12/15-Lipoxygenase Inhibition or Gene Deficiency Counteract Nitrosative Stress Associated with Prediabetic and Diabetic Neuropathies
Abstract Number: 975-P
Authors: ROMAN STAVNIICHUK, VIKTOR DREL, JERRY L. NADLER, IRINA G. OBROSOVA
Institutions: Baton Rouge, LA, Norfolk, VA
Results: Evidence for important roles of 12/15-lipoxygenase (12/15-LO) and peroxynitrite in prediabetic and diabetic neuropathies is emerging. Accumulation of 12/15-LO-derived 12(S)-hydroxyeicosatetraenoic acid [12(S)HETE] leads to ROS production and lipid peroxidation. We evaluated the contribution of 12/15-LO to oxidative-nitrosative stress in tissue-sites for peripheral neuropathy in mouse models of Type 1 diabetes and Type 2 prediabetes and obesity, and in high glucose-exposed cultured human Schwann cells (HSC). In experiment 1, control and streptozotocin-diabetic C57Bl6/J mice were maintained with/without treatment with the 12/15-LO inhibitor, cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC), 8 mgkg-1d-1 s.c., for 4 wks after 12 wks without treatment. In experiment 2, 12/15-LO-deficient and wild-type mice were fed normal or high-fat diets for 16 wks. In experiment 3, human Schwann cells (HSC) were cultured in 5.5 mM glucose, 30 mM L-glucose, or 30 mM D-glucose with or without CDC. 12/15-LO and nitrated protein expressions were evaluated by Western blot analysis, and 12(S)HETE, a measure of 12/15-LO activity, by ELISA. 12/15-LO overexpression and activation were present in sciatic nerve and spinal cord of STZ-diabetic and high fat diet-fed mice. 12/15-LO inhibition with CDC did not affect diabetes-induced 12/15-LO protein overexpression, but blunted 12(S)HETE and nitrated protein accumulation. 12/15-LO gene deficiency prevented or decreased 12(S)HETE accumulation and nitrosative stress in sciatic nerve and spinal cord of high-fat diet fed mice. 12/15-LO overexpression and activation were present in HSC cultured in 30 mM D-glucose. CDC treatment blunted high glucose-induced 12(S)HETE and nitrated protein accumulations. HSC exposed to 30 mM L-glucose (osmolarity control) did not display 12/15-LO overexpression/activation or enhanced nitrosative stress. In conclusion, 12/15-LO is implicated in nitrosative stress in tissue-sites for neuropathy associated with prediabetes and diabetes. Its presence in HSC, upregulation by high glucose, and contribution to hyperglycemia-induced peroxynitrite damage suggest an involvement in human disease.