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Omega-3 polyunsaturated fatty acids and corneal nerve health: Current evidence and future directions. Ocul Surf 2023; 27:1-12. [PMID: 36328309 DOI: 10.1016/j.jtos.2022.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022]
Abstract
Corneal nerves play a key role in maintaining ocular surface integrity. Corneal nerve damage, from local or systemic conditions, can lead to ocular discomfort, pain, and, if poorly managed, neurotrophic keratopathy. Omega-3 polyunsaturated fatty acids (PUFAs) are essential dietary components that play a key role in neural development, maintenance, and function. Their potential application in modulating ocular and systemic inflammation has been widely reported. Omega-3 PUFAs and their metabolites also have neuroprotective properties and can confer benefit in neurodegenerative disease. Several preclinical studies have shown that topical administration of omega-3 PUFA-derived lipid mediators promote corneal nerve recovery following corneal surgery. Dietary omega-3 PUFA supplementation can also reduce corneal epithelial nerve loss and promote corneal nerve regeneration in diabetes. Omega-3 PUFAs and their lipid mediators thus show promise as therapeutic approaches to modulate corneal nerve health in ocular and systemic disease. This review discusses the role of dietary omega-3 PUFAs in maintaining ocular surface health and summarizes the possible applications of omega-3 PUFAs in the management of ocular and systemic conditions that cause corneal nerve damage. In examining the current evidence, this review also highlights relatively underexplored applications of omega-3 PUFAs in conferring neuroprotection and addresses their therapeutic potential in mediating corneal nerve regeneration.
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Yu FSX, Lee PSY, Yang L, Gao N, Zhang Y, Ljubimov AV, Yang E, Zhou Q, Xie L. The impact of sensory neuropathy and inflammation on epithelial wound healing in diabetic corneas. Prog Retin Eye Res 2022; 89:101039. [PMID: 34991965 PMCID: PMC9250553 DOI: 10.1016/j.preteyeres.2021.101039] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 12/10/2021] [Accepted: 12/20/2021] [Indexed: 02/08/2023]
Abstract
Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes, with several underlying pathophysiological mechanisms, some of which are still uncertain. The cornea is an avascular tissue and sensitive to hyperglycemia, resulting in several diabetic corneal complications including delayed epithelial wound healing, recurrent erosions, neuropathy, loss of sensitivity, and tear film changes. The manifestation of DPN in the cornea is referred to as diabetic neurotrophic keratopathy (DNK). Recent studies have revealed that disturbed epithelial-neural-immune cell interactions are a major cause of DNK. The epithelium is supplied by a dense network of sensory nerve endings and dendritic cell processes, and it secretes growth/neurotrophic factors and cytokines to nourish these neighboring cells. In turn, sensory nerve endings release neuropeptides to suppress inflammation and promote epithelial wound healing, while resident immune cells provide neurotrophic and growth factors to support neuronal and epithelial cells, respectively. Diabetes greatly perturbs these interdependencies, resulting in suppressed epithelial proliferation, sensory neuropathy, and a decreased density of dendritic cells. Clinically, this results in a markedly delayed wound healing and impaired sensory nerve regeneration in response to insult and injury. Current treatments for DPN and DNK largely focus on managing the severe complications of the disease. Cell-based therapies hold promise for providing more effective treatment for diabetic keratopathy and corneal ulcers.
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Affiliation(s)
- Fu-Shin X Yu
- Departments of Ophthalmology and Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
| | - Patrick S Y Lee
- Departments of Ophthalmology and Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Lingling Yang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Nan Gao
- Departments of Ophthalmology and Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Yangyang Zhang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Alexander V Ljubimov
- Departments of Biomedical Sciences and Neurosurgery, Cedars-Sinai Medical Center, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Ellen Yang
- Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA
| | - Qingjun Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Lixin Xie
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China.
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Hossain MJ, Kendig MD, Letton ME, Morris MJ, Arnold R. Peripheral Neuropathy Phenotyping in Rat Models of Type 2 Diabetes Mellitus: Evaluating Uptake of the Neurodiab Guidelines and Identifying Future Directions. Diabetes Metab J 2022; 46:198-221. [PMID: 35385634 PMCID: PMC8987683 DOI: 10.4093/dmj.2021.0347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/25/2022] [Indexed: 11/08/2022] Open
Abstract
Diabetic peripheral neuropathy (DPN) affects over half of type 2 diabetes mellitus (T2DM) patients, with an urgent need for effective pharmacotherapies. While many rat and mouse models of T2DM exist, the phenotyping of DPN has been challenging with inconsistencies across laboratories. To better characterize DPN in rodents, a consensus guideline was published in 2014 to accelerate the translation of preclinical findings. Here we review DPN phenotyping in rat models of T2DM against the 'Neurodiab' criteria to identify uptake of the guidelines and discuss how DPN phenotypes differ between models and according to diabetes duration and sex. A search of PubMed, Scopus and Web of Science databases identified 125 studies, categorised as either diet and/or chemically induced models or transgenic/spontaneous models of T2DM. The use of diet and chemically induced T2DM models has exceeded that of transgenic models in recent years, and the introduction of the Neurodiab guidelines has not appreciably increased the number of studies assessing all key DPN endpoints. Combined high-fat diet and low dose streptozotocin rat models are the most frequently used and well characterised. Overall, we recommend adherence to Neurodiab guidelines for creating better animal models of DPN to accelerate translation and drug development.
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Affiliation(s)
- Md Jakir Hossain
- Department of Pharmacology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
| | - Michael D. Kendig
- Department of Pharmacology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
| | - Meg E. Letton
- Department of Exercise Physiology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
| | - Margaret J. Morris
- Department of Pharmacology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
| | - Ria Arnold
- Department of Pharmacology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
- Department of Exercise Physiology, School of Medical Sciences, University of New South Wales (UNSW) Sydney, Sydney, Australia
- Department of Exercise and Rehabilitation, School of Medical, Indigenous and Health Science, University of Wollongong, Wollongong, Australia
- Corresponding author: Ria Arnold https://orcid.org/0000-0002-7469-6587 Department of Exercise Physiology, School of Health Sciences, UNSW Sydney, Sydney, NSW 2052, Australia E-mail:
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Hu W, Zhang D, Tu H, Li YL. Reduced Cell Excitability of Cardiac Postganglionic Parasympathetic Neurons Correlates With Myocardial Infarction-Induced Fatal Ventricular Arrhythmias in Type 2 Diabetes Mellitus. Front Neurosci 2021; 15:721364. [PMID: 34483832 PMCID: PMC8416412 DOI: 10.3389/fnins.2021.721364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/30/2021] [Indexed: 01/09/2023] Open
Abstract
Objective Withdrawal of cardiac vagal activity is considered as one of the important triggers for acute myocardial infarction (MI)-induced ventricular arrhythmias in type 2 diabetes mellitus (T2DM). Our previous study demonstrated that cell excitability of cardiac parasympathetic postganglionic (CPP) neurons was reduced in T2DM rats. This study investigated whether cell excitability of CPP neurons is associated with cardiac vagal activity and MI-induced ventricular arrhythmias in T2DM rats. Methods Rat T2DM was induced by a high-fat diet plus streptozotocin injection. MI-evoked ventricular arrhythmia was achieved by surgical ligation of the left anterior descending coronary artery. Twenty-four-hour, continuous ECG recording was used to quantify ventricular arrhythmic events and heart rate variability (HRV) in conscious rats. The power spectral analysis of HRV was used to evaluate autonomic function. Cell excitability of CPP neurons was measured by the whole-cell patch-clamp technique. Results Twenty-four-hour ECG data demonstrated that MI-evoked fatal ventricular arrhythmias are more severe in T2DM rats than that in sham rats. In addition, the Kaplan-Meier analysis demonstrated that the survival rate over 2 weeks after MI is significantly lower in T2DM rats (15% in T2DM+MI) compared to sham rats (75% in sham+MI). The susceptibility to ventricular tachyarrhythmia elicited by programmed electrical stimulation was higher in anesthetized T2DM+MI rats than that in rats with MI or T2DM alone (7.0 ± 0.58 in T2DM+MI group vs. 3.5 ± 0.76 in sham+MI). Moreover, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of increase of left ventricular pressure (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in T2DM rats. Furthermore, T2DM increased heterogeneity of ventricular electrical activities and reduced cardiac parasympathetic activity and cell excitability of CPP neurons (current threshold-inducing action potentials being 62 ± 3.3 pA in T2DM rats without MI vs. 27 ± 1.9 pA in sham rats without MI). However, MI did not alter vagal control of the ventricular function and CPP neuronal excitability, although it also induced cardiac autonomic dysfunction and enhanced heterogeneity of ventricular electrical activities. Conclusion The reduction of CPP neuron excitability is involved in decreased cardiac vagal function, including cardiac parasympathetic activity and vagal control of ventricular function, which is associated with MI-induced high mortality and malignant ventricular arrhythmias in T2DM.
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Affiliation(s)
- Wenfeng Hu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States.,Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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Abstract
Neuropathy is a common complication of long-term diabetes that impairs quality of life by producing pain, sensory loss and limb amputation. The presence of neuropathy in both insulin-deficient (type 1) and insulin resistant (type 2) diabetes along with the slowing of progression of neuropathy by improved glycemic control in type 1 diabetes has caused the majority of preclinical and clinical investigations to focus on hyperglycemia as the initiating pathogenic lesion. Studies in animal models of diabetes have identified multiple plausible mechanisms of glucotoxicity to the nervous system including post-translational modification of proteins by glucose and increased glucose metabolism by aldose reductase, glycolysis and other catabolic pathways. However, it is becoming increasingly apparent that factors not necessarily downstream of hyperglycemia can also contribute to the incidence, progression and severity of neuropathy and neuropathic pain. For example, peripheral nerve contains insulin receptors that transduce the neurotrophic and neurosupportive properties of insulin, independent of systemic glucose regulation, while the detection of neuropathy and neuropathic pain in patients with metabolic syndrome and failure of improved glycemic control to protect against neuropathy in cohorts of type 2 diabetic patients has placed a focus on the pathogenic role of dyslipidemia. This review provides an overview of current understanding of potential initiating lesions for diabetic neuropathy and the multiple downstream mechanisms identified in cell and animal models of diabetes that may contribute to the pathogenesis of diabetic neuropathy and neuropathic pain.
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Effects of Different n6/n3 PUFAs Dietary Ratio on Cardiac Diabetic Neuropathy. Nutrients 2020; 12:nu12092761. [PMID: 32927766 PMCID: PMC7551002 DOI: 10.3390/nu12092761] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 12/16/2022] Open
Abstract
We studied the influence of experimentally induced DM1, in combination with different dietary n6:n3 polyunsaturated fatty acid (PUFA) ratios on different types of nerve fibers in rat myocardium, in order to reveal whether protective/unfavorable effects of different PUFAs on myocardial function in diabetic patients could be a (partial) repercussion of their effect on the changes in cardiac innervation. The control group (c) and diabetic group (stz) were fed with an n6/n3 ratio of ≈7; the diet of the stz+n6 group had an n6/n3 ratio ≈60, while the diet for the stz+DHA group contained 2.5% of fish oil (containing 16% eicosapentaenoic acid—EPA and 19% docosahexaenoic acid—DHA), n6/n3 ratio of ≈1. DM1 was induced by i.p. injection of streptozotocin (55 mg/kg) and rats were euthanized 30 days after induction. Immunohistochemistry was used for the detection and quantification of different types of neuronal fibers in the cardiac septum. We found changes in cardiac innervations characteristics for the initial phase of experimental DM1, which manifested as an increase in total number and area density of all neuronal fibers, measured by Pgp9.5 immunoreactivity. By detailed analysis, we found that this increase consisted mostly of heavy myelinated NF200 immunoreactive fibers and TH immunoreactive sympathetic fibers, while the density of ChAT immunoreactive parasympathetic fibers decreased. In the deep (middle) part of the myocardium, where rare fibers (of all studied types) were found, significant differences were not found. Surprisingly, we found a more consistent protective effect of n6 PUFAs, in comparison to n3 PUFAs supplementation. These results may provide a better understanding of the potential impacts of different PUFA ratios in the diet of diabetic patients on cardiac innervation and genesis and outcome of diabetic autonomic cardiomyopathy.
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Russell JS, Griffith TA, Naghipour S, Vider J, Du Toit EF, Patel HH, Peart JN, Headrick JP. Dietary α-Linolenic Acid Counters Cardioprotective Dysfunction in Diabetic Mice: Unconventional PUFA Protection. Nutrients 2020; 12:nu12092679. [PMID: 32887376 PMCID: PMC7551050 DOI: 10.3390/nu12092679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/12/2020] [Accepted: 08/26/2020] [Indexed: 12/15/2022] Open
Abstract
Whether dietary omega-3 (n-3) polyunsaturated fatty acid (PUFA) confers cardiac benefit in cardiometabolic disorders is unclear. We test whether dietary -linolenic acid (ALA) enhances myocardial resistance to ischemia-reperfusion (I-R) and responses to ischemic preconditioning (IPC) in type 2 diabetes (T2D); and involvement of conventional PUFA-dependent mechanisms (caveolins/cavins, kinase signaling, mitochondrial function, and inflammation). Eight-week male C57Bl/6 mice received streptozotocin (75 mg/kg) and 21 weeks high-fat/high-carbohydrate feeding. Half received ALA over six weeks. Responses to I-R/IPC were assessed in perfused hearts. Localization and expression of caveolins/cavins, protein kinase B (AKT), and glycogen synthase kinase-3 β (GSK3β); mitochondrial function; and inflammatory mediators were assessed. ALA reduced circulating leptin, without affecting body weight, glycemic dysfunction, or cholesterol. While I-R tolerance was unaltered, paradoxical injury with IPC was reversed to cardioprotection with ALA. However, post-ischemic apoptosis (nucleosome content) appeared unchanged. Benefit was not associated with shifts in localization or expression of caveolins/cavins, p-AKT, p-GSK3β, or mitochondrial function. Despite mixed inflammatory mediator changes, tumor necrosis factor-a (TNF-a) was markedly reduced. Data collectively reveal a novel impact of ALA on cardioprotective dysfunction in T2D mice, unrelated to caveolins/cavins, mitochondrial, or stress kinase modulation. Although evidence suggests inflammatory involvement, the basis of this "un-conventional" protection remains to be identified.
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Affiliation(s)
- Jake S. Russell
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - Tia A. Griffith
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - Saba Naghipour
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - Jelena Vider
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - Eugene F. Du Toit
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - Hemal H. Patel
- VA San Diego Healthcare System and Department of Anesthesiology, University of California, San Diego, CA 92093, USA;
| | - Jason N. Peart
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
| | - John P. Headrick
- School of Medical Science, Griffith University Gold Coast, Southport QLD 4217, Australia; (J.S.R.); (T.A.G.); (S.N.); (J.V.); (E.F.D.T.); (J.N.P.)
- Correspondence: ; Tel.: +61-7-5552-8292
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Coppey L, Davidson E, Shevalye H, Obrosov A, Torres M, Yorek MA. Progressive Loss of Corneal Nerve Fibers and Sensitivity in Rats Modeling Obesity and Type 2 Diabetes Is Reversible with Omega-3 Fatty Acid Intervention: Supporting Cornea Analyses as a Marker for Peripheral Neuropathy and Treatment. Diabetes Metab Syndr Obes 2020; 13:1367-1384. [PMID: 32425569 PMCID: PMC7189026 DOI: 10.2147/dmso.s247571] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/31/2020] [Indexed: 12/21/2022] Open
Abstract
PURPOSE To determine whether cornea nerve fiber density and/or corneal function are valid markers for early detection and treatment of peripheral neuropathy in rats modeling prediabetes and type 2 diabetes. METHODS High-fat feeding combined without or with low-dose streptozotocin was used to create rat models for prediabetes and type 2 diabetes that were longitudinally studied for loss of structure and function of sensory nerves in the cornea and skin as well as nerve conduction velocity and vascular reactivity of epineurial arterioles. There were three time points examined in each of the three conditions with 12 rats per group. The latest time point (24 weeks of high-fat diet with or without 16 weeks of hyperglycemia) was used to examine reversibility of neuro and vascular pathology following 16 weeks of treatment with menhaden oil, a natural source of long-chain omega-3 polyunsaturated fatty acids. The number of rats in the intervention study ranged from 6 to 17. RESULTS Our longitudinal study demonstrated that vascular and neural dysfunction associated with obesity or type 2 diabetes occur early and are progressive. Decrease in cornea nerve fiber length and function were valid markers of disease in both the pre-diabetic and diabetic rat models and were more sensitive than decrease in intraepidermal nerve fiber density of the skin and thermal nociception of the hindpaw. Late intervention with menhaden oil significantly reversed both vascular and peripheral nerve damage induced by chronic obesity or type 2 diabetes. CONCLUSION These studies provide support for examination of corneal structure and function as an early marker of peripheral neuropathy in prediabetes and type 2 diabetes. Furthermore, we demonstrate that omega-3 polyunsaturated fatty acids derived from fish oil are an effective treatment for peripheral neuropathy that occurs with chronic obesity or type 2 diabetes.
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Affiliation(s)
- Lawrence Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Eric Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Alexander Obrosov
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Michael Torres
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Mark A Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
- Department of Veterans Affairs, Iowa City Health Care System, Iowa City, IA, USA
- Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA
- Correspondence: Mark A Yorek Department of Veterans Affairs, Iowa City Health Care System, Iowa City, IA52246Tel +1-319-338-0581 ext. 7696Fax +1-319-339-7162 Email
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Specialized pro-resolving mediators in diabetes: novel therapeutic strategies. Clin Sci (Lond) 2019; 133:2121-2141. [DOI: 10.1042/cs20190067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 02/07/2023]
Abstract
AbstractDiabetes mellitus (DM) is an important metabolic disorder characterized by persistent hyperglycemia resulting from inadequate production and secretion of insulin, impaired insulin action, or a combination of both. Genetic disorders and insulin receptor disorders, environmental factors, lifestyle choices and toxins are key factors that contribute to DM. While it is often referred to as a metabolic disorder, modern lifestyle choices and nutrient excess induce a state of systemic chronic inflammation that results in the increased production and secretion of inflammatory cytokines that contribute to DM. It is chronic hyperglycemia and the low-grade chronic-inflammation that underlies the development of microvascular and macrovascular complications leading to damage in a number of tissues and organs, including eyes, vasculature, heart, nerves, and kidneys. Improvements in the management of risk factors have been beneficial, including focus on intensified glycemic control, but most current approaches only slow disease progression. Even with recent studies employing SGLT2 inhibitors demonstrating protection against cardiovascular and kidney diseases, kidney function continues to decline in people with established diabetic kidney disease (DKD). Despite the many advances and a greatly improved understanding of the pathobiology of diabetes and its complications, there remains a major unmet need for more effective therapeutics to prevent and reverse the chronic complications of diabetes. More recently, there has been growing interest in the use of specialised pro-resolving mediators (SPMs) as an exciting therapeutic strategy to target diabetes and the chronic complications of diabetes.
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Coppey L, Davidson E, Shevalye H, Obrosov A, Yorek M. Effect of Early and Late Interventions with Dietary Oils on Vascular and Neural Complications in a Type 2 Diabetic Rat Model. J Diabetes Res 2019; 2019:5020465. [PMID: 31485451 PMCID: PMC6702827 DOI: 10.1155/2019/5020465] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/28/2019] [Accepted: 07/08/2019] [Indexed: 02/07/2023] Open
Abstract
AIMS Determine the effect of dietary oils enriched in different mono- or polyunsaturated fatty acids, i.e., olive oil (18 : 1, oleic acid), safflower oil (18 : 2 n-6, linoleic acid), flaxseed oil (18 : 3 n-3, alpha linolenic acid), evening primrose oil (18 : 3 n-6, gamma linolenic acid), or menhaden oil (20:5/22 : 6 n-3 eicosapentaenoic/docosahexaenoic acids), on vascular and neural complications in high-fat-fed low-dose streptozotocin-treated Sprague-Dawley rats, an animal model for late-stage type 2 diabetes. MATERIALS AND METHODS Rats were fed a high-fat diet (45% kcal as fat primarily derived from lard) for 8 weeks and then treated with a low dose of streptozotocin (30 mg/kg) in order to induce hyperglycemia. After an additional 8 (early intervention) or 20 (late intervention) weeks, the different groups of rats were fed diets with 1/2 of the kcal of fat derived from lard replaced by the different dietary oils. In addition, a control group fed a standard diet (4.25% kcal as fat) and a diabetic group maintained on the high-fat diet were maintained. The treatment period was approximately 16 weeks. The endpoints evaluated included vascular reactivity of epineurial arterioles, motor and sensory nerve conduction velocity, thermal and corneal sensitivity, and innervation of sensory nerves in the cornea and skin. RESULTS Our findings show that menhaden and flaxseed oil provided the greatest benefit for correcting peripheral nerve damage caused by diabetes, whereas enriching the high-fat diet with menhaden oil provided the most benefit to acetylcholine-mediated vascular relaxation of epineurial arterioles of the sciatic nerve. Enriching the diets with fatty acids derived from the other oils provided none to partial improvements. CONCLUSIONS These studies imply that long-chain n-6 and n-3 polyunsaturated fatty acids could be an effective treatment for diabetic peripheral neuropathy with n-3 polyunsaturated fatty acids derived from fish oil being the most effective.
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MESH Headings
- Animals
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/diet therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/diet therapy
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Diabetic Angiopathies/diet therapy
- Diabetic Angiopathies/metabolism
- Diabetic Angiopathies/physiopathology
- Diabetic Neuropathies/diet therapy
- Diabetic Neuropathies/metabolism
- Diabetic Neuropathies/physiopathology
- Diet, High-Fat
- Dietary Fats, Unsaturated/administration & dosage
- Dietary Fats, Unsaturated/pharmacology
- Drug Administration Schedule
- Fatty Liver/metabolism
- Fatty Liver/pathology
- Fatty Liver/physiopathology
- Lipid Metabolism/drug effects
- Male
- Rats
- Rats, Sprague-Dawley
- Sciatic Nerve/drug effects
- Sciatic Nerve/physiopathology
- Streptozocin
- Time Factors
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Affiliation(s)
- Lawrence Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Eric Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Alexander Obrosov
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Mark Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, USA
- Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA
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Abstract
PURPOSE OF REVIEW This review will summarize recent findings of the effect of supplemental fatty acids, with an emphasis on omega-3 polyunsaturated fatty acids, as a treatment for diabetic peripheral neuropathy. RECENT FINDINGS Pre-clinical studies have provided evidence that treating diabetic rodents with δ linolenic acid (omega-6 18:3) and to a greater extent with eicosapentaenoic and docosahexaenoic acids (omega-3 20:5 and 22:6, respectively) improve and even reverse vascular and neural deficits. Additional studies have shown resolvins, metabolites of eicosapentaenoic and docosahexaenoic acids, can induce neurite outgrowth in neuron cultures and that treating type 1 or type 2 diabetic mice with resolvin D1 or E1 provides benefit for peripheral neuropathy similar to fish oil. Omega-3 polyunsaturated fatty acids derived from fish oil and their derivatives have anti-inflammatory properties and could provide benefit for diabetic peripheral neuropathy. However, clinical trials are needed to determine whether this statement is true.
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Affiliation(s)
- Mark A Yorek
- Department of Veterans Affairs Iowa City Health Care System, Room 127, Building 41, Iowa City, IA, 52246, USA.
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, 52242, USA.
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Impaired Corneal Sensation and Nerve Loss in a Type 2 Rat Model of Chronic Diabetes Is Reversible With Combination Therapy of Menhaden Oil, α-Lipoic Acid, and Enalapril. Cornea 2018; 36:725-731. [PMID: 28476051 DOI: 10.1097/ico.0000000000001182] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE This study investigated the efficacy of monotherapy versus combination of menhaden oil, α-lipoic acid, and enalapril on corneal sensation and morphometry and other neuropathy-related endpoints in a rat model of type 2 diabetes. METHODS Male Sprague-Dawley rats (aged 12 weeks) were fed a high-fat diet for 8 weeks followed by 30 mg/kg streptozotocin. After 16 weeks of hyperglycemia, 12-week treatments consisting of menhaden oil, α-lipoic acid, enalapril, or their combination were initiated. Before and after treatments, we performed analyses of multiple neural and vascular endpoints including corneal sensitivity, corneal nerve density, vascular reactivity of epineurial arterioles, motor and sensory nerve conduction velocity, intraepidermal nerve fiber density, and thermal nociception. RESULTS Before treatment, all the neural and vascular endpoints in diabetic rats were impaired. Treating diabetic rats with monotherapy was effective in improving neural and vascular deficits with menhaden oil being most efficacious. However, the combination therapy provided the greatest benefit and improved/reversed all nerve and vascular deficits. The effect of combination therapy on corneal relative sensitivity and structure (in mm/mm), primary endpoints for this study, for control, diabetic, and diabetic treated rats was 4.2 ± 1.4 and 7.5 ± 0.5, 12.1 ± 1.3* and 3.8 ± 0.2*, and 6.6 ± 2.3 and 7.3 ± 0.5, respectively (*P < 0.05 compared with control rats; P < 0.05 compared with diabetic rats). CONCLUSIONS These studies suggest that a combination therapeutic approach may be most effective for treating vascular and neural complications of type 2 diabetes.
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Coppey L, Davidson E, Shevalye H, Torres ME, Yorek MA. Effect of dietary oils on peripheral neuropathy-related endpoints in dietary obese rats. Diabetes Metab Syndr Obes 2018; 11:117-127. [PMID: 29674850 PMCID: PMC5898889 DOI: 10.2147/dmso.s159071] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE This study aimed to determine the effect of dietary oils (olive, safflower, evening primrose, flaxseed, or menhaden) enriched in different mono unsaturated fatty acids or polyunsaturated fatty acids on peripheral neuropathies in diet-induced obese Sprague-Dawley rats. MATERIALS AND METHODS Rats at 12 weeks of age were fed a high-fat diet (45% kcal) for 16 weeks. Afterward, the rats were fed diets with 50% of the kilocalories of fat derived from lard replaced by the different dietary oils. In addition, a control group fed a standard diet (4% kcal fat) and a high fat fed group (45% kcal) were maintained. The treatment period was 32 weeks. The endpoints evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and vascular relaxation by epineurial arterioles. RESULTS Menhaden oil provided the greatest benefit for improving peripheral nerve damage caused by dietary obesity. Similar results were obtained when we examined acetylcholine-mediated vascular relaxation of epineurial arterioles of the sciatic nerve. Enriching the diets with fatty acids derived from the other oils provided minimal to partial improvements. CONCLUSION These studies suggest that omega-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for neural and vascular complications associated with obesity.
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Affiliation(s)
- Lawrence Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Eric Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Michael E Torres
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Mark A Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, USA
- Department of Veterans Affairs, Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA
- Correspondence: Mark A Yorek, Building 41, Room 127, 601 Highway 6 West, Veteran Affairs Medical Center, Iowa City, IA 52246, USA, Tel +1 319 338 0581, ext 7696, Fax +1 319 339 7162, Email
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Davidson EP, Coppey LJ, Shevalye H, Obrosov A, Yorek MA. Effect of Dietary Content of Menhaden Oil with or without Salsalate on Neuropathic Endpoints in High-Fat-Fed/Low-Dose Streptozotocin-Treated Sprague Dawley Rats. J Diabetes Res 2018; 2018:2967127. [PMID: 30057911 PMCID: PMC6051246 DOI: 10.1155/2018/2967127] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/03/2018] [Indexed: 12/18/2022] Open
Abstract
In this study, we wanted to extend our investigation of the efficacy of fish oil with or without salsalate on vascular and neural complications using a type 2 diabetic rat model. Four weeks after the onset of hyperglycemia, diabetic rats were treated via the diet with 3 different amounts of menhaden oil with or without salsalate for 12 weeks. Afterwards, vascular reactivity of epineurial arterioles and neuropathy-related endpoints were examined. The addition of salsalate to high-fat diets enriched with 10% or 25% kcal of menhaden oil protected vascular reactivity to acetylcholine and calcium gene-related peptide, motor and sensory nerve conduction velocity, thermal nociception, intraepidermal nerve fiber density, and cornea sensitivity to a greater extent than 10% or 25% menhaden oil alone. Vascular and neural function was maximally protected with diet containing 45% kcal as menhaden oil, and adding salsalate did not provide any additional benefit. Salsalate alone in the high-fat diet of diabetic rats provided minimal protection/improvement of vascular and neural dysfunction. These studies imply that dietary salsalate in combination with lower amounts of menhaden oil can provide greater benefit toward diabetes-induced vascular and neural impairment than menhaden oil alone.
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Affiliation(s)
- Eric P. Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Lawrence J. Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Alexander Obrosov
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Mark A. 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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15
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Obrosov A, Coppey LJ, Shevalye H, Yorek MA. Effect of Fish Oil vs. Resolvin D1, E1, Methyl Esters of Resolvins D1 or D2 on Diabetic Peripheral Neuropathy. ACTA ACUST UNITED AC 2017; 8. [PMID: 29423332 PMCID: PMC5800519 DOI: 10.4172/2155-9562.1000453] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Objective Fish oil is enriched in omega-3 polyunsaturated fatty acids primarily eicosapentaenoic and docosahexaenoic fatty acids. Metabolites of these two polyunsaturated fatty acids include the E and D series resolvins. Omega-3 polyunsaturated fatty acids and resolvins have been reported to have anti-inflammatory and neuroprotective properties. The objective of this study was to evaluate the efficacy of menhaden oil, a fish oil derived from the menhaden, resolvins D1 and E1 and the methyl esters of resolvins D1 and D2 on diabetic peripheral neuropathy. Hypothesis being examined was that the methyl esters of resolvins D1 and D2 would be move efficacious than resolvins D1 or E1 due to an extended half-life. Methods A model of type 2 diabetes in C57BL/6J mice was created through a combination of a high fat diet followed 8 weeks later with treatment of low dosage of streptozotocin. After 8 weeks of untreated hyperglycemia type 2 diabetic mice were treated for 8 weeks with menhaden oil in the diet or daily injections of 1 ng/g body weight resolvins D1, E1 or methyl esters of resolvins D1 or D2. Afterwards, multiple neurological endpoints were examined. Results Menhaden oil or resolvins did not improve hyperglycemia. Untreated diabetic mice were thermal hypoalgesic, had mechanical allodynia, reduced motor and sensory nerve conduction velocities and decreased innervation of the cornea and skin. These endpoints were significantly improved with menhaden oil or resolvin treatment. However, the methyl esters of resolvins D1 or D2, contrary to our hypothesis, were generally less potent than menhaden oil or resolvins D1 or E1. Conclusion These studies further support omega-3 polyunsaturated fatty acids derived from fish oil via in part due to their metabolites could be an effective treatment for diabetic neuropathy.
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Affiliation(s)
| | | | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, USA
| | - Mark A Yorek
- Department of Internal Medicine, University of Iowa, Iowa City, USA.,Department of Veterans Affairs, Iowa City Health Care System, Iowa City, USA.,Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, USA
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Yorek MS, Obrosov A, Shevalye H, Coppey LJ, Kardon RH, Yorek MA. Early vs. late intervention of high fat/low dose streptozotocin treated C57Bl/6J mice with enalapril, α-lipoic acid, menhaden oil or their combination: Effect on diabetic neuropathy related endpoints. Neuropharmacology 2016; 116:122-131. [PMID: 28025096 DOI: 10.1016/j.neuropharm.2016.12.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/28/2016] [Accepted: 12/21/2016] [Indexed: 01/06/2023]
Abstract
We have previously demonstrated that enalapril, α-lipoic acid and menhaden (fish) oil has potential as a treatment for diabetic peripheral neuropathy. In this study we sought to determine the efficacy of these treatments individually or in combination on multiple neuropathic endpoints in a high fat fed low dose streptozotocin treated mouse, a model of type 2 diabetes, following early or late intervention. Four or twelve weeks after the onset of hyperglycemia, diabetic mice were treated with enalapril, α-lipoic acid, menhaden oil or their combination for 12 weeks. Afterwards, endpoints including glucose tolerance, motor and sensory nerve conduction velocity, thermal nociception, and intraepidermal and cornea nerve fiber density was determined. Glucose clearance was impaired in diabetic mice and significantly improved only with combination treatment and early intervention. Diabetes caused steatosis, slowing of motor and sensory nerve conduction velocity, thermal hypoalgesia and reduction in intraepidermal and cornea nerve fiber density. Treating diabetic mice with enalapril, α-lipoic acid or menhaden oil partially protected diabetic mice from these deficits, whereas the combination of these three treatments was more efficacious following early or late intervention. These studies suggest that a combination therapy may be more effective for treating neural complications of type 2 diabetes.
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Affiliation(s)
- Matthew S Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, 52246, USA; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, 52246, USA.
| | - Alexander Obrosov
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA.
| | - Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA.
| | - Lawrence J Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA.
| | - Randy H Kardon
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA, 52246, USA; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, 52242, USA; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, 52246, 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, 52242, USA; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, 52246, USA; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, 52242, USA.
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17
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Davidson EP, Holmes A, Coppey LJ, Yorek MA. Effect of combination therapy consisting of enalapril, α-lipoic acid, and menhaden oil on diabetic neuropathy in a high fat/low dose streptozotocin treated rat. Eur J Pharmacol 2015; 765:258-67. [PMID: 26291662 DOI: 10.1016/j.ejphar.2015.08.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/10/2015] [Accepted: 08/11/2015] [Indexed: 01/20/2023]
Abstract
We have previously demonstrated that treating diabetic rats with enalapril, an angiotensin converting enzyme (ACE) inhibitor, α-lipoic acid, an antioxidant, or menhaden oil, a natural source of omega-3 fatty acids can partially improve diabetic peripheral neuropathy. In this study we sought to determine the efficacy of combining these three treatments on vascular and neural complications in a high fat fed low dose streptozotocin treated rat, a model of type 2 diabetes. Rats were fed a high fat diet for 8 weeks followed by a 30 mg/kg dose of streptozotocin. Eight weeks after the onset of hyperglycemia diabetic rats were treated with a combination of enalapril, α-lipoic acid and menhaden oil. Diabetic rats not receiving treatment were continued on the high fat diet. Glucose clearance was impaired in diabetic rats and significantly improved with treatment. Diabetes caused steatosis, elevated serum lipid levels, slowing of motor and sensory nerve conduction, thermal hypoalgesia, reduction in intraepidermal nerve fiber profiles, decrease in cornea sub-basal nerve fiber length and corneal sensitivity and impairment in vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineurial arterioles of the sciatic nerve. Treating diabetic rats with the combination of enalapril, α-lipoic acid and menhaden oil reversed all these deficits to near control levels except for motor nerve conduction velocity which was also significantly improved compared to diabetic rats but remained significantly decreased compared to control rats. These studies suggest that a combination therapeutic approach may be most effective for treating vascular and neural complications of type 2 diabetes.
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Affiliation(s)
- Eric P Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, 52242 IA, USA
| | - Amey Holmes
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, 52246 IA, USA
| | - Lawrence J Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, 52242 IA, USA
| | - Mark A Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, 52246 IA, USA; Department of Internal Medicine, University of Iowa, Iowa City, 52242 IA, USA; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, 52242 IA, USA.
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18
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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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19
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Shevalye H, Yorek MS, Coppey LJ, Holmes A, Harper MM, Kardon RH, Yorek MA. Effect of enriching the diet with menhaden oil or daily treatment with resolvin D1 on neuropathy in a mouse model of type 2 diabetes. J Neurophysiol 2015; 114:199-208. [PMID: 25925322 DOI: 10.1152/jn.00224.2015] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 04/24/2015] [Indexed: 12/14/2022] Open
Abstract
The purpose of this study was to determine the effect of supplementing the diet of a mouse model of type 2 diabetes with menhaden (fish) oil or daily treatment with resolvin D1 on diabetic neuropathy. The end points evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and the retinal ganglion cell complex thickness. Menhaden oil is a natural source for n-3 polyunsaturated fatty acids, which have been shown to have beneficial effects in other diseases. Resolvin D1 is a metabolite of docosahexaenoic acid and is known to have anti-inflammatory and neuroprotective properties. To model type 2 diabetes, mice were fed a high-fat diet for 8 wk followed by a low dosage of streptozotocin. After 8 wk of hyperglycemia, mice in experimental groups were treated for 6 wk with menhaden oil in the diet or daily injections of 1 ng/g body wt resolvin D1. Our findings show that menhaden oil or resolvin D1 did not improve elevated blood glucose, HbA1C, or glucose utilization. Untreated diabetic mice were thermal hypoalgesic, had reduced motor and sensory nerve conduction velocities, had decreased innervation of the cornea and skin, and had thinner retinal ganglion cell complex. These end points were significantly improved with menhaden oil or resolvin D1 treatment. Exogenously, resolvin D1 stimulated neurite outgrowth from primary cultures of dorsal root ganglion neurons from normal mice. These studies suggest that n-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for diabetic neuropathy.
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Affiliation(s)
- Hanna Shevalye
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Matthew S Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa; and
| | - Lawrence J Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Amey Holmes
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa
| | - Matthew M Harper
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa; and
| | - Randy H Kardon
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa; and
| | - Mark A Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa; Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa; and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
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Combined oral supplementation of fish oil and quercetin enhances neuroprotection in a chronic rotenone rat model: relevance to Parkinson's disease. Neurochem Res 2015; 40:894-905. [PMID: 25687767 DOI: 10.1007/s11064-015-1542-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 01/24/2023]
Abstract
While the neuromodulatory efficacy of n-3 polyunsaturated fatty acids present in fish and fish oil (FO) are well known, some evidence in animal models suggests that chronic consumption of FO supplements may predispose the brain to lipid peroxidation. In view of this, recent approaches envisage the use of dietary antioxidants as adjuncts with FO to obtain a better clinical outcome in neurological disorders. In furtherance of our previous work, in the present study, we examined whether enrichment of FO with quercetin (Q) would enhance the neuroprotective outcome employing a chronic rotenone (ROT) model of neurotoxicity in rats. Growing male rats supplemented either with FO (2 mL/kg bw) or Q (25 mg/kg bw) or FO + Q for 28 days were administered with ROT (0.5 mg/kg bw, 21 days). Monitoring the behavioral phenotype by a battery of tests, terminally, oxidative response in brain regions, mitochondrial dysfunctions and striatal dopamine levels were determined. While both FO and Q offered varying degree of protection, the FO + Q combination offered a higher degree of protection. FO + Q combination significantly attenuated behavioral impairments, restored the ROT-induced oxidative markers, depleted dopamine levels in striatum and reduced mitochondrial dysfunction. These salient findings besides corroborating with our previous data suggest that enrichment of FO with Q indeed offers a higher degree of neuroprotection under chronic exposure to a model neurotoxin such as ROT. Hence, we propose that a combination of FO with known antioxidants such as quercetin is more likely to provide a superior therapeutic advantage in the prevention/treatment of oxidative stress-mediated neurodegenerative conditions such as Parkinson's disease.
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21
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Dominguez JM, Yorek MA, Grant MB. Combination therapies prevent the neuropathic, proinflammatory characteristics of bone marrow in streptozotocin-induced diabetic rats. Diabetes 2015; 64:643-53. [PMID: 25204979 PMCID: PMC4876792 DOI: 10.2337/db14-0433] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We previously showed that peripheral neuropathy of the bone marrow was associated with loss of circadian rhythmicity of stem/progenitor cell release into the circulation. Bone marrow neuropathy results in dramatic changes in hematopoiesis that lead to microvascular complications, inflammation, and reduced endothelial repair. This series of events represents early pathogenesis before development of diabetic retinopathy. In this study we characterized early alterations within the bone marrow of streptozotocin (STZ)-induced diabetic rats following treatments that prevent experimental peripheral neuropathy. We asked whether bone marrow neuropathy and the associated bone marrow pathology were reversed with treatments that prevent peripheral neuropathy. Three strategies were tested: inhibition of neutral endopeptidase, inhibition of aldose reductase plus lipoic acid supplementation, and insulin therapy with antioxidants. All strategies prevented loss of nerve conduction velocity resulting from STZ-induced diabetes and corrected the STZ-induced diabetes-associated increase of immunoreactivity of neuropeptide Y, tyrosine hydroxylase, and somatostatin. The treatments also reduced concentrations of interleukin-1β, granulocyte colony-stimulating factor, and matrix metalloproteinase 2 in STZ-induced diabetic bone marrow supernatant and decreased the expression of NADPH oxidase 2, nitric oxide synthase 2, and nuclear factor-κB1 mRNA in bone marrow progenitor cells. These therapies represent novel approaches to attenuate the diabetic phenotype within the bone marrow and may constitute an important therapeutic strategy for diabetic microvascular complications.
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Affiliation(s)
- James M Dominguez
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL
| | - Mark A Yorek
- Department of Veterans Affairs, Iowa City VA Health Care System, Iowa City, IA Department of Internal Medicine, University of Iowa, Iowa City, IA
| | - Maria B Grant
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN
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Holmes A, Coppey LJ, Davidson EP, Yorek MA. Rat Models of Diet-Induced Obesity and High Fat/Low Dose Streptozotocin Type 2 Diabetes: Effect of Reversal of High Fat Diet Compared to Treatment with Enalapril or Menhaden Oil on Glucose Utilization and Neuropathic Endpoints. J Diabetes Res 2015; 2015:307285. [PMID: 26229968 PMCID: PMC4503545 DOI: 10.1155/2015/307285] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/17/2015] [Accepted: 06/21/2015] [Indexed: 12/13/2022] Open
Abstract
We examined whether reversal of high fat diet, stimulating weight loss, compared to two treatments previously shown to have beneficial effects, could improve glucose utilization and peripheral neuropathy in animal models of obesity and type 2 diabetes. Rats were fed a high fat diet and treated with a low dose of streptozotocin to create models of diet induced obesity or type 2 diabetes, respectively. Afterwards, rats were transferred to a normal diet or treated with enalapril or dietary enrichment with menhaden oil for 12 weeks. Obesity and to a greater extent type 2 diabetes were associated with impaired glucose utilization and peripheral neuropathy. Placing obese rats on a normal diet improved glucose utilization. Steatosis but not peripheral neuropathy was improved after placing obese or diabetic rats on a normal diet. Treating obese and diabetic rats with enalapril or a menhaden oil enriched diet generally improved peripheral neuropathy endpoints. In summary, dietary improvement with weight loss in obese or type 2 diabetic rats was not sufficient to correct peripheral neuropathy. These results further stress the need for discovery of a comprehensive treatment for peripheral neuropathy.
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Affiliation(s)
- Amey Holmes
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
| | - Lawrence J. Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Eric P. Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, 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 52242, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA
- *Mark A. Yorek:
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Coppey LJ, Davidson EP, Obrosov A, Yorek MA. Enriching the diet with menhaden oil improves peripheral neuropathy in streptozotocin-induced type 1 diabetic rats. J Neurophysiol 2014; 113:701-8. [PMID: 25376787 DOI: 10.1152/jn.00718.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The purpose of this study was to determine the effect of supplementing the diet of type 1 diabetic rats with menhaden oil on diabetic neuropathy. Menhaden oil is a natural source for n-3 fatty acids, which have been shown to have beneficial effects in cardiovascular disease and other morbidities. Streptozotocin-induced diabetic rats were used to examine the influence of supplementing their diet with 25% menhaden oil on diabetic neuropathy. Both prevention and intervention protocols were used. Endpoints included motor and sensory nerve conduction velocity, thermal and mechanical sensitivity, and innervation and sensitivity of the cornea and hindpaw. Diabetic neuropathy as evaluated by the stated endpoints was found to be progressive. Menhaden oil did not improve elevated HbA1C levels or serum lipid levels. Diabetic rats at 16-wk duration were thermal hypoalgesic and had reduced motor and sensory nerve conduction velocities, and innervation and sensitivity of the cornea and skin were impaired. These endpoints were significantly improved with menhaden oil treatment following the prevention or intervention protocol. We found that supplementing the diet of type 1 diabetic rats with menhaden oil improved a variety of endpoints associated with diabetic neuropathy. These results suggest that enriching the diet with n-3 fatty acids may be a good treatment strategy for diabetic neuropathy.
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Affiliation(s)
- Lawrence J Coppey
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Eric P Davidson
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Alexander Obrosov
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Mark A Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, Iowa; Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Veterans Affairs Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa; and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
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24
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Davidson EP, Coppey LJ, Holmes A, Lupachyk S, Dake BL, Oltman CL, Peterson RG, Yorek MA. Characterization of diabetic neuropathy in the Zucker diabetic Sprague-Dawley rat: a new animal model for type 2 diabetes. J Diabetes Res 2014; 2014:714273. [PMID: 25371906 PMCID: PMC4211210 DOI: 10.1155/2014/714273] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 09/09/2014] [Indexed: 01/22/2023] Open
Abstract
Recently a new rat model for type 2 diabetes the Zucker diabetic Sprague-Dawley (ZDSD/Pco) was created. In this study we sought to characterize the development of diabetic neuropathy in ZDSD rats using age-matched Sprague-Dawley rats as a control. Rats were examined at 34 weeks of age 12 weeks after the onset of hyperglycemia in ZDSD rats. At this time ZDSD rats were severely insulin resistant with slowing of both motor and sensory nerve conduction velocities. ZDSD rats also had fatty livers, elevated serum free fatty acids, triglycerides, and cholesterol, and elevated sciatic nerve nitrotyrosine levels. The corneas of ZDSD rats exhibited a decrease in subbasal epithelial corneal nerves and sensitivity. ZDSD rats were hypoalgesic but intraepidermal nerve fibers in the skin of the hindpaw were normal compared to Sprague-Dawley rats. However, the number of Langerhans cells was decreased. Vascular reactivity of epineurial arterioles, blood vessels that provide circulation to the sciatic nerve, to acetylcholine and calcitonin gene-related peptide was impaired in ZDSD rats. These data indicate that ZDSD rats develop many of the neural complications associated with type 2 diabetes and are a good animal model for preclinical investigations of drug development for diabetic neuropathy.
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Affiliation(s)
- Eric P. Davidson
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Lawrence J. Coppey
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Amey Holmes
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
| | - Sergey Lupachyk
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Brian L. Dake
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Christine L. Oltman
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
| | | | - Mark A. Yorek
- Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
- Iowa City Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City, IA 52246, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA
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25
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Feng XT, Chen Q, Xie Z, Liang X, Jiang ZH, Zhao W, Leng J. Pollen Typhae total flavone improves insulin resistance in high-fat diet and low-dose streptozotocin-induced type 2 diabetic rats. Biosci Biotechnol Biochem 2014; 78:1738-42. [DOI: 10.1080/09168451.2014.930318] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Pollen Typhae total flavone (PTF), the extract from Pollen Typhae, is reported to enhance glucose uptake in C2C12 myotubes in vitro, but the convincing evidence is lacking in vivo. In this study, PTF ameliorated insulin resistance and dyslipidemia, but failed to significantly increase body weight in type 2 diabetic rats induced by high-fat diet and low-dose streptozotocin.
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Affiliation(s)
- Xiao-Tao Feng
- Guangxi Scientific Experimental Center for Traditional Chinese Medicine, Guangxi University of Chinese Medicine, Nanning, China
| | - Qun Chen
- Guangxi Scientific Experimental Center for Traditional Chinese Medicine, Guangxi University of Chinese Medicine, Nanning, China
| | - Zhen Xie
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Guangxi University of Chinese Medicine, Nanning, China
| | - Xiao Liang
- Guangxi Scientific Experimental Center for Traditional Chinese Medicine, Guangxi University of Chinese Medicine, Nanning, China
| | - Ze-Hui Jiang
- Guangxi Scientific Experimental Center for Traditional Chinese Medicine, Guangxi University of Chinese Medicine, Nanning, China
| | - Wei Zhao
- Department of Endocrinology, The First Affiliated Hospital, Guangxi University of Chinese Medicine, Nanning, China
| | - Jing Leng
- Guangxi Scientific Experimental Center for Traditional Chinese Medicine, Guangxi University of Chinese Medicine, Nanning, China
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26
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Galt NJ, Froehlich JM, Meyer BM, Barrows FT, Biga PR. High-fat diet reduces local myostatin-1 paralog expression and alters skeletal muscle lipid content in rainbow trout, Oncorhynchus mykiss. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:875-886. [PMID: 24264425 PMCID: PMC4016181 DOI: 10.1007/s10695-013-9893-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 11/15/2013] [Indexed: 06/02/2023]
Abstract
Muscle growth is an energetically demanding process that is reliant on intramuscular fatty acid depots in most fishes. The complex mechanisms regulating this growth and lipid metabolism are of great interest for human health and aquaculture applications. It is well established that the skeletal muscle chalone, myostatin, plays a role in lipid metabolism and adipogenesis in mammals; however, this function has not been fully assessed in fishes. We therefore examined the interaction between dietary lipid levels and myostatin expression in rainbow trout (Oncorhynchus mykiss). Five weeks of high-fat diet (HFD; 25 % lipid) intake increased white muscle lipid content and decreased circulating glucose levels and hepatosomatic index when compared to low-fat diet (LFD; 10 % lipid) intake. In addition, HFD intake reduced myostatin-1a and myostatin-1b expression in white muscle and myostatin-1b expression in brain tissue. Characterization of the myostatin-1a, myostatin-1b, and myostatin-2a promoters revealed putative binding sites for a subset of transcription factors associated with lipid metabolism. Taken together, these data suggest that HFD may regulate myostatin expression through cis-regulatory elements sensitive to increased lipid intake. Further, these findings provide a framework for future investigations of mechanisms describing the relationships between myostatin and lipid metabolism in fish.
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Affiliation(s)
- Nicholas J. Galt
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58108
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Jacob Michael Froehlich
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58108
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Ben M. Meyer
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58108
| | - Frederic T. Barrows
- USDA, Agricultural Research Service, Fish Technology Center, Bozeman, MT 59715
| | - Peggy R. Biga
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58108
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294
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27
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K.M. DJ, Muralidhara. Neuroprotective efficacy of a combination of fish oil and ferulic acid against 3-nitropropionic acid-induced oxidative stress and neurotoxicity in rats: behavioural and biochemical evidence. Appl Physiol Nutr Metab 2014; 39:487-96. [DOI: 10.1139/apnm-2013-0262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The beneficial effects of fish oil (FO) supplements on the central nervous system have been adequately demonstrated. However, FO supplementation at higher doses for longer duration is likely to cause oxidative stress in vivo. To overcome this, attempts have been made to enrich FO with known antioxidants/phytochemicals. In the present study, we examined the hypothesis that a combination of FO with ferulic acid (FA), a naturally occurring phenolic compound, is likely to provide higher degree of neuroprotection. This was examined by employing 3-nitropropionic acid (NPA), a well-known neurotoxin used to mimic behavioural and neurochemical features of Huntington’s disease. Growing male rats administered with NPA (25 mg/kg of body weight (bw) for 4 days) were provided with either FO (2 mL/kg bw), FA (50 mg/kg bw) or FO+FA for 2 weeks. Interestingly, FO+FA not only offered significant protection against NPA-induced behavioural impairments, but also markedly attenuated oxidative stress in brain regions (striatum/cerebellum) as evidenced by the reduction in reactive species, malondialdehyde, hydroperoxides and nitric oxide (NO) levels. Further, FO+FA combination restored the activities of various antioxidant enzymes and the levels of cytosolic calcium. In striatum, activity levels of acetylcholinesterase enzyme and dopamine levels were markedly restored among FO+FA rats. Interestingly, NPA-induced mitochondrial dysfunctions were also attenuated among FO+FA rats. Collectively, our findings suggest the advantage of co-treatment of FO with known antioxidants to achieve a higher therapeutic benefit in the treatment of oxidative stress-mediated neurodegenerative conditions.
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Affiliation(s)
- Denny Joseph K.M.
- Department of Biochemistry and Nutrition, Council of Scientific and Industrial Research–Central Food Technological Research Institute, Mysore 570020, India
| | - Muralidhara
- Department of Biochemistry and Nutrition, Council of Scientific and Industrial Research–Central Food Technological Research Institute, Mysore 570020, India
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28
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Guilford BL, Wright DE. Chewing the fat: genetic approaches to model dyslipidemia-induced diabetic neuropathy in mice. Exp Neurol 2013; 248:504-8. [PMID: 23933575 DOI: 10.1016/j.expneurol.2013.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/16/2013] [Accepted: 07/25/2013] [Indexed: 01/11/2023]
Abstract
Emerging clinical evidence now suggests that dyslipidemia may be strongly linked with the development and progression of neuropathy in diabetic patients, and dyslipidemia is considered an important risk factor for the development of diabetic neuropathy. However, because of important species differences, current animal models fall short of accurately replicating human diabetic dyslipidemia. Rodents resist expansion in low-density lipoprotein cholesterol (LDL-C) and typically maintain or increase high-density lipoprotein cholesterol (HDL-C), despite prolonged high-fat feeding. Here, we discuss the findings of Hinder et al., in which they utilized novel genetic experimental approaches to develop a diabetic mouse model with human-like dyslipidemia. The authors created a mouse with an apolipoprotein E (ApoE) knockout in conjunction with a leptin receptor mutation. A triple mutant mouse with both ApoE and apolipoprotein B48 knockout and leptin deficiency was also created in an effort to generate a model of diabetic dyslipidemia that better mimics the human condition. The long-term goal of these studies is to develop more faithful models to address how hyperglycemia and hyperlipidemia may drive the development and progression of neuropathy. Hinder and colleagues were successful at creating a diabetic mouse model with severe hypertriglyceridemia, hypercholesterolemia, and a significant increase in the total cholesterol to HDL-C ratio. This work was successful in establishing a model of diabetic dyslipidemia that more closely emulates the poor lipid profile observed in human diabetic patients with neuropathy. This commentary will also review current models used to study the effects of dyslipidemia on diabetic neuropathy and highlight a proposed mechanism for the role of dyslipidemia in the pathogenesis of diabetic neuropathy.
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Affiliation(s)
- B L Guilford
- University of Kansas Medical Center, Department of Anatomy and Cell Biology, USA.
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29
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Diabetic neuropathy and oxidative stress: therapeutic perspectives. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:168039. [PMID: 23738033 PMCID: PMC3655656 DOI: 10.1155/2013/168039] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 02/22/2013] [Accepted: 03/18/2013] [Indexed: 12/15/2022]
Abstract
Diabetic neuropathy (DN) is a widespread disabling disorder comprising peripheral nerves' damage. DN develops on a background of hyperglycemia and an entangled metabolic imbalance, mainly oxidative stress. The majority of related pathways like polyol, advanced glycation end products, poly-ADP-ribose polymerase, hexosamine, and protein kinase c all originated from initial oxidative stress. To date, no absolute cure for DN has been defined; although some drugs are conventionally used, much more can be found if all pathophysiological links with oxidative stress would be taken into account. In this paper, although current therapies for DN have been reviewed, we have mainly focused on the links between DN and oxidative stress and therapies on the horizon, such as inhibitors of protein kinase C, aldose reductase, and advanced glycation. With reference to oxidative stress and the related pathways, the following new drugs are under study such as taurine, acetyl-L-carnitine, alpha lipoic acid, protein kinase C inhibitor (ruboxistaurin), aldose reductase inhibitors (fidarestat, epalrestat, ranirestat), advanced glycation end product inhibitors (benfotiamine, aspirin, aminoguanidine), the hexosamine pathway inhibitor (benfotiamine), inhibitor of poly ADP-ribose polymerase (nicotinamide), and angiotensin-converting enzyme inhibitor (trandolapril). The development of modern drugs to treat DN is a real challenge and needs intensive long-term comparative trials.
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