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Yorek M. Combination therapy is it in the future for successfully treating peripheral diabetic neuropathy? Front Endocrinol (Lausanne) 2024; 15:1357859. [PMID: 38812811 PMCID: PMC11133577 DOI: 10.3389/fendo.2024.1357859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/16/2024] [Indexed: 05/31/2024] Open
Abstract
In 2022, the Center for Disease Control and Prevention reported that 11.3% of the United States population, 37.3 million people, had diabetes and 38% of the population had prediabetes. A large American study conducted in 2021 and supported by many other studies, concluded that about 47% of diabetes patients have peripheral neuropathy and that diabetic neuropathy was present in 7.5% of patients at the time of diabetes diagnosis. In subjects deemed to be pre-diabetes and impaired glucose tolerance there was a wide range of prevalence estimates (interquartile range (IQR): 6%-34%), but most studies (72%) reported a prevalence of peripheral neuropathy ≥10%. There is no recognized treatment for diabetic peripheral neuropathy (DPN) other than good blood glucose control. Good glycemic control slows progression of DPN in patients with type 1 diabetes but for patients with type 2 diabetes it is less effective. With obesity and type 2 diabetes at epidemic levels the need of a treatment for DPN could not be more important. In this article I will first present background information on the "primary" mechanisms shown from pre-clinical studies to contribute to DPN and then discuss mono- and combination therapies that have demonstrated efficacy in animal studies and may have success when translated to human subjects. I like to compare the challenge of finding an effective treatment for DPN to the ongoing work being done to treat hypertension. Combination therapy is the recognized approach used to normalize blood pressure often requiring two, three or more drugs in addition to lifestyle modification to achieve the desired outcome. Hypertension, like DPN, is a progressive disease caused by multiple mechanisms. Therefore, it seems likely as well as logical that combination therapy combined with lifestyle adjustments will be required to successfully treat DPN.
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Affiliation(s)
- Mark Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, IA, United States
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, United States
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, United States
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Yorek M. Treatment for Diabetic Peripheral Neuropathy: What have we Learned from Animal Models? Curr Diabetes Rev 2022; 18:e040521193121. [PMID: 33949936 PMCID: PMC8965779 DOI: 10.2174/1573399817666210504101609] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/07/2021] [Accepted: 02/13/2021] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Animal models have been widely used to investigate the etiology and potential treatments for diabetic peripheral neuropathy. What we have learned from these studies and the extent to which this information has been adapted for the human condition will be the subject of this review article. METHODS A comprehensive search of the PubMed database was performed, and relevant articles on the topic were included in this review. RESULTS Extensive study of diabetic animal models has shown that the etiology of diabetic peripheral neuropathy is complex, with multiple mechanisms affecting neurons, Schwann cells, and the microvasculature, which contribute to the phenotypic nature of this most common complication of diabetes. Moreover, animal studies have demonstrated that the mechanisms related to peripheral neuropathy occurring in type 1 and type 2 diabetes are likely different, with hyperglycemia being the primary factor for neuropathology in type 1 diabetes, which contributes to a lesser extent in type 2 diabetes, whereas insulin resistance, hyperlipidemia, and other factors may have a greater role. Two of the earliest mechanisms described from animal studies as a cause for diabetic peripheral neuropathy were the activation of the aldose reductase pathway and increased non-enzymatic glycation. However, continuing research has identified numerous other potential factors that may contribute to diabetic peripheral neuropathy, including oxidative and inflammatory stress, dysregulation of protein kinase C and hexosamine pathways, and decreased neurotrophic support. In addition, recent studies have demonstrated that peripheral neuropathy-like symptoms are present in animal models, representing pre-diabetes in the absence of hyperglycemia. CONCLUSION This complexity complicates the successful treatment of diabetic peripheral neuropathy, and results in the poor outcome of translating successful treatments from animal studies to human clinical trials.
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Affiliation(s)
- Mark Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242 USA
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, 52246 USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, 52242 USA
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Yorek MS, Obrosov A, Lu B, Gerard C, Kardon RH, Yorek MA. Effect of Inhibition or Deletion of Neutral Endopeptidase on Neuropathic Endpoints in High Fat Fed/Low Dose Streptozotocin-Treated Mice. J Neuropathol Exp Neurol 2016; 75:1072-1080. [PMID: 27634964 PMCID: PMC7714044 DOI: 10.1093/jnen/nlw083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Previously we demonstrated that a vasopeptidase inhibitor of angiotensin converting enzyme and neutral endopeptidase (NEP), a protease that degrades vaso- and neuro-active peptides, improves neural function in diabetic rodent models. The purpose of this study was to determine whether inhibition or deletion of NEP provides protection from neuropathy caused by diabetes with an emphasis on morphology of corneal nerves as a primary endpoint. Diabetes, modeling type 2, was induced in C57Bl/6J and NEP deficient mice through a combination of a high fat diet and streptozotocin. To inhibit NEP activity, diabetic C57Bl/6J mice were treated with candoxatril using a prevention or intervention protocol. Twelve weeks after the induction of diabetes in C57Bl/6J mice, the existence of diabetic neuropathy was determined through multiple endpoints including decrease in corneal nerves in the epithelium and sub-epithelium layer. Treatment of diabetic C57Bl/6J mice with candoxatril improved diabetic peripheral neuropathy and protected corneal nerve morphology with the prevention protocol being more efficacious than intervention. Unlike C57Bl/6J, mice deficient in NEP were protected from the development of neuropathologic alterations and loss of corneal nerves upon induction of diabetes. These studies suggest that NEP contributes to the development of diabetic neuropathy and may be a treatable target.
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Affiliation(s)
- Matthew S Yorek
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
| | - Alexander Obrosov
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
| | - Bao Lu
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
| | - Craig Gerard
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
| | - Randy H Kardon
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
| | - Mark A Yorek
- From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children's Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA(RHK, MAY) and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA(MAY)
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Yorek MA. Vascular Impairment of Epineurial Arterioles of the Sciatic Nerve: Implications for Diabetic Peripheral Neuropathy. Rev Diabet Stud 2015; 12:13-28. [PMID: 26676659 PMCID: PMC5397981 DOI: 10.1900/rds.2015.12.13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 04/30/2015] [Indexed: 12/11/2022] Open
Abstract
This article reviews the impact of diabetes and its treatment on vascular function with a focus on the reactivity of epineurial arterioles, blood vessels that provide circulation to the sciatic nerve. Another focus is the relationship between the dysregulation of neurovascular function and diabetic peripheral neuropathy. Diabetic peripheral neuropathy is a debilitating disorder that occurs in more than 50 percent of patients with diabetes. The etiology involves metabolic, vascular, and immunologic pathways besides neurohormonal growth factor deficiency and extracellular matrix remodeling. In the light of this complex etiology, an effective treatment for diabetic peripheral neuropathy has not yet been identified. Current opinion postulates that any effective treatment for diabetic peripheral neuropathy will require a combination of life style and therapeutic interventions. However, a more comprehensive understanding of the factors contributing to neurovascular and neural dysfunction in diabetes is needed before such a treatment strategy can be developed. After reading this review, the reader should have gained insight into the complex regulation of vascular function and blood flow to the sciatic nerve, and the impact of diabetes on numerous elements of vascular reactivity of epineurial arterioles of the sciatic nerve.
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Affiliation(s)
- Mark A Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
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Coppey L, Lu B, Gerard C, Yorek MA. Effect of Inhibition of Angiotensin-Converting Enzyme and/or Neutral Endopeptidase on Neuropathy in High-Fat-Fed C57Bl/6J Mice. J Obes 2012; 2012:326806. [PMID: 23056927 PMCID: PMC3465928 DOI: 10.1155/2012/326806] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 08/14/2012] [Accepted: 08/28/2012] [Indexed: 11/17/2022] Open
Abstract
We have demonstrated that treating diet-induced obese (DIO) mice with the vasopeptidase inhibitor ilepatril improved neural function. Vasopeptidase inhibitors block angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP) activity. We propose that increased activity of ACE and NEP contributes to pathophysiology of DIO. To address this issue C57Bl/6J mice or mice deficient in NEP were fed a high-fat diet and treated with ilepatril, enalapril, ACE inhibitor, or candoxatril, NEP inhibitor, using both prevention and intervention protocols. Endpoints included glucose utilization and neural function determination. In the prevention study glucose tolerance was impaired in DIO C57Bl/6J mice and improved with ilepatril or enalapril. Sensory nerve conduction velocity, thermal nociception, and intraepidermal nerve fiber density were impaired in DIO C57Bl/6J mice and improved with ilepatril or candoxatril. In the intervention study only enalapril improved glucose tolerance. Sensory nerve conduction velocity and intraepidermal nerve fiber density were improved by all three treatments, whereas thermal nociception was improved by ilepatril or candoxatril. In NEP-deficient mice DIO impaired glucose utilization and this was improved with enalapril. Nerve function was not impaired by DIO in NEP-deficient mice. These studies suggest that ACE and NEP play a role in pathophysiology associated with DIO.
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Affiliation(s)
- Lawrence Coppey
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA
| | - Bao Lu
- Ina Sue Perlmutter Laboratory, Children's Hospital, Department of Pediatrics and Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Craig Gerard
- Ina Sue Perlmutter Laboratory, Children's Hospital, Department of Pediatrics and Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Mark A. Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA
- *Mark A. Yorek:
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Davidson EP, Coppey LJ, Holmes A, Dake B, Yorek MA. Effect of treatment of high fat fed/low dose streptozotocin-diabetic rats with Ilepatril on vascular and neural complications. Eur J Pharmacol 2011; 668:497-506. [PMID: 21816138 DOI: 10.1016/j.ejphar.2011.07.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/23/2011] [Accepted: 07/07/2011] [Indexed: 10/17/2022]
Abstract
We have previously shown that treating streptozotocin-induced diabetic rats, an animal model of type 1 diabetes, with Ilepatril (an inhibitor of neutral endopeptidase and angiotensin converting enzyme (ACE)) improves vascular and neural functions. In this study we sought to determine the effect of Ilepatril treatment of high fat fed/low dose streptozotocin-diabetic rats, a model for type 2 diabetes, on vascular and neural complications. Following 8 weeks on a high fat diet rats were treated with 30 mg/kg streptozotocin (i.p.) and after 4 additional weeks a group of these rats was treated for 12 weeks with Ilepatril followed by analysis of neural and vascular functions. Included in these studies were age-matched control rats and rats fed a high fat diet and treated with or without Ilepatril. Diabetic and diet induced obese rats have characteristics of insulin resistance, slowing of nerve conduction velocity, thermal hypoalgesia, reduction in intraepidermal nerve fiber density in the hindpaw and impairment in vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineurial arterioles of the sciatic nerve. Treatment with Ilepatril was efficacious in improving all of these endpoints although improvement of insulin resistance in diabetic rats was minimal. These studies suggest that dual inhibition of angiotensin converting enzyme and neutral endopeptidase activity of type 2 diabetic rats is an effective approach for treatment of diabetic neural and vascular complications.
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Affiliation(s)
- Eric P Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA
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Davidson EP, Coppey LJ, Dake B, Yorek MA. Effect of Treatment of Sprague Dawley Rats with AVE7688, Enalapril, or Candoxatril on Diet-Induced Obesity. J Obes 2011; 2011:686952. [PMID: 20847891 PMCID: PMC2933895 DOI: 10.1155/2011/686952] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 06/29/2010] [Indexed: 12/30/2022] Open
Abstract
The objective of this study was to determine the effect of AVE7688, a drug that inhibits both angiotensin converting enzyme (ACE) and neutral endopeptidase (NEP) activity, on neural and vascular defects caused by diet induced obesity (DIO). Rats at 12 weeks of age were fed a standard or high fat diet with or without AVE7688 for 24 weeks. DIO rats had impaired glucose tolerance and developed sensory neuropathy. Vascular relaxation to acetylcholine and calcitonin gene-related peptide was decreased in epineurial arterioles of DIO rats. Rats fed a high fat diet containing AVE7688 did not become obese and vascular and sensory nerve dysfunction and impaired glucose tolerance were improved. DIO is associated with increased expression of NEP in epineurial arterioles. NEP degrades vasoactive peptides which may explain the decrease in neurovascular function in DIO.
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Affiliation(s)
- Eric P. Davidson
- Veteran Affairs Medical Center, Iowa City, IA 52246, USA
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Lawrence J. Coppey
- Veteran Affairs Medical Center, Iowa City, IA 52246, USA
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Brian Dake
- Veteran Affairs Medical Center, Iowa City, IA 52246, USA
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Mark A. Yorek
- Veteran Affairs Medical Center, Iowa City, IA 52246, USA
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
- *Mark A. Yorek:
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Role of the effect of inhibition of neutral endopeptidase on vascular and neural complications in streptozotocin-induced diabetic rats. Eur J Pharmacol 2010; 650:556-62. [PMID: 21040718 DOI: 10.1016/j.ejphar.2010.10.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 09/30/2010] [Accepted: 10/12/2010] [Indexed: 12/13/2022]
Abstract
We have previously shown that treating streptozotocin-induced diabetic rats, an animal model of type 1 diabetes, with Ilepatril (an inhibitor of neutral endopeptidase and angiotensin converting enzyme (ACE)) improves vascular and neural function. In this study we sought to determine the individual effect of inhibition of neutral endopeptidase and ACE on diabetes-induced vascular and neural dysfunction. After 4 weeks of untreated diabetes, rats were treated for 12 weeks with Ilepatril, Enalapril (ACE inhibitor) or Candoxatril (neutral endopeptidase inhibitor) followed by analysis of neural and vascular function. Diabetes caused slowing of motor and sensory nerve conduction, thermal hypoalgesia, reduction in intraepidermal nerve fiber density in the hindpaw and impairment in vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineural arterioles of the sciatic nerve and to atrial natriuretic peptide and calcitonin gene-related peptide in renal arteries. Inhibition of neutral endopeptidase or ACE improved neural function; however, dual inhibition of neutral endopeptidase and ACE with Ilepatril tended to have the greatest efficacy. Ilepatril and Candoxatril treatment of diabetic rats was more efficacious in improving vascular responsiveness in epineurial arterioles than treatment with Enalapril. Ilepatril, Enalapril or Candoxatril treatment of diabetic rats were all efficacious in renal arteries. These studies suggest that combination therapy may be the most effective approach for treatment of diabetic neural and vascular complications.
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Coppey L, Davidson E, Lu B, Gerard C, Yorek M. Vasopeptidase inhibitor ilepatril (AVE7688) prevents obesity- and diabetes-induced neuropathy in C57Bl/6J mice. Neuropharmacology 2010; 60:259-66. [PMID: 20849865 DOI: 10.1016/j.neuropharm.2010.09.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 08/26/2010] [Accepted: 09/08/2010] [Indexed: 01/30/2023]
Abstract
Previously we demonstrated that inhibition of neutral endopeptidase (NEP), a protease that degrades vaso- and neuro-active peptides, and angiotensin converting enzyme (ACE) with a vasopeptidase inhibitor improves vascular and neural function in diabetic rat models. The purpose of this study was to determine whether inhibition of NEP and ACE or deletion of NEP provides protection from nerve impairment caused by diabetes or diet induced obesity (DIO). To determine the role of NEP and ACE inhibition in neuropathy related to insulin-deficient diabetes or DIO we used C57Bl/6J mice treated with AVE7688, a vasopeptidase inhibitor, or NEP deficient (-/-) mice. Mice at 12 weeks of age were fed a high fat diet for 12 weeks or were diabetic for duration of 12 weeks following a single injection of high dose streptozotocin. Both a prevention and intervention protocol was used for AVE7688 treatment. Glucose utilization was impaired in DIO C57Bl/6J and NEP -/- mice. However, treating DIO C57Bl/6J or NEP -/- mice with AVE7688 improved glucose tolerance. Thermal hypoalgesia and nerve conduction slowing were present in both streptozotocin-diabetic and DIO C57Bl/6J mice but not in AVE7688 treated C57Bl/6J mice or NEP -/- mice exposed to either streptozotocin-induced diabetes or a high fat diet. Intraepidermal nerve fiber (IENF) profiles were decreased in the hindpaw of C57Bl/6J diabetic or DIO mice and this improved when the mice were treated with AVE7688. IENF profiles were not decreased in diabetic or DIO NEP (-/-) mice. These studies suggest that NEP plays a role in regulating nerve function in insulin-deficient diabetes and DIO.
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Affiliation(s)
- Lawrence Coppey
- Department of Veterans Affairs Iowa City Health Care System, University of Iowa, Iowa City, IA 52246, USA
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The roles of streptozotocin neurotoxicity and neutral endopeptidase in murine experimental diabetic neuropathy. EXPERIMENTAL DIABETES RESEARCH 2010; 2009:431980. [PMID: 20148083 PMCID: PMC2817866 DOI: 10.1155/2009/431980] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 11/18/2009] [Indexed: 01/02/2023]
Abstract
We demonstrated that inhibition of neutral endopeptidase (NEP), a protease that degrades vaso- and neuroactive peptides, improves vascular and neural function in diabetic animal models. In this study we explored the role of NEP in neuropathy related to either insulin-deficient diabetes or diet-induced obesity using NEP deficient (−/−) mice. Initial studies showed that streptozotocin, in the absence of subsequent hyperglycemia, did not induce nerve conduction slowing or paw thermal hypoalgesia. Glucose disposal was impaired in both C57Bl/6 and NEP −/− mice fed a high fat diet. Thermal hypoalgesia and nerve conduction slowing were present in both streptozotocin-diabetic and high fat fed C57Bl/6 mice but not in NEP −/− mice exposed to either streptozotocin-induced diabetes or a high fat diet. These studies suggest that streptozotocin does not induce neurotoxicity in mice and that NEP plays a role in regulating nerve function in insulin-deficient diabetes and diet-induced obesity.
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Vascular and neural dysfunctions in obese Zucker rats: effect of AVE7688. EXPERIMENTAL DIABETES RESEARCH 2009; 2009:912327. [PMID: 19536347 PMCID: PMC2695958 DOI: 10.1155/2009/912327] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 05/12/2009] [Indexed: 12/23/2022]
Abstract
The purpose of this study was to determine whether AVE7688 a drug that inhibits both angiotensin converting enzyme and neutral endopeptidase activity protects vascular and nerve functions in an animal model of metabolic syndrome. Obese Zucker rats at 20 weeks of age were treated for 12 weeks with AVE7688. Vasodilation in epineurial arterioles was measured by videomicroscopy and nerve conduction velocity was measured following electrical stimulation. Treatment with AVE7688 improved vascular relaxation in response to acetylcholine and motor and sensory nerve conduction velocity. In obese Zucker rats superoxide levels and nitrotyrosine staining were elevated in the aorta and treatment corrected both conditions. Obese Zucker rats were hypoalgesic in response to a thermal stimulus and demonstrated signs of impaired tactile response and both conditions were significantly improved with treatment. Even though obese Zucker rats are normoglycemic vascular and neural dysfunctions develop with age and can be improved by treatment with AVE7688.
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Oltman CL, Davidson EP, Coppey LJ, Kleinschmidt TL, Yorek MA. Treatment of Zucker diabetic fatty rats with AVE7688 improves vascular and neural dysfunction. Diabetes Obes Metab 2009; 11:223-33. [PMID: 18564175 PMCID: PMC2667677 DOI: 10.1111/j.1463-1326.2008.00924.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AIM Vasopeptidase inhibitors are drugs that inhibit angiotensin-converting enzyme and neutral endopeptidase (NEP). The latter is a protease that degrades vasoactive peptides and is increased in diabetes. We have previously shown that treating streptozotocin-induced diabetic rats, an animal model of type 1 diabetes, with AVE7688, a vasopeptidase inhibitor, improves neurovascular and neural function. In this study, we determined the effect of treating Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes, with AVE7688 on vascular and neural function. METHODS ZDF rats at 12 weeks of age were treated for 12 weeks with AVE7688 (500 mg/kg diet). Afterwards, vascular reactivity of epineurial arterioles of the sciatic nerve and nerve conduction velocity and blood flow was determined. RESULTS Vascular and neural function was significantly impaired in ZDF rats compared with age-matched lean (control) rats. Treating ZDF rats with AVE7688 improved vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineurial arterioles. Motor and sensory nerve conduction velocity, endoneurial blood flow and thermal nociception end-points were also improved by treatment compared with untreated ZDF rats. Superoxide and expression of NEP were increased in epineurial arterioles from ZDF rats and attenuated by treatment with AVE7688. CONCLUSIONS AVE7688 is an effective treatment for microvascular and neural disease in ZDF rats. Thus, vasopeptidase inhibitors may be an effective treatment for diabetic microvascular and neural complication in type 2 diabetes.
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Affiliation(s)
- C L Oltman
- Veteran Affairs Medical Center, Iowa City, IA 52246, USA
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Abstract
Cocaine- and amphetamine-regulated transcript (CART) and its associated peptides have been implicated in a number of physiologic processes including modulation of the hypothalamo-pituitary-adrenal (HPA) axis and cardiovascular regulation. Recently, we reported that in isolated cerebral arterioles, CART peptide (CARTp) acts directly to produce endothelium-dependent constriction via the endothelin signaling pathway. We used the rat closed cranial window model to determine the in vivo effects of CARTp on pial arteriolar diameter. Intravenous administration of 30 microg/kg CARTp produced a significant pressor effect and constriction of pial arterioles. The pressor response to systemic CARTp was blocked by the beta-adrenergic receptor antagonist propranolol (2 mg/kg IV). Direct application of 0.1 nM-1 microM CARTp to pial arterioles produced a dose-dependent and long-lasting constriction to approximately 88% of baseline diameter. The constriction response to topically applied 100 nM CARTp was blocked by both the endothelin A (ETA) receptor antagonist BQ-123 (10 microM) and the inhibitor of endothelin-converting enzyme, phosphoramidon (100 nM). These results demonstrate for the first time that CARTp constricts cerebral vessels in vivo, an action mediated by its effects on the endothelin system, specifically via activation of ETA receptors. This supports the notion that CARTp plays a physiologic role in cerebrovascular regulation, particularly during times of HPA axis activation.
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Davidson EP, Kleinschmidt TL, Oltman CL, Lund DD, Yorek MA. Treatment of streptozotocin-induced diabetic rats with AVE7688, a vasopeptidase inhibitor: effect on vascular and neural disease. Diabetes 2007; 56:355-62. [PMID: 17259379 DOI: 10.2337/db06-1180] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In epineurial arterioles, acetylcholine-mediated vascular relaxation is mediated by nitric oxide and endothelium-derived hyperpolarizing factor (EDHF), and both mechanisms are impaired by diabetes. The mediator responsible for the effect of EDHF is unknown. In epineurial arterioles, C-type natriuretic peptide (CNP) has properties consistent with EDHF-like activity. Epineurial arterioles express CNP, and exogenous CNP causes a concentration-dependent vascular relaxation. In streptozotocin-induced diabetic rats, CNP-mediated vascular relaxation in epineurial arterioles is decreased. Since CNP may be a regulator of vascular function, a vasopeptidase inhibitor may be an effective treatment for diabetes-induced vascular and neural disease. Vasopeptidase inhibitors inhibit ACE activity and neutral endopeptidase, which degrades natriuretic peptides. Streptozotocin-induced diabetic rats were treated with AVE7688 (450 mg/kg in the diet), a vasopeptidase inhibitor, for 8-10 weeks after 4 weeks of untreated diabetes. Treatment of diabetic rats corrected the diabetes-induced decrease in endoneurial blood flow, significantly improved motor and sensory nerve conduction velocity, prevented the development of hypoalgesia in the hind paw, and reduced superoxide and nitrotyrosine levels in epineurial arterioles. The diabetes-induced decrease in acetylcholine-mediated vascular relaxation by epineurial arterioles was significantly improved with treatment. These studies suggest that vasopeptidase inhibitors may be an effective approach for the treatment of diabetic vascular and neural dysfunction.
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Affiliation(s)
- Eric P Davidson
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
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15
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Iliff JJ, Alkayed NJ, Gloshani KJ, Traystman RJ, West GA. Cocaine- and amphetamine-regulated transcript (CART) peptide: a vasoactive role in the cerebral circulation. J Cereb Blood Flow Metab 2005; 25:1376-85. [PMID: 15874973 DOI: 10.1038/sj.jcbfm.9600136] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) peptides are known to be involved in the stress response and have been implicated in the regulation of the cardiovascular system. We evaluated the direct vasoactive properties of CART in the cerebral circulation and its potential mechanisms of action. Penetrating cerebral arterioles, isolated from male Sprague-Dawley rats, were cannulated using a concentric micropipette setup, pressurized and perfused. The vascular response to intraluminal and extraluminal CART peptide was characterized. The endothelium dependence of this response was assessed by means of the endothelial light-dye injury model. The nonspecific endothelin receptor antagonist PD-145065, the ET(A)-specific antagonist BQ-123, the ET(B)-specific antagonist BQ-788, and the inhibitor of endothelin-converting enzyme phosphoramidon were used to characterize the involvement of the endothelin pathway in the vascular response to CART peptide. Extraluminal and intraluminal application of CART peptide (0.1 nm to 1 micromol/L) evoked a long-lasting dose-dependent constriction of isolated penetrating cerebral arterioles to approximately 80% of resting myogenic tone. Disruption of the endothelium by the endothelial light/dye injury model resulted in the abolition of this response (P<0.05). Extraluminal administration of PD-145065, BQ-123, and phosphoramidon blocked the constriction response to CART peptide (P<0.01). The ET(B) antagonist, BQ-788, did not alter the constriction response to CART peptide. Cocaine- and amphetamine-regulated transcript peptide is a potent vasoconstrictor in the cerebral circulation. Its direct vasoactive properties are endothelium-dependent and are mediated by ET(A), not ET(B), endothelin receptors.
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Affiliation(s)
- Jeffrey J Iliff
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon 97239, USA
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16
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Zimmermann M, Vatter H, Weyrauch E, Lange BN, Krishnan R, Raabe A, Seifert V. Characterization of the potent combined endothelin(A/B)-antagonist PD 142893 on cerebral vessels. Neurol Res 2004; 26:692-7. [PMID: 15327761 DOI: 10.1179/016164104225015967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
A disturbed balance between endothelin (ET)-1 and nitric oxide (NO) seems to play a key role in the development of delayed cerebral vasospasm following subarachnoidal hemorrhage. Therefore, the effect of PD 142893 one of the first potent ET(A)- and ET(B)-receptor antagonists was characterized on the contraction and relaxation induced by ET-1 and bigET-1 on rat basilar artery (BA). Concentration-effect curves (CECs) were constructed by cumulative application of ET-1 or big ET-1 on BA ring segments with (E+) and without (E-) functionally intact endothelium. The effect of PD 142893 was determined by the modified pK(b) value and the shift between the CECs. PD 142893 inhibited the contraction by ET-1 and bigET-1. The pK(b)-values were for ET-1: 5.17 (E+) and 5.15 (E-) and for big ET-1: 5.34 (E+) and 5.57 (E-), respectively. A significant relaxation of pre-contracted segments by ET-1 or big ET-1 was neither observed in the presence nor in the absence of the receptor antagonist. The present data suggest a competitive inhibition of the ET(A)-receptor mediated contraction of cerebral arteries by PD 142893. The ET(B)-dependent relaxation of the cerebrovasculature is inhibited by PD 142893 at least in a comparable amount of contraction.
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Affiliation(s)
- Michael Zimmermann
- Department of Neurosurgery, Johann Wolfgang Goethe-University, Frankfurt, Germany.
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17
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Zimmermann M, Jung C, Raabe A, Spanehl O, Fach K, Seifert V. Inhibition of Endothelin-converting Enzyme Activity in the Rabbit Basilar Artery. Neurosurgery 2001. [DOI: 10.1227/00006123-200104000-00043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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19
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Schilling L, Vatter H, Mursch K, Ehrenreich H, Schmiedek P. Characterization of the contractile and relaxant action of the endothelin-1 precursor, big endothelin-1, in the isolated rat basilar artery. Peptides 2000; 21:91-9. [PMID: 10704724 DOI: 10.1016/s0196-9781(99)00179-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The presence of functional endothelin converting enzyme (ECE) activity in basilar artery ring segments was investigated by measuring the contractile and relaxant effects of big endothelin (ET)-1. Under resting tension conditions cumulative application of big ET1-1 elicited a concentration-related contraction with the concentration-effect curve (CEC) shifted to the right against ET-1 by a factor of 31 and 29 in segments with the endothelium intact or mechanically removed, respectively. Preincubation with the ET(A) receptor antagonist, BQ123, induced an apparently parallel rightwards shift without affecting the maximum contraction. This shift was more pronounced for ET-1 than for big ET-1. With the putative ECE inhibitor phosphoramidon (10(-3) M) in the bath a small rightwards shift of the CEC for big ET-1 was observed in control segments and a more marked one in de-endothelialized segments. In segments precontracted with prostaglandin (PG) F(2alpha) big ET-1 induced a significant although transient relaxation whereas ET-1 did not. However, in the presence of BQ123 both ET-1 and big ET-1 elicited concentration-related relaxation with a significantly higher maximum effect obtained with big ET-1. The potency was 13 fold higher for ET-1, which is markedly less than that found for contraction. The results, therefore, suggest 1) the presence of functional ECE-activity in the rat basilar artery wall, and 2) differences in the functional ECE activity located in the endothelium and media.
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Affiliation(s)
- L Schilling
- Department of Neurosurgery, Division of Neurosurgical Research, University Clinic Mannheim, Faculty of Clinical Medicine Mannheim, University Heidelberg, Theodor Kutzer-Ufer 1-3, D-68135, Mannheim, Germany.
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