losartan-potassium and Diabetic-Neuropathies

Erythropoietin (EPO) is required for promoting the progress of erythroid differentiation. However, the discovery of EPO and the EPO receptor (EPOR) in the nervous system may contribute to new treatment strategies for the use of EPO in neurodegenerative disorders. Diabetic neuropathy is a neurodegenerative disease that affects a large proportion of diabetic patients and results in alterations in functionality, mood and sleep. The pathogenic mechanisms generating diabetic neuropathy involve: Schwannopathy, polyol pathway activity, advanced glycation end-products (AGEs) accumulation, protein kinase C (PKC) activity, increased hexosamine pathway flux, oxidative stress, nitric oxide and inflammation. In this sense, evidence from both clinical and experimental studies indicates that EPO may reverse diabetic neuropathy through an antioxidant action by decreasing pro-inflammatory cytokines, restoring Na+/K+-ATPase activity, and blocking the generation of pro-apoptotic proteins. The aim of this review is to discuss the neuroprotector effect of EPO on pathogenic mechanisms of diabetic neuropathy.

Topics: Animals; Apoptosis; Diabetic Neuropathies; Disease Management; Erythropoietin; Humans; Oxidative Stress

Carbamylated erythropoietin (CEPO) is a modified erythropoietin molecule not affecting hematocrit. It is a potentially important pharmacological agent that may be applied to the treatment of several diseases affecting central and peripheral system neurons.. Carbamylated erythropoietin is a prime candidate for development because of its potent cell survival and function enhancing effects. This article reviews the preclinical development profile of CEPO in animal models to determine whether further clinical development is justified.. The review spans a detailed analysis of patents and scientific publications related to CEPO in animal models.. Use of CEPO in treating diseases such as stroke and traumatic brain and spinal cord injuries is important because these conditions affect millions of patients every year. Extensive preclinical studies support further clinical studies of CEPO for acute ischemic stroke. However, further studies are required for testing CEPO in patients with many other indications.

Topics: Animals; Brain Injuries; Clinical Trials as Topic; Diabetic Neuropathies; Disease Models, Animal; Erythropoietin; Humans; Motor Neuron Disease; Nervous System Diseases; Spinal Cord Injuries; Stroke; Treatment Outcome

Both chronic kidney disease (CKD) and type II diabetes mellitus (DM) are increasing in frequency among Western populations and both are potent risk factors for the development of anaemia. The presence of CKD and diabetes together represent the most important aetiopathogenic combination for the development of anaemia. New evidence has highlighted some of the underlying mechanisms which make diabetic patients more susceptible to dyserythropoiesis, particularly once they have developed concomitant CKD. In addition, recent publications from large-scale epidemiological studies have highlighted the impact of anaemia on diabetic patients. The purpose of this review was to focus on the pathophysiology and impact of anaemia in DM.

Topics: Anemia; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Erythropoietin; Female; Humans; Kidney Failure, Chronic; Male; Quality of Life

Peripheral neuropathy is one of the most common and debilitating complications of type 1 and type 2 diabetes mellitus. Recent studies have shown that several small, non-neural peptides possess neurotrophic activity and exert beneficial effects on nervous system function in experimental and clinical diabetes. Two of these, C-peptide and islet neogenesis-associated protein peptide, are derived from pancreatic proteins and use related signal transduction mechanisms. Derivatives of erythropoietin possess similar properties in the nervous system. As a group, these peptides are of increasing interest as leads to potential new approaches in the treatment of diabetes-associated neuropathies and other neurodegenerative conditions. This review addresses the recent advances made with these peptides in the context of diabetic neuropathy, and highlights similarities and differences in their mechanisms of action from the perspective of combination therapy.

Topics: Animals; C-Peptide; Cytokines; Diabetic Neuropathies; Erythropoietin; Humans; Pancreatitis-Associated Proteins; Peptide Fragments; Signal Transduction

Anemia has recently been recognized as a frequent complication of diabetic nephropathy, appearing earlier than in nondiabetic renal disease and amplifying the risks of cardiovascular and microvascular complications. A major cause is an inappropriate erythropoietin response to anemia, often accompanied by iron deficiency and therapy with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

Topics: Anemia; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Disease Progression; Erythropoietin; Heart Diseases; Humans

Anaemia is a frequent complication of diabetic nephropathy. It has only recently been recognised that in diabetic patients anaemia is seen not only in preterminal renal failure, but also frequently in patients with only minor derangement of renal function. At any level of glomerular filtration rate (GFR) anaemia is more frequent and severe in diabetic compared to nondiabetic patients. A major cause of anaemia is an inappropriate response of erythropoietin to anaemia. Additional factors are iron deficiency and iatrogenic factors, e.g. ACE inhibitor treatment. When serum creatinine is still normal, the erythropoietin concentration is predictive of more rapid loss of glomerular function. When serum creatinine is elevated, the haemoglobin values are predictive of the rate of progression. It is currently under investigation whether reversal of anaemia attenuates the rate of progression. Because most of the late complications of diabetes (retinopathy, neuropathy, heart disease, peripheral arterial disease) involve ischaemic tissue damage, it would be intuitively plausible that treatment with human recombinant erythropoietin should be beneficial, but definite evidence for this hypothesis is currently not available.

Topics: Anemia; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Erythrocytes, Abnormal; Erythropoietin; Heart Failure; Humans; Kidney Failure, Chronic; Myocardial Ischemia; Peripheral Vascular Diseases

Diabetes as the dominant cause of ESRD is also the major cause of renal anaemia. However, most patients with diabetic kidney disease will succumb to co-morbid vascular disease or heart failure before developing severe renal impairment. In these patients, anaemia is also common finding, with a 2-3 times greater prevalence and earlier onset than in patients with renal impairment from other causes. We have recently shown that at least one in five outpatients with type 1 or type 2 diabetes in tertiary referral clinics have anaemia, in whom it constitutes a significant additional burden. Impaired renal erythropoietin release in response to declining haemoglobin levels appears to be the major contributor to anaemia in diabetes. This may be due to the predominance of damage to cells and vascular architecture of the renal tubulointerstitium associated with diabetic nephropathy that may be apparent, like albuminuria, before demonstrable changes in renal function. In addition, systemic inflammation, autonomic neuropathy and reduce red cell survival may also compound anaemia in diabetes. While anaemia may be considered a marker of diabetic kidney disease, reduced haemoglobin levels, even within the normal range, identify diabetic patients with an increased risk of hospitalisation and mortality. Anaemia may also be significant in determining the outcome of heart failure and hypoxia-induced organ damage in patients with diabetes. Upcoming studies will determine whether correction of anaemia in diabetes will lead to improved outcomes in these patients.

Topics: Anemia; Blood Pressure; Diabetes Complications; Diabetic Angiopathies; Diabetic Neuropathies; Diabetic Retinopathy; Erythrocytes; Erythropoietin; Glomerular Filtration Rate; Hematopoiesis; Humans; Infections; Kidney; Microcirculation; Prevalence; Wound Healing

Topics: Anemia; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Autonomic Nervous System Diseases; Diabetic Nephropathies; Diabetic Neuropathies; Erythropoietin; Humans; Recombinant Proteins

Although erythropoietin ameliorates experimental type 2 diabetes with neuropathy, serious side effects limit its potential clinical use. ARA 290, a nonhematopoietic peptide designed from the structure of erythropoietin, interacts selectively with the innate repair receptor that mediates tissue protection. ARA 290 has shown efficacy in preclinical and clinical studies of metabolic control and neuropathy. To evaluate the potential activity of ARA 290 in type 2 diabetes and painful neuropathy, subjects were enrolled in this phase 2 study. ARA 290 (4 mg) or placebo were self-administered subcutaneously daily for 28 d and the subjects followed for an additional month without further treatment. No potential safety issues were identified. Subjects receiving ARA 290 exhibited an improvement in hemoglobin A(1c) (Hb A(1c)) and lipid profiles throughout the 56 d observation period. Neuropathic symptoms as assessed by the PainDetect questionnaire improved significantly in the ARA 290 group. Mean corneal nerve fiber density (CNFD) was reduced significantly compared with normal controls and subjects with a mean CNFD >1 standard deviation from normal showed a significant increase in CNFD compared with no change in the placebo group. These observations suggest that ARA 290 may benefit both metabolic control and neuropathy in subjects with type 2 diabetes and deserves continued clinical evaluation.

Topics: Aged; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Double-Blind Method; Erythropoietin; Female; Glycated Hemoglobin; Humans; Lipids; Male; Middle Aged; Oligopeptides

Topics: Adult; Anemia; Blood Pressure; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Erythropoietin; Female; Follow-Up Studies; Humans; Hypotension, Orthostatic; Middle Aged; Recombinant Proteins; Time Factors

High-flux haemodialysis (HD) has recently been vigorously promoted as a novel standard, and it can indeed efficiently reduce the occurrence of most uraemic symptoms due to middle molecular toxins and/or underdialysis. However, some symptoms remain problematical, particularly peripheral polyneuropathy (PPN). One of the possible reasons for this is that the patients may have low concentrations of some nutrients, e.g. vitamin B(6), necessary for normal peripheral neuron function.. Predialysis serum pyridoxal-5'-phosphate (P5P) level was determined in 36 chronic HD patients who were undergoing high-flux HD and receiving human recombinant erythropoietin. Among them, 26 patients suffered from PPN. Prior to supplementation, these 26 patients were examined and their neurological symptoms were ranked according to our PPN symptom score. Vitamin B(6) (60 mg/day) was randomly prescribed to 14 of them, and vitamin B(12) (500 microg/day) was prescribed to the others. After 4 weeks, all the patients were re-examined.. We found that predialysis serum P5P levels of HD patients with PPN were not significantly lower than those of matched HD patients without PPN. Nonetheless, it was demonstrated that supplementation with vitamin B(6) for 4 weeks significantly increased the predialysis level of P5P and dramatically attenuated PPN symptoms compared with initial symptoms. No improvement was observed in response to vitamin B(12) supplementation.. This result suggests that although vitamin B(6) deficiency could not be demonstrated in patients with chronic renal failure on high-flux HD, vitamin B(6) supplementation was effective in improving PPN symptoms of various aetiologies, possibly because of vitamin B(6) resistance to PPN in these patients.

Topics: Chronic Disease; Diabetic Neuropathies; Erythropoietin; Female; Glomerulonephritis; Humans; Kidney Failure, Chronic; Male; Middle Aged; Polyneuropathies; Pyridoxal Phosphate; Pyridoxine; Recombinant Proteins; Renal Dialysis; Vitamin B 12

High glucose-evoked oxidative stress and apoptosis within Schwann cells (SCs) are mechanisms facilitating the procession of diabetic peripheral neuropathy (DPN). Although erythropoietin (EPO) was demonstrated to have neuroprotective effects in neurodegenerative diseases, the effects of EPO on glucose-evoked oxidative stress and apoptosis of SCs remain unknown.. Primary cultured SCs isolated from streptozotocin (STZ)-induced diabetic peripheral neuropathic rats and normal control rats were exposed to high or normal glucose condition with or without EPO incubation for 72 h. Cell viability, apoptotic rate, cellular reactive oxygen species (ROS) level, total glutathione (GSH) level, EPO mRNA and erythropoietin receptor (EPOR) mRNA levels were assayed.. SCs from diabetic rats showed a lower cell viability and a higher apoptotic rate. High glucose culture condition elevated ROS level and diminished total GSH level of SCs. EPO improved cell viability and decreased cell apoptotic rate of SCs. EPO also elevated total GSH level and decreased intracellular ROS level. SCs from diabetic rats exhibited higher EPO mRNA and EPOR mRNA levels than SCs from normal control rats.. The data of this study offered fresh viewpoints for interpreting the pathogenesis of DPN and novel pharmacological principles implicit in the therapeutic effect of EPO.

Topics: Animals; Apoptosis; Cell Survival; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Glucose; Glutathione; Male; Oxidative Stress; Rats; Rats, Wistar; Reactive Oxygen Species; Receptors, Erythropoietin; RNA, Messenger; Schwann Cells; Streptozocin

We previously reported regulated expression of erythropoietin (EPO) over 4 weeks in the peripheral nerve in vivo, using a herpes simplex virus (HSV)-based vector containing a Tet-on regulatable gene expression cassette. To create a vector that would be appropriate for the treatment of chronic neuropathy, we constructed a HSV vector with expression of EPO under the control of the Tet-on system in which the HSV latency-associated promoter 2 element was used to drive the expression of the Tet-on transactivator. EPO expression from the vector was tightly controlled by administration of doxycycline (DOX) in vitro. One month after inoculation of the vector to transduce dorsal root ganglion (DRG) in vivo, administration of DOX-containing chow-induced expression of EPO. Mice with streptozotocin-induced diabetes, inoculated with the vector, were protected against the development of neuropathy by continuous administration of DOX-containing chow over the course of 3 months. Identical results were achieved when DOX was administered every other week over 3 months of diabetes, but administration of DOX, 1 week out of 3, provided only partial protection against the development of neuropathy. Taken together, these results suggest such a vector is well suited for clinical trial for the treatment of chronic or subacutely developing neuropathy.

Topics: Animals; Cell Line; Diabetic Neuropathies; Disease Progression; DNA-Binding Proteins; Doxycycline; Erythropoietin; Gene Expression Regulation; Gene Order; Genetic Therapy; Genetic Vectors; Humans; Male; Membrane Proteins; Mice; Promoter Regions, Genetic; Simplexvirus

This study assessed the added effect of 6 months of erythropoietin (EPO) administration in patients suffering from diabetic neuropathy with mild to moderate chronic kidney disease (CKD) managed with gabapentin. Twenty diabetic patients with mild to moderate CKD were included; 12 in gabapentin and 8 in EPO+gabapentin group. The subjects underwent nerve conduction studies (NCS) at the initiation of the investigation and after 6-month treatment. NCS were made in deep and superficial peroneal, tibial, and sural nerves. After 6 months, in both the groups, proximal motor latency (PML) nonsignificantly improved in deep peroneal and tibial nerves; conversely, dorsal motor latency (DML) got slightly impaired in these two nerves. A nonsignificant disruption and improvement was observed in deep peroneal and tibial motor nerve conduction velocity (MNCV), respectively, in gabapentin group. Although the F-wave of tibial and deep peroneal nerves remained stable in gabapentin group, a nonsignificant improvement was observed in EPO+gabapentin group. H-reflex of tibial nerve and all the evaluated parameters of sural and superficial peroneal nerves remained constant in all patients. Thus, it can be concluded that 6-month administration of EPO+gabapentin, or gabapentin alone in mild to moderate CKD patients with diabetic neuropathy could not improve nerve performance.

Topics: Aged; Aged, 80 and over; Amines; Cyclohexanecarboxylic Acids; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Neuropathies; Drug Therapy, Combination; Erythropoietin; Excitatory Amino Acid Antagonists; Female; Gabapentin; gamma-Aminobutyric Acid; Humans; Male; Middle Aged; Neural Conduction; Neurologic Examination; Peripheral Nervous System Diseases; Peroneal Nerve; Recombinant Proteins; Renal Insufficiency; Sural Nerve; Surveys and Questionnaires; Tibial Nerve

Previous studies have demonstrated that gene transfer of genes coding for neurotrophic factors to the dorsal root ganglion (DRG) using nonreplicating herpes simplex virus (HSV)-based vectors injected subcutaneously can prevent the progression of diabetic neuropathy. Because prolonged expression of neurotrophic factors could potentially have unwanted adverse effects, we constructed a nonreplicating HSV vector, vHrtEPO, to express erythropoietin (EPO) under the control of a tetracycline response element (TRE)-minimal cytomegalovirus (CMV) fusion promoter. Primary DRG neurons in culture infected with vHrtEPO express and release EPO in response to exposure to doxycycline (DOX). Animals infected with vHrtEPO by footpad inoculation demonstrated regulated expression of EPO in DRG under the control of DOX administered by gavage. Mice rendered diabetic by injection of streptozotocin (STZ), inoculated with vHrtEPO, and treated with DOX 4 days out of 7 each week for 4 weeks were protected against the development of diabetic neuropathy as assessed by electrophysiologic and behavioral measures. These studies indicate that intermittent expression of EPO in DRG achieved from a regulatable vector is sufficient to protect against the progression of neuropathy in diabetic animals, and provides proof-of-principle preclinical evidence for the development of such vectors for clinical trial.

Topics: Animals; Cells, Cultured; Chlorocebus aethiops; Diabetic Neuropathies; Electrophysiology; Enzyme-Linked Immunosorbent Assay; Erythropoietin; Ganglia, Spinal; Genetic Therapy; Genetic Vectors; Male; Mice; Nerve Growth Factors; Polymerase Chain Reaction; Promoter Regions, Genetic; Rats; Simplexvirus; Tetracycline; Vero Cells

Multiple complications can ensue in the cardiovascular, renal, and nervous systems during diabetes mellitus (DM). Given that endothelial cells (ECs) are susceptible targets to elevated serum D-glucose, identification of novel cellular mechanisms that can protect ECs may foster the development of unique strategies for the prevention and treatment of DM complications. Erythropoietin (EPO) represents one of these novel strategies but the dependence of EPO upon Wnt1 and its downstream signaling in a clinically relevant model of DM with elevated D-glucose has not been elucidated. Here we show that EPO can not only maintain the integrity of EC membranes, but also prevent apoptotic nuclear DNA degradation and the externalization of membrane phosphatidylserine (PS) residues during elevated D-glucose over a 48-hour period. EPO modulates the expression of Wnt1 and utilizes Wnt1 to confer EC protection during elevated D-glucose exposure, since application of a Wnt1 neutralizing antibody, treatment with the Wnt1 antagonist DKK-1, or gene silencing of Wnt1 with Wnt1 siRNA transfection abrogates the protective capability of EPO. EPO through a novel Wnt1 dependent mechanism controls the post-translational phosphorylation of the "pro-apoptotic" forkhead member FoxO3a and blocks the trafficking of FoxO3a to the cell nucleus to prevent apoptotic demise. EPO also employs the activation of protein kinase B (Akt1) to foster phosphorylation of GSK-3β that appears required for EPO vascular protection. Through this inhibition of GSK-3β, EPO maintains β-catenin activity, allows the translocation of β-catenin from the EC cytoplasm to the nucleus through a Wnt1 pathway, and requires β-catenin for protection against elevated D-glucose since gene silencing of β-catenin eliminates the ability of EPO as well as Wnt1 to increase EC survival. Subsequently, we show that EPO requires modulation of both Wnt1 and FoxO3a to oversee mitochondrial membrane depolarization, cytochrome c release, and caspase activation during elevated D-glucose. Our studies identify critical elements of the protective cascade for EPO that rely upon modulation of Wnt1, Akt1, FoxO3a, GSK-3β, β-catenin, and mitochondrial apoptotic pathways for the development of new strategies against DM vascular complications.

Topics: Animals; beta Catenin; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Disease Models, Animal; Endothelium, Vascular; Erythropoietin; Forkhead Box Protein O3; Forkhead Transcription Factors; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Signal Transduction; Wnt1 Protein

The Akita mouse is a robust model of diabetic autonomic neuropathy which develops severe diabetes following beta cell death, which occurs reproducibly at 3-4 weeks of age, and maintains the diabetic state without therapy for as long as 11 additional months. Neuritic dystrophy and neuronopathy involving prevertebral sympathetic superior mesenteric and celiac ganglia begin to develop within the first two months of onset of diabetes and are progressive with time. We have examined the effect of insulin implants resulting in normoglycemia and injections of ARA290, a small erythropoietin peptide which has no effect on glycemic parameters, on the reversal of established neuritic dystrophy and neuronopathy. We have found that 4 weeks of insulin therapy beginning at 2 months of diabetes resulted in normalization of blood glucose, body weight and HbA1c. Insulin therapy successfully reversed established neuritic dystrophy and neuronopathy to control levels. Numbers of sympathetic neurons were not significantly changed in either 3 month diabetic or insulin-treated Akita mice. Treatment with ARA290 for 7 weeks beginning at 4 months of diabetes did not result in altered metabolic severity of diabetes as measured by blood glucose, body weight or HbA1c levels. ARA290 treatment was able to decrease neuritic dystrophy by 55-74% compared to untreated diabetics or in comparison to a separate group of diabetic animals representing the 4 month treatment onset point. Surprisingly, there was no effect of ARA290 on ganglionic neuron number or ongoing neuronopathy (pale/degenerating neurons) in diabetic Akita mice during this time period. The development of neuroprotective EPO-like peptides may provide a possible future therapy for this debilitating complication of diabetes; however, it appears that discrete elements may be differentially targeted by the diabetic state and may require selective therapy.

Topics: Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Disease Models, Animal; Erythropoietin; Ganglia, Sympathetic; Hypoglycemic Agents; Insulin; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Microscopy, Electron; Nerve Degeneration; Neurites; Peptides

In diabetes mellitus (DM) reduced motor and sensory properties of peripheral nerves are linked with the dysfunction of neural vasculature. We investigated C-fibers and microvessels of sciatic nerve of normal, DM, and DM + epoetin delta-treated rats. C-fibers immunoreactive for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH), epoetin receptor (EpoR), and common beta receptor subunit of the interleukin 3 receptor (IL-3Rbeta) were present in all rats, whereas in DM and epoetin-treated rats C-fibers also showed neuronal (nNOS) and inducible (iNOS) nitric oxide synthases. The cross-sectional area of CGRP-positive C-fibers was decreased in DM, but it recovered after epoetin treatment. In all conditions, vascular endothelium showed scarce immunolabeling for endothelial nitric oxide synthase (eNOS); the profound immunoreactivity for eNOS, EpoR, and IL-3Rbeta was in pericytes. Some perivascular autonomic nerves were damaged and IL-3Rbeta positive. Findings are discussed in terms of declined sensory conduction velocity in DM, its improvement after epoetin treatment, and the possible vascular contribution to these phenomena.

Topics: Animals; Calcitonin Gene-Related Peptide; Cytokine Receptor Common beta Subunit; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Immunohistochemistry; Male; Microvessels; Nerve Fibers, Unmyelinated; Neural Conduction; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Pericytes; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Regional Blood Flow; Sciatic Nerve

We examined the efficacy of herpes simplex virus vector-mediated gene transfer of erythropoietin in preventing neuropathy in mouse model of streptozotocin-diabetes. A replication-incompetent herpes simplex virus vector with erythropoietin under the control of the human cytomegalovirus promoter (vector DHEPO) was constructed. DHEPO expressed and released erythropoietin from primary dorsal root ganglion neurons in vitro, and following subcutaneous inoculation in the foot, expressed erythropoietin in dorsal root ganglion neurons in vivo. At 2 weeks after induction of diabetes, subcutaneous inoculation of erythropoietin prevented the reduction in sensory nerve amplitude characteristic of diabetic neuropathy measured 4 weeks later, preserved autonomic function measured by pilocarpine-induced sweating, and prevented the loss of nerve fibres in the skin and reduction of neuropeptide calcitonin gene-related peptide in the dorsal horn of spinal cord of the diabetic mice. We further investigated whether vector-mediated local expression of erythropoietin in dorsal root ganglion neurons can protect in vivo as well as in vitro hyperglycemia-induced axonal degeneration. Our findings show that the AKT/GSK-3beta dependent pathway plays an important role in mediating the protection of erythropoietin against diabetic neuropathy. Herpes simplex virus-mediated transfer of erythropoietin to dorsal root ganglia may prove useful in treatment of diabetic neuropathy.

Topics: Animals; Autonomic Nervous System Diseases; Calcitonin Gene-Related Peptide; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Ganglia, Spinal; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hematocrit; Hot Temperature; Hyperglycemia; Mice; Pain Threshold; Peripheral Nervous System Diseases; Sensory Receptor Cells; Simplexvirus; Skin

Autonomic neuropathy is a significant diabetic complication resulting in increased morbidity and mortality. Studies of autopsied diabetic patients and several rodent models demonstrate that the neuropathologic hallmark of diabetic sympathetic autonomic neuropathy in prevertebral ganglia is the occurrence of synaptic pathology resulting in distinctive dystrophic neurites ("neuritic dystrophy"). Our prior studies show that neuritic dystrophy is reversed by exogenous IGF-I administration without altering the metabolic severity of diabetes, i.e. functioning as a neurotrophic substance. The description of erythropoietin (EPO) synergy with IGF-I function and the recent discovery of EPO's multifaceted neuroprotective role suggested it might substitute for IGF-I in treatment of diabetic autonomic neuropathy. Our current studies demonstrate EPO receptor (EPO-R) mRNA in a cDNA set prepared from NGF-maintained rat sympathetic neuron cultures which decreased with NGF deprivation, a result which demonstrates clearly that sympathetic neurons express EPO-R, a result confirmed by immunohistochemistry. Treatment of STZ-diabetic NOD-SCID mice have demonstrated a dramatic preventative effect of EPO and carbamylated EPO (CEPO, which is neuroprotective but not hematopoietic) on the development of neuritic dystrophy. Neither EPO nor CEPO had a demonstrable effect on the metabolic severity of diabetes. Our results coupled with reported salutary effects of EPO on postural hypotension in a few clinical studies of EPO-treated anemic diabetic and non-diabetic patients may reflect a primary neurotrophic effect of EPO on the sympathetic autonomic nervous system, rather than a primary hematopoietic effect. These findings may represent a major clinical advance since EPO has been widely and safely used in anemic patients due to a variety of clinical conditions.

Topics: Animals; Carbamates; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Ganglia, Sympathetic; Immunohistochemistry; Male; Mice; Mice, Inbred NOD; Mice, SCID; Neurites; Receptors, Erythropoietin; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

The present study investigated the relationship between hemoglobin (Hb) levels and autonomic failure using a sensitive marker, coefficient of variation of R-R intervals in electrocardiogram (CVR-R) in order to clarify a cause of normocytic normochromic anemia in type 1 diabetic patients without overt nephropathy. We recruited 46 patients with type 1 diabetes and measured creatinine clearance (Ccr), HbA1c, albuminuria, Hb levels and CVR-R of all patients. In addition, the status of diabetic retinopathy and neuropathy were also evaluated. Serum erythropoietin (EPO), Fe, total iron binding capacity, lactate dehydrogenase, total bilirubin levels and number of reticulocytes and mean corpuscular volume were also measured to distinguish types of anemia. To survey the statistical correlation existing between Hb and body mass index (BMI), Ccr, HbA1c, albuminuria or retinopathy, multiple regression analysis was performed. Serum EPO, Fe, TIBC, LDH and TB levels and number of reticulocytes and MCV were within normal limits. Multiple regression analysis disclosed that HbA1c, nephropathy evaluated by albuminuria and Ccr, and retinopathy has no concern with Hb level. There is only significant relationship between Hb levels and CVR-R. Similar results were obtained even if we analyzed a group of male and female separately. We conclude that CVR-R has the strong relationship on anemia without overt nephropathy in type 1 diabetes, indicating that autonomic failure contributes on the progression of anemia via a poor response of EPO to anemia.

Topics: Adult; Aged; Albuminuria; Anemia; C-Peptide; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Electrocardiography; Erythropoietin; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Sensitivity and Specificity

We describe here four male patients with long-term and poorly controlled type 2 diabetes mellitus. They shared many common characteristic complications, such as severe autonomic neuropathy, proliferative retinopathy and normocytic normochromic anemia without progressive renal failure and macroangiopathy. They also showed normal levels of erythropoietin and reticulocyte, which was considered relatively low. The coefficient of variation of R-R, a useful method to estimate autonomic failure, showed markedly advanced autonomic neuropathy in all four patients. Coronary angiography did not reveal stenosis, anomaly or collateral vessels, but left ventriclography showed diffuse or partial hypokinesis. Massive proteinuria, high urinary levels of N-acetyl-beta-D-glucosamidase (NAG) and beta2-microglobulin (beta2M) were detected, though creatinine clearance (Ccr) was not so deteriorated. Treatment with recombinant erythropoietin increased their hemoglobin and hematocrit levels. These common points have a possibility to be brought about by tubulointerstitial damage and microangiopathy may be involved in it.

Topics: Adult; Anemia; Autonomic Nervous System Diseases; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Erythropoietin; Humans; Male; Middle Aged; Reticulocyte Count

Erythropoietin (EPO) possesses generalized neuroprotective and neurotrophic actions. We tested the efficacy of recombinant human EPO (rhEPO) in preventing and reversing nerve dysfunction in streptozotocin (STZ)-induced diabetes in rats. Two days after STZ [60 mg/kg of body weight (b.w.), i.p.], diabetic animals were administered rhEPO (40 microg/kg of b.w.) three times weekly for 5 weeks either immediately (preventive) before or after a 5-week delay (therapeutic) after induction of hyperglycemia or at a lower dose (8 microg/kg of b.w. once per week) for 8 weeks (prolonged). Tail-nerve conduction velocities (NCV) was assessed at 5 and 11 weeks for the preventive and therapeutic schedule, respectively. Compared to nondiabetic rats, NCV was 20% lower after 5 weeks in the STZ group, and this decrease was attenuated 50% by rhEPO. Furthermore, the reduction of Na(+),K(+)-ATPase activity of diabetic nerves (by 55%) was limited to 24% in the rhEPO-treated group. In the therapeutic schedule, NCV was reduced by 50% after 11 weeks but by only 23% in the rhEPO-treated group. rhEPO treatment attenuated the decrease in compound muscle action potential in diabetic rats. In addition, rhEPO treatment was associated with a preservation of footpad cutaneous innervation, as assessed by protein gene product 9.5 immunostaining. Diabetic rats developed alterations in mechanical and thermal nociception, which were partially reversed by rhEPO given either in a preventative or therapeutic manner. These observations suggest that administration of rhEPO or its analogues may be useful in the treatment of diabetic neuropathy.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Electrophysiology; Erythropoietin; Humans; Male; Nerve Fibers; Nociceptors; Rats; Rats, Sprague-Dawley; Rats, Wistar; Recombinant Proteins; Sodium-Potassium-Exchanging ATPase

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Hematocrit; Humans; Neurons; Nociceptors; Recombinant Proteins; Sodium-Potassium-Exchanging ATPase

Erythropoietin (EPO) is both hematopoietic and tissue protective, putatively through interaction with different receptors. We generated receptor subtype-selective ligands allowing the separation of EPO's bioactivities at the cellular level and in animals. Carbamylated EPO (CEPO) or certain EPO mutants did not bind to the classical EPO receptor (EPOR) and did not show any hematopoietic activity in human cell signaling assays or upon chronic dosing in different animal species. Nevertheless, CEPO and various nonhematopoietic mutants were cytoprotective in vitro and conferred neuroprotection against stroke, spinal cord compression, diabetic neuropathy, and experimental autoimmune encephalomyelitis at a potency and efficacy comparable to EPO.

Topics: Animals; Apoptosis; Binding Sites; Cells, Cultured; Diabetic Neuropathies; Drug Design; Encephalomyelitis, Autoimmune, Experimental; Erythropoiesis; Erythropoietin; Female; Hematocrit; Humans; Ligands; Mice; Mice, Inbred C3H; Mutagenesis; Nervous System Diseases; Neurons; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Receptors, Erythropoietin; Recombinant Proteins; Signal Transduction; Spinal Cord Compression; Stroke; Structure-Activity Relationship

Erythropoietin (EPO)-deficient anaemia has been described in Type 1 diabetic patients with both severe autonomic neuropathy (AN) and proteinuria. This study was aimed at distinguishing between the effects of AN and nephropathy on haemoglobin and EPO levels in Type 2 diabetic patients at an early stage of diabetic nephropathy.. In 64 Type 2 diabetic patients (age 52 +/- 10 years, duration 10 +/- 9 years) without overt nephropathy and other causes of anaemia or EPO deficit, we assessed cardiovascular tests of AN, 24-h blood pressure (BP) monitoring, urinary albumin excretion rate (UAE), a full blood count, and serum EPO.. Although the Type 2 diabetic patients with AN did not show differences in haemoglobin and EPO when compared with patients without AN, the presence of haemoglobin < 13 g/dl was associated with the presence of AN (chi(2)= 3.9, P < 0.05) and of postural hypotension (chi(2)= 7.8, P < 0.05). In a multiple regression analysis including as independent variables gender, body mass index, duration of diabetes, smoking, creatinine, 24-h UAE, 24-h diastolic BP, ferritin, erythrocyte sedimentation rate, and autonomic score, we found that the only variables independently related to haematocrit were autonomic score, ferritin and erythrocyte sedimentation rate. Finally, the physiological inverse relationship between EPO and haemoglobin present in a control group of 42 non-diabetic non-anaemic subjects was completely lost in Type 2 diabetic patients. The slopes of the regression lines between EPO and haemoglobin of the control subjects and the Type 2 diabetic patients were significantly different (t = 14.4, P < 0.0001).. This study documents an early abnormality of EPO regulation in Type 2 diabetes before clinical nephropathy and points to a contributory role of AN in EPO dysregulation.

Topics: Adult; Aged; Albuminuria; Autonomic Nervous System Diseases; Blood Pressure; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Neuropathies; Erythropoietin; Female; Hemoglobins; Humans; Hypotension, Orthostatic; Male; Middle Aged

Patients with the acute porphyrias may develop renal failure and autonomic dysfunction. Renal damage and sympathetic failure may both cause erythropoietin (EPO) deficiency. In this study, we have investigated serum erythropoietin levels and autonomic function in patients with acute porphyria in clinical remission.. Serum erythropoietin levels and the corresponding haemoglobin (Hb) were assayed in 31 patients with acute porphyria and were compared to 15 type 1 diabetic patients with autonomic neuropathy, 23 patients with iron-deficiency anaemia and 18 healthy individuals.. 9 out of 31 porphyric patients showed a normochromic normocytic anaemia with normal ferritin levels. Three patients had borderline-raised serum creatinine levels, and one of them was anaemic. Autonomic function was investigated in seven patients, six of them being anaemic, and the results were normal. Patients with iron-deficiency anaemia showed the expected increase in serum erythropoietin levels in response to a decreasing haemoglobin (r=-0.86, p<0.001). Patients with porphyria had inappropriately low serum erythropoietin levels for the degree of anaemia compared to iron-deficiency patients (p<0.001) although there was still a significant increase in serum erythropoietin with decreasing haemoglobin levels (r=-0.46, p=0.01). In contrast, diabetic autonomic neuropathy patients demonstrated a significant decrease in serum erythropoietin with decreasing Hb levels (r=+0.53, p=0.05).. Patients with acute porphyria may have inappropriately low levels of EPO. In contrast to the diabetic patients, this does not appear to be due to autonomic neuropathy but it may reflect mild renal tubular impairment.

Topics: Adult; Anemia, Iron-Deficiency; Creatinine; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Erythropoietin; Female; Humans; Kidney; Male; Middle Aged; Porphyria, Acute Intermittent; Reference Values

An erythropoietin (EPO)-deficient anaemia is recognized in Type 1 diabetic patients with early nephropathy and symptomatic autonomic neuropathy (DN). The aim of this study was to determine whether the EPO response to hypoxia was deficient in order to clarify the mechanisms involved in this process.. Five Type 1 diabetic patients DN (age 39 (28-48) years (mean (range))) with EPO-deficient anaemia (haemoglobin, Hb 10.6 (9.5-12.0) g/dl, EPO 5.0 (3.2-6.5) IU/l) and early diabetic nephropathy (persistent proteinuria 1161.6 (130-2835) mg/day, serum creatinine 97.6 (63-123) micromol/l)) were compared with nine normal subjects (age 31 (24-39) years, Hb 13.4 (11.8-15.7) g/dl, EPO 7.6 (5.6-10.3) IU/l) and four patients with non-diabetic advanced chronic renal failure RF (proteinuria 2157.5 (571-4578) mg/day, serum creatinine 490.2 (406-659) micromol/l, Hb 10.3 (9.0-11.3) g/dl, EPO 4.6 (2.9-8.5) IU/l). The subjects were exposed to 6 h of hypoxia (inspired oxygen 11.6-12.6%) by breathing a gas mixture via a hood. Hourly serum EPO levels were measured.. All groups showed a rise in EPO production after 2 h. The diabetic DN group achieved a similar maximal response to the normal subjects at 6 h (EPO 17.3 +/-5.4 vs. 17.8 +/-7.9 IU/l). The renal failure patients mounted an EPO response to hypoxia but at lower EPO levels.. Although the DN patients have inappropriately low EPO levels for the severity of their anaemia, they can mount an appropriate EPO response to moderate hypoxia. The mechanism underlying the EPO-deficient anaemia present in some diabetic patients remains unclear.

Topics: Adult; Anemia; Autonomic Nervous System Diseases; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Diabetic Neuropathies; Erythropoietin; Female; Humans; Hypoxia; Kidney Failure, Chronic; Male; Middle Aged; Proteinuria

We report the case of a 52-year-old woman with long-term type 1 diabetes mellitus, complicated with proliferative retinopathy, autonomic neuropathy and microalbuminuria and moderate renal failure. A normochromic, normocytic are generative anaemia had been diagnosed for three years. Clinical and biological investigations for the aetiology of anaemia remained normal or negative. Anaemia was associated with a concentration of erythropoietin (EPO) in the normal range, but inappropriately low regarding anaemia. Treatment with recombinant EPO induced a rapid increase in haemoglobin level and improved the patient's quality of life. The role of diabetic neuropathy in the genesis of anaemia, in conjunction with a modest renal impairment is discussed.

Topics: Albuminuria; Anemia; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Electrocardiography; Erythropoietin; Female; Hemoglobins; Humans; Hypotension, Orthostatic; Kidney Failure, Chronic; Middle Aged; Quality of Life; Recombinant Proteins

Topics: Anemia; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Erythropoietin; Humans

To discover whether Type 1 diabetic patients with autonomic neuropathy might be anaemic and erythropoietin (EPO)-depleted.. Fifteen Type 1 diabetic patients with serious complications (DM-COMP) were selected because of severe symptomatic autonomic neuropathy, including significant postural hypotension. All had proteinuria from nephropathy (three microalbuminuria and 12 macroalbuminuria), but a normal serum creatinine (< 122 micromol/l). They were compared to age and duration matched Type 1 diabetic controls without autonomic neuropathy (DM-controls) and non-diabetic patients with and without hypochromic, microcytic anaemia.. The DM-COMP patients were anaemic (mean haemoglobin (Hb) 11.1+/-1.2 g/dl), sometimes severely (minimum Hb 9.2 g/dl), compared to non-neuropathic DM-controls (Hb 13.7+/-0.7 g/dl; P < 0.001). Furthermore, EPO failed to increase in association with anaemia in the DM-COMP group compared to the progressive increase in the non-diabetic, anaemic patients (difference of regression lines P < 0.001), indicating EPO depletion in the anaemic, diabetic patients. There was no other demonstrable cause for the anaemia. Treatment with EPO in 5 DM-COMP patients led to a rapid increase in haemoglobin (range 1.7-5.0 g/dl) with improvement in wellbeing.. Some Type 1 diabetic patients with autonomic neuropathy present with an EPO-depleted anaemia, which responds to treatment with EPO. This observation supports the concept of autonomic neuropathy as a cause of anaemia with EPO depletion, although the role of established renal damage cannot be excluded.

Topics: Adult; Albuminuria; Anemia; Autonomic Nervous System Diseases; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Diabetic Neuropathies; Erythropoietin; Female; Hemoglobins; Humans; Middle Aged; Proteinuria

Impaired omega-6 essential fatty acid metabolism and exaggerated polyol pathway flux contribute to the neurovascular abnormalities in streptozotocin-diabetic rats. The potential interactions between these mechanisms were examined by comparing the effects of threshold doses of aldose reductase inhibitors and evening primrose oil, alone and in combination, on neurovascular deficits. In addition, high-dose aldose reductase inhibitor and evening primrose oil treatment effects were challenged by co-treatment with the cyclo-oxygenase inhibitor, flurbiprofen, or the nitric oxide synthase inhibitor, NG-nitro-L-arginine. Eight weeks of diabetes caused an 18.9% reduction in sciatic motor conduction velocity (p < 0.001). This was only modestly ameliorated by a 0.1% dietary supplement of evening primrose oil or the aldose reductase inhibitors ZD5522 (0.25 mg.kg-1.day-1 and WAY121 509 (0.2 mg.kg-1.day-1 for the final 2 weeks. However, joint treatment with primrose oil and ZD5522 or WAY121 509 caused marked 71.5 and 82.4% corrections, respectively, of the conduction deficit. Sciatic nutritive blood flow was 43.1% reduced by diabetes (p < 0.001) and this was corrected by 67.8% with joint ZD5522 and primrose oil treatment (p < 0.001). High-dose WAY121 509 (10 mg. kg-1.day-1 and primrose oil (10% dietary supplement) prevented sciatic conduction velocity and nutritive blood flow deficits in 1-month diabetic rats (p < 0.001). However, these effects were abolished by flurbiprofen (5 mg.kg(-1).day-1 and NG-nitro-L-arginine (10 mg.kg-1.day-1) co-treatment (p < 0.001). Thus, the data provide evidence for synergistic interactions between polyol pathway/nitric oxide and essential fatty acid/cyclo-oxygenase systems in the control of neurovascular function in diabetic rats, from which a potential therapeutic advantage could be derived.

Topics: Acetanilides; Aldehyde Reductase; Analysis of Variance; Animals; Arginine; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Dietary Fats, Unsaturated; Enzyme Inhibitors; Erythropoietin; Fatty Acids, Essential; Flurbiprofen; Fructose; gamma-Linolenic Acid; Inositol; Linoleic Acids; Male; Neural Conduction; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Oenothera biennis; Plant Oils; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Regression Analysis; Sciatic Nerve; Sorbitol; Sulfones

We encountered two patients with non-insulin-dependent diabetes mellitus (DM) who developed normocytic normochromic anemia. Routine hematological examinations revealed no specific causes except for the reduced serum levels of erythropoietin. Since their renal functions were preserved, the anemias may not have been due to chronic renal failure. Treatment with human recombinant erythropoietin (rHuEPO) improved anemia, ascribing the cause of anemia to low levels of erythropoietin in these patients. Underlying common clinical features of the two patients were longstanding poorly controlled diabetes mellitus accompanied with advanced neuropathy. Since erythropoietin production is regulated in part by autonomic nervous system, the results suggest that erythropoietin production could be prematurely impaired in patients with severe diabetic autonomic neuropathy.

Topics: Anemia; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Erythropoietin; Female; Humans; Kidney Function Tests; Male; Middle Aged; Recombinant Proteins

Patients with orthostatic hypotension caused by autonomic neuropathy frequently have a decreased red-cell mass. This would be expected to compromise their effective circulating blood volume and aggravate the orthostatic hypotension. We studied the effect of increasing the red-cell mass with erythropoietin, given subcutaneously in a dose of 50 U per kilogram of body weight three times a week for 6 to 10 weeks to eight patients with orthostatic hypotension--four men, one teenage boy, and three women (age range, 17 to 68 years). Four patients had type I diabetes mellitus and autonomic neuropathy, three patients had pure autonomic failure, and one patient had sympathotonic orthostatic hypotension. Seven patients received fludrocortisone (0.1 or 0.2 mg per day) before, during, and after the trial of erythropoietin. The red-cell volume, plasma volume, and hemodynamic response to orthostatic stress were measured before and after therapy.. Erythropoietin increased the mean (+/- SD) hematocrit from 0.34 +/- 0.04 to 0.45 +/- 0.04 (P < 0.005) and increased the red-cell volume from 16.8 +/- 3.9 to 25.3 +/- 3.1 ml per kilogram (P < 0.005), but had no effect on plasma volume. The systolic blood pressure increased from 81 +/- 11 to 100 +/- 24 mm Hg (P < 0.01) and the diastolic blood pressure increased from 46 +/- 10 to 63 +/- 18 mm Hg (P < 0.01) while the patients were standing. The average systolic and diastolic blood pressure while the patients were supine did not increase significantly, although hypertension in the supine position developed in three patients. Orthostatic dizziness improved during treatment in six of the eight patients.. In patients with orthostatic hypotension, increasing the red-cell volume with erythropoietin elevates blood pressure while standing. Possible long-term adverse effects are not known.

Topics: Adolescent; Adult; Aged; Autonomic Nervous System Diseases; Blood Pressure; Diabetic Neuropathies; Erythrocyte Volume; Erythropoietin; Female; Humans; Hypotension, Orthostatic; Male; Middle Aged; Plasma Volume