine increased and creatinine clearances decreased by a magnitude of 40% during the first 6 months but thereafter remained stable in all but 2 patients. In the patients with functioning grafts studied at 1 year, retinopathy remained stable in 59% and progressed in 41% of the eyes (n = 39). Motor nerve conduction velocities were significantly increased and muscle action potentials remained stable in 24 patients with functioning grafts studied at 1 year, while in 14 patients in whom transplants failed there was a significant decrease in evoked muscle action potentials. A sustained euglycemic, insulin-independent state can be established in nonuremic, nonkidney diabetic recipients of pancreas transplants alone, with a beneficial effect on neuropathy, lack of an immediate benefit on advanced retinopathy, and an effect on nephropathy compounded by the influence of CsA on renal function.     

褪黑素抗氧化治疗糖尿病大鼠阴茎勃起功能障碍的研究

目的 观察褪黑素对糖尿病大鼠阴茎勃起功能的影响,探讨氧化应激在糖尿病性勃起功能障碍发病机制中的作用.方法 一次性腹腔注射STZ建立糖尿病大鼠模型,随机分为糖尿病组、褪黑素(MT)治疗组以及对照组.8周后通过电刺激各组大鼠勃起神经来检测海绵体内压,评价勃起功能;采用硫代芭比妥酸法检测阴茎海绵体组织中丙二醛(MDA)含量,黄嘌呤氧化酶法测超氧化物氧化酶(SOD)活性;免疫组化染色半定量分析各组大鼠阴茎海绵体中平滑肌及内皮的含量.结果 与正常对照组相比,阴茎海绵体组织中MDA含量显著增加(P＜0.01),SOD活性降低(P＜0.05),最大海绵体内压(ICP)亦显著降低(P＜0.05);与糖尿病组相比,MT组大鼠海绵体MDA含量明显降低(P＜0.05),其SOD活性和ICP显著升高(P＜0.05);且其海绵体平滑肌及海绵窦内皮细胞含量明显提高.结论 MT可通过改善组织中氧化应激水平,促进阴茎海绵体平滑肌和内皮组织修复,提高勃起功能;抗氧化治疗可能为糖尿病性勃起功能障碍的防治提供新的策略.     

Urinary marker for oxidative stress in kidneys in cisplatin-induced acute renal failure in rats.

BACKGROUND: Establishment of non-invasive urinary biomarkers for the prediction of acute renal failure (ARF) is important. We evaluated whether urinary oxidative stress markers reflect intrarenal oxidative stress in cisplatin (CDDP)-induced ARF, and whether these markers can be used for the prediction of future ARF. METHODS: Urinary malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured up to day 14 post-CDDP (6 mg/kg) injection in rats. MDA and 8-OHdG expressions were examined in kidneys. RESULTS: CDDP induced an increase in serum creatinine (Scr), blood urea nitrogen (BUN), and tubular damage at day 5, increased urinary MDA excretion and MDA expression in kidneys at day 1 (but returned to basal values by day 3), increased urinary excretion of 8-OHdG at day 5 till day 14 (though the number of 8-OHdG-positive tubular cells increased at day 5 and then gradually decreased). Urinary MDA levels at day 1 correlated significantly with Scr (rho = 0.721, P < 0.01) and tubular damage score (rho = 0.840, P < 0.01) at day 5. CONCLUSION: Our findings demonstrated divergent changes of urinary oxidative stress markers in CDDP-induced ARF, and suggested that urinary MDA may be a useful marker for the prediction of the development of CDDP-induced ARF.     

左旋精氨酸对糖尿病大鼠阴茎海绵体氧化应激损伤的保护作用

目的 探讨左旋精氨酸(L-Arg)对糖尿病大鼠阴茎海绵体氧化应激损伤的保护作用.方法 大剂量STZ腹腔注射建立糖尿病大鼠模型,随机分为糖尿病组、L-Arg治疗组,并设正常对照组.治疗8周后用电刺激各组大鼠勃起神经测定海绵体内压评价勃起功能采用黄嘌呤氧化酶法检测阴茎海绵体组织中超氧化物歧化酶(SOD)活性,硫代芭比妥酸法测丙二醛(MDA)含量;光镜下观察Masson染色切片.结果 糖尿病组较正常对照组,阴茎海绵体MDA含量显著增高(P<0.01),SOD活性显著下降(P<0.05),最大海绵体内压(ICP)显著降低(P<0.05);与糖尿病组比较,L-Arg可使海绵体MDA含量明显降低(P<0.05),显著提高其SOD活性及ICP(P<0.05).糖尿组大鼠阴茎组织中胶原纤维含量明显减少,排列紊乱、稀疏,平滑肌减少变薄,出现断裂;L-Arg组大鼠阴茎组织结构可见明显改善.结论 糖尿病大鼠阴茎海绵体存在氧化应激损伤,导致海绵体结构的改变是其勃起水平下降的重要因素,通过补充L-Arg,可以减轻勃起组织的氧化应激损伤,改善组织结构,从而提高勃起能力.     

Dehydroepiandrosterone prevents oxidative injury induced by transient ischemia/reperfusion in the brain of diabetic rats

Both chronic hyperglycemia and ischemia/reperfusion (IR) cause an imbalance in the oxidative state of tissues. Normoglycemic and streptozotocin (STZ)-diabetic rats were subjected to bilateral carotid artery occlusion for 30 min followed by reperfusion for 60 min. Rats had either been treated with dehydroepiandrosterone (DHEA) for 7, 14, or 21 days (2 or 4 mg/day per rat) or left untreated. Oxidative state, antioxidant balance, and membrane integrity were evaluated in isolated synaptosomes. IR increased the levels of reactive species and worsened the synaptic function, affecting membrane Na/K-ATPase activity and lactate dehydrogenase release in all rats. The oxidative imbalance was much severer when transient IR was induced in STZ-diabetic rats. DHEA treatment restored H2O2, hydroxyl radical, and reactive oxygen species to close to control levels in normoglycemic rats and significantly reduced the level of all reactive species in STZ-diabetic rats. Moreover, DHEA treatment counteracted the detrimental effect of IR on membrane integrity and function: the increase of lactate dehydrogenase release and the drop in Na/K-ATPase activity were significantly prevented in both normoglycemic and STZ-diabetic rats. The results confirm that DHEA, an adrenal steroid that is synthesized de novo by brain neurons and astrocytes, possesses a multitargeted antioxidant effect. They also show that DHEA treatment is effective in preventing both derangement of the oxidative state and neuronal damage induced by IR in experimental diabetes.     

氧化应激与糖尿病大鼠nephrin表达及足细胞凋亡的关系

本研究观察,氧化应激对糖尿病大鼠nephrin表达改变及足细胞凋亡的影响,以探讨糖尿病大鼠蛋白尿发生发展的分子机制. 一、材料与方法 1.材料:雄性SD大鼠,体质量170～220 g,由武汉大学动物试验中心提供.褪黑素溶液和链脲佐菌素STZ溶液购自美国Sigma公司.     

Role of oxidative stress in diabetic nephropathy

Accumulating research suggests that oxidative stress is a significant contributor to the pathogenesis of diabetic nephropathy. The normal kidney generates a substantial amount of oxidative stress because of its high metabolic activity that is balanced by an extensive antioxidant system. However, in pathologic states such as hyperglycemia, nitroso-oxidant balance shifts toward a pro-oxidant state that accelerates tissue and vascular injury. This oxidative damage progresses concomitant with worsening glucose metabolism, vascular dysfunction, and kidney disease. Accordingly, strategies to reduce oxidative stress in diabetes mellitus may exert favorable effects on the progression of diabetic nephropathy.     

Bi-layered living cellular construct resulted in greater healing in an alloxan-induced diabetic porcine model

Tissue-engineered skin constructs, including bi-layered living cellular constructs (BLCC) used in the treatment of chronic wounds, are structurally/functionally complex. While some work has been performed to understand their mechanisms, the totality of how BLCC may function in wound healing remains unknown. To this end, we have developed a delayed wound healing model to test BLCC cellular and molecular mechanisms of action. Diabetes was chemically-induced using alloxan in Yucatan miniature pigs, and full-thickness wounds were generated on their dorsum. These wounds were either allowed to heal by secondary intention alone (control) or treated with a single or multiple treatments of a porcine autologous BLCC. Results indicated a single treatment with porcine BLCC resulted in statistically significant wound healing at day 17, while four treatments resulted in statistically significant healing on days 10, 13, and 17 compared to control. Statistically accelerated wound closure was driven by re-epithelialisation rather than contraction or granulation. This porcine diabetic model and the use of a porcine BLCC allowed evaluation of healing responses in vivo without the complications typically seen with either xenogenic responses of human/animal systems or the use of immune compromised animals, expanding the knowledge base around how BLCC may impact chronic wounds.     

Ferulic acid prevents lead‐induced testicular oxidative stress and suppressed spermatogenesis in rats

Lead affects multiple organ systems including testis. We investigated the effects of ferulic acid (FA) on lead‐induced oxidative stress and spermatogenesis suppression in rats. Animals received lead acetate (500 mg/L in drinking water) and/or FA (50 mg/kg, i.g.) for eight weeks. Lead increased testicular malondialdehyde (MDA) and nitrite levels and decreased glutathione (GSH) content and catalase (CAT) activity. Lead decreased testis weight and testosterone level. Sperm parameters decreased in lead group. FA ameliorated the decreased testis weight, serum testosterone as well as sperm count, viability, motility and normal morphology in lead group. FA improved antioxidant capacity as well as sperm count, viability, motility and normal morphology. FA decreased Johnsen's mean testicular biopsy score (MTBS) criteria by restoring degeneration, atrophy and tubular disarrangement. FA also normalised spermatogonia, spermatocytes and spermatids numbers in lead group and led to increases in number of Leydig and Sertoli cells. FA showed beneficial effects in lead‐induced testicular oxidative stress and spermatological disorders, through inhibiting lipid peroxidation and enhancing antioxidant defence systems. The positive effects of FA on Leydig cells may be involved in restoring testosterone levels in lead group. FA can be considered a potential candidate to protect testis against the deleterious effect of lead intoxication.     

Effect of reinstitution of good glycemic control on retinal oxidative stress and nitrative stress in diabetic rats

Clinical and experimental studies have shown that reinstitution of good glycemic control (GC) after a period of poor glycemic control (PC) does not produce immediate benefits on the progression of retinopathy, and hyperglycemia is sufficient to initiate the development of diabetic retinopathy. In this study, the effect of reinstitution of GC on hyperglycemia-induced increased oxidative stress and nitrative stress was evaluated in the retina of rats maintained in PC before initiation of GC. In diabetic rats, 2 or 6 months of PC (GHb >11.0%) was followed by 7 months of GC (GHb <5.5%). Reinstitution of GC after 2 months of PC inhibited elevations in retinal lipid peroxides and NO levels by approximately 50%, but failed to have any beneficial effects on nitrotyrosine formation. However, reversal of hyperglycemia after 6 months of PC had no significant effect on retinal oxidative stress and NO levels (P < 0.02 vs. normal). In the same rats, inducible nitric oxide synthase expression and nitrotyrosine levels remained elevated by >80% compared with normal rats or rats kept in GC for the duration. This suggests that oxidative and nitrative modifications in retina occur early in the course of development of retinopathy in diabetes. These abnormalities are not easily reversed by reinstitution of GC, and the duration of PC before initiation of GC influences the outcome of the reversal. Characterization of the abnormalities responsible for the resistance of retinopathy to arrest after reinstitution of GC will help identify potential future therapies to inhibit progression of diabetic retinopathy.     

NG2蛋白多糖在糖尿病大鼠肾脏组织中表达的改变

糖尿病肾病（DN）的发病率在全世界范围内正在显著增加，已成为诱导终末期肾衰竭需要肾替代治疗的最常见的原因。早期DN的主要特征为肾小球肥大和进行性细胞外基质（ECM）积聚，其分子机制涉及到多种因素和途径，是目前研究的热点。本实验的目的为观察NG2蛋白多糖在正常大鼠和糖尿病大鼠肾脏中的表达，探讨NG2在DN中的作用机制。     

Cholesterol metabolism in alloxan-induced diabetic rabbits

The effect of diabetes control on the activities of hydroxymethylglutaryl-CoA reductase (HMG-CoA reductase), cholesterol acyltransferase (ACAT), and phenol 2-monooxygenase, the major enzymes regulating cholesterol metabolism, was determined in alloxan-induced diabetic rabbits, and the results obtained were correlated with lipid and lipoprotein levels. Although intestinal HMG-CoA reductase activity was significantly increased (P less than 0.001) in poorly controlled compared with moderately controlled diabetic rabbits, there was a significant reduction in the activities of intestinal ACAT (P less than 0.01), hepatic HMG-CoA reductase (P less than 0.05) and ACAT (P less than 0.001), and phenol 2-monooxygenase (P less than 0.01). The poorly controlled animals were hypercholesterolemic (P less than 0.01), and this was reflected in the very-low-density and high-density lipoprotein fractions. Serum cholesterol levels in the nondiabetic and moderately controlled diabetic groups were similar. This increase in intestinal HMG-CoA reductase activity in the poorly controlled diabetic animals occurred in the absence of hyperphagia. Although abnormalities in cellular cholesterol metabolism could be partly responsible for the alterations in serum cholesterol levels in diabetes, the precise mechanisms underlying these enzymatic changes have yet to be elucidated.