Sciatic Motor Nerve Conduction Velocity Research Articles

Lack of effect from genetic deletion of Hdac6 in a humanized mouse model of CMT2D.

Inhibition of HDAC6 has been proposed as a broadly applicable therapeutic strategy for Charcot-Marie-Tooth disease (CMT). Inhibition of HDAC6 increases the acetylation of proteins important in axonal trafficking, such as α-tubulin and Miro, and has been shown to be efficacious in several preclinical studies using mouse models of CMT. Here, we sought to expand on previous preclinical studies by testing the effect of genetic deletion of Hdac6 on mice carrying a humanized knockin allele of Gars1, a model of CMT-type 2D. Gars1ΔETAQ mice were bred to an Hdac6 knockout strain, and the resulting offspring were evaluated for clinically relevant outcomes. The genetic deletion of Hdac6 increased α-tubulin acetylation in the sciatic nerves of both wild-type and Gars1ΔETAQ mice. However, when tested at 5 weeks of age, the Gars1ΔETAQ mice lacking Hdac6 showed no changes in body weight, muscle atrophy, grip strength or endurance, sciatic motor nerve conduction velocity, compound muscle action potential amplitude, or peripheral nerve histopathology compared to Gars1ΔETAQ mice with intact Hdac6. Our results differ from those of two previous studies that demonstrated the benefit of the HDAC6 inhibitor tubastatin A in mouse models of CMT2D. While we cannot fully explain the different outcomes, our results offer a counterexample to the benefit of inhibiting HDAC6 in CMT2D, suggesting additional research is necessary.

Effect of vasodilator PGE1 on sciatic nerve function, VEGF level, vascular permeability and peripheral nerve in type 2 diabetic rats

Purpose: To investigate the effect of vasodilator prostaglandin E1 (PGE1) on sciatic nerve function, vascular endothelial growth factor (VEGF), vascular permeability and peripheral nerve in type 2 diabetes mellitus (T2DM) rats.
 Methods: Twenty-one rats in the study group were intraperitoneally injected with PGE1, while rats in T2DM untreated group (n = 21) were injected with an equivalent amount of normal saline. Seven rats were randomly selected from the study and the control groups every seven days for 21 days for determination of changes in sciatic nerve function, VEGF level, vascular permeability and peripheral nerves.
 Results: Sciatic nerve motor nerve conduction velocity (MNCV) was significantly higher in the study group than in T2DM untreated control group at the three time-points post-treatment (p < 0.01). The level of VEGF in the study group decreased, relative to the T2DM untreated control group on the 7th 14th and 21st days post- treatment (p < 0.05) while the water content of sciatic nerve tissue in study group was markedly decreased, relative to control value on day 21 (p < 0.05). Rats in the study group showed decreased TTT, relative to those in T2DM untreated group on days 7, 14 and 21 post-treatment (p < 0.01).
 Conclusion: PGE1 improves the sciatic nerve function of T2DM rats, reduces the level of serum VEGF and vascular permeability, and protects peripheral nerves. These findings provide a basis for the development of new T2DM drugs

Atorvastatin prevents the development of diabetic neuropathic nociception by possible involvement of nitrergic system.

Diabetic neuropathy has been identified as a common complication caused by diabetes. However, its pathophysiological mechanisms are not fully understood yet. Statins, also known as HMG-CoA reductase inhibitors, alleviate the production of cholesterol. Despite this cholesterol-reducing effect of statins, several reports have demonstrated their beneficial properties in neuropathic pain. In this study, we used streptozotocin (STZ)-induced diabetic model to investigate the possible role of nitric oxide (NO) in the antineuropathic-like effect of atorvastatin. Diabetes was induced by a single injection of STZ. Male rats orally received different doses of atorvastatin for 21 days. To access the neuropathy process, the thermal threshold of rats was assessed using hot plate and tail-flick tests. Moreover, sciatic motor nerve conduction velocity (MNCV) studies were performed. To assess the role of nitric oxide, N(G)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine (AG), and 7-nitroindazole (7NI) were intraperitoneally administered along with some specific doses of atorvastatin. Atorvastatin significantly reduced the hyperalgesia in diabetic rats. L-NAME pretreatment with atorvastatin showed the antihyperalgesic effect, suggesting the possible involvement of the NO pathway in atorvastatin protective action. Furthermore, co-administration of atorvastatin with AG and 7NI resulted in a significant increase in pain threshold in diabetic rats. Our results reveal that the atorvastatin protective effect on diabetic neuropathy is mediated at least in a part via the nitric oxide system.

Dose-dependent effect of the pulsed Nd:YAG laser in the treatment of crushed sciatic nerve in Wister rats: an experimental model

The objective of the study was to investigate the efficacy of three energy densities 4, 10, and 50J/cm2 of pulsed Nd:YAG laser for the treatment of crushed sciatic nerve in Wister rats by evaluating changes in the sciatic functional index and the electrophysiology.A total of 180 Wistar rats were involved in the study. Rats were randomly assigned to five groups. Rats were subjected to the sciatic nerve crushing. Control negative (CONT-ve), which received no crushing; control positive (CONT+ve), which received crushing with no laser; and HILT-4, HILT-10, and HILT-50 groups, which received pulsed Nd:YAG laser (10Hz, 360mJ/cm2) with energy densities 4, 10, and 50J/cm2, respectively. The SFI, the amilitude of compound motor action potential (CMAP) and sciatic motor nerve conduction velocity (MNCV) were measured before and after seven, 14, and 21days after crushing. For the SFI and electrophysiological analysis, repeated measures ANOVA is used, followed by Bonferroni's repeated-measures test. Statistical significance was set at p < 0.05. After oneweek, there was no significant difference in SFI, CMAP, and MNCV among the three laser groups with significant changes between them and CONT-ve and CONT+ve groups. There was a significant increase in either CMAP amplitude or MNCV after 14days with significant decrease in the SFI after 21days among all treatment groups. The pulsed Nd:YAG laser applied with energy densities 4, 10, and 50J/cm2 significantly decreased the SFI and increased the CMAP and MNCV of the crushed sciatic nerve in Wister rats. Among laser doses, the difference in the rate of recovery in the electrophysiology was found after twoweeks while in the SFI after threeweeks. The improvement after the nerve injury was time and dose dependent.

Effect of ropivacaine on peripheral neuropathy in streptozocin diabetes-induced rats through TRPV1-CGRP pathway.

Objective To determine the effect of ropivacaine on peripheral neuropathy in diabetic rats and its possible mechanism.Methods Forty-eight Sprague–Dawley rats were randomly divided into six groups: nondiabetic control group, nondiabetic group A (0.25% ropivacaine), nondiabetic group B (0.75% ropivacaine), diabetic control group (diabetic peripheral neuropathy (DPN) +artificial cerebrospinal fluid), diabetic group A (DPN+0.25% ropivacaine), and diabetic group B (DPN + 0.75% ropivacaine), with eight rats in each group. Within an hour of the last administration, the sciatic motor nerve conduction velocity (MNCV) of each group was measured, and the morphological changes of rat sciatic nerve were observed by HE, Weil’s staining and electron microscopy. The expression of transient receptor potential vanilloid (TRPV1) in the spinal cord dorsal horn of rats was analyzed by immunohistochemistry, and the expression of Calcitonin gene-related peptide (CGRP) protein in the spinal cord was analyzed by Western blot.Results Compared with the nondiabetic control group, elevated blood glucose, decreased weight and reduced average mechanical withdrawal threshold (MWT), additionally, the sciatic nerves showed significantly slowed conduction velocity (both P<0.001) and damaged pathological structure, the expression of TRPV1 and CGRP were decreased (both P<0.001) in the diabetic groups. Compared with the diabetic control group, down-regulation of TRPV1 and CGRP in spinal cord was significant for the diabetic groups A and B treated with 0.25 and 0.75% ropivacaine, the higher concentration of ropivacaine correlated with a greater change.Conclusion Ropivacaine can significantly block sciatic nerve conduction velocity in DPN rats in a concentration-dependent manner, which may be related to the expression of the TRPV1-CGRP pathway.

A Novel TNF-α Converting Enzyme (TACE) Selective Inhibitor JTP-96193 Prevents Insulin Resistance in KK-Ay Type 2 Diabetic Mice and Diabetic Peripheral Neuropathy in Type 1 Diabetic Mice.

Tumor necrosis factor-α (TNF-α) converting enzyme/a disintegrin and metalloproteinase domain-containing protein 17 (TACE/ADAM17) is a key sheddase that releases TNF-α from its inactive precursor and is thought as a new drug target to inhibit TNF-α production. In the present study, pharmacological effects of a novel TACE selective inhibitor, JTP-96193, on type 2 diabetes and diabetic peripheral neuropathy (DPN) as its major complication was examined. Enzyme inhibitory activity of JTP-96193 on TACE and other ADAMs was measured in in vitro. High fat-induced obese mice and type 2 diabetic KK-Ay mice were used to evaluate the effect of JTP-96193 on insulin resistance. Finally, streptozotocin (STZ)-induced diabetic mice were treated with JTP-96193 to evaluate the sciatic motor nerve conduction velocities (MNCV). JTP-96193 selectively inhibited human TACE activity with IC50 value of 5.4 nM and showed more than 1800-fold selectivity against other matrix metalloproteinases. In mouse models of obesity and diabetes, JTP-96193 reduced the TNF-α release from the fat tissue and prevented development of diabetes and improved insulin resistance, respectively. Furthermore, JTP-96193 prevented delay of sciatic MNCV without any effects on blood glucose or insulin levels in STZ-induced diabetic mice. TACE inhibitor is effective on insulin resistance and DPN independent from glucose-lowering effect. These pharmacological properties of JTP-96193 may be helpful to treat type 2 diabetes accompanied by its microvascular complications.

LOX-1-mediated injury in sensory neurons in type 2 diabetes

Our laboratory recently identified several differentially expressed genes (DEG) through microarray analysis of the sciatic nerves of 24-week-old BKS db/db (diabetic) and db/+ (nondiabetic) mice. We noted prominent increases in lipid metabolism genes, consistent with another model, the high fat-fed C57BL6/J mouse, where we postulated that oxidized low-density lipoproteins (oxLDL) activate a receptor-mediated inflammatory pathway of neuronal injury. Our findings support clinical observations that plasma lipids associate with neuropathy, and suggest that glucose and lipids together will be responsible for the most aggressive development of diabetic neuropathy. A role for oxLDL-induced injury remains to be proved in vivo, and this is the goal of the present study. First, we performed biostatistical network analysis to identify molecular interactions of our LOX-1 gene of interest, Olr1. Next, nondiabetic BKSdb/+ and diabetic BKSdb/db littermates received intraperitoneal injections of LOX-1 neutralizing antibody or control non-immune IgG every 48 h from 6-12 wk of age. At 12 wk of age, blood and tissues were harvested for metabolic and neuropathy phenotyping. We confirmed our network analysis by demonstrating that NFkappaB, a gene closely linked to Olr1 in our network, was decreased in anti-LOX-1 treated mice. Most metabolic parameters (blood glucose, glycated hemoglobin, plasma triglycerides and cholesterol) and also the sciatic motor nerve conduction velocity deficit were unchanged in the presence of anti-LOX-1 treatment compared with control IgG. However, there was a striking preservation of the sural nerve conduction velocity in anti-LOX-1-treated mice, demonstrating that this receptor is involved in sural nerve injury in type 2 diabetes.

The protective effects of aripiprazole on vincristine - induced peripheral neuropathy in a rat model

Clinical use of vincristine (VCR), an effective chemotherapeutic agent, has been limited due to its peripheral neuropathy toxicity. Aripiprazole, which is an antipsychotic agent is a partial agonist the dopaminergic D2 receptor (D2R) and the serotonin 5-HT1A and 5-HT7 receptors Several studies have shown that aripiprazole exerts neuroprotective and immunomodulatory properties. This study aimed to investigate the effects of aripiprazole on brain injury in a rat model. Male Wistar rats were intraperitoneally injected with VCR and normal saline four times per week for 2 weeks. In the treatment group, aripiprazole (3 mg/kg) was administered intraperitoneally 30 min prior to VCR injection every day. Mortality rate, weight variations and histopathological changes were monitored. Hot plate, tail flick, von fery and motor nerve conduction velocity (MNCV) tests were used to evaluate sensory and motor neuropathy. Levels of nNOS and iNOS were assessed by enzyme-linked immunosorbent assay (ELISA). Moreover, the protein levels of caspase-3, p65 nuclear factor kappa B (NF-<kappa>B) and phospho-p65 NF-<kappa>B in the dorsal ganglion root were examined by Western blot analysis. Co-administration of aripiprazole with VCR significantly reversed alterations in the hot plate, tail flick threshold, von frey and sciatic MNCV induced by VCR and also prevented mixed sensory-motor neuropathy, as indicated by better general conditions, behavioral and electrophysiological results. In addition, aripiprazole improved the body weight loss caused by VCR. The levels of iNOS and nNOS were significantly diminished in the treatment group. These findings were confirmed by western blot and histopathological analysis. In conclusion, this study demonstrated that aripiprazole significantly attenuated VCR-induced neuropathy and could be considered as a neuroprotective agent to prevent the VCR-induced neuropathy.

Anti-apoptotic Mechanism of Deep Electroacupuncture at "Huantiao" (GB 30) in Repair of the Injured Sciatic Nerve in Rats

To observe the effect of deep electroacupuncture (EA) at "Huantiao" (GB 30) on functional and pathological changes of the damaged sciatic nerve and apoptosis-related factors in lumbar dorsal root ganglia (DRGs) in rats, so as to study its mechanisms underlying relieving sciatica. Forty-eight SD rats were randomly divided into normal, mo-del, deep EA (DEA) and shallow EA (SEA) groups (n＝12 in each group)．The sciatic nerve injury model was established by silicone tube extrusion of the sciatic nerve stem. For DEA group, acupuncture needles were inserted into GB 30 about 8 mm deep to induce nerve impulse under the guidance of high-frequency ultrasound, and the needles were inserted into GB 30 about 3-5 mm in the SEA group. The EA treatment was applied to bilateral GB 30 for 20 min beginning from the 15th day on after modeling, once daily for 14 days. The sciatic nerve function index (SFI) and motor nerve conduction velocity (MNCV) were recorded and calculated. Pathological changes of the sciatic nerve were displayed by H. E. staining. The cell apoptosis and expression of PI 3 K and AKT proteins in lumbar 4-5 DRGs were detected by TUNEL staining, and immunohistochemistry, respectively. In comparison with the normal group, the SFI and MNCV were significantly decreased (P<0.01，P<0.05), the number of neuronal apoptosis and the expression of PI 3 K and AKT in L 4-L 5 DRGs were significantly increased in the model group (P<0.05). Following the treatment, the SFI, MNCV, and the number of neuronal apoptosis were reversed compared with the model group (P<0.01, P<0.05), both PI 3 K and AKT expression levels were significantly up-regulated in both DEA and SEA groups (P<0.05). The therapeutic effects were significantly better in the DEA group than in the SEA group in down-regulating cell apoptosis number and in up-regulating SFI, MNCV, and PI 3 K and AKT protein expression on day 28 of modeling (P<0.01，P<0.05). Deep EA at GB 30 can activate PI 3 K-AKT signaling pathway, inhibit the apoptosis of nerve cells in DRGs after sciatic nerve injury in rats, which may contribute to its effect in improving neurological impairment.

The protective effects of sumatriptan on vincristine - induced peripheral neuropathy in a rat model

Clinical use of vincristine (VCR), an effective chemotherapeutic agent, has been limited due to its peripheral neuropathy toxicity. Sumatriptan, which is an anti-migraine agent is a specific agonist for 5-hydroxytryptamine 1B, 1D (5HT1B, 1D) receptors. Several studies have shown that sumatriptan exerts anti-inflammatory and immunomodulatory properties. This study aimed to investigate the effects of sumatriptan on VCR-induced peripheral neuropathy in a rat model. Male Wistar rats were intraperitoneally injected with VCR and normal saline four times per week for 2 weeks. In the treatment group, sumatriptan (1 mg/kg) was administered intraperitoneally 30 min prior to VCR injection every day. Mortality rate, weight variations and histopathological changes were monitored. Hot plate, tail flick and motor nerve conduction velocity (MNCV) tests were used to evaluate sensory and motor neuropathy. Levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and caspase-3 in the dorsal ganglion root were assessed by quantitative reverse transcription-PCR (qRT-PCR). Moreover, the protein levels of p65 nuclear factor kappa B (NF-<kappa > B) and phospho-p65 NF-<kappa > B were examined by Western blot analysis. Co-administration of sumatriptan with VCR significantly reversed alterations in the hot plate, tail flick threshold and sciatic MNCV induced by VCR and also prevented mixed sensory-motor neuropathy, as indicated by better general conditions, behavioral and electrophysiological results. In addition, sumatriptan improved the body weight loss caused by VCR. The mRNA levels of TNF-α, IL-1β and caspase-3 were significantly diminished in the treatment group. These findings were confirmed by histopathological analysis. In conclusion, this study demonstrated that sumatriptan significantly attenuated VCR-induced neuropathy and could be considered as a neuroprotective agent to prevent the VCR-induced neuropathy.

The mechanism of bone marrow-derived endothelial progenitor cells in the treatment of peripheral neuropathy of diabetic rats

Objective To explore the mechanism of bone marrow-derived endothelial progenitor cells(EPCs)in the treatment of peripheral neuropathy of diabetic rats. Methods Rats with diabetic peripheral neuropathy(DPN)were induced by streptozotocin(60 mg/kg). Male SD rats were divided into normal control group(NC group), DPN group, DPN+ saline group(DPN+ S group), and DPN+ EPCs group. Sciatic nerve motor nerve conduction velocity(MNCV)was measured. The expressions of NF-κB and myelin basic protein(MBP)in sciatic nerve were detected by immunohistochemistry. Results Compared with DPN group, the expression of NF-κB was reduced in the sciatic nerve of DPN+ EPCs group, while the expression of NF-κB was increased in the sciatic nerve of DPN+ S group. There was no statistical difference in the expression of MBP between DPN and DPN+ EPCs groups. Compared with DPN+ S group, the expression of MBP was higher in DPN+ EPCs group. Conclusion Transplantation of EPCs inhibits the expression of NF-κB and increases the expression of MBP, which might be conducive to the repairs of nerve injury. (Chin J Endocrinol Metab, 2018, 34: 312-317) Key words: Endothelial progenitor cells; Diabetic rats; Diabetic peripheral neuropathy

Neuroprotective effect of liquiritin against neuropathic pain induced by chronic constriction injury of the sciatic nerve in mice

Managing of neuropathic pain remains clinically challenging because the existing pharmacotherapies are either ineffective or non-specific. Therefore, developing novel alternatives is essential for better treatment. Liquiritin is an active component extracted from Glycyrrhizae radix and has potential neuroprotective action. This study aimed to investigate the protective efficacy of liquiritin on chronic constriction injury (CCI)-induced neuropathic pain in mice. Liquiritin (30, 60, and 120mg/kg) and pregabalin (40mg/kg) were administered intragastrically for 7 consecutive days starting on the 8th day post-surgery. Behavioral parameters and sciatic functional index were assessed on days 0, 7, 8, 10, 12, and 14. Electrophysiological and histopathological changes were analyzed on the 14th day. Immunofluorescence and Western blot were used to evaluate the expression of glial cells and the protein levels of inflammatory cytokines in the spinal cord, respectively. Results showed that liquiritin dose-dependently reduced hyperalgesia and allodynia and increased the sciatic functional index and motor nerve conduction velocities. Moreover, liquiritin restored the injured axon and myelin sheath, inhibited the activation of astrocyte and microglia, down-regulated the pro-inflammatory cytokines including tumor necrosis factor alpha (TNF-α), interleukin (IL-6, and IL-1β), and simultaneously up-regulated the anti-inflammatory cytokine IL-10. Our study revealed that liquiritin exerted a neuroprotective effect on CCI-induced neuropathic pain, which might be attributed to its direct protective effect on damaged nerves and its anti-inflammatory activity at the level of the spinal cord. Therefore, liquiritin shows promise as a compound for the development of novel analgesic agents that can be used to effectively treat intractable neuropathic pain.

Traditional Chinese medicine Yisui Tongjing relieved neural severity in experimental autoimmune neuritis rat model.

ObjectiveTo study the effect of Yisui Tongjing (YSTJ) prescription on motor nerve conduction velocity (MNCV) and microstructure of the sciatic nerve in experimental autoimmune neuritis (EAN) rats, the Guillain–Barré syndrome classic animal models.Materials and methodsIn this study, we established an EAN model in Lewis rats by immunization. We evaluated the potential clinical application of a traditional Chinese medicine YSTJ by intragastric administration and compared its effect with immunoglobulin. The sciatic MNCV was measured by electrophysiology experiment. Hematoxylin–eosin staining and transmission electron microscope analysis were used to determine the pathologically morphological changes before and after YSTJ application.ResultsWe found that application of YSTJ could significantly alleviate the clinical signs in EAN rats. The treatment also increased MNCV in the sciatic nerve compared to that in the untreated nerve. Demyelination in the sciatic nerve in EAN rats was significantly ameliorated, and newly generated myelinated nerve fibers were observed with treatment of high dose of YSTJ.ConclusionThis study showed that the traditional Chinese medicine YSTJ was likely to serve as a therapeutic medicine in autoimmune neuropathies, providing an effective and economic means to the treatment of Guillain–Barré syndrome.

Decellularized nerve xenograft combined with lycium barbarum polysaccharide for repair of sciatic nerve defect in rats

Objective To explore the effect of lycium barbarum polysaccharide (LBP) and decellularized nerve xenograft combination on nerve regeneration and recovery in repairing rat sciatic nerve defects. Methods Xenogeneic acellular nerve scaffolds were prepared by chemical extraction of tibial nerves from rabbits. A 10 mm left sciatic nerve defect model was created in 90 healthy adult Sprague-Dawley rats who were randomly divided into 5 groups: blank group (n=18), model group (n=18), LBP group (n=18), scaffold group (n=18), LBP and scaffold combination group (n=18). Two weeks after model creation. The sciatic nerve defect in LBP, scaffold and combination groups was repaired either by LBP, by scaffold, or by the LBP xenograft combination. After the second surgery, the rats survived for 4, 8 and 12 weeks, respectively. Gross observation of the scaffold, nerve conduction study to measure sciatic nerve motor nerve conduction velocity (MNCV), and neuromorphometry analysis of the graft were carried out at these three time points. Results Neuroma formation at the proximal nerve end was observed in the model group and LBP group. Adhesion of nerve ends to the surrounding tissue was more severe in the model group than in the LBP group. The sizes of the nerve grafts in the scaffold group and combination group were comparable. Proficient vascularization on the surface of these grafts was seen. There was only slight adhesion to the surrounding tissue. The regenerated nerve fibers in the combination group were denser and better oriented. Motor nerve conduction velocity recovery and the number of myelinated nerve fibers in the grafts were measured at 12 weeks postoperatively for blank, model, LBP, scaffold and combination groups, respectively. The differences among the groups were significant (P<0.05). Conclusion The combination of LBP and xenogeneic acellular nerve scaffold enhances peripheral nerve regeneration and recovery when used to repair nerve defects. Key words: Sciatic nerve; Nerve regeneration; Xenogeneic acellular nerve scaffold; Lycium barbarum polysaccharide

Role of A3 adenosine receptor in diabetic neuropathy.

Neuropathy is the most common diabetic complication. Although the A1 and A2A adenosine receptors are important pharmacological targets in alleviating diabetic neuropathy, the role of the A3 adenosine receptor remains unknown. Because the A3 adenosine receptor regulates pain induced by chronic constriction injury or chemotherapy, its stimulation might also attenuate diabetic neuropathy. This study examines the effects of systemic treatment with the A3 adenosine receptor agonist 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA) on diabetic neuropathy and explores the putative mechanisms underlying its pharmacological effects. We show that IB-MECA alleviated mechanical hyperalgesia and thermal hypoalgesia in mice 2 weeks but not 4 weeks after streptozocin (STZ) treatment. Furthermore, IB-MECA prevented the reduction in sciatic motor nerve conduction velocity and sensory nerve conduction velocity in diabetic mice 2 weeks but not 4 weeks after STZ treatment. Similarly, IB-MECA inhibited the activation of nuclear factor-κB and decreased the generation of tumor necrosis factor-α in the spinal cord of mice 2 weeks but not 4 weeks after STZ treatment. These phenomena were associated with reduction of A3 adenosine receptor expression in the spinal cord after long-term diabetes. Our results suggest that the A3 adenosine receptor plays a critical role in regulating diabetic neuropathy and that reduction in A3 adenosine receptor expression/function might contribute to the progression of diabetic neuropathy. © 2016 Wiley Periodicals, Inc.

Effect of bone marrow-derived endothelial progenitor cells on peripheral neuropathy of diabetic rats

Objective To explore whether endothelial progenitor cells(EPCs)exerts therapeutic effects on rats with diabetic peripheral neuropathy(DPN). Methods Diabetes was induced by streptozotocin. Male SD rats were divided into normal control group(NC group), diabetic peripheral neuropathy group(DPN group), DPN+ saline group(DPN+ S group), and DPN+ EPCs group. Sciatic nerve motor nerve conduction velocity(MNCV)was measured by a electromyography and trigger potentiometer instrument. Pathological changes were observed under optical microscope and electron microscope. Results Compared with normal control group[(52.91±4.53)m/s], both DPN group and DPN+ S group had slower sciatic nerve MNCV[(36.51±6.30 and 25.37±5.48)m/s, P<0.01]. Compared with DPN group, the MNCV of sciatic nerve in DPN+ EPCs group had improved significantly[(36.51±6.30 vs 46.20±11.70)m/s, P<0.01]. Sciatic nerve pathological changes, characterized by demyelination and axonal degeneration under light microscope and electron microscope were observed in DPN group, DPN+ EPCs group, and DPN+ S group. Compared with DPN+ S group, the sciatic nerve pathological changes of DPN+ EPCs group were alleviated. Conclusion After fed for 12 weeks, diabetic rats could progress to DPN rats. Transplantation of EPCs could improve MNCV, demyelination and axonal degeneration changes of sciatic nerver of the DPN rats. (Chin J Endocrinol Metab, 2015, 31: 982-987) Key words: Endothelial progenitor cells; Diabetic rats; Peripheral neuropathy

Gender-specific differences in diabetic neuropathy in BTBR ob/ob mice

AimsTo identify a female mouse model of diabetic peripheral neuropathy (DPN), we characterized DPN in female BTBR ob/ob mice and compared their phenotype to non-diabetic and gender-matched controls. We also identified dysregulated genes and pathways in sciatic nerve (SCN) and dorsal root ganglia (DRG) of female BTBR ob/ob mice to determine potential DPN mechanisms. MethodsTerminal neuropathy phenotyping consisted of examining latency to heat stimuli, sciatic motor and sural sensory nerve conduction velocities (NCV), and intraepidermal nerve fiber (IENF) density. For gene expression profiling, DRG and SCN were dissected, RNA was isolated and processed using microarray technology and differentially expressed genes were identified. ResultsSimilar motor and sensory NCV deficits were observed in male and female BTBR ob/ob mice at study termination; however, IENF density was greater in female ob/ob mice than their male counterparts. Male and female ob/ob mice exhibited similar weight gain, hyperglycemia, and hyperinsulinemia compared to non-diabetic controls, although triglycerides were elevated more so in males than in females. Transcriptional profiling of nerve tissue from female mice identified dysregulation of pathways related to inflammation. ConclusionsSimilar to males, female BTBR ob/ob mice display robust DPN, and pathways related to inflammation are dysregulated in peripheral nerve.

Curcumin Ameliorates Functional and Structural Abnormalities in Cisplatin-induced Neuropathy

Peripheral neuropathy is one of the major side effects of cisplatin; however, effective treatments are lacking. Curcumin is a polyphenol found in the root of Curcuma longa and has been shown neuroprotective against several neurological diseases. Nevertheless, its effects on cisplatin neuropathy remain unclear. This study aimed to clarify this issue by inducing neuropathy in the rats with intraperitoneal injection of cisplatin 2 mg/kg twice a week for 5 consecutive weeks. Curcumin 200 mg/kg/day was given by gavage to a group of cisplatin-treated rats during these five weeks. The results showed that cisplatin induced thermal hypoalgesia in the 5th week which could be prevented by curcumin. In the 5th and 8th weeks, sciatic motor nerve conduction velocity was reduced in the cisplatin compared with the control groups. Curcumin significantly attenuated this deficit. Morphometric analysis of L4 dorsal root ganglia from the cisplatin group revealed nuclear and nucleolar atrophy including loss of neurons in the 8th week. These alterations were significantly blocked by curcumin. Moreover, curcumin also ameliorated the reduced myelin thickness in the sciatic nerve of cisplatin-treated rats. Taken together, our findings suggest the favorable effects of curcumin on both functional and structural abnormalities in cisplatin neuropathy. Future studies are needed to clarify the exact underlying mechanisms.

The neuroprotective effect of tropisetron on vincristine-induced neurotoxicity

Vincristine (VCR) peripheral neuropathy is a dose-limiting side effect. Several studies have shown that tropisetron, a 5-HT3 receptor antagonist, exerts anti-inflammatory and immunomodulatory properties. Current study was designed to investigate a suppressive effect of tropisetron on VCR-induced neuropathy and whether this effect exerts through the 5-HT3 receptor or not.Neuropathy was induced in rats by administration of vincristine (0.5mg/kg, 3 intraperitoneal injections on alternate days) and in treatment group, tropisetron (3mg/kg); m-chlorophenylbiguanide (mCPBG), a selective 5-HT3 receptor agonist (15mg/kg); tropisetron (3mg/kg) plus mCPBG (15mg/kg); granisetron, another selective 5-HT3 receptor antagonist (3mg/kg) were administered intraperitoneally 1h prior to vincristine injection. Hot plate, open field tests (total distance moved, mean velocity and percentage of total duration of the movement) and motor nerve conduction velocity (MNCV) were performed to evaluate the sensory and motor neuropathy. Further, plasma levels of tumor necrosis factor-alpha (TNF-α) and interleukin-2 (IL-2) and the level of TNF-α in sciatic nerve were assessed as well as histological examination.In only VCR-treated rats hot plate latencies were significantly increased, total distance moved, mean velocity, total duration of the movement and sciatic MNCV significantly decreased compared with control. In tropisetron and tropisetron plus mCPBG groups, one injection of tropisetron prior to each VCR injection robustly diminished TNF-α and IL-2 levels, and also prevented mixed sensory-motor neuropathy, as indicated by less mortality rate, better general conditions, behavioral and electrophysiological studies. Moreover, pathological evidence confirmed the results obtained from other findings. But granisetron and mCPBG had no significant effect on the mentioned parameters.In conclusion, these studies demonstrate that tropisetron significantly suppressed VCR-induced neuropathy and could be a neuroprotective agent for prevention of VCR-induced neuropathy via a receptor-independent pathway.

Na+/H+ exchanger 1 inhibition reverses manifestation of peripheral diabetic neuropathy in type 1 diabetic rats

Evidence for an important role for Na(+)/H(+) exchangers in diabetic complications is emerging. The aim of this study was to evaluate whether Na(+)/H(+) exchanger 1 inhibition reverses experimental peripheral diabetic neuropathy. Control and streptozotocin-diabetic rats were treated with the specific Na(+)/H(+) exchanger 1 inhibitor cariporide for 4 wk after 12 wk without treatment. Neuropathy end points included sciatic motor and sensory nerve conduction velocities, endoneurial nutritive blood flow, vascular reactivity of epineurial arterioles, thermal nociception, tactile allodynia, and intraepidermal nerve fiber density. Advanced glycation end product and markers of oxidative stress, including nitrated protein levels in sciatic nerve, were evaluated by Western blot. Rats with 12-wk duration of diabetes developed motor and sensory nerve conduction deficits, thermal hypoalgesia, tactile allodynia, and intraepidermal nerve fiber loss. All these changes, including impairment of nerve blood flow and vascular reactivity of epineurial arterioles, were partially reversed by 4 wk of cariporide treatment. Na(+)/H(+) exchanger 1 inhibition was also associated with reduction of diabetes-induced accumulation of advanced glycation endproduct, oxidative stress, and nitrated proteins in sciatic nerve. In conclusion, these findings support an important role for Na(+)/H(+) exchanger 1 in functional, structural, and biochemical manifestations of peripheral diabetic neuropathy and provide the rationale for development of Na(+)/H(+) exchanger 1 inhibitors for treatment of diabetic vascular and neural complications.