RESUMO
The purpose of this study was to determine the effect of supplementing the diet of a mouse model of type 2 diabetes with menhaden (fish) oil or daily treatment with resolvin D1 on diabetic neuropathy. The end points evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and the retinal ganglion cell complex thickness. Menhaden oil is a natural source for n-3 polyunsaturated fatty acids, which have been shown to have beneficial effects in other diseases. Resolvin D1 is a metabolite of docosahexaenoic acid and is known to have anti-inflammatory and neuroprotective properties. To model type 2 diabetes, mice were fed a high-fat diet for 8 wk followed by a low dosage of streptozotocin. After 8 wk of hyperglycemia, mice in experimental groups were treated for 6 wk with menhaden oil in the diet or daily injections of 1 ng/g body wt resolvin D1. Our findings show that menhaden oil or resolvin D1 did not improve elevated blood glucose, HbA1C, or glucose utilization. Untreated diabetic mice were thermal hypoalgesic, had reduced motor and sensory nerve conduction velocities, had decreased innervation of the cornea and skin, and had thinner retinal ganglion cell complex. These end points were significantly improved with menhaden oil or resolvin D1 treatment. Exogenously, resolvin D1 stimulated neurite outgrowth from primary cultures of dorsal root ganglion neurons from normal mice. These studies suggest that n-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for diabetic neuropathy.
Assuntos
Anti-Inflamatórios/farmacologia , Diabetes Mellitus Experimental/fisiopatologia , Neuropatias Diabéticas/dietoterapia , Neuropatias Diabéticas/tratamento farmacológico , Ácidos Docosa-Hexaenoicos/farmacologia , Óleos de Peixe/administração & dosagem , Animais , Células Cultivadas , Córnea/inervação , Córnea/patologia , Diabetes Mellitus Experimental/dietoterapia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2 , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Dieta Hiperlipídica , Suplementos Nutricionais , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/fisiologia , Temperatura Alta , Hiperalgesia/dietoterapia , Hiperalgesia/tratamento farmacológico , Hiperalgesia/fisiopatologia , Camundongos Endogâmicos C57BL , Condução Nervosa/fisiologia , Neuritos/efeitos dos fármacos , Neuritos/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/fisiologia , Fármacos Neuroprotetores/farmacologia , Células Ganglionares da Retina/patologia , Pele/inervação , Pele/patologiaRESUMO
We determined the impact diet-induced obesity (DIO) and types 1 and 2 diabetes have on peripheral neuropathy with emphasis on corneal nerve structural changes in C57Bl/6J mice. Endpoints examined included nerve conduction velocity, response to thermal and mechanical stimuli and innervation of the skin and cornea. DIO mice and to a greater extent type 2 diabetic mice were insulin resistant. DIO and both types 1 and 2 diabetic mice developed motor and sensory nerve conduction deficits. In the cornea of DIO and type 2 diabetic mice there was a decrease in sub-epithelial corneal nerves, innervation of the corneal epithelium, and corneal sensitivity. Type 1 diabetic mice did not present with any significant changes in corneal nerve structure until after 20 weeks of hyperglycemia. DIO and type 2 diabetic mice developed corneal structural damage more rapidly than type 1 diabetic mice although hemoglobin A1 C values were significantly higher in type 1 diabetic mice. This suggests that DIO with or without hyperglycemia contributes to development and progression of peripheral neuropathy and nerve structural damage in the cornea.
Assuntos
Córnea/inervação , Diabetes Mellitus Experimental/etiologia , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Dieta/efeitos adversos , Obesidade/etiologia , Aldeídos/metabolismo , Animais , Córnea/patologia , Gânglios Espinais/metabolismo , Teste de Tolerância a Glucose , Camundongos , Camundongos Endogâmicos C57BL , Condução Nervosa/fisiologia , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
BACKGROUND: Peroxynitrite, a product of the reaction of superoxide with nitric oxide, causes oxidative stress with concomitant inactivation of enzymes, poly(ADP-ribosylation), mitochondrial dysfunction and impaired stress signalling, as well as protein nitration. In this study, we sought to determine the effect of preventing protein nitration or increasing peroxynitrite decomposition on diabetic neuropathy in mice after an extended period of untreated diabetes. METHODS: C57Bl6/J male control and diabetic mice were treated with the peroxynitrite decomposition catalyst Fe(III) tetramesitylporphyrin octasulfonate (FeTMPS, 10 mg/kg/day) or protein nitration inhibitor (-)-epicatechin gallate (20 mg/kg/day) for 4 weeks, after an initial 28 weeks of hyperglycaemia. RESULTS: Untreated diabetic mice developed motor and sensory nerve conduction velocity deficits, thermal and mechanical hypoalgesia, tactile allodynia and loss of intraepidermal nerve fibres. Both FeTMPS and epicatechin gallate partially corrected sensory nerve conduction slowing and small sensory nerve fibre dysfunction without alleviation of hyperglycaemia. Correction of motor nerve conduction deficit and increase in intraepidermal nerve fibre density were found with FeTMPS treatment only. CONCLUSIONS: Peroxynitrite injury and protein nitration are implicated in the development of diabetic peripheral neuropathy. The findings indicate that both structural and functional changes of chronic diabetic peripheral neuropathy can be reversed and provide rationale for the development of a new generation of antioxidants and peroxynitrite decomposition catalysts for treatment of diabetic peripheral neuropathy.
Assuntos
Diabetes Mellitus Tipo 1/complicações , Neuropatias Diabéticas/metabolismo , Epiderme/inervação , Proteínas do Tecido Nervoso/metabolismo , Sistema Nervoso Periférico/metabolismo , Ácido Peroxinitroso/metabolismo , Animais , Antioxidantes/efeitos adversos , Antioxidantes/uso terapêutico , Comportamento Animal/efeitos dos fármacos , Catequina/efeitos adversos , Catequina/análogos & derivados , Catequina/uso terapêutico , Diabetes Mellitus Tipo 1/tratamento farmacológico , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Neuropatias Diabéticas/prevenção & controle , Epiderme/efeitos dos fármacos , Epiderme/metabolismo , Epiderme/patologia , Compostos Férricos/efeitos adversos , Compostos Férricos/uso terapêutico , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Masculino , Metaloporfirinas/efeitos adversos , Metaloporfirinas/uso terapêutico , Camundongos Endogâmicos C57BL , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Condução Nervosa/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Sistema Nervoso Periférico/efeitos dos fármacos , Sistema Nervoso Periférico/patologia , Sistema Nervoso Periférico/fisiopatologia , Ácido Peroxinitroso/antagonistas & inibidores , Tempo de Reação/efeitos dos fármacos , Células Receptoras Sensoriais/efeitos dos fármacos , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/patologiaRESUMO
We sought to determine the impact that duration of hyperglycemia and control has on corneal nerve fiber density in relation to standard diabetic neuropathy endpoints. Control and streptozotocin-diabetic C57Bl/6J mice were analyzed after 4, 8, 12, and 20 weeks. For the 20-week time point, five groups of mice were compared: control, untreated diabetic, and diabetic treated with insulin designated as having either poor glycemic control, good glycemic control, or poor glycemic control switched to good glycemic control. Hyperglycemia was regulated by use of insulin-releasing pellets. Loss of corneal nerves in the sub-epithelial nerve plexus or corneal epithelium progressed slowly in diabetic mice requiring 20 weeks to reach statistical significance. In comparison, slowing of motor and sensory nerve conduction velocity developed rapidly with significant difference compared with control mice observed after 4 and 8 weeks of hyperglycemia, respectively. In diabetic mice with good glycemic control, average blood glucose levels over the 20-week experimental period were lowered from 589 ± 2 to 251 ± 9 mg/dl. All diabetic neuropathy endpoints examined were improved in diabetic mice with good glycemic control compared with untreated diabetic mice. However, good control of blood glucose was not totally sufficient in preventing diabetic neuropathy.
Assuntos
Córnea/inervação , Diabetes Mellitus Experimental/complicações , Neuropatias Diabéticas/fisiopatologia , Hiperglicemia/complicações , Fibras Nervosas/fisiologia , Animais , Antibacterianos/toxicidade , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Neuropatias Diabéticas/etiologia , Epitélio Corneano/inervação , Hiperglicemia/induzido quimicamente , Hiperglicemia/tratamento farmacológico , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Estreptozocina/toxicidadeRESUMO
Evidence for an important role for Na(+)/H(+) exchangers in diabetic complications is emerging. The aim of this study was to evaluate whether Na(+)/H(+) exchanger 1 inhibition reverses experimental peripheral diabetic neuropathy. Control and streptozotocin-diabetic rats were treated with the specific Na(+)/H(+) exchanger 1 inhibitor cariporide for 4 wk after 12 wk without treatment. Neuropathy end points included sciatic motor and sensory nerve conduction velocities, endoneurial nutritive blood flow, vascular reactivity of epineurial arterioles, thermal nociception, tactile allodynia, and intraepidermal nerve fiber density. Advanced glycation end product and markers of oxidative stress, including nitrated protein levels in sciatic nerve, were evaluated by Western blot. Rats with 12-wk duration of diabetes developed motor and sensory nerve conduction deficits, thermal hypoalgesia, tactile allodynia, and intraepidermal nerve fiber loss. All these changes, including impairment of nerve blood flow and vascular reactivity of epineurial arterioles, were partially reversed by 4 wk of cariporide treatment. Na(+)/H(+) exchanger 1 inhibition was also associated with reduction of diabetes-induced accumulation of advanced glycation endproduct, oxidative stress, and nitrated proteins in sciatic nerve. In conclusion, these findings support an important role for Na(+)/H(+) exchanger 1 in functional, structural, and biochemical manifestations of peripheral diabetic neuropathy and provide the rationale for development of Na(+)/H(+) exchanger 1 inhibitors for treatment of diabetic vascular and neural complications.
Assuntos
Diabetes Mellitus Tipo 1/complicações , Neuropatias Diabéticas/tratamento farmacológico , Guanidinas/uso terapêutico , Proteína Carregadora de Folato Reduzido/antagonistas & inibidores , Sulfonas/uso terapêutico , Aldeídos/metabolismo , Animais , Arteríolas/fisiopatologia , Comportamento Animal/efeitos dos fármacos , Glicemia/metabolismo , Western Blotting , Peso Corporal/efeitos dos fármacos , Diabetes Mellitus Experimental/fisiopatologia , Neuropatias Diabéticas/psicologia , Produtos Finais de Glicação Avançada/metabolismo , Guanidinas/farmacologia , Masculino , Fibras Nervosas/fisiologia , Nitratos/metabolismo , Medição da Dor/efeitos dos fármacos , Aldeído Pirúvico/metabolismo , Ratos , Ratos Wistar , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/metabolismo , Pele/inervação , Sulfonas/farmacologia , Superóxidos/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
Purpose: We sought to define the role of Wwtr1 in murine ocular structure and function and determine the role of mechanotransduction in Fuchs' endothelial corneal dystrophy (FECD), with emphasis on interactions between corneal endothelial cells (CEnCs) and Descemet's membrane (DM). Methods: A Wwtr1 deficient mouse colony was established, and advanced ocular imaging, atomic force microscope (AFM), and histology/immunofluorescence were performed. Corneal endothelial wound healing was assessed using cryoinjury and phototherapeutic keratectomy in Wwtr1 deficient mice. Expression of WWTR1/TAZ was determined in the corneal endothelium from normal and FECD-affected patients; WWTR1 was screened for coding sequence variants in this FECD cohort. Results: Mice deficient in Wwtr1 had reduced CEnC density, abnormal CEnC morphology, softer DM, and thinner corneas versus wildtype controls by 2 months of age. Additionally, CEnCs had altered expression and localization of Na/K-ATPase and ZO-1. Further, Wwtr1 deficient mice had impaired CEnC wound healing. The WWTR1 transcript was highly expressed in healthy human CEnCs comparable to other genes implicated in FECD pathogenesis. Although WWTR1 mRNA expression was comparable between healthy and FECD-affected patients, WWTR1/TAZ protein concentrations were higher and localized to the nucleus surrounding guttae. No genetic associations were found in WWTR1 and FECD in a patient cohort compared to controls. Conclusions: There are common phenotypic abnormalities seen between Wwtr1 deficient and FECD-affected patients, suggesting that Wwtr1 deficient mice could function as a murine model of late-onset FECD. Despite the lack of a genetic association between FECD and WWTR1, aberrant WWTR1/TAZ protein subcellular localization and degradation may play critical roles in the pathogenesis of FECD.
Assuntos
Células Endoteliais , Distrofia Endotelial de Fuchs , Humanos , Camundongos , Animais , Células Endoteliais/metabolismo , Mecanotransdução Celular , Distrofia Endotelial de Fuchs/patologia , Endotélio Corneano/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional , Proteínas Adaptadoras de Transdução de Sinal/metabolismoRESUMO
Objective: Feeding mice a diet containing high fat and high sucrose has been promoted as a good model for type 2 diabetes. This study sought to determine the effect of feeding mice a high fat and high sucrose diet on neuropathy compared to mice fed only a high fat diet and mice fed a high diet and treated with streptozotocin. Methods: C57Bl/6J mice were divided into five groups and fed the following diets for 20 weeks: Normal (Control); Sucrose enriched (Control + Sucrose), High Fat (Diet-induced obesity (DIO)), High Fat and High Sucrose (DIO + sucrose) and High Fat diet/streptozotocin treated (Diabetic). The endpoints evaluated included motor and sensory nerve conduction velocity, thermal and mechanical sensitivity and innervation of sensory nerves in the cornea and skin. Results: Diabetic mice were hyperglycemic at the end of the study and along with DIO mice with or without Sucrose had impaired glucose utilization. DIO mice had slowed sensory nerve conduction velocity, mechanical allodynia and decreased innervation of the cornea and skin. DIO + Sucrose and to a greater extent diabetic mice were thermal hypoalgesic, had mechanical allodynia, reduced motor and sensory nerve conduction velocities and decrease innervation of the cornea and skin. Conclusions: Development of peripheral neuropathy was more severe in High Fat and High Sucrose fed mice compared to high fat fed mice but fasting hyperglycemia and impaired glucose utilization was similar for these two models. Peripheral neuropathy was most severe in diabetic mice.
RESUMO
Poly(ADP-ribose)polymerase (PARP) inhibitors prevent or alleviate diabetic nephropathy. This study evaluated the role for PARP-1 in diabetic kidney disease using the PARP-1-deficient mouse. PARP-1-/- and the wild-type (129S1/SvImJ) mice were made diabetic with streptozotocin, and were maintained for 12 weeks. Final blood glucose concentrations were increased â¼ 3.7-fold in both diabetic groups. PARP-1 protein expression (Western blot analysis) in the renal cortex was similar in non-diabetic and diabetic wild-type mice (100% and 107%) whereas all knockouts were PARP-1-negative. PARP-1 gene deficiency reduced urinary albumin (ELISA) and protein excretion prevented diabetes-induced kidney hypertrophy, and decreased mesangial expansion and collagen deposition (both assessed by histochemistry) as well as fibronectin expression. Renal podocyte loss (immunohistochemistry) and nitrotyrosine and transforming growth factor-ß1 accumulations (both by ELISA) were slightly lower in diabetic PARP-1-/- mice, but the differences with diabetic wild-type group did not achieve statistical significance. In conclusion, PARP-1-/- gene deficiency alleviates although does not completely prevent diabetic kidney disease.
Assuntos
Diabetes Mellitus Experimental/complicações , Nefropatias/enzimologia , Rim/metabolismo , Poli(ADP-Ribose) Polimerases/deficiência , Albuminúria/urina , Animais , Glicemia/metabolismo , Western Blotting , Ensaio de Imunoadsorção Enzimática , Hipertrofia/sangue , Hipertrofia/etiologia , Hipertrofia/urina , Imuno-Histoquímica , Rim/patologia , Nefropatias/etiologia , Nefropatias/genética , Masculino , Camundongos , Camundongos Endogâmicos , Camundongos Knockout , Podócitos/patologia , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases/genética , Fator de Crescimento Transformador beta1/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
Up-regulation of 12/15-lipoxygenase, which converts arachidonic acid to 12(S)- and 15(S)-hydroxyeicosatetraenoic acids, causes impaired cell signaling, oxidative-nitrosative stress, and inflammation. This study evaluated the role for 12/15-lipoxygenase in diabetic large and small fiber peripheral and autonomic neuropathies. Control and streptozotocin-diabetic wild-type and 12/15-lipoxygenase-deficient mice were maintained for 14 to 16 weeks. 12/15-lipoxygenase gene deficiency did not affect weight gain or blood glucose concentrations. Diabetic wild-type mice displayed increased sciatic nerve 12/15-lipoxygenase and 12(S)-hydroxyeicosatetraenoic acid levels. 12/15-lipoxygenase deficiency prevented or alleviated diabetes-induced thermal hypoalgesia, tactile allodynia, motor and sensory nerve conduction velocity deficits, and reduction in tibial nerve myelinated fiber diameter, but not intraepidermal nerve fiber loss. The frequencies of superior mesenteric-celiac ganglion neuritic dystrophy, the hallmark of diabetic autonomic neuropathy in mouse prevertebral sympathetic ganglia, were increased 14.8-fold and 17.2-fold in diabetic wild-type and 12/15-lipoxygenase-deficient mice, respectively. In addition, both diabetic groups displayed small (<1%) numbers of degenerating sympathetic neurons. In conclusion, whereas 12/15-lipoxygenase up-regulation provides an important contribution to functional changes characteristic for both large and small fiber peripheral diabetic neuropathies and axonal atrophy of large myelinated fibers, its role in small sensory nerve fiber degeneration and neuritic dystrophy and neuronal degeneration characteristic for diabetic autonomic neuropathy is minor. This should be considered in the selection of endpoints for future clinical trials of 12/15-lipoxygenase inhibitors.
Assuntos
Araquidonato 12-Lipoxigenase/metabolismo , Araquidonato 15-Lipoxigenase/metabolismo , Diabetes Mellitus Experimental/enzimologia , Neuropatias Diabéticas/enzimologia , Fibras Nervosas Mielinizadas/enzimologia , Fibras Nervosas Amielínicas/enzimologia , Análise de Variância , Animais , Araquidonato 12-Lipoxigenase/genética , Araquidonato 15-Lipoxigenase/genética , Western Blotting , Peso Corporal/genética , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patologia , Neuropatias Diabéticas/genética , Neuropatias Diabéticas/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fibras Nervosas Mielinizadas/patologia , Fibras Nervosas Amielínicas/patologia , Nervo Isquiático/enzimologiaRESUMO
To rigorously explore the role of omega-3 polyunsaturated fatty acids (PUFA) in the treatment of diabetic peripheral neuropathy (DPN), we have created a transgenic mouse utilizing a Cre-lox promoter to control overexpression of human 15-lipoxygenase-1 (15-LOX-1). In this study, we sought to determine the effect of treating type 2 diabetic wild-type mice and transgenic mice ubiquitously overexpressing 15-LOX-1 with menhaden oil on endpoints related to DPN. Wild-type and transgenic mice on a C57Bl/6J background were divided into three groups. Two of each of these groups were used to create a high-fat diet/streptozotocin model for type 2 diabetes. The remaining mice were control groups. Four weeks later, one set of diabetic mice from each group was treated with menhaden oil for twelve weeks and then evaluated using DPN-related endpoints. Studies were also performed using dorsal root ganglion neurons isolated from wild-type and transgenic mice. Wild-type and transgenic diabetic mice developed DPN as determined by slowing of nerve conduction velocity, decreased sensory nerve fibers in the skin and cornea, and impairment of thermal and mechanical sensitivity of the hindpaw compared to their respective control mice. Although not significant, there was a trend for the severity of these DPN-related deficits to be less in the diabetic transgenic mice compared to the diabetic wild-type mice. Treating diabetic wild-type and transgenic mice with menhaden oil improved the DPN-related endpoints with a trend for greater improvement or protection by menhaden oil observed in the diabetic transgenic mice. Treating dorsal root ganglion neurons with docosahexanoic acid but not eicosapentaenoic acid significantly increased neurite outgrowth with greater efficacy observed with neurons isolated from transgenic mice. Targeting pathways that will increase the production of the anti-inflammatory metabolites of omega-3 PUFA may be an efficacious approach to developing an effective treatment for DPN.
Assuntos
Araquidonato 15-Lipoxigenase/fisiologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Neuropatias Diabéticas/tratamento farmacológico , Óleos de Peixe/uso terapêutico , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Animais , Araquidonato 15-Lipoxigenase/genética , Diabetes Mellitus Tipo 2/complicações , Neuropatias Diabéticas/etiologia , Ácidos Docosa-Hexaenoicos/sangue , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Doenças do Sistema Nervoso Periférico/etiologiaRESUMO
Previous work by ourselves and others showed that mitoquinone (mitoQ) reduced oxidative damage and prevented hepatic fat accumulation in mice made obese with high-fat (HF) feeding. Here we extended these studies to examine the effect of mitoQ on parameters affecting liver function in rats treated with HF to induce obesity and in rats treated with HF plus streptozotocin (STZ) to model a severe form of type 2 diabetes. In prior reported work, we found that mitoQ significantly improved glycemia based on glucose tolerance data in HF rats but not in the diabetic rats. Here we found only non-significant reductions in insulin and glucose measured in the fed state at sacrifice in the HF mice treated with mitoQ. Metabolomic data showed that mitoQ altered several hepatic metabolic pathways in HF-fed obese rats toward those observed in control normal chow-fed non-obese rats. However, mitoQ had little effect on pathways observed in the diabetic rats, wherein diabetes itself induced marked pathway aberrations. MitoQ did not alter respiration or membrane potential in isolated liver mitochondria. MitoQ reduced liver fat and liver hydroperoxide levels but did not improve liver function as marked by circulating levels of aspartate and alanine aminotransferase (ALT). In summary, our results for HF-fed rats are consistent with past findings in HF-fed mice indicating decreased liver lipid hydroperoxides (LPO) and improved glycemia. However, in contrast to the HF obese mice, mitoQ did not improve glycemia or reset perturbed metabolic pathways in the diabetic rats.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Fígado Gorduroso/metabolismo , Fígado/efeitos dos fármacos , Obesidade/metabolismo , Compostos Organofosforados/farmacologia , Ubiquinona/análogos & derivados , Animais , Glicemia/efeitos dos fármacos , Respiração Celular/efeitos dos fármacos , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Tipo 2/sangue , Dieta Hiperlipídica , Fígado Gorduroso/sangue , Insulina/sangue , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/metabolismo , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Metabolômica , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/patologia , Mitocôndrias Hepáticas/fisiologia , Obesidade/sangue , Estresse Oxidativo/efeitos dos fármacos , Ratos Sprague-Dawley , Ubiquinona/farmacologiaRESUMO
OBJECTIVE: The lack of effective treatments against diabetic sensorimotor polyneuropathy demands the search for new strategies to combat or prevent the condition. Because reduced magnesium and increased methylglyoxal levels have been implicated in the development of both type 2 diabetes and neuropathic pain, we aimed to assess the putative interplay of both molecules with diabetic sensorimotor polyneuropathy. METHODS: In a cross-sectional study, serum magnesium and plasma methylglyoxal levels were measured in recently diagnosed type 2 diabetes patients with (n = 51) and without (n = 184) diabetic sensorimotor polyneuropathy from the German Diabetes Study baseline cohort. Peripheral nerve function was assessed using nerve conduction velocity and quantitative sensory testing. Human neuroblastoma cells (SH-SY5Y) and mouse dorsal root ganglia cells were used to characterize the neurotoxic effect of methylglyoxal and/or neuroprotective effect of magnesium. RESULTS: Here, we demonstrate that serum magnesium concentration was reduced in recently diagnosed type 2 diabetes patients with diabetic sensorimotor polyneuropathy and inversely associated with plasma methylglyoxal concentration. Magnesium, methylglyoxal, and, importantly, their interaction were strongly interrelated with methylglyoxal-dependent nerve dysfunction and were predictive of changes in nerve function. Magnesium supplementation prevented methylglyoxal neurotoxicity in differentiated SH-SY5Y neuron-like cells due to reduction of intracellular methylglyoxal formation, while supplementation with the divalent cations zinc and manganese had no effect on methylglyoxal neurotoxicity. Furthermore, the downregulation of mitochondrial activity in mouse dorsal root ganglia cells and consequently the enrichment of triosephosphates, the primary source of methylglyoxal, resulted in neurite degeneration, which was completely prevented through magnesium supplementation. CONCLUSIONS: These multifaceted findings reveal a novel putative pathophysiological pathway of hypomagnesemia-induced carbonyl stress leading to neuronal damage and merit further investigations not only for diabetic sensorimotor polyneuropathy but also other neurodegenerative diseases associated with magnesium deficiency and impaired energy metabolism.
Assuntos
Magnésio/metabolismo , Polineuropatias/metabolismo , Aldeído Pirúvico/metabolismo , Animais , Estudos Transversais , Diabetes Mellitus/metabolismo , Neuropatias Diabéticas/etiologia , Metabolismo Energético , Feminino , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Mitocôndrias/metabolismo , Neurônios/metabolismo , Polineuropatias/fisiopatologia , Córtex Sensório-Motor/metabolismoRESUMO
PURPOSE: To determine whether cornea nerve fiber density and/or corneal function are valid markers for early detection and treatment of peripheral neuropathy in rats modeling prediabetes and type 2 diabetes. METHODS: High-fat feeding combined without or with low-dose streptozotocin was used to create rat models for prediabetes and type 2 diabetes that were longitudinally studied for loss of structure and function of sensory nerves in the cornea and skin as well as nerve conduction velocity and vascular reactivity of epineurial arterioles. There were three time points examined in each of the three conditions with 12 rats per group. The latest time point (24 weeks of high-fat diet with or without 16 weeks of hyperglycemia) was used to examine reversibility of neuro and vascular pathology following 16 weeks of treatment with menhaden oil, a natural source of long-chain omega-3 polyunsaturated fatty acids. The number of rats in the intervention study ranged from 6 to 17. RESULTS: Our longitudinal study demonstrated that vascular and neural dysfunction associated with obesity or type 2 diabetes occur early and are progressive. Decrease in cornea nerve fiber length and function were valid markers of disease in both the pre-diabetic and diabetic rat models and were more sensitive than decrease in intraepidermal nerve fiber density of the skin and thermal nociception of the hindpaw. Late intervention with menhaden oil significantly reversed both vascular and peripheral nerve damage induced by chronic obesity or type 2 diabetes. CONCLUSION: These studies provide support for examination of corneal structure and function as an early marker of peripheral neuropathy in prediabetes and type 2 diabetes. Furthermore, we demonstrate that omega-3 polyunsaturated fatty acids derived from fish oil are an effective treatment for peripheral neuropathy that occurs with chronic obesity or type 2 diabetes.
RESUMO
This study sought to determine whether the addition of mitoquinone (Mito-Q) in the diet is an effective treatment for peripheral neuropathy in animal models of diet-induced obesity (pre-diabetes) and type 2 diabetes. Unlike other anti-oxidative stress compounds investigated as a treatment for peripheral neuropathy, Mito-Q specifically targets mitochondria. Although mito-Q has been shown to reduce oxidative stress generated by mitochondria there have been no studies performed of the effect of Mito-Q on peripheral neuropathy induced by diet-induced obesity or type 2 diabetes. Diet-induced obese (12 weeks after high fat diet) or type 2 diabetic rats (12 weeks of high fat diet and 4 weeks after the onset of hyperglycemia) were treated via the diet with Mito-Q (0.93 g/kg diet) for 12 weeks. Afterwards, glucose utilization, vascular reactivity of epineurial arterioles to acetylcholine and peripheral neuropathy related endpoints were examined. The addition of Mito-Q to the diets of obese and diabetic rats improved motor and/or sensory nerve conduction velocity, cornea and intraepidermal nerve fibre density, cornea sensitivity and thermal nociception. Surprisingly, treating obese and diabetic rats with Mito-Q did not improve glucose utilization or vascular reactivity by epineurial arterioles to acetylcholine. These studies imply that mitochondrial dysfunction contributes to peripheral neuropathy in animal models of pre-diabetes and late-stage type 2 diabetes. However, improvement in peripheral neuropathy following treatment with Mito-Q was not associated with improvement in glucose utilization or vascular reactivity of epineurial arterioles to acetylcholine.
Assuntos
Antioxidantes/farmacologia , Modelos Animais de Doenças , Hipoglicemiantes/farmacologia , Obesidade/tratamento farmacológico , Compostos Organofosforados/farmacologia , Ubiquinona/análogos & derivados , Animais , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 2/induzido quimicamente , Diabetes Mellitus Tipo 2/tratamento farmacológico , Dieta Hiperlipídica/efeitos adversos , Masculino , Mitocôndrias/efeitos dos fármacos , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Ratos , Ratos Sprague-Dawley , Estreptozocina , Ubiquinona/farmacologiaRESUMO
AIMS: Determine the effect of dietary oils enriched in different mono- or polyunsaturated fatty acids, i.e., olive oil (18 : 1, oleic acid), safflower oil (18 : 2 n-6, linoleic acid), flaxseed oil (18 : 3 n-3, alpha linolenic acid), evening primrose oil (18 : 3 n-6, gamma linolenic acid), or menhaden oil (20:5/22 : 6 n-3 eicosapentaenoic/docosahexaenoic acids), on vascular and neural complications in high-fat-fed low-dose streptozotocin-treated Sprague-Dawley rats, an animal model for late-stage type 2 diabetes. MATERIALS AND METHODS: Rats were fed a high-fat diet (45% kcal as fat primarily derived from lard) for 8 weeks and then treated with a low dose of streptozotocin (30 mg/kg) in order to induce hyperglycemia. After an additional 8 (early intervention) or 20 (late intervention) weeks, the different groups of rats were fed diets with 1/2 of the kcal of fat derived from lard replaced by the different dietary oils. In addition, a control group fed a standard diet (4.25% kcal as fat) and a diabetic group maintained on the high-fat diet were maintained. The treatment period was approximately 16 weeks. The endpoints evaluated included vascular reactivity of epineurial arterioles, motor and sensory nerve conduction velocity, thermal and corneal sensitivity, and innervation of sensory nerves in the cornea and skin. RESULTS: Our findings show that menhaden and flaxseed oil provided the greatest benefit for correcting peripheral nerve damage caused by diabetes, whereas enriching the high-fat diet with menhaden oil provided the most benefit to acetylcholine-mediated vascular relaxation of epineurial arterioles of the sciatic nerve. Enriching the diets with fatty acids derived from the other oils provided none to partial improvements. CONCLUSIONS: These studies imply that long-chain n-6 and n-3 polyunsaturated fatty acids could be an effective treatment for diabetic peripheral neuropathy with n-3 polyunsaturated fatty acids derived from fish oil being the most effective.
Assuntos
Diabetes Mellitus Tipo 2/dietoterapia , Angiopatias Diabéticas/dietoterapia , Neuropatias Diabéticas/dietoterapia , Gorduras Insaturadas na Dieta/administração & dosagem , Animais , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/dietoterapia , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 2/induzido quimicamente , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Angiopatias Diabéticas/metabolismo , Angiopatias Diabéticas/fisiopatologia , Neuropatias Diabéticas/metabolismo , Neuropatias Diabéticas/fisiopatologia , Dieta Hiperlipídica , Gorduras Insaturadas na Dieta/farmacologia , Esquema de Medicação , Fígado Gorduroso/metabolismo , Fígado Gorduroso/patologia , Fígado Gorduroso/fisiopatologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/fisiopatologia , Estreptozocina , Fatores de TempoRESUMO
In this study, we wanted to extend our investigation of the efficacy of fish oil with or without salsalate on vascular and neural complications using a type 2 diabetic rat model. Four weeks after the onset of hyperglycemia, diabetic rats were treated via the diet with 3 different amounts of menhaden oil with or without salsalate for 12 weeks. Afterwards, vascular reactivity of epineurial arterioles and neuropathy-related endpoints were examined. The addition of salsalate to high-fat diets enriched with 10% or 25% kcal of menhaden oil protected vascular reactivity to acetylcholine and calcium gene-related peptide, motor and sensory nerve conduction velocity, thermal nociception, intraepidermal nerve fiber density, and cornea sensitivity to a greater extent than 10% or 25% menhaden oil alone. Vascular and neural function was maximally protected with diet containing 45% kcal as menhaden oil, and adding salsalate did not provide any additional benefit. Salsalate alone in the high-fat diet of diabetic rats provided minimal protection/improvement of vascular and neural dysfunction. These studies imply that dietary salsalate in combination with lower amounts of menhaden oil can provide greater benefit toward diabetes-induced vascular and neural impairment than menhaden oil alone.
Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Neuropatias Diabéticas/tratamento farmacológico , Dieta , Óleos de Peixe/farmacologia , Salicilatos/farmacologia , Animais , Glicemia , Dieta com Restrição de Gorduras , Dieta Hiperlipídica , Modelos Animais de Doenças , Masculino , Doenças do Sistema Nervoso Periférico , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/patologiaRESUMO
PURPOSE: This study aimed to determine the effect of dietary oils (olive, safflower, evening primrose, flaxseed, or menhaden) enriched in different mono unsaturated fatty acids or polyunsaturated fatty acids on peripheral neuropathies in diet-induced obese Sprague-Dawley rats. MATERIALS AND METHODS: Rats at 12 weeks of age were fed a high-fat diet (45% kcal) for 16 weeks. Afterward, the rats were fed diets with 50% of the kilocalories of fat derived from lard replaced by the different dietary oils. In addition, a control group fed a standard diet (4% kcal fat) and a high fat fed group (45% kcal) were maintained. The treatment period was 32 weeks. The endpoints evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and vascular relaxation by epineurial arterioles. RESULTS: Menhaden oil provided the greatest benefit for improving peripheral nerve damage caused by dietary obesity. Similar results were obtained when we examined acetylcholine-mediated vascular relaxation of epineurial arterioles of the sciatic nerve. Enriching the diets with fatty acids derived from the other oils provided minimal to partial improvements. CONCLUSION: These studies suggest that omega-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for neural and vascular complications associated with obesity.
RESUMO
Previously, we had shown that a vasopeptidase inhibitor drug containing ACE and neprilysin inhibitors was an effective treatment for diabetic vascular and neural complications. However, side effects prevented further development. This led to the development of sacubitril/valsartan, a drug containing angiotensin II receptor blocker and neprilysin inhibitor that we hypothesized would be an effective treatment for diabetic peripheral neuropathy. Using early and late intervention protocols (4 and 12 weeks posthyperglycemia, respectively), type 2 diabetic rats were treated with valsartan or sacubitril/valsartan for 12 weeks followed by an extensive evaluation of vascular and neural end points. The results demonstrated efficacy of sacubitril/valsartan in improving vascular and neural function was superior to valsartan alone. In the early intervention protocol, sacubitril/valsartan treatment was found to slow progression of these deficits and, with late intervention treatment, was found to stimulate restoration of vascular reactivity, motor and sensory nerve conduction velocities, and sensitivity/regeneration of sensory nerves of the skin and cornea in a rat model of type 2 diabetes. These preclinical studies suggest that sacubitril/valsartan may be an effective treatment for diabetic peripheral neuropathy, but additional studies will be needed to investigate these effects further.
Assuntos
Aminobutiratos/uso terapêutico , Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Antagonistas de Receptores de Angiotensina/uso terapêutico , Diabetes Mellitus Tipo 2/complicações , Angiopatias Diabéticas/prevenção & controle , Neuropatias Diabéticas/prevenção & controle , Tetrazóis/uso terapêutico , Valsartana/uso terapêutico , Animais , Compostos de Bifenilo , Fármacos Cardiovasculares/uso terapêutico , Angiopatias Diabéticas/tratamento farmacológico , Angiopatias Diabéticas/fisiopatologia , Neuropatias Diabéticas/tratamento farmacológico , Neuropatias Diabéticas/fisiopatologia , Retinopatia Diabética/tratamento farmacológico , Retinopatia Diabética/fisiopatologia , Retinopatia Diabética/prevenção & controle , Dieta Hiperlipídica/efeitos adversos , Progressão da Doença , Combinação de Medicamentos , Masculino , Neprilisina/antagonistas & inibidores , Neprilisina/metabolismo , Condução Nervosa/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Inibidores de Proteases/uso terapêutico , Ratos Sprague-Dawley , Resistência Vascular/efeitos dos fármacosRESUMO
AIMS/INTRODUCTION: Peripheral neuropathy is a common complication of diabetes and also occurs in 30% of human obese individuals with impaired glucose tolerance. Even though peripheral neuropathy affects both sexes, most pre-clinical studies have been carried out using male rodents. The aim of the present study was to create diet-induced obesity and type 2 diabetes in female rats and mice in order to examine the development of peripheral neuropathy. MATERIALS AND METHODS: At 12 weeks-of-age, rats and mice were separated into three groups. Two groups or rats and mice were fed a 60-kcal% high-fat diet for 12 weeks (rats) or 8 weeks (mice). To induce type 2 diabetes, one group of high-fat diet-fed rats and mice were treated with a low dose of streptozotocin. Analyses of multiple neural end-points were carried out 12 weeks later. RESULTS: Glucose utilization was impaired in diet-induced obese female rats and mice, as was a number of neurological end-points including nerve conduction velocity, intraepidermal and subepithelial corneal nerve fiber densities, and thermal and mechanical sensitivity. When female diet-induced obese rats or mice were made hyperglycemic, glucose utilization and sensory nerve density of the skin and cornea, as well as thermal and mechanical sensitivity, were more significantly impaired compared with diet-induced obese female rodents. CONCLUSIONS: These studies show that diet-induced obese and type 2 diabetic female rodents develop peripheral neuropathy that is similar to that occurring in male rodents. However, for female rats, more aggressive treatment is required to induce dietary obesity.
Assuntos
Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/patologia , Dieta Hiperlipídica/efeitos adversos , Doenças do Sistema Nervoso Periférico/sangue , Doenças do Sistema Nervoso Periférico/patologia , Animais , Glicemia/metabolismo , Diabetes Mellitus Experimental/complicações , Dieta Hiperlipídica/tendências , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Doenças do Sistema Nervoso Periférico/etiologia , Ratos , Ratos Sprague-Dawley , Estreptozocina , Resultado do TratamentoRESUMO
In this study, we sought to determine the efficacy of tempol on multiple neuropathic endpoints in a diet-induced obese mouse, a model of pre-diabetes, and a high-fat fed low-dose streptozotocin treated mouse, a model of type 2 diabetes. Tempol (4-hydroxy-2,2,6,6-tetramethylpiperdine -1-oxyl) is a low molecular weight, water soluble, membrane permeable, and metal-independent superoxide dismutase mimetic that has been widely used in cellular studies for the removal of intracellular and extracellular superoxide. This in vivo study was designed to be an early intervention. Fourteen weeks post-high-fat diet (6 weeks post-hyperglycemia) control, obese, and diabetic mice were divided into no treatment and treatment groups. The treated mice received tempol by gavage (150 mg/kg in water), while the untreated mice received vehicle. The diet-induced obese and the diabetic mice were maintained on the high-fat diet for the duration of the study, while the control group was maintained on the standard diet. Obesity and diabetes caused slowing of motor and sensory nerve conduction, reduction in intraepidermal nerve fiber density, thermal hypoalgesia, and mechanical allodynia. Treatment with tempol partially or completely protected obese and diabetic mice from these deficits. These studies suggest that tempol or other effective scavengers of reactive oxygen species may be a viable option for treating neural complications associated with obesity or type 2 diabetes.