Animal Models Of Nerve Injury Research Articles

Versatile conductive hydrogel orchestrating neuro–immune microenvironment for rapid diabetic wound healing through peripheral nerve regeneration

Diabetic wound (DW), notorious for prolonged healing processes due to the unregulated immune response, neuropathy, and persistent infection, poses a significant challenge to clinical management. Current strategies for treating DW primarily focus on alleviating the inflammatory milieu or promoting angiogenesis, while limited attention has been given to modulating the neuro-immune microenvironment. Thus, we present an electrically conductive hydrogel dressing and identify its neurogenesis influence in a nerve injury animal model initially by encouraging the proliferation and migration of Schwann cells. Further, endowed with the synergizing effect of near-infrared responsive release of curcumin and nature-inspired artificial heterogeneous melanin nanoparticles, it can harmonize the immune microenvironment by restoring the macrophage phenotype and scavenging excessive reactive oxygen species. This in-situ formed hydrogel also exhibits mild photothermal therapy antibacterial efficacy. In the infected DW model, this hydrogel effectively supports nerve regeneration and mitigates the immune microenvironment, thereby expediting the healing progress. The versatile hydrogel exhibits significant therapeutic potential for application in DW healing through fine-tuning the neuro-immune microenvironment.

Development and validation of an LC-MS/MS method for quantifying NAD+ and related metabolites in mice sciatic nerves and its application to a nerve injury animal model

Recent studies highlight the pivotal roles of Nicotinamide adenine dinucleotide (NAD+) and its metabolites in aging and neurodegeneration. Accurate quantification of NAD+ and its metabolite levels in cells or tissues is crucial for advancing biochemical research and interventions targeting aging and neurodegenerative diseases. This study presents an accurate, precise, and rapid LC-MS/MS method using a surrogate matrix to quantify endogenous substances NAD+, nicotinamide mononucleotide (NMN), nicotinamide (NAM), adenosine diphosphate ribose (ADPR), and cyclic adenosine diphosphate ribose (cADPR) concentrations in mice sciatic nerves. Considering the properties of the phosphate groups in the analytes, the column and mobile phase were systematically optimized. These five polar analytes exhibited excellent analytical performance and baseline separation within 5 min on an Atlantis Premier BEH C18 AX column, with methylene phosphonic acid as a mobile phase additive. Enhanced sensitivity addressed the challenges posed by the small sample size of mice sciatic nerve and low NMN and cADPR detection. The method was fully validated, with linear correlation coefficients exceeding 0.992, precision (%relative standard deviation, RSD) values within 8.8%, and accuracy values between 92.2% and 107.3%, suggesting good reproducibility. Analytical recoveries in spiked and diluted matrix ranged from 87.8% to 104.7%, indicating the suitability of water as a surrogate matrix. Application of the method to quantify NAD+ and its metabolite levels in normal and injured mice sciatic nerve identified cADPR as a sensitive biomarker in the nerve injury model. This method is anticipated to deepen our understanding of the connections between NAD+ and its metabolites in health and disease, potentially improving diagnoses of various neurological disorders and aiding drug development for aging and neurodegenerative diseases.

Metabotropic glutamate receptor 5-mediated inhibition of inward-rectifying K+ channel 4.1 contributes to orofacial ectopic mechanical allodynia following inferior alveolar nerve transection in male mice.

Inward-rectifying K+ channel 4.1 (Kir4.1), which regulates the electrophysiological properties of neurons and glia by affecting K+ homeostasis, plays a critical role in neuropathic pain. Metabotropic glutamate receptor 5 (mGluR5) regulates the expression of Kir4.1 in retinal Müller cells. However, the role of Kir4.1 and its expressional regulatory mechanisms underlying orofacial ectopic allodynia remain unclear. This study aimed to investigate the biological roles of Kir4.1 and mGluR5 in the trigeminal ganglion (TG) in orofacial ectopic mechanical allodynia and the role of mGluR5 in Kir4.1 regulation. An animal model of nerve injury was established via inferior alveolar nerve transection (IANX) in male C57BL/6J mice. Behavioral tests indicated that mechanical allodynia in the ipsilateral whisker pad lasted at least 14 days after IANX surgery and was alleviated by the overexpression of Kir4.1 in the TG, as well as intraganglionic injection of an mGluR5 antagonist (MPEP hydrochloride) or a protein kinase C (PKC) inhibitor (chelerythrine chloride); Conditional knockdown of the Kir4.1 gene downregulated mechanical thresholds in the whisker pad. Double immunostaining revealed that Kir4.1 and mGluR5 were co-expressed in satellite glial cells in the TG. IANX downregulated Kir4.1 and upregulated mGluR5 and phosphorylated PKC (p-PKC) in the TG; Inhibition of mGluR5 reversed the changes in Kir4.1 and p-PKC that were induced by IANX; Inhibition of PKC activation reversed the downregulation of Kir4.1 expression caused by IANX (p < .05). In conclusion, activation of mGluR5 in the TG after IANX contributed to orofacial ectopic mechanical allodynia by suppressing Kir4.1 via the PKC signaling pathway.

Modulation of Aryl Hydrocarbon Receptor Expression Alleviated Neuropathic Pain in a Chronic Constriction Nerve Injury Animal Model.

Neuropathic pain is well known to occur after damage to the somatosensory system. Aryl hydrocarbon receptor (AhR) has neuroprotective effects when the central nervous system is subjected to internal and external stimulations. However, the exact mechanism by which AhR regulates neuropathic pain is poorly understood. Nerve explant culture and the chronic constrictive nerve injury (CCI) model in wild or AhR-knockout mice were used in this study. In the nerve explant culture, the ovoid number increased in the AhR−/− condition and was decreased by omeprazole (AhR agonist) in a dose-dependent manner. Increased nerve degeneration and the associated inflammation response appeared in the AhR−/− condition, and these changes were attenuated by omeprazole. High expression of AhR in the injured nerve was noted after CCI. Deletion of AhR aggravated nerve damages and this was restored by omeprazole. Deletion of AhR increased NGF expression and reduced axon number in the paw skin, but this was attenuated by omeprazole. A highly expressed inflammation reaction over the dorsal spinal cord, somatosensory cortex, and hippocampus was noted in the AhR-deleted animals. Administration of omeprazole attenuated not only the inflammatory response, but also the amplitude of somatosensory evoked potential. Deletion of AhR further aggravated the neurobehavior compared with the wild type, but such behavior was attenuated by omeprazole. Chronic constrictive nerve injury augmented AhR expression of the injured nerve, and AhR deletion worsened the damage, while AhR agonist omeprazole counteracted such changes. AhR agonists could be potential candidates for neuropathic pain treatment.

Functional, morphological and molecular characteristics in a novel rat model of spinal sacral nerve injury-surgical approach, pathological process and clinical relevance

Spinal sacral nerve injury represents one of the most serious conditions associated with many diseases such as sacral fracture, tethered cord syndrome and sacral canal tumor. Spinal sacral nerve injury could cause bladder denervation and detrusor underactivity. There is limited clinical experience resolving spinal sacral nerve injury associated detrusor underactivity patients, and thus the treatment options are also scarce. In this study, we established a spinal sacral nerve injury animal model for deeper understanding and further researching of this disease. Forty 8 w (week) old Sprague Dawley rats were included and equally divided into sham (n = 20) and crush group (n = 20). Bilateral spinal sacral nerves of rats were crushed in crush group, and sham group received same procedure without nerve crush. Comprehensive evaluations at three time points (1 w, 4 w and 6 w) were performed to comprehend the nature process of this disease. According to urodynamic test, ultrasonography and retrograde urography, we could demonstrate severe bladder dysfunction after spinal sacral nerve injury along the observation period compared with sham group. These functional changes were further reflected by histological examination (hematoxylin-eosin and Masson’s trichrome staining) of microstructure of nerves and bladders. Immunostaining of nerve/bladder revealed schwann cell death, axon degeneration and collagen remodeling of bladder. Polymerase Chain Reaction results revealed vigorous nerve inflammation and bladder fibrosis 1 week after injury and inflammation/fibrosis returned to normal at 4 w. The CatWalk gait analysis was performed and there was no obvious difference between two groups. In conclusion, we established a reliable and reproducible model for spinal sacral nerve injury, this model provided an approach to evaluate the treatment strategies and to understand the pathological process of spinal sacral nerve injuries. It allowed us to understand how nerve degeneration and bladder fibrosis changed following spinal sacral nerve injury and how recovery could be facilitated by therapeutic options for further research.

Intracavernous Injection of Botulinum Toxin may Improve Erectile Function in a Bilateral Cavernous Nerve Injury Animal Model

ABSTRACT Introduction Erectile dysfunction (ED) is common after treatments for prostate cancer, such as radical prostatectomy (RP) and can negatively impact both patient and partner quality of life. Botulinum toxin (Botox) promotes smooth muscle relaxation and may augment erectile function by reducing basal sympathetic tone in the corpora cavernosa. Botox utilization has suggested a neuroprotective and nerve regenerative role after peripheral nerve injury. Objective We investigated Botox as a durable treatment option for ED in a bilateral cavernous nerve injury (BCNI) animal model. We evaluated the structural changes in penile smooth muscle after intracavernous injection of Botox in an animal model of post-RP ED. Methods Sixteen Sprague Dawley rats (4.5months; 450-550g) were randomized to 4 groups: (1) Sham + NS (2) BCNI + NS (3) Sham + Botox (4) BCNI + Botox. When cavernous nerves were identified during surgery, they were either crushed (BCNI) or left untouched (Sham). Next, either 10 units of Botox or 80umL of normal saline (NS) were injected into the corpora cavernosa. On day 14, erectile function was assessed via cavernous nerve electro-stimulation induced intracavernous pressure (ICP) changes. Penile tissue was harvested for immunohistochemistry and Western blot for neuronal nitric oxide synthase (nNOS) and smooth muscle α-actin (SMA). Results Fourteen animals were included for analysis; one animal in groups 2 and 3 were euthanized for weight loss and lethargy. The Botox treatment groups had a net weight loss whereas the NS groups had weight gain (p&amp;lt;0.05). Erectile function after BCNI recovered with Botox injections and both group 3 &amp; 4 had mean peak ICP and area under the curve values analogous to baseline (group 1) and statistically improved compared to control (group 2) (Figure 1). Western blot analysis revealed a recovery of both nNOS and SMA after Botox treatment (P=0.06). Conclusions This is the first animal study evaluating intracavernous Botox injections for treating ED after BCNI and compared to placebo, the intervention appears to recover erectile function. Further preclinical studies are needed to support this finding, but there may be a future role for using Botox to treat post-prostatectomy ED. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: boston scientific

Adipose-Derived Mesenchymal Stem Cells From a Hypoxic Culture Improve Neuronal Differentiation and Nerve Repair.

Hypoxic expansion has been demonstrated to enhance in vitro neuronal differentiation of bone-marrow derived mesenchymal stem cells (BMSCs). Whether adipose-derived mesenchymal stem cells (ADSCs) increase their neuronal differentiation potential following hypoxic expansion has been examined in the study. Real-time quantitative reverse transcription-polymerase chain reaction and immunofluorescence staining were employed to detect the expression of neuronal markers and compare the differentiation efficiency of hypoxic and normoxic ADSCs. A sciatic nerve injury animal model was used to analyze the gastrocnemius muscle weights as the outcomes of hypoxic and normoxic ADSC treatments, and sections of the regenerated nerve fibers taken from the conduits were analyzed by histological staining and immunohistochemical staining. Comparisons of the treatment effects of ADSCs and BMSCs following hypoxic expansion were also conducted in vitro and in vivo. Hypoxic expansion prior to the differentiation procedure promoted the expression of the neuronal markers in ADSC differentiated neuron-like cells. Moreover, the conduit connecting the sciatic nerve gap injected with hypoxic ADSCs showed the highest recovery rate of the gastrocnemius muscle weights in the animal model, suggesting a conceivable treatment for hypoxic ADSCs. The percentages of the regenerated myelinated fibers from the hypoxic ADSCs detected by toluidine blue staining and myelin basic protein (MBP) immunostaining were higher than those of the normoxic ones. On the other hand, hypoxic expansion increased the neuronal differentiation potential of ADSCs compared with that of the hypoxic BMSCs in vitro. The outcomes of animals treated with hypoxic ADSCs and hypoxic BMSCs showed similar results, confirming that hypoxic expansion enhances the neuronal differentiation potential of ADSCs in vitro and improves in vivo therapeutic potential.

Studying nerve transfers: Searching for a consensus in nerve axons count

Axonal count is the base for efficient nerve transfer; despite its capital importance, few studies have been published on human material, most research approaches being performed on experimental animal models of nerve injury. Thus, standard analysis methods are still lacking. Quantitative data obtained have to be reproducible and comparable with published data by other research groups. To share results with the scientific community, the standardization of quantitative analysis is a fundamental step. For this purpose, the experiences of the Italian, Austrian, German, Greek, and Iberian-Latin American groups have been compared with each other and with the existing literature to reach a consensus in the fiber count and draw up a protocol that can make future studies from different centers comparable. The search for a standardization of the methodology was aimed to reduce all the factors that are associated with an increase in the variability of the results. All the preferential methods to be used have been suggested. On the other hand, alternative methods and different methods have been identified to achieve the same goal, which in our experience are completely comparable; therefore, they can be used indifferently by the different centers according to their experience and availability.

Translational neuropathic pain research.

The traditional translational approach in neuropathic pain research has mainly consisted to date in translating basic findings from animal models of nerve injury to the clinic. Because of the difficulty to extrapolate mechanisms from animals to humans, an inverse translational approach ("top-down") has been advocated and contributed to the development of therapy. In particular, a number of treatments such as neurostimulation techniques have been initially assessed in patients and then translated to animal models for further investigation of their mechanisms. Therapeutic approaches based on an in-depth assessment of sensory phenotypes, suggestive of mechanisms, have also been implemented. The biggest trend in recent translational research is to investigate mechanisms or predict therapeutic response in patients by integrating multimodal approaches. The present narrative review emphasizes these various aspects of translational research in neuropathic pain.

Neurotrophic support by traumatized muscle-derived multipotent progenitor cells: Role of endothelial cells and Vascular Endothelial Growth Factor-A

BackgroundAdult mesenchymal stem cells (MSCs) have been shown to increase nerve regeneration in animal models of nerve injury. Traumatized muscle-derived multipotent progenitor cells (MPCs) share important characteristics with MSCs and are isolated from severely damaged muscle tissue following surgical debridement. Previous investigations have shown that MPCs may be induced to increase production of several neurotrophic factors, suggesting the possible utility of autologous MPCs in peripheral nerve regeneration following injury. Recent findings have also shown that components of the vascular niche, including endothelial cells (ECs) and vascular endothelial growth factor (VEGF)-A, regulate neural progenitor cells and sensory neurons.MethodsIn this study, we have investigated the neuroinductive activities of MPCs, particularly MPC-produced VEGF-A, in the context of an aligned, neuroconductive nerve guide conduit and the endothelial component of the vascular system. Embryonic dorsal root ganglia (DRG) seeded on poly-ϵ-caprolactone aligned nanofibrous scaffold (NF) constructs and on tissue culture plastic, were cocultured with induced MPCs or treated with their conditioned medium (MPC-CM).ResultsIncreased neurite extension was observed on both NF and tissue culture plastic in the presence of MPC-CM versus cell-free control CM. The addition of CM from ECs significantly increased the neurotrophic activity of induced MPC-CM, suggesting that MPC and EC neurotrophic activity may be synergistic. Distinctly higher VEGF-A production was seen in MPCs following neurotrophic induction versus culture under normal growth conditions. Selective removal of VEGF-A from MPC-CM reduced the observed DRG neurite extension length, indicating VEGF-A involvement in neurotrophic activity of the CM.ConclusionsTaken together, these findings suggest the potential of MPCs to encourage nerve growth via a VEGF-A-dependent action, and the use of MPC-CM or a combination of MPC and CM from ECs for peripheral nerve repair in conjunction with NFs in a nerve guide conduit. Due to the ease of use, application of bioactive agents derived from cultured cells to enhance neurotrophic support presents a promising line of research into peripheral nerve repair.

Molecular Changes at the Post-Synapse and Improved Motor Function Suggest Accelerated Recovery with SARM Treatment in an Androgen-Depleted Animal Model of Nerve Injury

Molecular Changes at the Post-Synapse and Improved Motor Function Suggest Accelerated Recovery with SARM Treatment in an Androgen-Depleted Animal Model of Nerve Injury

Model making of radioactive optic nerve injury

Background Radiation-induced optic neuropathy (RION) is a severe complication after radiotherapy for head and neck cancer, which threatens the visual acuity and quality of life of patients.Till now, there is no recognized treatment for RION.It is of great significance to study the natural progression of the RION, and to prevent and treat RION. Objective This study was to establish an ideal radioactive optic nerve injury animal model. Methods Healthy 8-week SD rats with hygiene grade were randomly divided into normal control group and model group, with 6 rats in each group.The total 30 Gy dose of radiation with 3 portions was used to irradiate the head model group rats; ELISA was performed to analysis the changes of endothelin-1 (ET-1) and Von Willebrand factor (vWF) concentrations in blood 2, 4 and 8 weeks after irradiation.Hematoxylin-eosin staining and transmission electron microscope were performed to observe the changes of optic structure.The use and care of the experimental animals complied with the ARVO statement. Results The concentrations of ET-1 in the model group were (23.18±0.11), (27.98±0.22), (33.90±0.11), (65.25±0.38) and (43.82±0.09)pg/ml before irradiation, 1 day, 2, 4, 6 weeks after irradiation, those in the normal control group were (22.65±0.14), (23.18±0.19), (23.68±0.15), (24.23±0.12) and (23.58±0.16)pg/ml.The concentrations of vWF in the model group were (63.16±2.21), (88.32±2.06), (123.38±1.36), (191.40±0.61) and (141.69±0.82)pg/ml before irradiation, 1 day, 2, 4, 6 weeks after irradiation, those in the normal control group were (62.82±1.56), (63.35±2.06), (64.12±1.76), (63.52±2.02) and (63.48±1.55)pg/ml.There were significant differences of ET-1 and vWF concentrations among different groups and time points (ET-1: Fgroup=32.160, P=0.012; Ftime=21.180, P=0.023.vWF: Fgroup=73.110, P=0.001; Ftime=46.180, P=0.002). The nerve fiber bundles was swelled with disordered arrangement and vacuolization 8 weeks after irradiation.Axon swell and atrophy, axons with myelin sheath layer plate separation were obtained.The rates of axon demyelination in the normal control group and model group were (1.35±0.79)% and (14.44±2.32)%, respectively.There was a statistically significant difference between the two groups (t=14.07, P<0.01). Conclusions The total 30 Gy dose of radiation on the head of rats can make stable radioactive optic nerve injury model.This model making method is simple, cheap and practical, which is worth further study. Key words: Optic nerve diseases/etiology; Endothelin-1; Von Willebrand factor; Demyelinating

A new model of nerve injury in the rat reveals a role of Regulator of G protein Signaling 4 in tactile hypersensitivity

Tactile hypersensitivity is one of the most debilitating symptoms of neuropathic pain syndromes. Clinical studies have suggested that its presence at early postoperative stages may predict chronic (neuropathic) pain after surgery. Currently available animal models are typically associated with consistent tactile hypersensitivity and are therefore limited to distinguish between mechanisms that underlie tactile hypersensitivity as opposed to mechanisms that protect against it. In this study we have modified the rat model of spared nerve injury, restricting the surgical lesion to a single peripheral branch of the sciatic nerve. This modification reduced the prevalence of tactile hypersensitivity from nearly 100% to approximately 50%. With this model, we here also demonstrated that the Regulator of G protein Signaling 4 (RGS4) was specifically up-regulated in the lumbar dorsal root ganglia and dorsal horn of rats developing tactile hypersensitivity. Intrathecal delivery of the RGS4 inhibitor CCG63802 was found to reverse tactile hypersensitivity for a 1h period. Moreover, tactile hypersensitivity after modified spared nerve injury was most frequently persistent for at least four weeks and associated with higher reactivity of glial cells in the lumbar dorsal horn. Based on these data we suggest that this new animal model of nerve injury represents an asset in understanding divergent neuropathic pain outcomes, so far unravelling a role of RGS4 in tactile hypersensitivity. Whether this model also holds promise in the study of the transition from acute to chronic pain will have to be seen in future investigations.

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MP52-01 NANOTECHNOLOGY IMPROVED ADIPOSE DERIVED STEM CELL THERAPY IN ERECTILE DYSFUNCTION IN POST RADICAL PROSTATECTOMY ANIMAL MODEL

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research I1 Apr 2015MP52-01 NANOTECHNOLOGY IMPROVED ADIPOSE DERIVED STEM CELL THERAPY IN ERECTILE DYSFUNCTION IN POST RADICAL PROSTATECTOMY ANIMAL MODEL Haocheng Lin, Nadeem Dhanani, Hubert Tseng, Glauco Souza, and Run Wang Haocheng LinHaocheng Lin More articles by this author , Nadeem DhananiNadeem Dhanani More articles by this author , Hubert TsengHubert Tseng More articles by this author , Glauco SouzaGlauco Souza More articles by this author , and Run WangRun Wang More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1718AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Recently, intracavernous injection (ICI) of stem cells has shown some promise for erectile dysfunction (ED). However, most stem cells were washed out immediately due to the communication between corpus cavernosum (CC) and the blood circulation. We previously reported a novel nanotechnology to keep adipose derived stem cells (ADSCs) in CC in animal model. The present study was designed to investigate the effect of this therapy on erectile dysfunction by cavernous nerve injury. METHODS Adipose-derived stem cells (ADSCs) were isolated from inguinal fat tissue of adult male Sprague–Dawley (SD) rats and cultured in DMED/F12 medium. NanoShuttle were added to ADSCs. ED animal models were created by bilateral cavernous nerve crush (BCNC) injury and randomly assigned into four groups (n=6). Group A: BCNC. Group B: ADSCs ICI. Group C: ADSCs with NanoShuttle ICI. Group D: ADSCs with NanoShuttle ICI + magnetic probes. Intracavernous pressure / Mean arterial pressure (ICP/MAP) was recorded under cavernous nerve stimulation at day 28 after ICI. Then, rat penes were harvested and processed for immunohistology and western blot of platelet endothelial cell adhesion molecule (PECAM-1) and alpha smooth muscle Actin (α-SMA). RESULTS Group B, C and D improved erectile function in rats after BCNC injury. Group D had a significant better effect than Group B and Group C (P<0.05). Group B, C and D significantly increased the expressions of PECAM-1 and α-SMA in CC compared with Group A (P<0.05); while Group D had a significant higher expression than Group B and Group C (P<0.05). CONCLUSIONS NanoShuttle plus magnetic probe improved ADSCs therapy for ED in nerve injury animal model. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e628 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Haocheng Lin More articles by this author Nadeem Dhanani More articles by this author Hubert Tseng More articles by this author Glauco Souza More articles by this author Run Wang More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

The effect of minocycline in the expression of induced nitric oxide synthase (iNOS) in rat after optic never injury

Objective To investigate the optic neuroprotective mechanism of minocycline in rats after optic nerve crush.Methods Fifty-four adult SD rats were divided into 3 group according to random check list:the nomal group (6 rats,6 right eyes),the treatment group (24 rats,24 right eyes),the control group(24 rats,24 right eyes).There was no treatment in normal group.In the other two groups,the right eye of each rat was made into optic nerve injury animal model successfully,and intraperitoneal injections of minocycline solution (45mg/kg) or normal saline was performed in the treatment group or the control group respectively once per day until 14 d after injury.The rats were killed at day 1,3,7,14.The morphological changes of retinal tissue were observed by HE staining.The expression levels of iNOS in retinal tissue were detected by immunohisto-chemistry.Results Retinal tissue of the treatment group had lower expression levels of iNOS than the control group at day 1,3,7,14 postoperatively (tid =9.497,t3d =11.203,t7d =15.622,t14d =4.889,P ＜ 0.05).Conclusion Minocycline can reduce the expression levels of iNOS in rat retina after optic never injury.Minocycline protects retina by inhibiting apoptosis and promoting repair of retinal neuron. Key words: Injury, optical nerve; Minocycline; Induced nitric oxide synthase; Apoptosis; Oxidization

Adenoviral-Mediated Glial Cell Line–Derived Neurotrophic Factor Gene Transfer Has a Protective Effect on Sciatic Nerve Following Constriction-Induced Spinal Cord Injury

Neuropathic pain due to peripheral nerve injury may be associated with abnormal central nerve activity. Glial cell-line-derived neurotrophic factor (GDNF) can help attenuate neuropathic pain in different animal models of nerve injury. However, whether GDNF can ameliorate neuropathic pain in the spinal cord dorsal horn (SCDH) in constriction-induced peripheral nerve injury remains unknown. We investigated the therapeutic effects of adenoviral-mediated GDNF on neuropathic pain behaviors, microglial activation, pro-inflammatory cytokine expression and programmed cell death in a chronic constriction injury (CCI) nerve injury animal model. In this study, neuropathic pain was produced by CCI on the ipsilateral SCDH. Mechanical allodynia was examined with von Frey filaments and thermal sensitivity was tested using a plantar test apparatus post-operatively. Target proteins GDNF-1, GDNFRa-1, MMP2, MMP9, p38, phospho-p38, ED1, IL6, IL1β, AIF, caspase-9, cleaved caspase-9, caspase-3, cleaved caspase-3, PARP, cleaved PARP, SPECTRIN, cleaved SPECTRIN, Beclin-1, PKCσ, PKCγ, iNOS, eNOS and nNOS were detected. Microglial activity was measured by observing changes in immunoreactivity with OX-42. NeuN and TUNEL staining were used to reveal whether apoptosis was attenuated by GDNF. Results showed that administrating GDNF began to attenuate both allodynia and thermal hyperalgesia at day 7. CCI-rats were found to have lower GDNF and GDNFRa-1 expression compared to controls, and GDNF re-activated their expression. Also, GDNF significantly down-regulated CCI-induced protein expression except for MMP2, eNOS and nNOS, indicating that the protective action of GDNF might be associated with anti-inflammation and prohibition of microglia activation. Immunocytochemistry staining showed that GDNF reduced CCI-induced neuronal apoptosis. In sum, GDNF enhanced the neurotrophic effect by inhibiting microglia activation and cytokine production via p38 and PKC signaling. GDNF could be a good therapeutic tool to attenuate programmed cell death, including apoptosis and autophagy, consequent to CCI-induced peripheral nerve injury.

Beyond taxol: microtubule-based treatment of disease and injury of the nervous system

Contemporary research has revealed a great deal of information on the behaviours of microtubules that underlie critical events in the lives of neurons. Microtubules in the neuron undergo dynamic assembly and disassembly, bundling and splaying, severing, and rapid transport as well as integration with other cytoskeletal elements such as actin filaments. These various behaviours are regulated by signalling pathways that affect microtubule-related proteins such as molecular motor proteins and microtubule severing enzymes, as well as a variety of proteins that promote the assembly, stabilization and bundling of microtubules. In recent years, translational neuroscientists have earmarked microtubules as a promising target for therapy of injury and disease of the nervous system. Proof-of-principle has come mainly from studies using taxol and related drugs to pharmacologically stabilize microtubules in animal models of nerve injury and disease. However, concerns persist that the negative consequences of abnormal microtubule stabilization may outweigh the positive effects. Other potential approaches include microtubule-active drugs with somewhat different properties, but also expanding the therapeutic toolkit to include intervention at the level of microtubule regulatory proteins.

An implantable electrical stimulator used for peripheral nerve rehabilitation in rats

This study evaluated an implantable electrical stimulator using a sciatic nerve injury animal model, and ethological, electrophysiological and histological assessments. Forty Sprague-Dawley rats were used in the study, and were subjected to crushing of the right sciatic nerve with a micro-vessel clamp. Electrical stimulators were implanted in twenty of the rats (the implantation group), while the remaining twenty rats were assigned to the control group. At three and six weeks following the surgery, the sciatic nerve function index (SFI) and the motor nerve conduction velocity (MCV) were demonstrated to be significantly higher in the implantation group compared with the control group (P<0.05). Histological analysis, using hematoxylin and eosin (H&E) staining, showed the typical pathological atrophy, and an assessment of the nerve that had been crushed revealed distal axonal breakdown in the control group. These results suggest that the implantable electrical stimulator was effective, and was suitable for implantation in a Sprague-Dawley rat model.

Neurotropin inhibits axonal transport in cultured mouse dorsal root ganglion neurons

Axonal transport is a basic neuronal cell function and important for the supply of materials that maintain neuronal cells, and any increase or decrease in axonal transport expresses the state of neurons. Neurotropin is an analgesic agent commonly used for the treatment of chronic pain, but its mechanism of action remains not fully understood. The effects of neurotropin have been investigated in various animal models of nerve injury and chronic pain. In the present study, we dissected the effects of neurotropin on sensory neurons with a special focus on axonal transport using cultured mouse dorsal root ganglion (DRG) neurons. Movement of organelles in neurites was recorded by real-time video-enhanced microscopy. Neurotropin significantly reduced bidirectional axonal transport in time- and concentration-dependent manners without affecting the diameter of these neurites. This is the first report to show the inhibitory effect of neurotropin on axonal transport, and suggest that this action may mediate, at least in part, the analgesic effects of this agent.