RESUMO
An insertion polymorphism of the angiotensin-I converting enzyme gene (ACE) is common in humans and the higher expressing allele is associated with an increased risk of diabetic complications. The ACE polymorphism does not significantly affect blood pressure or angiotensin II levels, suggesting that the kallikrein-kinin system partly mediates the effects of the polymorphism. We have therefore explored the influence of lack of both bradykinin receptors (B1R and B2R) on diabetic nephropathy, neuropathy, and osteopathy in male mice heterozygous for the Akita diabetogenic mutation in the insulin 2 gene (Ins2). We find that all of the detrimental phenotypes observed in Akita diabetes are enhanced by lack of both B1R and B2R, including urinary albumin excretion, glomerulosclerosis, glomerular basement membrane thickening, mitochondrial DNA deletions, reduction of nerve conduction velocities and of heat sensation, and bone mineral loss. Absence of the bradykinin receptors also enhances the diabetes-associated increases in plasma thiobarbituric acid-reactive substances, mitochondrial DNA deletions, and renal expression of fibrogenic genes, including transforming growth factor beta1, connective tissue growth factor, and endothelin-1. Thus, lack of B1R and B2R exacerbates diabetic complications. The enhanced renal injury in diabetic mice caused by lack of B1R and B2R may be mediated by a combination of increases in oxidative stress, mitochondrial DNA damage and over expression of fibrogenic genes.
Assuntos
Diabetes Mellitus Experimental/genética , Receptor B1 da Bradicinina/deficiência , Receptor B2 da Bradicinina/deficiência , Animais , Densidade Óssea , DNA Mitocondrial/genética , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/metabolismo , Nefropatias Diabéticas/etiologia , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Neuropatias Diabéticas/etiologia , Neuropatias Diabéticas/genética , Neuropatias Diabéticas/metabolismo , Neuropatias Diabéticas/fisiopatologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Osteoporose/etiologia , Osteoporose/genética , Osteoporose/metabolismo , Fenótipo , Receptor B1 da Bradicinina/genética , Receptor B2 da Bradicinina/genéticaRESUMO
Diabetic neuropathy is a common complication of diabetes. While multiple pathways are implicated in the pathophysiology of diabetic neuropathy, there are no specific treatments and no means to predict diabetic neuropathy onset or progression. Here, we identify gene expression signatures related to diabetic neuropathy and develop computational classification models of diabetic neuropathy progression. Microarray experiments were performed on 50 samples of human sural nerves collected during a 52-week clinical trial. A series of bioinformatics analyses identified differentially expressed genes and their networks and biological pathways potentially responsible for the progression of diabetic neuropathy. We identified 532 differentially expressed genes between patient samples with progressing or non-progressing diabetic neuropathy, and found these were functionally enriched in pathways involving inflammatory responses and lipid metabolism. A literature-derived co-citation network of the differentially expressed genes revealed gene subnetworks centred on apolipoprotein E, jun, leptin, serpin peptidase inhibitor E type 1 and peroxisome proliferator-activated receptor gamma. The differentially expressed genes were used to classify a test set of patients with regard to diabetic neuropathy progression. Ridge regression models containing 14 differentially expressed genes correctly classified the progression status of 92% of patients (P < 0.001). To our knowledge, this is the first study to identify transcriptional changes associated with diabetic neuropathy progression in human sural nerve biopsies and describe their potential utility in classifying diabetic neuropathy. Our results identifying the unique gene signature of patients with progressive diabetic neuropathy will facilitate the development of new mechanism-based diagnostics and therapies.
Assuntos
Neuropatias Diabéticas/genética , Progressão da Doença , Nervo Sural/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Regulação para Baixo , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Nervo Sural/fisiopatologia , Regulação para CimaRESUMO
IGF-I and -II are potent neuronal mitogens and survival factors. The actions of IGF-I and -II are mediated via the type I IGF receptor (IGF-IR) and IGF binding proteins regulate the bioavailability of the IGFs. Cell viability correlates with IGF-IR expression and intact IGF-I/IGF-IR signaling pathways, including activation of MAPK/phosphatidylinositol-3 kinase. The expression of IGF-I and -II, IGF-IR, and IGF binding proteins are developmentally regulated in the central and peripheral nervous system. IGF-I therapy demonstrates mixed therapeutic results in the treatment of peripheral nerve injury, neuropathy, and motor neuron diseases such as amyotrophic lateral sclerosis. In this review we discuss the role of IGFs during peripheral nervous system development and the IGF signaling system as the potential therapeutic target for the treatment of nerve injury and motor neuron diseases.
Assuntos
Sistema Nervoso Periférico/metabolismo , Somatomedinas/metabolismo , Animais , Expressão Gênica , Humanos , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/genética , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/metabolismo , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/fisiologia , Modelos Biológicos , Sistema Nervoso Periférico/fisiologia , Receptores de Somatomedina/genética , Receptores de Somatomedina/metabolismo , Receptores de Somatomedina/fisiologia , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Somatomedinas/genética , Somatomedinas/fisiologiaRESUMO
Diabetic neuropathy (DN) is a common complication of diabetes. Currently, there is no drug treatment to prevent or slow the development of DN. Rosiglitazone (Rosi) is a potent insulin sensitizer and may also slow the development of DN by a mechanism independent of its effect on hyperglycemia. A two by two design was used to test the effect of Rosi treatment on the development of DN. Streptozotocin-induced diabetic DBA/2J mice were treated with Rosi. DN and oxidative stress were quantified, and gene expression was profiled using the Affymetrix Mouse Genome 430 2.0 microarray platform. An informatics approach identified key regulatory elements activated by Rosi. Diabetic DBA/2J mice developed severe hyperglycemia, DN, and elevated oxidative stress. Rosi treatment did not affect hyperglycemia but did reduce oxidative stress and prevented the development of thermal hypoalgesia. Two novel transcription factor binding modules were identified that may control genes correlated to changes in DN after Rosi treatment: SP1F_ZBPF and EGRF_EGRF. These targets may be useful in designing drugs with the same efficacy as Rosi in treating DN but with fewer undesirable effects.
Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/genética , Neuropatias Diabéticas/tratamento farmacológico , Neuropatias Diabéticas/genética , Hipoglicemiantes/farmacologia , Tiazolidinedionas/farmacologia , Animais , Glicemia/metabolismo , Feminino , Expressão Gênica/efeitos dos fármacos , Genômica , Hormônio do Crescimento/sangue , Hiperalgesia/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos DBA , Análise de Sequência com Séries de Oligonucleotídeos , Estresse Oxidativo/efeitos dos fármacos , Regiões Promotoras Genéticas/fisiologia , RosiglitazonaRESUMO
Clinical studies suggest that impaired glucose tolerance (IGT) is associated with the development of neuropathy. The aim of the current study was to determine if neuropathy developed in the female Zucker Diabetic Fatty (ZDF) rat, an animal model of IGT and type 2 diabetes. The ZDF rat develops impaired glucose tolerance (IGT) when fed a control diet, and frank diabetes when fed a high fat diet. Following 10 weeks of hyperglycemia, sensory nerve action potentials (SNAP) and compound motor action potentials (CMAP) were reduced and sensory conduction velocities were slowed (distal>proximal) in the tail and hind limb in ZDF animals with IGT and frank diabetes (p<0.01). Neuropathy was coupled with evidence of increased reactive oxygen species (ROS) and cellular injury in dorsal root ganglion (DRG) neurons from IGT animals. Our study supports the hypothesis that neuropathy develops in an animal model of IGT and is associated with evidence of oxidative injury in DRG and peripheral nerves.
Assuntos
Diabetes Mellitus/sangue , Neuropatias Diabéticas/sangue , Intolerância à Glucose/sangue , Estresse Oxidativo/fisiologia , Animais , Glicemia/genética , Glicemia/metabolismo , Diabetes Mellitus/genética , Diabetes Mellitus/patologia , Neuropatias Diabéticas/genética , Neuropatias Diabéticas/patologia , Feminino , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Intolerância à Glucose/genética , Intolerância à Glucose/patologia , Ratos , Ratos ZuckerRESUMO
The receptor for advanced glycation end products (RAGE) may promote diabetic vascular and renal disease through the activation of intracellular signaling pathways that promote oxidative stress. Oxidative stress is a mediator of hyperglycemia-induced cell injury and a unifying theme for all mechanisms of diabetic complications, but there are few studies on the expression and potential contribution of RAGE in diabetic neuropathy. The current study demonstrates that dorsal root ganglia neurons express functional RAGE and respond to the RAGE ligand S100 with similar downstream signaling, oxidative stress, and cellular injury as other diabetic complication-prone tissues. RAGE-induced phosphatidylinositol-3 kinase activity is associated with formation of reactive oxygen species, caspase-3 activation, and nuclear DNA degradation. These events are prevented by treatment with the antioxidant alpha-lipoic acid. Our data indicate that therapies aimed at decreasing RAGE ligands, blocking RAGE signaling, or preventing oxidative stress could significantly decrease the development of neuropathy in diabetic patients.
Assuntos
Neurônios Aferentes/metabolismo , Neurônios Aferentes/patologia , Estresse Oxidativo , Receptores Imunológicos/metabolismo , Animais , Sobrevivência Celular , Células Cultivadas , Relação Dose-Resposta a Droga , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Glucose/administração & dosagem , Glucose/farmacologia , Produtos Finais de Glicação Avançada/metabolismo , Membranas Intracelulares/metabolismo , Ligantes , NADPH Oxidases/metabolismo , Neurônios Aferentes/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Receptor para Produtos Finais de Glicação Avançada , Proteínas S100/farmacologia , Transdução de SinaisRESUMO
BACKGROUND: A reduction in the number of podocytes and podocyte density has been documented in the kidneys of patients with diabetes mellitus. Additional studies have shown that podocyte injury and loss occurs in both diabetic animals and humans. However, most studies in animals have examined relatively long-term changes in podocyte number and density and have not examined effects early after initiation of diabetes. We hypothesized that streptozotocin diabetes in rats and mice would result in an early reduction in podocyte density and that this reduction would be prevented by antioxidants. METHODS: The number of podocytes per glomerular section and the podocyte density in glomeruli from rats and mice with streptozotocin (STZ)-diabetes mellitus was determined at several time points based on detection of the glomerular podocyte specific antigens, WT-1 and GLEPP1. The effect of insulin administration or treatment with the antioxidant, alpha-lipoic acid, on podocyte number was assessed. RESULTS: Experimental diabetes resulted in a rapid decline in apparent podocyte number and podocyte density. A significant reduction in podocytes/glomerular cross-section was found in STZ diabetes in rats at 2 weeks (14%), 6 weeks (18%) and 8 weeks (34%) following STZ injection. Similar declines in apparent podocyte number were found in STZ diabetes in C57BL/6 mice at 2 weeks, but not at 3 days after injection. Treatment with alpha-lipoic acid substantially prevented podocyte loss in diabetic rats but treatment with insulin had only a modest effect. CONCLUSION: STZ diabetes results in reduction in apparent podocyte number and in podocyte density within 2 weeks after onset of hyperglycemia. Prevention of these effects with antioxidant therapy suggests that this early reduction in podocyte density is due in part to increased levels of reactive oxygen species as well as hyperglycemia.
Assuntos
Antioxidantes/farmacologia , Nefropatias Diabéticas/patologia , Podócitos/efeitos dos fármacos , Podócitos/patologia , Ácido Tióctico/farmacologia , Animais , Contagem de Células , Diabetes Mellitus Experimental/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Here we describe a technique for imaging of the outer contours of the mitochondrial membrane using atomic force microscopy, subsequent to or during a toxic or metabolic challenge. Pore formation in both glucose-challenged and 1,3-dinitrobenzene (DNB)-challenged mitochondria was observed using this technique. Our approach enables quantification of individual mitochondrial membrane pore formations. With this work, we have produced some of the highest resolution images of the outer contours of the in situ mitochondrial membrane published to date. These are potentially the first images of the component protein clusters at the time of formation of the mitochondrial membrane transition pore in situ. With the current work, we have extended the application of atomic force microscopy of mitochondrial membranes to fluid imaging. We have also begun to correlate 3-D surface features of mitochondria dotted with open membrane pores with features previously viewed with electron microscopy (EM) of fixed sections.
Assuntos
Membranas Intracelulares/fisiologia , Microscopia de Força Atômica/métodos , Mitocôndrias/fisiologia , Porinas/análise , Animais , Humanos , Dilatação Mitocondrial/fisiologiaRESUMO
This paper describes the application of database technology to medical information with the goal of providing medical and clinical researchers with the tools necessary to plan bioinformatics projects. Commercial database management systems were utilized, standard database design practices were applied, a user interface was created, data entered, and the development of analysis tools, including data mining technologies is underway. Databases were constructed based on animal and cell culture models of diabetes and clinical data. Bioinformatics is a useful tool in both basic research and clinical settings. The advantages of relational databases and an approach to managing bioinformatics projects are discussed.
Assuntos
Pesquisa Biomédica , Biologia Computacional , Sistemas de Gerenciamento de Base de Dados , Animais , Segurança Computacional , Bases de Dados Factuais , Diabetes Mellitus/fisiopatologia , HumanosRESUMO
OBJECTIVE: Patients with diabetic neuropathy (DN) demonstrate variable degrees of nerve regeneration and degeneration. Our aim was to identify risk factors associated with sural nerve degeneration in patients with DN. RESEARCH DESIGN AND METHODS: Demographic, anthropometric, biochemical, and anatomical data of subjects with DN from a 52-week trial of acetyl-L-carnitine were retrospectively examined. Based on the change in sural nerve myelinated fiber density (ΔMFD%), subjects were divided into three groups: regenerator (top 16 percentiles, n = 67), degenerator (bottom 16 percentiles, n = 67), and intermediate (n = 290), with dramatically increased, decreased, and steady ΔMFD%, respectively. ANOVA, Fisher exact test, and multifactorial logistic regression were used to evaluate statistical significance. RESULTS: ΔMFD%s were 35.6 ± 17.4 (regenerator), -4.8 ± 12.1 (intermediate), and -39.8 ± 11.0 (degenerator). HbA1c at baseline was the only factor significantly different across the three groups (P = 0.01). In multifactorial logistic regression, HbA1c at baseline was also the only risk factor significantly different between regenerator (8.3 ± 1.6%) and degenerator (9.2 ± 1.8%) (odds ratio 0.68 [95% CI 0.54-0.85]; P < 0.01). Support Vector Machine classifier using HbA1c demonstrated 62.4% accuracy of classifying subjects into regenerator or degenerator. A preliminary microarray experiment revealed that upregulated genes in the regenerator group are enriched with cell cycle and myelin sheath functions, while downregulated genes are enriched in immune/inflammatory responses. CONCLUSIONS: These data, based on the largest cohort with ΔMFD% information, suggest that HbA1c levels predict myelinated nerve fiber regeneration and degeneration in patients with DN. Therefore, maintaining optimal blood glucose control is likely essential in patients with DN to prevent continued nerve injury.
Assuntos
Neuropatias Diabéticas/complicações , Degeneração Neural/diagnóstico , Regeneração Nervosa/fisiologia , Nervo Sural/ultraestrutura , Biópsia , Contagem de Células , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Método Duplo-Cego , Fenômenos Eletrofisiológicos , Feminino , Seguimentos , Humanos , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Degeneração Neural/etiologia , Degeneração Neural/fisiopatologia , Prognóstico , Estudos Retrospectivos , Nervo Sural/fisiopatologia , Fatores de TempoRESUMO
Patients with diabetes are at higher risk of stroke and experience increased morbidity and mortality after stroke. We hypothesized that cortical neurons develop insulin resistance, which decreases neuroprotection via circulating insulin and insulin-like growth factor-I (IGF-I). Acute insulin treatment of primary embryonic cortical neurons activated insulin signaling including phosphorylation of the insulin receptor, extracellular signal-regulated kinase (ERK), Akt, p70S6K, and glycogen synthase kinase-3ß (GSK-3ß). To mimic insulin resistance, cortical neurons were chronically treated with 25 mM glucose, 0.2 mM palmitic acid (PA), or 20 nM insulin before acute exposure to 20 nM insulin. Cortical neurons pretreated with insulin, but not glucose or PA, exhibited blunted phosphorylation of Akt, p70S6K, and GSK-3ß with no change detected in ERK. Inhibition of the phosphatidylinositol 3-kinase (PI3-K) pathway during insulin pretreatment restored acute insulin-mediated Akt phosphorylation. Cortical neurons in adult BKS-db/db mice exhibited higher basal Akt phosphorylation than BKS-db(+) mice and did not respond to insulin. Our results indicate that prolonged hyperinsulinemia leads to insulin resistance in cortical neurons. Decreased sensitivity to neuroprotective ligands may explain the increased neuronal damage reported in both experimental models of diabetes and diabetic patients after ischemia-reperfusion injury.
Assuntos
Córtex Cerebral/citologia , Resistência à Insulina/fisiologia , Neurônios/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Western Blotting , Butadienos/farmacologia , Células Cultivadas , Cromonas/farmacologia , Inibidores Enzimáticos/farmacologia , Feminino , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Imuno-Histoquímica , Insulina/metabolismo , Resistência à Insulina/genética , Fator de Crescimento Insulin-Like I , Morfolinas/farmacologia , Neurônios/citologia , Nitrilas/farmacologia , Fosforilação/efeitos dos fármacos , Gravidez , Proteínas Proto-Oncogênicas c-akt/genética , Ratos , Ratos Sprague-Dawley , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/fisiologiaRESUMO
Animal models, particularly mice, are used extensively to investigate neurological diseases. Basic research regarding animal models of human neurological disease requires that the animals exhibit hall mark characteristics of the disease. These include disease specific anatomical, metabolic and behavioral changes. Nerve conduction velocity (NCV) is the predominant method used to assess peripheral nerve health. Normative data adjusted for age, gender and height is available for human patients; however, these data are not available for most rodents including mice. NCV may be affected by animal age and size, body temperature, stimulus strength and anesthesia. While the effects of temperature, age and size are documented, the direct and indirect effects of anesthesia on NCV are not well reported. Our laboratory is primarily concerned with animal models of diabetic neuropathy (DN) and uses NCV to confirm the presence of neuropathy. To ensure that subtle changes in NCV are reliably assayed and not directly or indirectly affected by anesthesia, we compared the effects of 4 commonly used anesthetics, isoflurane, ketamine/xylazine, sodium pentobarbital and 2-2-2 tribromoethanol on NCV in a commonly used rodent model, the C57Bl6/J mouse. Our results indicate that of the anesthetics tested, isoflurane has minimal impact on NCV and is the safest, most effective method of anesthesia. Our data strongly suggest that isoflurane should become the anesthetic of choice when performing NCV on murine models of neurological disease.
Assuntos
Anestésicos/farmacologia , Condução Nervosa/efeitos dos fármacos , Nervos Periféricos/efeitos dos fármacos , Animais , Etanol/análogos & derivados , Etanol/toxicidade , Isoflurano/toxicidade , Ketamina/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Condução Nervosa/fisiologia , Pentobarbital/toxicidade , Nervos Periféricos/fisiologia , Xilazina/toxicidadeRESUMO
BACKGROUND: Reactive oxygen species (ROS) are known mediators of cellular damage in multiple diseases including diabetic complications. Despite its importance, no comprehensive database is currently available for the genes associated with ROS. METHODS: We present ROS- and diabetes-related targets (genes/proteins) collected from the biomedical literature through a text mining technology. A web-based literature mining tool, SciMiner, was applied to 1,154 biomedical papers indexed with diabetes and ROS by PubMed to identify relevant targets. Over-represented targets in the ROS-diabetes literature were obtained through comparisons against randomly selected literature. The expression levels of nine genes, selected from the top ranked ROS-diabetes set, were measured in the dorsal root ganglia (DRG) of diabetic and non-diabetic DBA/2J mice in order to evaluate the biological relevance of literature-derived targets in the pathogenesis of diabetic neuropathy. RESULTS: SciMiner identified 1,026 ROS- and diabetes-related targets from the 1,154 biomedical papers (http://jdrf.neurology.med.umich.edu/ROSDiabetes/). Fifty-three targets were significantly over-represented in the ROS-diabetes literature compared to randomly selected literature. These over-represented targets included well-known members of the oxidative stress response including catalase, the NADPH oxidase family, and the superoxide dismutase family of proteins. Eight of the nine selected genes exhibited significant differential expression between diabetic and non-diabetic mice. For six genes, the direction of expression change in diabetes paralleled enhanced oxidative stress in the DRG. CONCLUSIONS: Literature mining compiled ROS-diabetes related targets from the biomedical literature and led us to evaluate the biological relevance of selected targets in the pathogenesis of diabetic neuropathy.
Assuntos
Mineração de Dados/métodos , Diabetes Mellitus/genética , Diabetes Mellitus/metabolismo , Publicações Periódicas como Assunto , Espécies Reativas de Oxigênio/metabolismo , Pesquisa , Animais , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/metabolismo , Gânglios Espinais/metabolismo , Perfilação da Expressão Gênica , Humanos , Camundongos , Proteínas/metabolismo , Células Receptoras Sensoriais/metabolismoRESUMO
OBJECTIVE: To evaluate mechanisms underlying diabetic neuropathy progression using indexes of sural nerve morphometry obtained from two identical randomized, placebo-controlled clinical trials. RESEARCH DESIGN AND METHODS: Sural nerve myelinated fiber density (MFD), nerve conduction velocities (NCVs), vibration perception thresholds, clinical symptom scores, and a visual analog scale for pain were analyzed in participants with diabetic neuropathy. A loss of > or =500 fibers/mm(2) in sural nerve MFD over 52 weeks was defined as progressing diabetic neuropathy, and a MFD loss of < or =100 fibers/mm(2) during the same time interval as nonprogressing diabetic neuropathy. The progressing and nonprogressing cohorts were matched for baseline characteristics using an O'Brien rank-sum and baseline MFD. RESULTS: At 52 weeks, the progressing cohort demonstrated a 25% decrease (P < 0.0001) from baseline in MFD, while the nonprogressing cohort remained unchanged. MFD was not affected by active drug treatment (P = 0.87), diabetes duration (P = 0.48), age (P = 0.11), or BMI (P = 0.30). Among all variables tested, elevated triglycerides and decreased peroneal motor NCV at baseline significantly correlated with loss of MFD at 52 weeks (P = 0.04). CONCLUSIONS: In this cohort of participants with mild to moderate diabetic neuropathy, elevated triglycerides correlated with MFD loss independent of disease duration, age, diabetes control, or other variables. These data support the evolving concept that hyperlipidemia is instrumental in the progression of diabetic neuropathy.
Assuntos
Neuropatias Diabéticas/fisiopatologia , Progressão da Doença , Triglicerídeos/sangue , Adulto , Idoso , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Neuropatias Diabéticas/sangue , Neuropatias Diabéticas/patologia , Eletrofisiologia , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Multicêntricos como Assunto , Fibras Nervosas Mielinizadas/patologia , Fibras Nervosas Mielinizadas/fisiologia , Nervo Sural/patologia , Nervo Sural/fisiopatologia , VibraçãoRESUMO
Diabetic neuropathy (DN) is a serious and debilitating complication of both type 1 and type 2 diabetes. Despite intense research efforts into multiple aspects of this complication, including both vascular and neuronal metabolic derangements, the only treatment remains maintenance of euglycemia. Basic research into the mechanisms responsible for DN relies on using the most appropriate animal model. The advent of genetic manipulation has moved mouse models of human disease to the forefront. The ability to insert or delete genes affected in human patients offers unique insight into disease processes; however, mice are still not humans and difficulties remain in interpreting data derived from these animals. A number of studies have investigated and described DN in mice but it is difficult to compare these studies with each other or with human DN due to experimental differences including background strain, type of diabetes, method of induction and duration of diabetes, animal age and gender. This review describes currently used DN animal models. We followed a standardized diabetes induction protocol and designed and implemented a set of phenotyping parameters to classify the development and severity of DN. By applying standard protocols, we hope to facilitate the comparison and characterization of DN across different background strains in the hope of discovering the most human like model in which to test potential therapies.
Assuntos
Nefropatias Diabéticas/fisiopatologia , Modelos Animais de Doenças , Animais , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 2/complicações , Nefropatias Diabéticas/diagnóstico , Nefropatias Diabéticas/epidemiologia , Nefropatias Diabéticas/terapia , Feminino , Humanos , Masculino , Camundongos , Fenótipo , Índice de Gravidade de DoençaRESUMO
Hyperglycemia-induced oxidative stress is an inciting event in the development of diabetic complications including diabetic neuropathy. Our observations of significant oxidative stress and morphological abnormalities in mitochondria led us to examine manganese superoxide dismutase (SOD2), the enzyme responsible for mitochondrial detoxification of oxygen radicals. We demonstrate that overexpression of SOD2 decreases superoxide (O(2)(-)) in cultured primary dorsal root ganglion (DRG) neurons and subsequently blocks caspase-3 activation and cellular injury. Underexpression of SOD2 in dissociated DRG cultures from adult SOD2(+/-) mice results in increased levels of O2-, activation of caspase-3 cleavage and decreased neurite outgrowth under basal conditions that are exacerbated by hyperglycemia. These profound changes in sensory neurons led us to explore the effects of decreased SOD2 on the development of diabetic neuropathy (DN) in mice. DN was assessed in SOD2(+/-) C57BL/6J mice and their SOD2(+/+) littermates following streptozotocin (STZ) treatment. These animals, while hyperglycemic, do not display any signs of DN. DN was observed in the C57BL/6Jdb/db mouse, and decreased expression of SOD2 in these animals increased DN. Our data suggest that SOD2 activity is an important cellular modifier of neuronal oxidative defense against hyperglycemic injury.
Assuntos
Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Fármacos Neuroprotetores/metabolismo , Superóxido Dismutase/metabolismo , Animais , Caspase 3/metabolismo , Células Cultivadas , Diabetes Mellitus/genética , Diabetes Mellitus Experimental , Neuropatias Diabéticas/metabolismo , Neuropatias Diabéticas/prevenção & controle , Ativação Enzimática , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Potenciais da Membrana , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Membranas Mitocondriais , Condução Nervosa , Neurônios Aferentes/metabolismo , Neurônios Aferentes/patologia , Estresse Oxidativo , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/deficiência , TransfecçãoRESUMO
Diabetic neuropathy (DN) is a debilitating complication of type 1 and type 2 diabetes. Rodent models of DN do not fully replicate the pathology observed in human patients. We examined DN in streptozotocin (STZ)-induced [B6] and spontaneous type 1 diabetes [B6Ins2(Akita)] and spontaneous type 2 diabetes [B6-db/db, BKS-db/db]. Despite persistent hyperglycemia, the STZ-treated B6 and B6Ins2(Akita) mice were resistant to the development of DN. In contrast, DN developed in both type 2 diabetes models: the B6-db/db and BKS-db/db mice. The persistence of hyperglycemia and development of DN in the B6-db/db mice required an increased fat diet while the BKS-db/db mice developed severe DN and remained hyperglycemic on standard mouse chow. Our data support the hypothesis that genetic background and diet influence the development of DN and should be considered when developing new models of DN.
Assuntos
Neuropatias Diabéticas/genética , Neuropatias Diabéticas/fisiopatologia , Modelos Animais de Doenças , Animais , Fragmentação do DNA , Neuropatias Diabéticas/induzido quimicamente , Neuropatias Diabéticas/classificação , Hiperalgesia/etiologia , Marcação In Situ das Extremidades Cortadas/métodos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Endogâmicos NOD/genética , Fibras Nervosas/patologia , Condução Nervosa/fisiologia , Medição da Dor , Tempo de Reação , Estreptozocina , Tirosina/análogos & derivados , Tirosina/metabolismo , Ubiquitina Tiolesterase/metabolismoRESUMO
PURPOSE OF REVIEW: Diabetic neuropathy is a debilitating consequence of type 1 and 2 diabetes. Hyperglycemia disrupts the normal function of neurons and their supporting glia at multiple levels. The complexity of this complication, combined with difficulties of delivering therapy to sensory, sympathetic and parasympathetic neurons, contributes to the intractability of this serious diabetic complication. This review summarizes recent reviews examining the state of research on and treatment of diabetic neuropathy and highlights areas of clinical and basic research that may yield new diagnostic and treatment options. RECENT FINDINGS: Recent reviews summarize the effects of hyperglycemia on the peripheral nervous system as well as diagnosis and treatment of patients with diabetic neuropathy. Advances in the analysis of intraepidermal fiber densities could shorten the time course of clinical trials and extend data analyses to include sympathetic as well as sensory information. Unchecked glucose-mediated oxidative stress and advanced glycation endproduct signaling through receptors for advanced glycation endproducts are implicated in diabetic neuropathy and may serve as new therapeutic targets. SUMMARY: The best efforts of countless investigators have yet to find effective treatments either to stop the progression of axonal degeneration and cell death or regrow damaged axons. Basic research into the prevention of oxidative stress caused by excess glucose as well as the prevention of advanced glycation endproduct/receptor for advanced glycation endproduct signaling may offer new therapeutic targets. The use of skin biopsies may aid in early detection of both sensory and autonomic neuropathy, and perhaps in the case of patients with type 2 diabetes, diagnose neuropathy prior to the onset of symptoms.