Nerve Injury Model Research Articles

Spinal Interferon Regulatory Factor 8 and Brain-derived Neurotrophic Factor in the Prefrontal Cortex are Involved in Pain-induced Depression Relief via Ultrasound-guided Pulsed Radiofrequency in a Rat Spared Nerve Injury Model

BACKGROUND: Pain-depression comorbidity has become a great burden to individuals and society. Nevertheless, the mechanisms underlying comorbid diseases have still not been fully revealed. Ultrasound-guided pulsed radiofrequency (PRF) on peripheral nerves, which produces remarkable analgesia via high-frequency electromagnetic energy, has become a main, minimally invasive treatment for chronic neuropathic pain. OBJECTIVES: The aim of this study was to explore the effect of ultrasound-guided PRF on the sciatic nerve of spared nerve injury (SNI) rats to relieve pain-induced depression. STUDY DESIGN: Experimental trial in rats. SETTING: The research took place in the Laboratory of The First Affiliated Hospital of Wenzhou Medical University. METHODS: Sixty male Wistar rats were randomly divided into a sham group, an SNI group, an SNI + free-PRF group, and an SNI + PRF group. Ultrasound-guided PRF was applied to the sciatic nerve on day 7 after SNI. The basal paw mechanical withdrawal threshold (PMWT) was evaluated as a measure for pain-related behavior, and a sucrose preference test was performed as a measure for depression-related behavior. The expression levels of spinal interferon regulatory factor 8 (IRF8) and of brain-derived neurotrophic factor (BDNF) in the prefrontal cortex (PFC) were also studied on days 21 and 42. RESULTS: The results showed that the PMWT was significantly decreased in rats following SNI operation; the decreased levels of PMWT were reversed in the SNI + PRF group after the application of PRF on the sciatic nerve on day 7. There were no statistically significant differences among the groups in the sucrose preference rate on day 21 after SNI operation. The sucrose preference rate on day 42 was higher in the SNI + PRF group than in the SNI + free-PRF group. Western blot and reverse transcription polymerase chain reaction also demonstrated that ultrasound-guided PRF on the sciatic nerve downregulated overexpression of spinal IRF8 and increased the levels of BDNF in the PFC. LIMITATIONS: This study was performed using only an SNI rat model which cannot represent all rodent neuropathic pain models. Only the short-term effectiveness of ultrasound-guided PRF on the sciatic nerve of SNI rats was investigated. The BDNF changes of other important brain areas were not taken into consideration in this study. CONCLUSIONS: These findings suggest that ultrasound-guided PRF on sciatic nerve could alleviate pain-induced depression. The mechanisms of this treatment may be involved in the downregulated spinal IRF8 and the increased BDNF in PFC. KEY WORDS: Neuropathic pain, depression, ultrasound, pulsed radiofrequency, interferon regulatory factor 8, brain-derived neurotrophic factor, spinal cord, prefrontal cortex

Spinal dopaminergic D1-and D2-like receptors have a sex-dependent effect in an experimental model of fibromyalgia

There is evidence about the importance of sex in pain. The purpose of this study was to investigate the effect of sex in the antiallodynic activity of spinal dopamine D1-and D2-like receptors in a model of fibromyalgia-type pain in rats. Reserpine induced the same extent of tactile allodynia in female and male rats. Intrathecal injection of SCH-23390 (3–30 nmol, D1-like receptor antagonist), pramipexole (0.15–15 nmol) or quinpirole (1–10 nmol D2-like receptor agonists) increased withdrawal threshold in reserpine-treated female rats. Those drugs induced a greater antiallodynic effect in female rats. Sex-difference was also observed in a nerve injury model. Ovariectomy abated the antiallodynic effect of SCH-23390 (30 nmol) in reserpine-treated rats, while systemic reconstitution of 17β-estradiol levels or intrathecal injection of estrogen receptor-α agonist protopanaxatriol in ovariectomized reserpine-treated females restored the antiallodynic effect of SCH-23390. Intrathecal administration of ICI-182,780 (estrogen receptor-α/β antagonist) or methyl-piperidino-pyrazole hydrate (estrogen receptor-α antagonist) abated 17β-estradiol-restored antiallodynic effect of SCH-23390 in rats. In contrast, ovariectomy slightly reduced the effect of pramipexole (15 nmol) or quinpirole (10 nmol) in reserpine-treated rats, whereas systemic reconstitution of 17β-estradiol levels did not modify the antiallodynic effect of both drugs. Combination 17β-estradiol/progesterone, but not 17β-estradiol nor progesterone alone, restored the antiallodynic effect of pramipexole and quinpirole in the rats. Mifepristone (progesterone receptor antagonist) abated 17β-estradiol + progesterone restoration of the antiallodynic effect of pramipexole and quinpirole. These data suggest that the antiallodynic effect of dopamine D1-and D2-like receptors in fibromyalgia-type pain depends on spinal 17β-estradiol/estrogen receptor-α and progesterone receptors, respectively.

Anti-Inflammatory Activity of Synaptamide in the Peripheral Nervous System in a Model of Sciatic Nerve Injury.

N-docosahexaenoylethanolamine (DHEA), or synaptamide, is an endogenous metabolite of docosahexaenoic acid (DHA) that exhibits synaptogenic and neurogenic effects. In our previous studies, synaptamide administration inhibited the neuropathic pain-like behavior and reduced inflammation in the central nervous system following sciatic nerve injury. In the present study, we examine the effect of synaptamide on the peripheral nervous system in a neuropathic pain condition. The dynamics of ionized calcium-binding adapter molecule 1 (iba-1), CD68, CD163, myelin basic protein, and the production of interleukin 1β and 6 within the sciatic nerve, as well as the neuro-glial index and the activity of iba-1, CD163, glial fibrillary acidic protein (GFAP), neuronal NO synthase (nNOS), substance P (SP), activating transcription factor 3 (ATF3) in the dorsal root ganglia (DRG), are studied. According to our results, synaptamide treatment (4 mg/kg/day) (1) decreases the weight-bearing deficit after nerve trauma; (2) enhances the remyelination process in the sciatic nerve; (3) shows anti-inflammatory properties in the peripheral nervous system; (4) decreases the neuro-glial index and GFAP immunoreactivity in the DRG; (5) inhibits nNOS- and SP-ergic activity in the DRG, which might contribute to neuropathic pain attenuation. In general, the current study demonstrates the complex effect of synaptamide on nerve injury, which indicates its high potential for neuropathic pain management.

Electroacupuncture Induces Bilateral S1 and ACC Epigenetic Regulation of Genes in a Mouse Model of Neuropathic Pain

Clinical and animal studies have shown that acupuncture may benefit controlling neuropathic pain. However, the underlying molecular mechanisms are poorly understood. In a well-established mouse unilateral tibial nerve injury (TNI) model, we confirmed the efficacy of electroacupuncture (EA) in reducing mechanical allodynia and measured methylation and hydroxy-methylation levels in the primary somatosensory cortex (S1) and anterior cingulate cortex (ACC), two cortical regions critically involved in pain processing. TNI resulted in increased DNA methylation of both the contra- and ipsilateral S1, while EA only reduced contralateral S1 methylation. RNA sequencing of the S1 and ACC identified differentially expressed genes related to energy metabolism, inflammation, synapse function, and neural plasticity and repair. One week of daily EA decreased or increased the majority of up- or downregulated genes, respectively, in both cortical regions. Validations of two greatly regulated genes with immunofluorescent staining revealed an increased expression of gephyrin in the ipsilateral S1 after TNI was decreased by EA; while TNI-induced increases in Tomm20, a biomarker of mitochondria, in the contralateral ACC were further enhanced after EA. We concluded that neuropathic pain is associated with differential epigenetic regulations of gene expression in the ACC and S1 and that the analgesic effect of EA may involve regulating cortical gene expression.

Clinical, electrophysiological, and histomorphological effects of local coenzyme Q10 and vitamin E use in a rat model of peripheral nerve injury.

This study aimed to investigate the clinical, electrophysiological, and histomorphological effects of local use of coenzyme Q10 and vitamin E combination in a rat model of peripheral nerve injury. Forty adult female Wistar-Albino rats weighing 250-350 g were kept in a room with a temperature of 20-22°C and a light/dark cycle of 12 hours. They had free access to food and water. The right sciatic nerves of 40 rats were transected and repaired. Subjects were divided into 4 groups: controls (control-4 weeks and control-8 weeks) and treatments (treatment-4 weeks and treatment-8 weeks). A combination of coenzyme Q10 and vitamin E was applied to the repair site by a catheter placed subcutaneously in the treatment group. Only transection-repair was done in the control group. All groups were divided into 2 subgroups for histomorphological, clinical, and electrophysiological experiments because of concerns about possible interference with histomorphological preparation (5 rats in each group). The experiment results were examined by the thermal plantar test, action potential and latency time measurements, and electron microscopy at the end of 4 and 8 weeks. The intact group was studied as the uninterrupted 10 left sciatic nerves of control for 4 weeks. The mean thermal plantar test results of the intact group were better than those of the control groups (P < .05). However, there was no significant difference between the intact and treatment groups. In the histomorphological examination, the number of myelinated axons increased significantly, and the myelin structure was closer to that of the intact group, especially when the treatment-8 group was compared with the control groups (control-4: P < .0001, control-8: P < .01). Local use of coenzyme Q10 and vitamin E seems useful in the experimental rat sciatic nerve transection-repair model.

Bifidobacterium promotes retinal ganglion cell survival by regulating the balance of retinal glial cells.

Optic nerve injury is a leading cause of irreversible blindness worldwide. The retinal ganglion cells (RGCs) and their axons cannot be regenerated once damaged. Therefore, reducing RGC damage is crucial to prevent blindness. Accordingly, we aimed to investigate the potential influence of the gut microbiota on RGC survival, as well as the associated action mechanisms. We evaluated the effects of microbiota, specifically Bifidobacterium, on RGC. Optic nerve crush (ONC) was used as a model of optic nerve injury. Vancomycin and Bifidobacterium were orally administered to specific pathogen-free (SPF) mice. Bifidobacterium promoted RGC survival and optic nerve regeneration. The administration of Bifidobacterium inhibited microglia activation but promoted Müller cell activation, which was accompanied by the downregulation of inflammatory cytokines and upregulation of neurotrophic factors and retinal ERK/Fos signaling pathway activation. Our study demonstrates that Bifidobacterium-induced changes in intestinal flora promote RGC survival. The protective effect of Bifidobacterium on RGC can be attributed to the inhibition of microglia activation and promotion of Müller cell activation and the secondary regulation of inflammatory and neurotrophic factors.

Epigenetic combined with transcriptomic analysis of the m6A methylome after spared nerve injury-induced neuropathic pain in mice.

Epigenetic changes in the spinal cord play a key role in the initiation and maintenance of nerve injury-induced neuropathic pain. N6-methyladenosine (m6A) is one of the most abundant internal RNA modifications and plays an essential function in gene regulation in many diseases. However, the global m6A modification status of mRNA in the spinal cord at different stages after neuropathic pain is unknown. In this study, we established a neuropathic pain model in mice by preserving the complete sural nerve and only damaging the common peroneal nerve. High-throughput methylated RNA immunoprecipitation sequencing results showed that after spared nerve injury, there were 55 m6A methylated and differentially expressed genes in the spinal cord. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway results showed that m6A modification triggered inflammatory responses and apoptotic processes in the early stages after spared nerve injury. Over time, the differential gene function at postoperative day 7 was enriched in "positive regulation of neurogenesis" and "positive regulation of neural precursor cell proliferation." These functions suggested that altered synaptic morphological plasticity was a turning point in neuropathic pain formation and maintenance. Results at postoperative day 14 suggested that the persistence of neuropathic pain might be from lipid metabolic processes, such as "very-low-density lipoprotein particle clearance," "negative regulation of cholesterol transport" and "membrane lipid catabolic process." We detected the expression of m6A enzymes and found elevated mRNA expression of Ythdf2 and Ythdf3 after spared nerve injury modeling. We speculate that m6A reader enzymes also have an important role in neuropathic pain. These results provide a global landscape of mRNA m6A modifications in the spinal cord in the spared nerve injury model at different stages after injury.

Rats, Neuregulins and Radical Prostatectomy: A Conceptual Overview

In the contemporary era of early detection, with mostly curative initial treatment for prostate cancer (PC), mortality rates have significantly diminished. In addition, mean age at initial PC diagnosis has decreased. Despite technical advancements, the probability of erectile function (EF) recovery post radical prostatectomy (RP) has not significantly changed throughout the last decade. Due to virtually unavoidable intraoperative cavernous nerve (CN) lesions and operations with younger patients, post-RP erectile dysfunction (ED) has now begun affecting these younger patients. To address this pervasive limitation, a plethora of CN lesion animal model investigations have analyzed the use of systemic/local treatments for EF recovery post-RP. Most promisingly, neuregulins (NRGs) have demonstrated neurotrophic effects in both neurodegenerative disease and peripheral nerve injury models. Recently, glial growth factor 2 (GGF2) has demonstrated far superior, dose-dependent, neuroprotective/restorative effects in the CN injury rat model, as compared to previous therapeutic counterparts. Although potentially impactful, these initial findings remain limited and under-investigated. In an effort to aid clinicians, our paper reviews post-RP ED pathogenesis and currently available therapeutic tools. To stimulate further experimentation, a standardized preparation protocol and in-depth analysis of applications for the CN injury rat model is provided. Lastly, we report on NRGs, such as GGF2, and their potentially revolutionary clinical applications, in hopes of identifying relevant future research directions.

GPR55 contributes to neutrophil recruitment and mechanical pain induction after spinal cord compression in mice

Pain transmission and processing in the nervous system are modulated by various biologically active substances, including lysophospholipids, through direct and indirect actions on the somatosensory pathway. Lysophosphatidylglucoside (LysoPtdGlc) was recently identified as a structurally unique lysophospholipid that exerts biological actions via the G protein-coupled receptor GPR55. Here, we demonstrated that GPR55-knockout (KO) mice show impaired induction of mechanical pain hypersensitivity in a model of spinal cord compression (SCC) without the same change in the models of peripheral tissue inflammation and peripheral nerve injury. Among these models, only SCC recruited peripheral inflammatory cells (neutrophils, monocytes/macrophages, and CD3+ T-cells) in the spinal dorsal horn (SDH), and GPR55-KO blunted these recruitments. Neutrophils were the first cells recruited to the SDH, and their depletion suppressed the induction of SCC-induced mechanical hypersensitivity and inflammatory responses in compressed SDH. Furthermore, we found that PtdGlc was present in the SDH and that intrathecal administration of an inhibitor of secretory phospholipase A2 (an enzyme required for producing LysoPtdGlc from PtdGlc) reduced neutrophil recruitment to compressed SDH and suppressed pain induction. Finally, by screening compounds from a chemical library, we identified auranofin as a clinically used drug with an inhibitory effect on mouse and human GPR55. Systemically administered auranofin to mice with SCC effectively suppressed spinal neutrophil infiltration and pain hypersensitivity. These results suggest that GPR55 signaling contributes to the induction of inflammatory responses and chronic pain after SCC via the recruitment of neutrophils and may provide a new target for reducing pain induction after spinal cord compression, such as spinal canal stenosis.

Comparison of the Nerve Regeneration Capacity and Characteristics between Sciatic Nerve Crush and Transection Injury Models in Rats

ObjectiveTo provide useful information for selecting the most appropriate peripheral nerve injury model for different research purposes in nerve injury and repair studies, and to compare nerve regeneration capacity and characteristics between them. MethodsSixty adult SD rats were randomly divided into two groups and underwent crush injury alone (group A, n = 30) or transection injury followed by surgical repair (group B, n = 30) of the right hind paw. Each group was subjected to the CatWalk test, gastrocnemius muscle evaluation, pain threshold measurement, electrophysiological examination, retrograde neuronal labeling, and quantification of nerve regeneration before and 7, 14, 21, and 28 days after injury. ResultsGait analysis showed that the recovery speed in group A was significantly faster than that in group B at 14 days. At 21 days, the compound muscle action potential of the gastrocnemius muscle in group A was significantly higher than that in group B, and the number of labeled motor neurons in group B was lower than that in group A. The number of new myelin sheaths and the g-ratio were higher in group A than in group B. There was a 7-day time difference in the regeneration rate between the two injury groups. ConclusionThe regeneration of nerve fibers was rapid after crush nerve injury, whereas the transection injury was relatively slow, which provides some ideas for the selection of clinical research models.

Pharmacokinetics of Orally Applied Cannabinoids and Medical Marijuana Extracts in Mouse Nervous Tissue and Plasma: Relevance for Pain Treatment.

Cannabis sativa plants contain a multitude of bioactive substances, which show broad variability between different plant strains. Of the more than a hundred naturally occurring phytocannabinoids, Δ9-Tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) have been the most extensively studied, but whether and how the lesser investigated compounds in plant extracts affect bioavailability or biological effects of Δ9-THC or CBD is not known. We therefore performed a first pilot study to assess THC concentrations in plasma, spinal cord and brain after oral administration of THC compared to medical marijuana extracts rich in THC or depleted of THC. Δ9-THC levels were higher in mice receiving the THC-rich extract. Surprisingly, only orally applied CBD but not THC alleviated mechanical hypersensitivity in the mouse spared nerve injury model, favoring CBD as an analgesic compound for which fewer unwanted psychoactive effects are to be expected.

Brain-Derived Neurotrophic Factor Is Indispensable to Continence Recovery after a Dual Nerve and Muscle Childbirth Injury Model.

In women, stress urinary incontinence (SUI), leakage of urine from increased abdominal pressure, is correlated with pudendal nerve (PN) injury during childbirth. Expression of brain-derived neurotrophic factor (BDNF) is dysregulated in a dual nerve and muscle injury model of childbirth. We aimed to use tyrosine kinase B (TrkB), the receptor of BDNF, to bind free BDNF and inhibit spontaneous regeneration in a rat model of SUI. We hypothesized that BDNF is essential for functional recovery from the dual nerve and muscle injuries that can lead to SUI. Female Sprague-Dawley rats underwent PN crush (PNC) and vaginal distension (VD) and were implanted with osmotic pumps containing saline (Injury) or TrkB (Injury + TrkB). Sham Injury rats received sham PNC + VD. Six weeks after injury, animals underwent leak-point-pressure (LPP) testing with simultaneous external urethral sphincter (EUS) electromyography recording. The urethra was dissected for histology and immunofluorescence. LPP after injury and TrkB was significantly decreased compared to Injury rats. TrkB treatment inhibited reinnervation of neuromuscular junctions in the EUS and promoted atrophy of the EUS. These results demonstrate that BDNF is essential to neuroregeneration and reinnervation of the EUS. Treatments aimed at increasing BDNF periurethrally could promote neuroregeneration to treat SUI.

The spatiotemporal matching pattern of Ezrin/Periaxin involved in myoblast differentiation and fusion and Charcot-Marie-Tooth disease-associated muscle atrophy

BackgroundClinically, Charcot-Marie-Tooth disease (CMT)-associated muscle atrophy still lacks effective treatment. Deletion and mutation of L-periaxin can be involved in CMT type 4F (CMT4F) by destroying the myelin sheath form, which may be related to the inhibitory role of Ezrin in the self-association of L-periaxin. However, it is still unknown whether L-periaxin and Ezrin are independently or interactively involved in the process of muscle atrophy by affecting the function of muscle satellite cells.MethodA gastrocnemius muscle atrophy model was prepared to mimic CMT4F and its associated muscle atrophy by mechanical clamping of the peroneal nerve. Differentiating C2C12 myoblast cells were treated with adenovirus-mediated overexpression or knockdown of Ezrin. Then, overexpression of L-periaxin and NFATc1/c2 or knockdown of L-periaxin and NFATc3/c4 mediated by adenovirus vectors were used to confirm their role in Ezrin-mediated myoblast differentiation, myotube formation and gastrocnemius muscle repair in a peroneal nerve injury model. RNA-seq, real-time PCR, immunofluorescence staining and Western blot were used in the above observation.ResultsFor the first time, instantaneous L-periaxin expression was highest on the 6th day, while Ezrin expression peaked on the 4th day during myoblast differentiation/fusion in vitro. In vivo transduction of adenovirus vectors carrying Ezrin, but not Periaxin, into the gastrocnemius muscle in a peroneal nerve injury model increased the numbers of muscle myosin heavy chain (MyHC) I and II type myofibers, reducing muscle atrophy and fibrosis. Local muscle injection of overexpressed Ezrin combined with incubation of knockdown L-periaxin within the injured peroneal nerve or injection of knockdown L-periaxin into peroneal nerve-injured gastrocnemius muscle not only increased the number of muscle fibers but also recovered their size to a relatively normal level in vivo. Overexpression of Ezrin promoted myoblast differentiation/fusion, inducing increased MyHC-I+ and MyHC-II + muscle fiber specialization, and the specific effects could be enhanced by the addition of adenovirus vectors for knockdown of L-periaxin by shRNA. Overexpression of L-periaxin did not alter the inhibitory effects on myoblast differentiation and fusion mediated by knockdown of Ezrin by shRNA in vitro but decreased myotube length and size. Mechanistically, overexpressing Ezrin did not alter protein kinase A gamma catalytic subunit (PKA-γ cat), protein kinase A I alpha regulatory subunit (PKA reg Iα) or PKA reg Iβ levels but increased PKA-α cat and PKA reg II α levels, leading to a decreased ratio of PKA reg I/II. The PKA inhibitor H-89 remarkably abolished the effects of overexpressing-Ezrin on increased myoblast differentiation/fusion. In contrast, knockdown of Ezrin by shRNA significantly delayed myoblast differentiation/fusion accompanied by an increased PKA reg I/II ratio, and the inhibitory effects could be eliminated by the PKA reg activator N6-Bz-cAMP. Meanwhile, overexpressing Ezrin enhanced type I muscle fiber specialization, accompanied by an increase in NFATc2/c3 levels and a decrease in NFATc1 levels. Furthermore, overexpressing NFATc2 or knocking down NFATc3 reversed the inhibitory effects of Ezrin knockdown on myoblast differentiation/fusion.ConclusionsThe spatiotemporal pattern of Ezrin/Periaxin expression was involved in the control of myoblast differentiation/fusion, myotube length and size, and myofiber specialization, which was related to the activated PKA-NFAT-MEF2C signaling pathway, providing a novel L-Periaxin/Ezrin joint strategy for the treatment of muscle atrophy induced by nerve injury, especially in CMT4F.

Allogenic bone marrow-derived mesenchymal stem cells and its conditioned media for repairing acute and sub-acute peripheral nerve injuries in a rabbit model

The present study evaluated healing potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) and BM-MSCs-conditioned medium (BM-MSCs-CM) for acute and subacute injuries in the rabbit peripheral nerve injury model. The regenerative capacity of MSCs was evaluated in 40 rabbits divided into eight groups, four groups each for acute and subacute injury models. BM-MSCs and BM-MSCS-CM were prepared by isolating allogenic bone marrow from the iliac crest. After inducing sciatic nerve crush injury, different treatments consisting of PBS, Laminin, BM-MSCs + laminin, and BM-MSCS-CM + laminin were used on the day of injury in the acute injury model and after ten days of crush injury in the subacute groups. The parameters studied included: pain, total neurological score, gastrocnemius muscle weight and volume ratio, histopathology of the sciatic nerve and gastrocnemius muscle, and scanning electron microscopy (SEM). Findings indicate that BM-MSCs and BM-MSCS-CM have augmented the regenerative capacity in acute and subacute injury groups with a slightly better improvement in the subacute groups than the animals in acute injury groups. Histopathology data revealed different levels of regenerative process undergoing in the nerve. Neurological observations, gastrocnemius muscle evaluation, muscle histopathology, and the SEM results depicted better healing in animals treated with BM-MSCs and BM-MSCS-CM. With this data, it could be concluded that BM-MSCs support the healing of injured peripheral nerves, and the BM-MSCS-CM does accelerate the healing of acute and subacute peripheral nerve injuries in rabbits. However, stem cell therapy may be indicated during the subacute phase for better results.

Establishment of an animal model of sciatic nerve injury induced by local anesthetics.

Peripheral neurotoxicity injury caused by local anesthetics is a common complication of clinical anesthesia. The study of its mechanism is helpful to prevent and treat the neurotoxic injury of local anesthetics. Previous studies on peripheral neurotoxicity injury caused by local anesthetics have mainly focused on in vitro cell experiments. Due to the lack of an animal model of peripheral neurotoxicity damage caused by local anesthetics, there are few in vivo experimental studies regarding this topic. Herein, 1% ropivacaine hydrochloride was injected into the sciatic nerve by direct incision and exposure of the sciatic nerve to create a local anesthetic neurotoxic injury model. The results showed that 1% ropivacaine hydrochloride could reduce the lower limb motor score and mechanical paw withdrawal threshold in mice 48hours after injection. Pathological sections showed that 48hours after treatment with 1% ropivacaine hydrochloride, the sciatic nerve showed increased axonal edema and degeneration, edema between nerve fiber bundles, increased degeneration of axon and myelin sheath vacuoles, edema of nerve bundle membrane and local degeneration and necrosis, and a large number of inflammatory cells around the nerve adventitia were soaked. The above results show that under open vision, 1% ropivacaine hydrochloride can cause injury to the sciatic nerve after 48h of treatment, which can simulate the neurotoxic damage of local anesthetics. This animal model provides a research tool for studying the mechanism of neurotoxic injury caused by local anesthetics.

Transcriptional Profiling of TGF-β Superfamily Members in Lumbar DRGs of Rats Following Sciatic Nerve Axotomy and Activin C Inhibits Neuropathic Pain.

Neuroinflammation and cytokines play critical roles in neuropathic pain and axon degeneration/regeneration. Cytokines of transforming growth factor-β superfamily have implications in pain and injured nerve repair processing. However, the transcriptional profiles of the transforming growth factor-β superfamily members in dorsal root ganglia under neuropathic pain and axon degeneration/regeneration conditions remain elusive. We aimed to plot the transcriptional profiles of transforming growth factor-β superfamily components in lumbar dorsal root ganglia of sciatic nerve-axotomized rats and to further verify the profiles by testing the analgesic effect of activin C, a representative cytokine, on neuropathic pain. Adult male rats were axotomized in sciatic nerves, and lumbar dorsal root ganglia were isolated for total RNA extraction or section. A custom microarray was developed and employed to plot the gene expression profiles of transforming growth factor-β superfamily components. Realtime RT-PCR was used to confirm changes in the expression of activin/inhibin family genes, and then in situ hybridization was performed to determine the cellular locations of inhibin α, activin βC, BMP-5 and GDF-9 mRNAs. The rat spared nerve injury model was performed, and a pain test was employed to determine the effect of activin C on neuropathic pain. The expression of transforming growth factor-β superfamily cytokines and their signaling, including some receptors and signaling adaptors, were robustly upregulated. Activin βC subunit mRNAs were expressed in the small-diameter dorsal root ganglion neurons and upregulated after axotomy. Single intrathecal injection of activin C inhibited neuropathic pain in spared nerve injury model. This is the first report to investigate the transcriptional profiles of members of transforming growth factor-β superfamily in axotomized dorsal root ganglia. The distinct cytokine profiles observed here might provide clues toward further study of the role of transforming growth factor-β superfamily in the pathogenesis of neuropathic pain and axon degeneration/regeneration after peripheral nerve injury.

Adipose-derived Stem Cell Transplantation Enhances Peripheral Nerve Regeneration in a Peroneal Nerve Injury Model in the Rat

Introduction: Despite advances in the treatment of peripheral nerve injury, patients still suffer from incomplete motor recovery. In vivo and in vitro studies demonstrated that adipose derived stem cells (AdSCs) promote peripheral nerve regeneration, but the effect on motor recovery remains unclear. Materials and Methods: According to sample size calculation and randomization 48 rats received either intramuscular, intraneural, combined or vehicle injection of AdSCs following common peroneal nerve contusion injury in narcosis. During the four-week follow-up period, the animals underwent weekly footprint and videometric joint-angle analysis. Finally, the animals underwent isometric force measurement of the tibialis anterior muscle for twitch force, tetanic force, fatigue and electromyography. Results: During the four weeks of follow-up all groups regained full recovery of their gait, marked by Inserra’s peroneal functional index analysing toespread and the joint angle analysis. In Isometric force measurement using twitch force, tetanic force and fatique, intramuscular transplantation was superior to intraneural or combined transplantation. Muscle trophy was highest in intraneural injection, measured by wet weight of the tibialis anterior muscle. Conclusion: Our preliminary data indicate a superior force regeneration with intramuscular AdSC transplantation compared to intraneural, combined or vehicle transplantation. Further exploratory data suggest that transplantation of extracellular vesicles presented with even higher force regeneration.

Artificial PGA/Collagen-based Bilayer Conduit in Short Gap Interposition Setting Provides Comparable Regenerative Potential to Direct Suture.

Sixty-six female Lewis rats were randomly divided into the sham group (n = 13); no reconstruction (no-recon) group (n = 13; rat model with 10 mm sciatic nerve defect); direct group (n = 20; rat sciatic nerve injury directly connected by 10-0 Nylon); and SGI group (n = 20; sciatic nerve injury repaired using 5-mm Nerbridge). Motor function and histological recovery were evaluated. The sciatic nerve and gastrocnemius muscle were harvested for quantification of the degree of nerve regeneration and muscle atrophy. The SGI and direct groups achieved equal recovery in both functional and histological outcomes. At weeks 3 and 8 postsurgery, there was a significant improvement in the sciatic functional index of the SGI group when compared with that of the no-recon group (P < 0.05). Furthermore, the direct and SGI groups had less muscle atrophy at 4 and 8 weeks postsurgery compared with the no-recon group (P < 0.05). The axon density and diameter at the distal site in the SGI group were significantly higher than that in the no-recon group and comparable to that in the direct and sham groups. An artificial nerve conduit has equal potential as direct suture in motor nerve reconstruction when used in the SGI setting.

Aligned Polyhydroxyalkanoate Blend Electrospun Fibers as Intraluminal Guidance Scaffolds for Peripheral Nerve Repair.

The use of nerve guidance conduits (NGCs) to treat peripheral nerve injuries is a favorable approach to the current "gold standard" of autografting. However, as simple hollow tubes, they lack specific topographical and mechanical guidance cues present in nerve grafts and therefore are not suitable for treating large gap injuries (30-50 mm). The incorporation of intraluminal guidance scaffolds, such as aligned fibers, has been shown to increase neuronal cell neurite outgrowth and Schwann cell migration distances. A novel blend of PHAs, P(3HO)/P(3HB) (50:50), was investigated for its potential as an intraluminal aligned fiber guidance scaffold. Aligned fibers of 5 and 8 μm diameter were manufactured by electrospinning and characterized using SEM. Fibers were investigated for their effect on neuronal cell differentiation, Schwann cell phenotype, and cell viability in vitro. Overall, P(3HO)/P(3HB) (50:50) fibers supported higher neuronal and Schwann cell adhesion compared to PCL fibers. The 5 μm PHA blend fibers also supported significantly higher DRG neurite outgrowth and Schwann cell migration distance using a 3D ex vivo nerve injury model.

Application of Proteomics Analysis and Animal Models in Optic Nerve Injury Diseases.

Optic nerve damage is a common cause of blindness. Optic nerve injury is often accompanied by fundus vascular disease, retinal ganglion cell apoptosis, and changes in retinal thickness. These changes can cause alterations in protein expression within neurons in the retina. Proteomics analysis offers conclusive evidence to decode a biological system. Furthermore, animal models of optic nerve injury made it possible to gain insight into pathological mechanisms, therapeutic targets, and effective treatment of such injuries. Proteomics takes the proteome as the research object and studies protein changes in cells and tissues. At present, a variety of proteomic analysis methods have been widely used in the research of optic nerve injury diseases. This review summarizes the application of proteomic research in optic nerve injury diseases and animal models of optic nerve injury. Additionally, differentially expressed proteins are summarized and analyzed. Various optic nerve injuries, including those associated with different etiologies, are discussed along with their potential therapeutic targets and future directions.