Protective effect of stobadine on NCV in streptozotocin-diabetic rats: augmentation by vitamin E

Hyperglycaemia-induced oxidative stress makes an important contribution to the aetiology of diabetic neuropathy. Elevated reactive oxygen species (ROS) cause cumulative damage to neurons and Schwan cells, however, they also have a deleterious effect on nerve blood flow causing endoneurial hypoxia, which is responsible for early nerve conduction velocity (NCV) deficits and contributes to an increase in resistance to ischaemic conduction failure (RICF). We tested whether antioxidants - stobadine, vitamin E or the combination of these drugs, could prevent the early signs of neural dysfunction in animal model of diabetes in 8-9 weeks old male Wistar rats, made diabetic by streptozotocin (55 mg/kg i.v.) 4 months prior to testing. Neuropathy was evaluated electrophysiologically by measuring motor NCV and RICF of sciatic nerve in vitro. We observed that treatment with the combination of stobadine and vitamin E significantly (p < 0.001) reduced the NCV slowing in diabetic rats, although it did not fully prevent the NCV impairment. Significant effect (p < 0.05) was observed also in stobadine monotherapy. The RICF elevated in diabetic animals was not affected by any drug applied. This study confirmed that treatment with appropriate antioxidants, especially their combination could partially prevented the decrease in NCV in diabetic rats.     

Effects of resveratrol on nerve functions, oxidative stress and DNA fragmentation in experimental diabetic neuropathy

Oxidative stress has been implicated in pathophysiology of diabetic neuropathy. All the pathways responsible for development of diabetic neuropathy are linked to oxidative stress in one way or the other. In the present study, we have targeted oxidative stress in diabetic neuropathy using resveratrol, a potent antioxidant. Eight weeks streptozotocin-diabetic rats developed neuropathy which was evident from significant reduction in motor nerve conduction velocity (MNCV), nerve blood flow (NBF) and increased thermal hyperalgesia. The 2-week treatment with resveratrol (10 and 20 mg/kg, i.p.) started 6 weeks after diabetes induction significantly ameliorated the alterations in MNCV, NBF, and hyperalgesia. Resveratrol also attenuated enhanced levels of malondialdehyde (MDA), peroxynitrite and produced increase in catalase levels in diabetic rats. There was marked reduction in DNA fragmentation observed after resveratrol treatment in diabetic rats as evident from decrease in Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cells in sciatic nerve sections. Results of the present study suggest the potential of resveratrol in treatment of diabetic neuropathy and its protective effect may be mediated through reduction in oxidative stress and DNA fragmentation.     

Protective effects of 4-amino1,8-napthalimide, a poly (ADP-ribose) polymerase inhibitor in experimental diabetic neuropathy

Peripheral diabetic neuropathy is a heterogeneous group of disorders, and is known to affect 50-60% of diabetic patients. Poly (ADP-ribose) polymerase (PARP) activation has been identified as one of the key components in the pathogenesis of diabetic neuropathy. In the present study we have targeted PARP overactivation in diabetic neuropathy using a known PARP inhibitor, 4 amino 1, 8-napthalimide (4-ANI). Streptozotocin induced diabetic rats developed neuropathy within 6 weeks, which was evident from significant reduction in motor nerve conduction velocity (MNCV), nerve blood flow (NBF) along with neuropathic pain and abnormal sensory perception. Six weeks after diabetes induction Sprague Dawley rats were treated with 4-ANI (3 and 10 mg/kg, p.o.) for a period of two weeks (seventh and eighth weeks). Two week treatment with 4-ANI showed improvement in nerve conduction, nerve blood flow and reduction in tail flick responses and mechanical allodynia in diabetic animals. 4-ANI also attenuated PAR immunoreactivity and NAD depletion in nerves of diabetic animals. Results of present study suggest the potential of PARP inhibitors like 4-ANI in the treatment of diabetic neuropathy.     

Na,K-atpase alterations in diabetic rats: relationship with lipid metabolism and nerve physiological parameters.

Type 1 diabetes induces several metabolic and biochemical disturbances which result in the alteration ofNa,K-ATPase, an enzyme implicated in the physiopathology of neuropathy Several fatty acid supplementations lessen this alteration. The aims of this study were to determine the possible relationships between Na,K-ATPase activity in nerves and red blood cells (RBCs) and, on one hand, the fatty acid alterations induced by diabetes in these tissues and plasma and on the other, on nerve physiological parameters. Two groups of rats, control and diabetic (n = 15), were sacrified 8 weeks after induction of diabetes with streptozotocin. Nerve conduction velocity (NCV), nerve blood flow (NBF), Na,K-ATPase activity and membrane fatty acid composition of sciatic nerves, red blood cells (RBCs) and plasma were measured. NCV, NBF and Na,K-ATPase activity in RBCs and in sciatic nerves were significantly decreased in diabetic rats. We revealed a positive correlation between Na,K-ATPase activity in sciatic nerves and both NBF and NCV and between Na,K-ATPase activity in RBCs and NBF and the same activity in sciatic nerve. Diabetes induced major changes in plasma fatty acids and RBC membranes and less important changes in sciatic nerve membranes. Na,K-ATPase activity correlated negatively with C20: 4 (n-6) and C22: 4 (n-6) levels in nerves and with C18: 2 (n-6) levels in RBCs. During diabetes, changes in the membrane fatty acid composition suggest the existence of a tissue-specific regulation, and the decrease in Na,K-ATPase activity correlates with the alteration in the level of specific fatty acids in RBCs and sciatic nerves. Modifications in the lipidic environment of Na,K-ATPase would be involved in the alteration of its activity. Na,K-ATPase activity seems to be implicated in the decrease of both NCV and NBF during diabetes.     

Tanshinone IIA improves impaired nerve functions in experimental diabetic rats

Diabetic neuropathy is one of the most common complications in diabetes mellitus. Thus far, effective therapeutic agents for restoring the impaired motor and sensory nerve functions in diabetic neuropathy are still lacking. The antioxidant and neuroprotective properties of tanshinone IIA make it a promising candidate for the treatment of diabetic neuropathy. Therefore, the present study investigated the possible beneficial effect of tanshinone IIA on the impaired nerve functions displayed by a rat diabetic model. Insulin-dependent diabetes in rats was developed by a single dose of streptozotocin (STZ) at 50 mg/kg. The diabetic rats were randomly divided into four groups (n = 10 in each group), and were intraperitoneally administrated daily for 4 weeks with tanshinone IIA (20 mg/kg, 50 mg/kg and 100 mg/kg), or normal saline from the fourth day after STZ injection, respectively. At the end of tanshinone IIA administration, thermal and mechanical nociceptive threshold were determined by a hot plate test and Von Frey hairs; motor nerve conducting velocity (MNCV) was determined by an electrophysiological method; nerve blood flow (NBF) was detected using a laser Doppler flow meter; Na⁺,K⁺ATPase activity, the level of superoxide dismutase (SOD), catalase and malondialdehyde (MDA) in sciatic nerves, and the serum total antioxidant capability were also determined. We found that tanshinone IIA was capable of restoring diabetes-induced deficit in nerve functions (MNCV and NBF), and impairment in thermal and mechanical nociceptive capability. In addition, tanshinone IIA significantly increased the serum total antioxidant capability, improved the activities of Na⁺,K⁺ATPase, increased the levels of SOD and catalase, and reduced the MDA level in sciatic nerves in diabetic rats. All the findings indicate the beneficial effect of tanshinone IIA on impaired nerve functions and raise the possibility of developing tanshinone IIA as a therapeutic agent for diabetic neuropathy.     

A comparison of sciatic nerve neuropathy in diabetic and aged rats

We compared the development of sciatic nerve neuropathy in young diabetic rats with that in non-diabetic aged rats. Diabetes was induced in six-month old rats by injection with alloxan and was moderately controlled by single daily injections of insulin. Blood insulin levels in diabetic rats were significantly reduced compared to the aged animals, and glucose was significantly higher in diabetic rats. Sciatic nerve conduction velocities were measured monthly. Both motor and sensory conduction velocities decreased in the diabetic rats to a level that was similar to those in 36-month old rats. The decreases in conduction velocities in the diabetic rats were most dramatic during months 6 through 12 of diabetes. After 6 and 12 months of diabetes, sciatic nerves were examined by electron microscopy and compared to nerves from 24- and 36-month old rats respectively. Ultrastructural changes in the sciatic nerves of diabetic rats at 6 months included disruptions of myelin and dense axoplasm. In comparison, the 24-month old rats only had distorted contours of the nerve fibres. After 12 months of diabetes, the axoplasm had large spaces and the myelin was thickened and deformed. The axoplasm of 36-month old rats was normal in appearance; however the myelin sheath was thickened and split into layers. The Schwann cells were vacuolated and irregular in shape. These observations indicate that diabetes results in the early onset of age-like changes in the sciatic nerve. It suggests that the control of hyperglycemia in humans may preserve sciatic nerve structure and function.     

C 肤对糖尿病大鼠坐骨神经结构和功能的影响

目的：探讨外源性C肽对Ⅰ型糖尿病大鼠坐骨神经结构及功能的影响。方法：选取Wistar大鼠40只,分为正常对照组（NC组）和糖尿病组（Dia组）,糖尿病组链脲佐菌素诱发大鼠成模后,再随机分为三组：糖尿病组（Dia组）、胰岛素治疗组（In组）和C肽治疗组（CP组）8周后,测定各组大鼠运动、感觉神经传导速度,并对病变大鼠的坐骨神经进行病理定量图像分析及超微结构分析,结果：1．In组、CP肽组与DM组相比：大鼠运动、感觉神经传导速度均明显增加（P〈0．01）;2．腓肠神经纤维的数量和总横截面面积也显著增加（P〈0.01）。3．CP组与In组相比运动、感觉神经传导速度也显著增加（P〈0．01）。4．电镜显示：Dia组有髓神经纤维髓鞘发生分离并有无颗粒囊胞状结构聚集现象,In组有髓神经纤维髓鞘分离现象明显减轻但仍有无颗粒囊胞状结构聚集现象．而CP组有髓神经纤维结构完全接近正常组。结论：C肽在改善糖尿病大鼠的神经结构和功能方面明显优于胰岛素．     

The effects of zenarestat, an aldose reductase inhibitor, on minimal F-wave latency and nerve blood flow in streptozotocin-induced diabetic rats

The effects of zenarestat, 3-(4-bromo-2-fluorobenzyl)-7-chloro-3,4-dihydro-2,4-dioxo-1(2H)-quinazolineacetic acid, an aldose reductase inhibitor (ARI), on F-wave conduction abnormalities, nerve blood flow (NBF) reduction and sorbitol accumulation were studied in streptozotocin-induced diabetic rats. Two weeks after the induction of diabetes, zenarestat was given once a day for two weeks. In diabetic control rats, marked accumulation of sorbitol, reduction of NBF and prolongation of minimal F-wave latency (FWL) were observed as compared to normal rats. Zenarestat, at a dose of 32 mg/kg, inhibited sorbitol concentration to nearly the normal rat level and significantly improved not only NBF but also minimal FWL. At a dose of 3.2 mg/kg, sorbitol accumulation was inhibited by approximately 40% and there was a tendency to increase in NBF; however, minimal FWL was not improved at all. These data suggest that a highly inhibition of the nerve sorbitol accumulation is requisite for the treatment of diabetic peripheral neuropathy.     

Neuroprotective potential of combination of resveratrol and 4-amino 1,8 naphthalimide in experimental diabetic neuropathy: Focus on functional,sensorimotor and biochemical changes

The present study investigated whether combination of resveratrol and 4-amino 1,8 naphthalimide (4-ANI) is effective in the development of diabetic neuropathy (DN). After 6 weeks of diabetes induction, rats were treated for 2 weeks with resveratrol and 4-amino 1,8 naphthalimide (4-ANI) either alone or in combination. Experimental end points included functional, behavioural and biochemical parameters along with PAR immunohistochemistry and were performed at the end of treatment. Combination of resveratrol (10 mg/kg) and 4-ANI (3 mg/kg) attenuated conduction and nerve blood flow deficits and resulted in amelioration of diabetic neuropathic pain. Significant reversal of biochemical alterations (peroxynitrite, MDA and NAD levels) were also observed, as well as PAR accumulation in the sciatic nerve. This study suggests the beneficial effect of combining resveratrol and 4-ANI in experimental diabetic neuropathy.     

Altered Neurotrophin mRNA Levels in Peripheral Nerve and Skeletal Muscle of Experimentally Diabetic Rats

Abstract: The levels of neurotrophin mRNA in sensory ganglia, sciatic nerve, and skeletal muscle were measured in the streptozotocin-diabetic rat using northern blotting. Periods of diabetes of 4, 6, and 12 weeks significantly elevated brain-derived neurotrophic factor (BDNF) mRNA levels in soleus muscle compared with age-matched controls, the increase being highest at 6 weeks. At all time periods studied, the levels of nerve growth factor (NGF) mRNA in soleus muscle were decreased by 21–47%. Following 12 weeks of diabetes, BDNF mRNA levels were increased approximately two-to threefold in L4 and L5 dorsal root ganglia (DRG), and in sciatic nerve, NGF mRNA levels were raised 1.65-fold. Intensive insulin treatment of diabetic rats for the final 4 weeks of the 12-week period of diabetes reversed the up-regulation of BDNF mRNA in DRG and muscle and NGF mRNA in sciatic nerve. All diabetes-induced changes in neurotrophin mRNA were not paralleled by similar alterations in the levels of β-actin mRNA in muscle and nerve, or of GAP-43 mRNA in DRG and nerve. It is proposed that the up-regulation of neurotrophin mRNA is an endogenous protective and/or repair mechanism induced by insult and, as such, appears as an early marker of peripheral nerve and muscle damage in experimental diabetes.     

Effect of the NAD(P)H oxidase inhibitor,apocynin, on peripheral nerve perfusion and function in diabetic rats

Upregulation of vascular NAD(P)H oxidase has been considered an important source for elevated levels of reactive oxygen species that contribute to several cardiovascular disease states, including the vascular complications of diabetes mellitus. Previous studies have shown that treatment with antioxidants corrects impaired nerve function and blood flow in diabetic rats. The aim was to assess the degree of involvement of NAD(P)H oxidase in experimental diabetic neuropathy. To this end, after 6 weeks of untreated streptozotocin-diabetes, rats were treated for 2 weeks with the NAD(P)H oxidase, apocynin. Two high doses (15 and 100 mg/kg) were used to ensure that maximal effects were registered. Diabetes caused a 20% reduction in sciatic nerve motor conduction velocity, and a 14% deficit for sensory saphenous nerve. Apocynin treatment corrected these defects by 32% and 48%, respectively: there were no significant differences between the effects of the 2 doses. Sciatic nerve nutritive endoneurial perfusion was measured by hydrogen clearance microelectrode polarography. Blood flow and vascular conductance were 47% and 40% reduced by diabetes, respectively. Both doses of apocynin had similar effects, correcting the blood flow deficit by 31% and conductance by 47%. Thus, the data show that NAD(P)H oxidase contributes to the neurovascular deficits in diabetic rats. While only accounting for part of the elevated reactive oxygen species production in diabetes, this mechanism could provide a novel therapeutic candidate for further investigation in diabetic neuropathy and vasculopathy.     

Effects of U83836E on nerve functions, hyperalgesia and oxidative stress in experimental diabetic neuropathy

Oxidative stress has been implicated to play an important role in the pathogenesis of diabetic neuropathy, which is the most common complication of diabetes mellitus affecting more than 50% of diabetic patients. In the present study, we have investigated the effect of U83836E [(-)-2-((4-(2,6-Di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl)methyl)-3,4-dihydro-2,3,7,8-tetramethyl-2H-1-benzopyran-6-ol, 2HCl], a potent free radical scavenger in streptozotocin (STZ)-induced diabetic neuropathy in rats. STZ-induced diabetic rats showed significant deficit in motor nerve conduction velocity (MNCV), nerve blood flow (NBF) and thermal hyperalgesia after 8 weeks of diabetes induction, indicating development of diabetic neuropathy. Antioxidant enzyme (superoxide dismutase and catalase) levels were reduced and malondialdehyde (MDA) levels were significantly increased in diabetic rats as compared to the age-matched control rats, this indicates the involvement of oxidative stress in diabetic neuropathy. The 2-week treatment with U83836E (3 and 9 mg/kg, i.p.) started 6 weeks after diabetes induction significantly ameliorated the alterations in MNCV, NBF, hyperalgesia, MDA levels and antioxidant enzymes in diabetic rats. Results of the present study suggest the potential of U83836E in treatment of diabetic neuropathy.     

Slowing of Motor Nerve Conduction Velocity in Streptozotocin-induced Diabetic Rats is Preceded by Impaired Vasodilation in Arterioles that Overlie the Sciatic Nerve

Diabetes mellitus produces marked abnormalities in motor nerve conduction, but the mechanism is not clear. In the present study we hypothesized that in the streptozotocin (STZ)-induced diabetic rat impaired vasodilator function in arterioles that provide circulation to the region of the sciatic nerve is associated with reduced endoneural blood flow (EBF) and that these defects precede slowing of motor nerve conduction velocity, and thereby may contribute to nerve dysfunction. As early as three days after the induction of diabetes endoneural blood flow was reduced in the STZ-induced diabetic rat. Furthermore, after 1 week of diabetes acetylcholine- induced vasodilation was found to be impaired. This was accompanied by an increase in the superoxide level in arterioles that provide circulation to the region of the sciatic nerve as well as changes in the level of other markers of oxidative stress including an increase in serum levels of thiobarbituric acid reactive substances and a decrease in lens glutathione level. In contrast to the vascular related changes that occur within 1 week of diabetes, motor nerve conduction velocity and sciatic nerve Na⁺/k⁺ ATPase activity were significantly reduced following 2 and 4 weeks of diabetes, respectively. These studies demonstrate that changes in vascular function in the STZ-induced diabetic rat precede the slowing of motor nerve conduction velocity (MNCV) and are accompanied by an increase in superoxide levels in arterioles that provide circulation to the region of the sciatic nerve.     

Pentoxifylline Effects on Nerve Conduction Velocity and Blood Flow in Diabetic Rats

Pentoxifylline has several actions that improve blood rheology and tissue perfusion and may therefore potentially be applicable to diabetic neuropathy. The aims of this study were to ascertain whether 2 weeks of treatment with pentoxifylline could correct nerve conduction velocity and blood flow deficits in 6-week streptozotocin-diabetic rats and to examine whether the effects were blocked by co-treatment with the cyclooxygenase inhibitor, flurbiprofen, or the nitric oxide synthase inhibitor, N^G-nitro-ʟ-arginine. Diabetic deficits in sciatic motor and saphenous sensory nerve conduction velocity were 56.5% and 69.8% corrected, respectively, with pentoxifylline treatment. Sciatic endoneurial blood flow was approximately halved by diabetes and this deficit was 50.4% corrected by pentoxifylline. Flurbiprofen co-treatment markedly attenuated these actions of pentoxifylline on nerve conduction and blood flow whereas N^G-nitro-ʟ-arginine was without effect. Thus, pentoxifylline treatment confers neurovascular benefits in experimental diabetic neuropathy, which are linked at least in part to cyclooxygenasemediated metabolism.     

Evaluation of alpha(1)-adrenoceptor antagonist on diabetes-induced changes in peripheral nerve function, metabolism, and antioxidative defense.

The role for nerve blood flow (NBF) vs. other factors in motor nerve conduction (MNC) slowing in short-term diabetes was assessed by evaluating alpha(1)-adrenoceptor antagonist prazosin on NBF, MNC, as well as metabolic imbalances and oxidative stress in the neural tissue. Control and diabetic rats were treated with or without prazosin (5 mg.kg(-1).d(-1) for 3 wk). NBF was measured by hydrogen clearance. Both endoneurial vascular conductance and MNC velocity were decreased in diabetic rats vs. controls, and this decrease was prevented by prazosin. Free NAD(+):NADH ratios in mitochondrial cristae, matrix, and cytosol assessed by metabolite indicator method, as well as phosphocreatine levels and phosphocreatine/creatine ratios, were decreased in diabetic rats, and this reduction was ameliorated by prazosin. Neither diabetes-induced accumulation of two major glycation agents, glucose and fructose, as well as sorbitol and total malondialdehyde plus 4-hydroxyalkenals nor depletion of myo-inositol, GSH, and taurine or decrease in (Na/K)-ATP-ase activity were affected by prazosin. In conclusion, decreased NBF, but not metabolic imbalances or oxidative stress in the neural tissue, is a key mechanism of MNC slowing in short-term diabetes. Further experiments are needed to estimate whether preservation of NBF is sufficient for prevention of nerve dysfunction and morphological abnormalities in long-standing diabetes or whether the aforementioned metabolic imbalances closely associated with impaired neurotropism are of greater importance in advanced than in early diabetic neuropathy.     

Targeting Apoptosis Signalling Kinase-1 (ASK-1) Does Not Prevent the Development of Neuropathy in Streptozotocin-Induced Diabetic Mice

Apoptosis signal-regulating kinase-1 (ASK1) is a mitogen-activated protein 3 kinase (MAPKKK/MAP3K) which lies upstream of the stress-activated MAPKs, JNK and p38. ASK1 may be activated by a variety of extracellular and intracellular stimuli. MAP kinase activation in the sensory nervous system as a result of diabetes has been shown in numerous preclinical and clinical studies. As a common upstream activator of both p38 and JNK, we hypothesised that activation of ASK1 contributes to nerve dysfunction in diabetic neuropathy. We therefore wanted to characterize the expression of ASK1 in sensory neurons, and determine whether the absence of functional ASK1 would protect against the development of neuropathy in a mouse model of experimental diabetes. ASK1 mRNA and protein is constitutively expressed by multiple populations of sensory neurons of the adult mouse lumbar DRG. Diabetes was induced in male C57BL/6 and transgenic ASK1 kinase-inactive (ASK1n) mice using streptozotocin. Levels of ASK1 do not change in the DRG, spinal cord, or sciatic nerve following induction of diabetes. However, levels of ASK2 mRNA increase in the spinal cord at 4 weeks of diabetes, which could represent a future target for this field. Neither motor nerve conduction velocity deficits, nor thermal or mechanical hypoalgesia were prevented or ameliorated in diabetic ASK1n mice. These results suggest that activation of ASK1 is not responsible for the nerve deficits observed in this mouse model of diabetic neuropathy.     

Transplantation of bone marrow-derived mononuclear cells improves mechanical hyperalgesia, cold allodynia and nerve function in diabetic neuropathy

Relief from painful diabetic neuropathy is an important clinical issue. We have previously shown that the transplantation of cultured endothelial progenitor cells or mesenchymal stem cells ameliorated diabetic neuropathy in rats. In this study, we investigated whether transplantation of freshly isolated bone marrow-derived mononuclear cells (BM-MNCs) alleviates neuropathic pain in the early stage of streptozotocin-induced diabetic rats. Two weeks after STZ injection, BM-MNCs or vehicle saline were injected into the unilateral hind limb muscles. Mechanical hyperalgesia and cold allodynia in SD rats were measured as the number of foot withdrawals to von Frey hair stimulation and acetone application, respectively. Two weeks after the BM-MNC transplantation, sciatic motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNCV), sciatic nerve blood flow (SNBF), mRNA expressions and histology were assessed. The BM-MNC transplantation significantly ameliorated mechanical hyperalgesia and cold allodynia in the BM-MNC-injected side. Furthermore, the slowed MNCV/SNCV and decreased SNBF in diabetic rats were improved in the BM-MNC-injected side. BM-MNC transplantation improved the decreased mRNA expression of NT-3 and number of microvessels in the hind limb muscles. There was no distinct effect of BM-MNC transplantation on the intraepidermal nerve fiber density. These results suggest that autologous transplantation of BM-MNCs could be a novel strategy for the treatment of painful diabetic neuropathy.     

Concurrent targeting of nitrosative stress-PARP pathway corrects functional, behavioral and biochemical deficits in experimental diabetic neuropathy

Peroxynitrite mediated nitrosative stress, an indisputable initiator of DNA damage and overactivation of poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated after sensing DNA damage, are two crucial pathogenetic mechanisms in diabetic neuropathy. The intent of the present study was to investigate the effect of combination of a peroxynitrite decomposition catalyst (PDC), FeTMPyP and a PARP inhibitor, 4-ANI against diabetic peripheral neuropathy. The end points of evaluation of the study included motor nerve conduction velocity (MNCV) and nerve blood flow (NBF) for evaluating nerve functions; thermal hyperalgesia and mechanical allodynia for assessing nociceptive alterations, malondialdehyde and peroxynitrite levels to detect oxidative stress-nitrosative stress; NAD concentration in sciatic nerve to assess overactivation of PARP. Additionally immunohistochemical studies for nitrotyrosine and Poly(ADP-ribose) (PAR) was also performed. Treatment with the combination of FeTMPyP and 4-ANI led to significant improvement in nerve functions and pain parameters and also attenuated the oxidative-nitrosative stress markers. Further, the combination also reduced the overactivation of PARP as evident from increased NAD levels and decreased PAR immunopositivity in sciatic nerve microsections. Thus, it can be concluded that treatment with the combination of a PDC and PARP inhibitor attenuates alteration in peripheral nerves in diabetic neuropathy (DN).