Tissue specific metabolic abnormalities resulting form insulin deficiency and hyperglycemia are thought to contribute heavily to the development of diabetic neuropathy and other chronic complications of diabetes, although independent genetic and environmental variables are probably also operative. As the most common clinical complication of diabetes and the cause of most amputations in diabetic patients, diabetic neuropathy represents a major public health problem that has no generally accepted method of prevention of treatment. Over the last decade, animal, in vitro, and human studies emanating from this laboratory have defined biochemical likes between hyperglycemia, polyol pathway activation, myo-inositol (Ml) depletion, abnormalities in phosphoinositide (PPl) metabolism, protein kinase C (PKC), Na/K-ATPase, impaired impulse conduction, and the development of subtle structural defects in peripheral nerve from diabetic animals and patients. Recent studies with aldose reductase inhibitors (ARl's) that inhibit the rate-limiting enzyme in the polyol pathway, have tentatively implicated elements of this same metabolic pathway in the blunted regenerative response to injury and a putative decrease in """"""""neurotrophic tone"""""""" that may contribute to this """"""""dying back"""""""" distal symmetric peripheral polyneuropathy. A full understanding of these polyol- pathway-and Mi-linked metabolic factors and their role in nerve fiver damage, repair and regeneration should facilitate the rational development of new forms of intervention. Insight into this pathogenetic cascade is presently limited by (1) the increasingly recognized complexity of PPl metabolism and its role and regulation in cell function and growth; and (2) the cellular heterogeneity of the multicellular tissues involved in diabetic complications. This competing renewal application proposes detailed study of the mechanisms and implications of glucose-induced alterations in PPl metabolism in 2 newly developed human cell culture models that exhibit biochemical and functional abnormalities similar to those of diabetic nerve: non-transformed human retinal pigment epithelial (hRPE) cells, and a cloned, well-differentiated and genetically stable human neuroblastoma SH-SY5Y. Glucose-induced defects in cell function and growth such as decreased retinal rod outer segment (ROS) phagocytosis, and impaired ouabain-sensitive 86Rb-uptake and serum-and growth-factor-induced ornithine decarboxylase (ODC) induction in hRPE and Sy5Y cells respectively will be compared with abnormalities in basal and stimulated PPl metabolism under carefully defined experimental conditions simulating hyperglycemia and insulin deficiency. These studies should identify the locus or loci of glucose-sensitivity in the PPl cascade, and characterize the mechanism(s) by which glucose-induced defects in basal or stimulated PPl metabolism interfere with Na/K-ATPase regulation and growth-factor signal transduction that may be relevant to the pathogenesis of diabetic neuropathy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK038304-06
Application #
3237560
Study Section
Pathology A Study Section (PTHA)
Project Start
1986-05-01
Project End
1995-04-30
Budget Start
1991-05-01
Budget End
1992-04-30
Support Year
6
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Type
Schools of Medicine
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Pop-Busui, Rodica; Marinescu, Victor; Van Huysen, Carol et al. (2002) Dissection of metabolic, vascular, and nerve conduction interrelationships in experimental diabetic neuropathy by cyclooxygenase inhibition and acetyl-L-carnitine administration. Diabetes 51:2619-28
Stevens, M J; Obrosova, I; Cao, X et al. (2000) Effects of DL-alpha-lipoic acid on peripheral nerve conduction, blood flow, energy metabolism, and oxidative stress in experimental diabetic neuropathy. Diabetes 49:1006-15
Kato, K; Thomas, T P; Stevens, M J et al. (1999) 2-Chloroadenosine reverses hyperglycemia-induced inhibition of phosphoinositide synthesis in cultured human retinal pigment epithelial cells and prevents reduced nerve conduction velocity in diabetic rats. Metabolism 48:827-33
Porcellati, F; Hosaka, Y; Hlaing, T et al. (1999) Alternate splicing in human Na+-MI cotransporter gene yields differentially regulated transport isoforms. Am J Physiol 276:C1325-37
Magnani, P; Thomas, T P; Tennekoon, G et al. (1998) Regulation of glucose transport in cultured Schwann cells. J Peripher Nerv Syst 3:28-36
Sima, A A; Dunlap, J A; Davidson, E P et al. (1997) Supplemental myo-inositol prevents L-fucose-induced diabetic neuropathy. Diabetes 46:301-6
Karihaloo, A; Kato, K; Greene, D A et al. (1997) Protein kinase and Ca2+ modulation of myo-inositol transport in cultured retinal pigment epithelial cells. Am J Physiol 273:C671-8
Stevens, M J; Lattimer, S A; Feldman, E L et al. (1996) Acetyl-L-carnitine deficiency as a cause of altered nerve myo-inositol content, Na,K-ATPase activity, and motor conduction velocity in the streptozotocin-diabetic rat. Metabolism 45:865-72
Sima, A A; Ristic, H; Merry, A et al. (1996) Primary preventive and secondary interventionary effects of acetyl-L-carnitine on diabetic neuropathy in the bio-breeding Worcester rat. J Clin Invest 97:1900-7
Shindo, H; Thomas, T P; Larkin, D D et al. (1996) Modulation of basal nitric oxide-dependent cyclic-GMP production by ambient glucose, myo-inositol, and protein kinase C in SH-SY5Y human neuroblastoma cells. J Clin Invest 97:736-45

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