Epalrestat protects against diabetic peripheral neuropathy by alleviating oxidative stress and inhibiting polyol pathway

Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.     

Lipid peroxide and antioxidant enzymes in muscle and nonmuscle of dystrophic mouse

To determine whether abnormality in redox metabolism occurs specifically in certain individual dystrophic muscles, thiobarbituric acid reactivity, free radical scavengers, and oxidative marker enzymes were measured in the liver, kidney, erythrocytes, heart, and four different individual skeletal muscles from C57BL/6J dy/dy mice. Superoxide dismutases were assayed by specific radioimmunoassays, which enabled the study of a small individual murine muscle. Glutathione peroxidase and catalase were increased markedly in each individual dystrophic skeletal muscle studied and less markedly in the heart. Manganosuperoxide dismutase and thiobarbituric acid reactivity were decreased to a similar extent in each dystrophic skeletal muscle. Cuprozinc superoxide dismutase was decreased in the soleus muscle. Only a minimal biochemical change occurred in nonmuscles. Fumarase activity correlated closely with the level of manganosuperoxide dismutase. These results suggest that muscle protein breakdown occurs independently of lipid peroxidation despite the presence of tissue-specific abnormality of redox metabolism in dystrophic muscle.     

Hyperbaric oxygenation and erythrocyte antioxidant enzymes in multiple sclerosis patients

Erythrocyte glutathione peroxidase, catalase, and superoxide dismutase activities were measured in 18 patients with clinically definite MS, and results compared with those from neurological controls. These studies indicated that glutathione peroxidase activity in erythrocytes of MS patients was not different from that of the neurological controls. However, superoxide dismutase was lower in the MS patients compared to neurological controls. The effect of hyperbaric oxygenation on these erythrocyte enzymes in MS patient's was also investigated. Exposure of MS patients to 2 ata with either 10% O2 or 100% O2 had no effect on glutathione peroxidase activity. Comparison of each individual MS patient's pre- and post-treatment superoxide dismutase values indicated a significant increase after 100% O2. Similar examination of each individual's catalase activity indicated an increase after exposure to both 10% O2 and 100% O2 at 2 ata. These data suggest that erythrocyte enzyme response to oxygen stress does not involve changes in activity of all the antioxidant enzymes. Instead, only specific enzymes appear to be affected by HBO.     

Pretreated quercetin protects gerbil hippocampal CA1 pyramidal neurons from transient cerebral ischemic injury by increasing the expression of antioxidant enzymes

Quercetin(QE; 3,5,7,3′,4′-pentahydroxyflavone), a well-known flavonoid, has been shown to prevent against neurodegenerative disorders and ischemic insults. However, few studies are reported regarding the neuroprotective mechanisms of QE after ischemic insults. Therefore, in this study, we investigated the effects of QE on ischemic injury and the expression of antioxidant enzymes in the hippocampal CA1 region of gerbils subjected to 5 minutes of transient cerebral ischemia. QE was pre-treated once daily for 15 days before ischemia. Pretreatment with QE protected hippocampal CA1 pyramidal neurons from ischemic injury, which was confirmed by neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining. In addition, pretreatment with QE significantly increased the expression levels of endogenous antioxidant enzymes Cu/Zn superoxide dismutase, Mn superoxide dismutase, catalase and glutathione peroxidase in the hippocampal CA1 pyramidal neurons of animals with ischemic injury. These findings demonstrate that pretreated QE displayed strong neuroprotective effects against transient cerebral ischemia by increasing the expression of antioxidant enzymes.     

Overexpressions of myoglobin and antioxidant enzymes in ragged-red fibers of skeletal muscle from patients with mitochondrial encephalomyopathy

To determine the relationship between myoglobin (Mb) and the defense system against reactive oxygen species in various myopathies, we performed immunohistochemical analyses of Mb and various antioxidant enzymes, including manganese superoxide dismutase (Mn-SOD), copper zinc SOD (CuZn-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px). Biopsied muscle specimens were obtained from patients with chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayre syndrome (KSS), Duchenne muscular dystrophy (DMD), and polymyositis (PM). In patients with CPEO/KSS, stainings of Mb, SOD, CAT, and GSH-Px in nonatrophic ragged-red fibers (RRFs) were more intense than those in non-RRFs. These pronounced stainings corresponded to ragged-red lesions. The staining intensities of these antioxidant enzymes were significantly correlated with that of Mb (P < 0.001). Atrophic RRFs in specimens from patients with CPEO/KSS showed intense stainings of these antioxidant enzymes but not intense staining of Mb. In specimens from patients with DMD/PM, the antioxidant enzymes but not Mb were overexpressed in degenerative fibers. These results suggest that oxidative stress is associated with Mb expression specifically in mitochondrial diseases. The antioxidant enzymes seem to be upregulated to protect against muscle damage in nonatrophic RRFs. However, the Mb-mediated oxidative damage may become more extensive and result in further mitochondrial dysfunction and progressive atrophy of RRF with impaired upregulation of Mb.     

Age-related changes in antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione in different regions of mouse brain

It has been proposed that neurodegenerative processes of aging are associated with the generation of reactive oxygen species (ROS) during cellular metabolism. These reactive oxygen species are scavenged by antioxidant enzymes in biological systems. The present study was designed to determine the selective distribution of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase activity and reduced glutathione (GSH) levels in different regions of the C57BL/6N mouse brain and to determine if any alterations occurred with age. Catalase activity did not show any significant change except in cerebellum. Activity of superoxide dismutase was increased with age in all regions of the brain except in hippocampus of 2-yr-old mice. The glutathione peroxidase activity in the caudate nucleus increased in all regions of the brain, however, the activity did not change at one, six and 12 months. A significant increasing pattern of glutathione content was found in the cerebellum and brain stem with age. These data demonstrate that although the level of antioxidant enzymes varied in different regions of the brain, overall the enzyme activities tend to increase with age.     

Polymorphonuclear leukocyte nitrite content and antioxidant enzymes in Parkinson's disease patients

OBJECTIVE: The present study was undertaken to evaluate the alteration in the peripheral neuronal nitric oxide synthase (NOS) activity in Parkinson's disease patients. Therefore, basal nitrite content in PMNs, platelets and in the plasma of PD and control Indian population were evaluated. MATERIALS AND METHODS: We estimated nitrite, the nitric oxide (NO) metabolite, in neutrophils (PMNs), platelets and in plasma of control and in L-dopa treated Parkinson's disease (PD) patients. We also measured the activity of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the PMNs. RESULTS: We observed a significant increase in the basal nitrite content in PMNs of PD patients without any alteration in the plasma and platelets. Thus, the change was specific to PMNs. Catalase activity was significantly less in the PMNs of PD patients, but SOD and GPx remained unaltered. CONCLUSION: Results obtained in the PD patients exhibit an increase in the NOS activity in PMNs. Thus, involvement of NO is suggested in PD.     

Immunohistochemical detection of anti-oxidative stress enzymes in the dog brain

Anti-oxidative stress enzymes were immunohistochemically detected in the brain from young to very-aged dogs. More than half of the neurons in the cerebral cortex of the young dogs (< 5 years old) were positive for copper (Cu), zinc (Zn) superoxide dismutase (SOD), and the staining intensity was strong. The number of Cu, Zn SOD-positive neurons decreased with age, and only 10–50% of neurons were positive for SOD in the aged and very aged (> 9 years old) dogs. In contrast, no glial cells were immunostained for Cu, Zn SOD in the young dogs, and the number, as well as the staining intensity, increased with age, reaching > 50% in the aged and very aged dogs. Apoptotic brain cells, which were conspicuous in the aged dog brain, were negative for Cu, Zn SOD. The Cu, Zn SOD immunoreactions were also observed in the degenerative neurites of amyloid type senile plaques, vessels affected with cerebral amyloid angiopathy (CAA) and reactive astroglia around these amyloid plaques and CAA in the aged and very aged dog brains. Diffuse type senile plaques were negative for Cu, Zn SOD. The number of catalase- or glutathione peroxidase-positive cells varied among dogs regardless of their age. An age-related decrease in number of Cu, Zn SOD-positive neurons may enhance the toxicity of oxygen free radicals, resulting in neuronal cell death.     

Changes on cerebral antioxidant enzymes, peroxidation, and the glutathione system of frogs after aging and catalase inhibition

The five major antioxidant enzymes, glutathione, and in vivo or in vitro stimulated (Fe(++)-ascorbate) peroxidation were similar in old and young Rana perezi frogs. Long-term (2.5 months) treatment with aminotriazole strongly decreased cerebral catalase (CAT) activity and increased in vivo but not in vitro peroxidation in the brain. This suggests that the increase in endogenous brain peroxidation after CAT inhibition is due to an increased free-radical attack on cerebral membranes, and not to a possible increase in their sensitivity to peroxidative damage. The increase of in vivo peroxidation is especially remarkable taking into account the low levels of CAT present in the vertebrate brain. On the other hand, these changes were not accompanied by any effect on the survival of the animals. Comparison of these results with those obtained in other species suggests the possibility that O2-free radicals be of minor importance in relation to brain aging in animals with low rates of oxygen consumption.     

糖尿病性周围神经病患者受累神经的分布特点

目的 探讨糖尿病件周围神经病(DPN)患者受累神经的分布特点.方法 对900例2型糖尿病并发DPN患者进行感觉及运动神经传导速度检测,对受累神经的分布进行分析.结果 本组感觉神经异常率为89.3%;包括65.2%(587例)的正中神经、38.9%(350例)的尺神经、89.3%(804例)的腓浅神经、60.4%(544例)的腓肠神经及29.6%(64例)的胫后神经异常.运动神经异常率为34.5%;包括32.1%(289例)的正中神经、28.7%(258例)的腓总神经、22.7%(49例)的胫神经异常.感觉神经异常率明显高于运动神经异常率(P<0.01);下肢感觉神经异常率明显高于上肢(P<0.01).结论 DPN患者受累的感觉神经以腓浅神经、正中神经、腓肠神经最普遍,受累的运动神经以正中神经、腓总神经为多见.     

Conduction block in diabetic neuropathy

Symmetric sensorimotor polyneuropathy is a common complication of diabetes. Sensory and motor evoked amplitudes and conduction velocities are reduced. Both demyelination and axon loss have been reported in pathologic studies. Conduction block (CB), a manifestation of segmental demyelination, has not been previously studied in diabetic neuropathy. We determined the prevalence of conduction block in patients with diabetes by analyzing electrodiagnostic data from 24 diabetics. Conduction block was defined as a greater than 20% drop in peak-to-peak amplitude, and a less than 15% change in negative-peak duration between proximal and distal stimulation sites. A total of 76 nerve segments were studied. The criteria for conduction block were met in only 6 segments in 6 patients. The mean decrease in peak-to-peak amplitude between stimulation sites was 28% (range 21% to 40%). We conclude that conduction block over long nerve segments is uncommon in diabetic neuropathy, and, if present, suggests that other causes for neuropathy in diabetic patients should be sought.     

MPTP对小鼠黑质及纹状体活性氧自由基代谢酶基因表达的影响

活性氧自由基是 1 甲基 4 苯基 1,2 ,3,6 四氢吡啶 (1 methyl 4 phenyl 1,2 ,3,6 tetrahydropyridine,MPTP)诱发多巴胺能神经元损伤的一种可能性因素。通过MPTP注射诱导C5 7BL小鼠神经元损伤 ,利用逆转录PCR方法检测铜锌超氧化物歧化酶 (CuZn SOD)、锰超氧化物歧化酶 (Mn SOD)以及谷胱甘肽过氧化物酶 (GSH PX)三种相关基因的表达变化。结果显示 ,在小鼠黑质与纹状体中 ,MPTP导致Mn SOD基因表达显著降低 ,而CuZn SOD与GSH PX基因的表达则没有明显变化。推测Mn SOD基因表达的变化可能与MPTP对线粒体的毒性作用有关。     

Oxygen toxicity protecting enzymes in the human brain

Summary Regional distribution of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities were studied in 22 anatomic sites of 5 human brains. No significant regional differences were observed in cytosolic activities of any enzyme studied, nor in particulate activities of superoxide dismutase, catalase and glutathione reductase, whereas particulate glutathione peroxidase activities were distributed unevenly, the highest activities observed in the basal nucleus and amygdala. There were significant interindividual differences in the activities of each enzyme. This was shown to result partly from the decrease of cytosolic superoxide dismutase and catalase activities with age, concurrently with age-related decrease of particulate glutathione peroxidase and glutathione reductase activities.     

Median nerve ultrasound in diabetic peripheral neuropathy with and without carpal tunnel syndrome

Introduction: Median nerve ultrasound shows increased cross‐sectional area (CSA) in carpal tunnel syndrome (CTS) and diabetic peripheral neuropathy (PN). The role of ultrasound in diagnosing CTS superimposed on diabetic PN is unknown. The objective of this study is to evaluate ultrasound for diagnosis of CTS in diabetic PN. Methods: Prospective recruitment of diabetics with electrodiagnostically proven PN, subdivided into cases (with CTS) or controls (without CTS). The gold standard for CTS was clinical diagnosis. NCS were correlated with blinded median nerve CSA ultrasound measurements. Results: Eight cases (CTS) and eight controls (no CTS) were recruited. Nerve conduction studies (NCS): Median nerve distal latencies (antidromic sensory; palmar; lumbrical motor; and lumbrical motor to ulnar interosseous difference) were significantly prolonged in CTS cases. No ultrasound measurement (distal median CSA, wrist‐forearm ratio, wrist‐forearm difference) reached significance to detect CTS. Area under the curve was greatest for lumbrical distal latency by receiver operator characteristic analysis (0.85). Conclusions: In this pilot study, NCS may be superior to ultrasound for identification of superimposed CTS in diabetic PN patients, but larger numbers are needed for confirmation. Muscle Nerve 47: 437–439, 2013     

Brain glutathione reductase induction increases early survival and decreases lipofuscin accumulation in aging frogs

Brain catalase was continuously depleted throughout the life span starting with a large population of initially young and old frogs. Free radical-related parameters were measured in the brain tissue once per year after 2.5, 14.5, and 26.5 months of experimentation. Brain lipofuscin accumulation was observed after 14.5 and 26.5 months, and survival was continuously followed during 33 months. The age of the animal did not decrease endogenous antioxidants nor increase tissue peroxidation either in cross-sectional or longitudinal comparisons. Continuous catalase depletion similarly affected young and old animals, inducing glutathione reductase, tending to decrease oxidized glutathione/reduced glutathione (GSSG/GSH) ratio, decreasing lipofuscin accumulation in the brain, and increasing survival from 46% to 91% after 14.5 months. At 26.5 months of experimentation the loss of the glutathione reductase induction in catalase-depleted animals was accompanied by the presence of higher lipofuscin deposits than in controls and was followed by a great increase in mortality rate. Even though the maximal life span (7 years) was the same in the control and treated animals which were already old (4.2 years) at the beginning of the experiment, the treated animals showed a strong reduction in the rates of early death. It is proposed that the maintenance of a high antioxidant/prooxidant balance in the vertebrate brain greatly increases the probability of the individual to reach the final segments of its species-specific life span. © 1993 Wiley-Liss, Inc.     

The role of growth factors in diabetic peripheral neuropathy

Peripheral neuropathy afflicts 60% of all diabetic patients. Underlying the clinical disorder is the loss or degeneration of neurons, Schwann cells, and neuronal fibers. This degenerative pathology has prompted interest in the potential of growth factors as a therapy in diabetic neuropathy. Three lines of evidence support the theory that growth factors may be important in this disorder: (1) endogenous growth factors promote survival and health of neurons, (2) expression levels of growth factors are altered in diabetic neuropathy and peripheral neuron injury, and (3) growth factors induce neuronal regeneration in in vitro and in vivo models of diabetic injury. This review surveys the roles of several growth factors in diabetic neuropathy, including the neurotrophins, insulin-like growth factors, cytokine-like growth factors, and vascular endothelial growth factor. These growth factors are examined in terms of their expression during peripheral nerve injury and their protective and regenerative effects on peripheral neurons. Growth factor-mediated neuroprotective signaling is discussed, particularly in relation to the recent research, suggesting that diabetic neuropathy-induced degeneration stems from oxidative stress. Finally, the potential of growth factors as therapeutic agents is addressed, including an assessment of past growth factor clinical trials and other potential avenues of growth factor therapy.     

Antioxidant enzymatic activities after experimental subarachnoid hemorrhage in rats

Lipid peroxidation has been hypotesized as one of possible factors involved in the pathogenesis of neuronal damage and delayed vasospasm after subarachnoid hemorrhage. In the brain there are anti-oxidant enzymatic systems which act as scavengers of superoxides and free radicals. In the present study the pattern of enzymatic anti-oxidant activities (Cu-Zn and Mn superoxide dismutase, and glutathione peroxidase) was investigated in an experimental model of subarachnoid hemorrhage in the rat in order to verify whether the hemorrhagic insult may be responsible for an impairment of such anti-oxidant systems. Enzymatic activities were assayed in three different rat brain areas (cerebral cortex, hippocampus and brain stem) of sham-operated and at 30 min, 1, 6 and 48 h after subarachnoid hemorrhage induction. After the hemorrhage induction the Cu-Zn superoxide dismutase activity in cerebral cortex was significantly reduced at all the set times (p <.05), while Mn-superoxide dismutase activity was significantly decreased since 1 h (p <.05) until 48 h (p <.05). Glutathione peroxidase activity was significantly reduced only in the late phase (48 h) of subarachnoid hemorrhage (p <.01). In the hippocampus, all enzymatic activities were significantly reduced in the late phase. In the brain stem Cu-Zn superoxide dismutase was significantly impaired at 1 and 6 h (p <.05) after subarachnoid hemorrhage induction, while in the late phase (48 h) reached the control value. The mitochondrial Mn-superoxide dismutase was significantly reduced since 1 h (p <.05) until 48 h (p <.02) after subarachnoid hemorrhage. Glutathione peroxidase activity in this area was impaired at 1, 6 (p <.01) and 48 h (p <.02). These results suggest that subarachnoid hemorrhage causes a significant reduction of anti-oxidant enzymatic activities in brain compartment: Cu-Zn and Mn superoxide dismutase, which are specific scavengers of superoxide radicals, show an early decrease, while glutathione peroxidase activity is significantly reduced in a delayed phase.     

Ischemia-reperfusion injury of peripheral nerve in experimental diabetic neuropathy

The pathogenesis of human diabetic neuropathy likely involves the interplay of hyperglycemia, ischemia, and oxidative stress. Mild-moderate ischemia-reperfusion to streptozotocin (STZ)-induced diabetes results in florid fiber degeneration in diabetic but not in normal nerves. Uncertainty exists as to the influence of duration of diabetes on this susceptibility. We therefore studied diabetic tibial and sciatic nerves using a rat ischemia-reperfusion (IR) model after 1 month and 4 months of diabetes utilizing electrophysiological, behavioral, and neuropathological methods. Electrophysiological abnormalities were present in 1-month diabetic rats (D) and persisted over 4 months. Behavioral scores were decreased markedly at 4 months (p<0.05). Endoneurial edema and ischemia fiber degeneration (IFD) were observed at both the 1-month (p<0.01 and p<0.001) and 4-month (p<0.001) durations in diabetic nerves, whereas only mild or no damage was observed in age-matched control nerves. These findings demonstrate that STZ-induced diabetes exacerbates the morphological and electrophysiological pathology in peripheral nerve to IR injury both in the early timepoint of 1 month and late timepoint of 4 months, although there was a gradation of injury, which is more severe at the later timepoint. Reperfusion exaggerated morphological pathology in 1-month STZ-induced diabetic peripheral nerve.     

桡神经超声结合神经传导检查在糖尿病周围神经病变患者中的应用

目的:探讨2型糖尿病伴周围神经病变患者桡神经的超声特征及电生理表现,企为临床诊治及预后评估提供参考依据.方法:选取西宁市第一人民医院70例2型糖尿病患者,分为合并周围神经病变组35例及未合并周围神经病变组35例,同时选择健康体检者35例作对照,所有受检者行桡神经超声检查及神经传导检测.结果:糖尿病合并周围神经病变者桡神经超声表现为神经束回声减低,平行线状低回声结构消失,神经外膜增厚分界不清;神经传导检测提示桡神经运动传导速度(MCV)及感觉传导速度(SCV)均有异常,且SCV更为敏感,异常率更高;糖尿病未合并周围神经病变组与正常对照组超声及神经传导检查比较,差异无统计学意义.结论:超声与神经传导检查两者结合,可以从功能及形态学两方面更明确地为临床提供糖尿病患者是否合并周围神经病的依据和判断病变程度,有助于临床诊治及预后评估.