Evidence for importance of oxidative-nitrosamine stress in peripheral diabetic neuropathy (PDN) is emerging, but the mechanisms are not well understood. Up regulation of Na? exchanger-1 (NHE-1), previously demonstrated in several tissue-sites for diabetes complications, causes an increase in cytosolic ph and related activation of the upper part of glycolysis. The overall hypothesis of this proposal is that NHE-1 plays an important role in PDN, because NHE-1-driven activation of the upper part of glycolysis, under conditions of diabetes-induced inhibition (endothelial cells) or insufficient activation (Schwann cells, SC) of glyceraldehyde- 3-phosphate dehydrogenate, underlies diversion of the excessive glycolytic flux towards formation of a-glycerophosphate and methylglyoxal, with resulting activation of two major free radical-generating mechanisms i.e., non-enzymatic glycation and NAD(P)H oxidase. In support of this hypothesis, our preliminary studies have shown that 1) NHE-1 is abundantly expressed in rat and mouse peripheral nerve, rat DRG neurons, and human SC;2) HSC basal ph and NHE-1 expression and activity increase in response to high glucose;3) the upper part of glycolysis is activated in the diabetic peripheral nerve;4) the specific NHE-1 inhibitor cariporide, at least, partially prevents nerve conduction deficits, sensory neuropathy, neurovascular dysfunction, and metabolic imbalances in STZ-diabetic rats;5) STZ-diabetic NHE-1 mice develop less severe PDN than STZ-diabetic wild-type mice. The OBJECTIVE of this proposal is to evaluate the role of NHE-1 in PDN in animal models of Type 1 and Type 2 diabetes.
The specific aims are 1) elucidate if NHE-1 inhibition reverses PDN in STZ- diabetic and ZDF rats;2) determine the roles of HIF-1a and aldosterone in diabetes- and high glucose-induced NHE-1 overexpression;and 3) evaluate the contribution of NHE-1 to oxidative-nitrosative stress in peripheral nerve, vasa nervorum, spinal cord, and DRG neurons of diabetic rats and high glucose-exposed cultured HSC and co-cultured rat SC and DRG neurons. The project combines physiological, behavioral, biochemical, immunohistochemical, and structural studies in animal models with molecular studies in cultured HSC and co- cultured rat SC and DRG neurons. The findings will generate new information on the role for NHE-1 in PDN in two types of diabetes and may provide rationale for development of NHE-1 inhibitors and NHE-1 inhibitor- containing drug combinations.

Public Health Relevance

Peripheral diabetic neuropathy (PDN) is the most devastating complication of diabetes mellitus, and a leading cause of foot amputation. Evidence for importance of free radicals and oxidants in PDN is emerging from both animal and human studies, but the mechanisms are not well understood. Upregulation of Na? exchanger-1 (NHE-1), previously demonstrated in several tissues of diabetic animals, causes an increase in cytosolic ph and related activation of the upper part of glycolysis. The overall hypothesis of this proposal is that NHE-1 plays an important role in PDN, because NHE-1-driven activation of the upper part of glycolysis, under conditions of diabetes-induced inhibition (endothelial cells) or insufficient activation (Schwann cells, SC) of glyceraldehyde-3-phosphate dehydrogenase, underlies diversion of the excessive glycolytic flux towards two major free radical-generating pathways i.e., non-enzymatic glycation and NAD (P) H oxidase. The hypothesis is supported by our preliminary data demonstrating that 1) NHE-1 is abundantly expressed in rat and mouse peripheral nerve, rat DRG neurons, and human SC;2) HSC basal ph and NHE-1 expression and activity are increased by high glucose;3) the upper part of glycolysis is activated in the diabetic nerve;4) the specific NHE- 1 inhibitor cariporide, at least, partially prevents PDN in STZ-diabetic rats;5) diabetic NHE-1 mice develop less severe PDN than diabetic mice with normal NHE-1 content. The OBJECTIVE of this proposal is to evaluate the role of NHE-1 in PDN in animal models of Type 1 and Type 2 diabetes.
The SPECIFIC AIMS are 1) elucidate if NHE-1 inhibition reverses PDN in STZ-diabetic and ZDF rats;2) evaluate the mechanisms of diabetes-induced NHE-1 over expression;and 3) assess the contribution of NHE-1 to oxidative-nitrosative stress in peripheral nervous system of diabetic rats and high glucose-exposed cultured HSC and co-cultured rat SC and DRG neurons. The project combines physiological, behavioral, biochemical, immunohistochemical, and structural studies in animal's models with molecular studies in cell cultures. The findings will generate new information on the role for NHE-1 in PDN in two types of diabetes and may provide rationale for development of NHE-1 inhibitors and NHE-1 inhibitor-containing drug combinations for prevention and treatment of PDN.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK077141-05
Application #
8279360
Study Section
Special Emphasis Panel (ZRG1-BDCN-J (03))
Program Officer
Jones, Teresa L Z
Project Start
2008-07-01
Project End
2013-01-31
Budget Start
2012-06-01
Budget End
2013-01-31
Support Year
5
Fiscal Year
2012
Total Cost
$121,726
Indirect Cost
$53,835
Name
Lsu Pennington Biomedical Research Center
Department
None
Type
Organized Research Units
DUNS #
611012324
City
Baton Rouge
State
LA
Country
United States
Zip Code
70808
Stavniichuk, Roman; Obrosov, Alexander A; Drel, Viktor R et al. (2013) 12/15-Lipoxygenase inhibition counteracts MAPK phosphorylation in mouse and cell culture models of diabetic peripheral neuropathy. J Diabetes Mellitus 3:
Lupachyk, Sergey; Watcho, Pierre; Obrosov, Alexander A et al. (2013) Endoplasmic reticulum stress contributes to prediabetic peripheral neuropathy. Exp Neurol 247:342-8
Lupachyk, Sergey; Watcho, Pierre; Shevalye, Hanna et al. (2013) Na+/H+ exchanger 1 inhibition reverses manifestation of peripheral diabetic neuropathy in type 1 diabetic rats. Am J Physiol Endocrinol Metab 305:E396-404
Lupachyk, Sergey; Watcho, Pierre; Stavniichuk, Roman et al. (2013) Endoplasmic reticulum stress plays a key role in the pathogenesis of diabetic peripheral neuropathy. Diabetes 62:944-52
Lupachyk, Sergey; Stavniichuk, Roman; Komissarenko, Julia I et al. (2012) Na+/H+-exchanger-1 inhibition counteracts diabetic cataract formation and retinal oxidative-nitrative stress and apoptosis. Int J Mol Med 29:989-98
Shevalye, Hanna; Lupachyk, Sergey; Watcho, Pierre et al. (2012) Prediabetic nephropathy as an early consequence of the high-calorie/high-fat diet: relation to oxidative stress. Endocrinology 153:1152-61
Stavniichuk, Roman; Shevalye, Hanna; Hirooka, Hiroko et al. (2012) Interplay of sorbitol pathway of glucose metabolism, 12/15-lipoxygenase, and mitogen-activated protein kinases in the pathogenesis of diabetic peripheral neuropathy. Biochem Pharmacol 83:932-40
Lupachyk, Sergey; Watcho, Pierre; Hasanova, Nailia et al. (2012) Triglyceride, nonesterified fatty acids, and prediabetic neuropathy: role for oxidative-nitrosative stress. Free Radic Biol Med 52:1255-63
Watcho, Pierre; Stavniichuk, Roman; Tane, Pierre et al. (2011) Evaluation of PMI-5011, an ethanolic extract of Artemisia dracunculus L., on peripheral neuropathy in streptozotocin-diabetic mice. Int J Mol Med 27:299-307
Drel, Viktor R; Pacher, Pal; Stavniichuk, Roman et al. (2011) Poly(ADP-ribose)polymerase inhibition counteracts renal hypertrophy and multiple manifestations of peripheral neuropathy in diabetic Akita mice. Int J Mol Med 28:629-35

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