EZH2-dependent myelination following sciatic nerve injury

Demyelination and remyelination have been major focal points in the study of peripheral nerve regeneration following peripheral nerve injury.Notably,the gene regulatory network of regenerated myelin differs from that of native myelin.Silencing of enhancer of zeste homolog 2(EZH2)hinders the differentiation,maturation,and myelination of Schwann cells in vitro.To further determine the role of EZH2 in myelination and recovery post-peripheral nerve injury,conditional knockout mice lacking Ezh2 in Schwann cells(Ezh2^(fl/fl);Dhh-Cre and Ezh2^(fl/fl);Mpz-Cre)were generated.Our results show that a significant proportion of axons in the sciatic nerve of Ezh2-depleted mice remain unmyelinated.This highlights the crucial role of Ezh2 in initiating Schwann cell myelination.Furthermore,we observed that 21 days after inducing a sciatic nerve crush injury in these mice,most axons had remyelinated at the injury site in the control nerve,while Ezh2^(fl/fl);Mpz-Cre mice had significantly fewer remyelinated axons compared with their wild-type littermates.This suggests that the absence of Ezh2 in Schwann cells impairs myelin formation and remyelination.In conclusion,EZH2 has emerged as a pivotal regulatory factor in the process of demyelination and myelin regeneration following peripheral nerve injury.Modulating EZH2 activity during these processes may offer a promising therapeutic target for the treatment of peripheral nerve injuries.

Advances in therapies using mesenchymal stem cells and their exosomes for treatment of peripheral nerve injury:state of the art and future perspectives

“Peripheral nerve injury”refers to damage or trauma affecting nerves outside the brain and spinal cord.Peripheral nerve injury results in movements or sensation impairments,and represents a serious public health problem.Although severed peripheral nerves have been effectively joined and various therapies have been offered,recovery of sensory or motor functions remains limited,and efficacious therapies for complete repair of a nerve injury remain elusive.The emerging field of mesenchymal stem cells and their exosome-based therapies hold promise for enhancing nerve regeneration and function.Mesenchymal stem cells,as large living cells responsive to the environment,secrete various factors and exosomes.The latter are nano-sized extracellular vesicles containing bioactive molecules such as proteins,microRNA,and messenger RNA derived from parent mesenchymal stem cells.Exosomes have pivotal roles in cell-to-cell communication and nervous tissue function,offering solutions to changes associated with cell-based therapies.Despite ongoing investigations,mesenchymal stem cells and mesenchymal stem cell-derived exosome-based therapies are in the exploratory stage.A comprehensive review of the latest preclinical experiments and clinical trials is essential for deep understanding of therapeutic strategies and for facilitating clinical translation.This review initially explores current investigations of mesenchymal stem cells and mesenchymal stem cell-derived exosomes in peripheral nerve injury,exploring the underlying mechanisms.Subsequently,it provides an overview of the current status of mesenchymal stem cell and exosomebased therapies in clinical trials,followed by a comparative analysis of therapies utilizing mesenchymal stem cells and exosomes.Finally,the review addresses the limitations and challenges associated with use of mesenchymal stem cell-derived exosomes,offering potential solutions and guiding future directions.

Multilevel analysis of the central-peripheral-target organ pathway:contributing to recovery after peripheral nerve injury

Peripheral nerve injury is a common neurological condition that often leads to severe functional limitations and disabilities.Research on the pathogenesis of peripheral nerve injury has focused on pathological changes at individual injury sites,neglecting multilevel pathological analysis of the overall nervous system and target organs.This has led to restrictions on current therapeutic approaches.In this paper,we first summarize the potential mechanisms of peripheral nerve injury from a holistic perspective,covering the central nervous system,peripheral nervous system,and target organs.After peripheral nerve injury,the cortical plasticity of the brain is altered due to damage to and regeneration of peripheral nerves;changes such as neuronal apoptosis and axonal demyelination occur in the spinal cord.The nerve will undergo axonal regeneration,activation of Schwann cells,inflammatory response,and vascular system regeneration at the injury site.Corresponding damage to target organs can occur,including skeletal muscle atrophy and sensory receptor disruption.We then provide a brief review of the research advances in therapeutic approaches to peripheral nerve injury.The main current treatments are conducted passively and include physical factor rehabilitation,pharmacological treatments,cell-based therapies,and physical exercise.However,most treatments only partially address the problem and cannot complete the systematic recovery of the entire central nervous system-peripheral nervous system-target organ pathway.Therefore,we should further explore multilevel treatment options that produce effective,long-lasting results,perhaps requiring a combination of passive(traditional)and active(novel)treatment methods to stimulate rehabilitation at the central-peripheral-target organ levels to achieve better functional recovery.

Bridging bioengineering and nanotechnology: Bone marrow derived mesenchymal stem cell-exosome solutions for peripheral nerve injury

Peripheral nerve injury(PNI)is a common disease that is difficult to nerve regeneration with current therapies.Fortunately,Zou et al demonstrated the role and mechanism of bone marrow derived mesenchymal stem cells(BMSCs)in promoting nerve regeneration,revealing broad prospects for BMSCs trans-plantation in alleviating PNI.We confirmed the fact that BMSCs significantly alleviate PNI,but there are shortcomings such as low cell survival rate and immune rejection,which limit the wide application of BMSCs.BMSCs-derived exosomes(Exos)are considered as a promising cell-free nanomedicine for PNI,avoiding the ethical issues of BMSCs.Exos in combination with bioengineering therapeutics(including extracellular matrix,hydrogel)brings new hope for PNI,provides a favorable microenvironment for neurological restoration and a therapeutic strategy with a favorable safety profile,significantly increases ex-pression of neurotrophic factors,promotes axonal and myelin regeneration,and demonstrates a strong potential to enhance neurogenesis.Therefore,engineered Exos exhibit better properties,such as stronger targeting and more beneficial components.This article briefly describes the role of nanotechnology and bioe-ngineering therapies for BMSCs in PNI,proposes clinical application prospects and challenges of nanotechnology and bioengineering BMSCs-derived Exos in PNI to improve the efficacy of BMSCs in the treatment of PNI.

Mesenchymal stem cells’“garbage bags”at work:Treating radial nerve injury with mesenchymal stem cell-derived exosomes

Unlike central nervous system injuries,peripheral nerve injuries(PNIs)are often characterized by more or less successful axonal regeneration.However,structural and functional recovery is a senile process involving multifaceted cellular and molecular processes.The contemporary treatment options are limited,with surgical intervention as the gold-standard method;however,each treatment option has its associated limitations,especially when the injury is severe with a large gap.Recent advancements in cell-based therapy and cell-free therapy approaches using stem cell-derived soluble and insoluble components of the cell secretome are fast-emerging therapeutic approaches to treating acute and chronic PNI.The recent pilot study is a leap forward in the field,which is expected to pave the way for more enormous,systematic,and well-designed clinical trials to assess the therapeutic efficacy of mesenchymal stem cell-derived exosomes as a bio-drug either alone or as part of a combinatorial approach,in an attempt synergize the best of novel treatment approaches to address the complexity of the neural repair and regeneration.

Bone marrow mesenchymal stem cells in treatment of peripheral nerve injury

Peripheral nerve injury(PNI)is a common neurological disorder and complete functional recovery is difficult to achieve.In recent years,bone marrow mesenchymal stem cells(BMSCs)have emerged as ideal seed cells for PNI treatment due to their strong differentiation potential and autologous trans-plantation ability.This review aims to summarize the molecular mechanisms by which BMSCs mediate nerve repair in PNI.The key mechanisms discussed include the differentiation of BMSCs into multiple types of nerve cells to promote repair of nerve injury.BMSCs also create a microenvironment suitable for neuronal survival and regeneration through the secretion of neurotrophic factors,extracellular matrix molecules,and adhesion molecules.Additionally,BMSCs release pro-angiogenic factors to promote the formation of new blood vessels.They modulate cytokine expression and regulate macrophage polarization,leading to immunomodulation.Furthermore,BMSCs synthesize and release proteins related to myelin sheath formation and axonal regeneration,thereby promoting neuronal repair and regeneration.Moreover,this review explores methods of applying BMSCs in PNI treatment,including direct cell trans-plantation into the injured neural tissue,implantation of BMSCs into nerve conduits providing support,and the application of genetically modified BMSCs,among others.These findings confirm the potential of BMSCs in treating PNI.However,with the development of this field,it is crucial to address issues related to BMSC therapy,including establishing standards for extracting,identifying,and cultivating BMSCs,as well as selecting application methods for BMSCs in PNI such as direct transplantation,tissue engineering,and genetic engineering.Addressing these issues will help translate current preclinical research results into clinical practice,providing new and effective treatment strategies for patients with PNI.

Inferior alveolar nerve injury after sagittal split osteotomy of the mandible:A literature review

Background:Inferior alveolar nerve(IAN)injury is a serious potential complication of orthognathic surgery because the osteotomy cut-line during sagittal split osteotomy(SSO)of the mandible runs close to the mandibular canal.According to statistics,9%–85%of patients who undergo such surgery suffer from complications.It causes neurosensory disorders(NSD)of the lower lip and chin with a wide variety of symptoms such as numbness,hypoesthesia,hyperesthesia,hypoalgesia,hyperalgesia,and allodynia.However,the accurate planning and thorough analysis using cone-beam computed tomography helps improve the predictability of possible IAN damage by considering the specific anatomical features of each patient and all risk factors.This study aimed to review the frequency of IAN occurrence,risk factors,and diagnostic,prophylactic,and treatment methods used for inferior alveolar nerve regeneration and IAN sensory disturbance recovery following SSO of the mandible.Methods:We conducted a comprehensive literature search(2020–2024)across PubMed,Scopus,Google Scholar,and ScienceDirect,focusing on mandibular SSO complications,IAN damage,nerve regeneration,and treatments such as corticosteroids,vitamin B12,platelet concentrates,and low-level laser therapy.All systematic review,randomized controlled trial,controlled clinical trial,or retrospective/prospective study involving both animals and humans were included.Results:Surgeons prescribed medicines for general therapy before surgery and applied intraoperative treatment methods to minimize the degree of NSD manifestation after surgery.Fortunately,majority instances of NSD recover spontaneously by 6 months after the operation;however,if symptoms persist after 1 year,it is considered permanent NSD,which may cause a significant decrease in quality of life.In the postoperative period,assessing neurosensory disturbances with subjective(questionnaires)and objective tests(light touch,2-point discrimination tests,and others),or their combination,is necessary for determining the management.According to recent studies,dexamethasone,a complex of vitamin B,melatonin,and low-level lasers,is actively used in inferior alveolar nerve regeneration during and after SSO.Moreover,isolated studies have reported the intraoperative use of platelet concentrates during SSO.Conclusion:The mentioned treatment methods demonstrated positive results in decreasing NSD.However,their effectiveness for IAN regeneration has not been sufficiently studied.

Routine exposure of recurrent laryngeal nerve in thyroid surgery can prevent nerve injury

To determine the value of dissecting the recurrent laryngeal nerve during thyroid surgery with respect to preventing recurrent laryngeal nerve injury, we retrospectively analyzed clinical data from 5 344 patients undergoing thyroidectomy. Among these cases, 548 underwent dissection of the recurrent laryngeal nerve, while 4 796 did not. There were 12 cases of recurrent laryngeal nerve injury following recurrent laryngeal nerve dissection （injury rate of 2.2%） and 512 cases of recurrenl laryngeal nerve injury in those not undergoing nerve dissection （injury rate of 10.7%）. This difference remained statistically significant between the two groups in terms of type of thyroid disease, type of surgery, and number of surgeries. Among the 548 cases undergoing recurrent laryngeal nerve dissection, 128 developed anatomical variations of the recurrent laryngeal nerve （incidence rate of 23.4%）, but no recurrent laryngeal nerve injury was found. In addition, the incidence of recurrent laryngeal nerve injury was significantly lower in patients with the infedor parathyroid gland and middle thyroid veins used as landmarks for locating the recurrent laryngeal nerve compared with those with the entry of the recurrent laryngeal nerve into the larynx as a landmark. These findings indicate that anatomical variations of the recurrent laryngeal nerve are common, and that dissecting the recurrent laryngeal nerve during thyroid surgery is an effective means of preventing nerve injury.

The effects of claudin 14 during early Wallerian degeneration after sciatic nerve injury

Claudin 14 has been shown to promote nerve repair and regeneration in the early stages of Wallerian degeneration （0-4 days） in rats with sciatic nerve injury, but the mechanism underlying this process remains poorly understood. This study reported the effects of claudin 14 on nerve degeneration and regeneration during early Wallerian degeneration. Claudin 14 expression was up-regulated in sciatic nerve 4 days after Wallerian degeneration. The altered expression of claudin 14 in Schwann cells resulted in expression changes of cytokines in vitro. Expression of claudin 14 affected c-Jun, but not Akt anal ERK1/2 patl^ways, l^urther studies reve^ed that enhanced expression of claudin 14 could promote Schwann cell proliferation and migration. Silencing of claudin 14 expression resulted in Schwann cell apoptosis and reduction in Schwann cell proliferation. Our data revealed the role of claudin 14 in early Wallerian degeneration, which may provide new insights into the molecular mechanisms of Wallerian degeneration.

Differential gene expression in proximal and distal nerve segments of rats with sciatic nerve injury during Wallerian degeneration

Wallerian degeneration is a subject of major interest in neuroscience. A large number of genes are differentially regulated during the distinct stages of Wallerian degeneration： transcription factor activation, immune response, myelin cell differentiation and dedifferentiation. Although gene expression responses in the distal segment of the sciatic nerve after peripheral nerve injury are known, differences in gene expression between the proximal and distal segments remain unclear. In the present study in rats, we used microarrays to analyze changes in gene expression, biological processes and signaling pathways in the proximal and distal segments of sciatic nerves under- going Wallerian degeneration. More than 6,000 genes were differentially expressed and 20 types of expression tendencies were identified, mainly between proximal and distal segments at 7-14 days after injury. The differentially expressed genes were those involved in cell differentiation, cytokinesis, neuron differentiation, nerve development and axon regeneration. Furthermore, 11 biological processes were represented, related to responses to stimuli, cell apoptosis, inflammato- ry response, immune response, signal transduction, protein kinase activity, and cell proliferation. Using real-time quantitative PCR, western blot analysis and immunohistochemistry, microarray data were verified for four genes： aquaporin-4, interleukin 1 receptor-like 1, matrix metallopro- teinase-12 and periaxin. Our study identifies differential gene expression in the proximal and distal segments of a nerve during Wallerian degeneration, analyzes dynamic biological changes of these genes, and provides a useful platform for the detailed study of nerve injury and repair during Wallerian degeneration.

Differential expression of microRNAs in dorsal root ganglia after sciatic nerve injury

This study investigated the possible involvement of microRNAs in the regulation of genes that participate in peripheral neural regeneration. A microRNA microarray analysis was conducted and 23 microRNAs were identiifed whose expression was signiifcantly changed in rat dorsal root ganglia after sciatic nerve transection. The expression of one of the downregulated microRNAs, microRNA-214, was validated using quantitative reverse transcriptase-PCR. MicroRNA-214 was predicted to target the 3′-untranslated region of Slit-Robo GTPase-activating protein 3. In situ hybridization veriifed that microRNA-214 was located in the cytoplasm of dorsal root ganglia primary neurons and was downregulated following sciatic nerve transection. Moreover, a com-bination of in situ hybridization and immunohistochemistry revealed that microRNA-214 and Slit-Robo GTPase-activating protein 3 were co-localized in dorsal root ganglion primary neu-rons. Western blot analysis suggested that Slit-Robo GTPase-activating protein 3 was upregulated in dorsal root ganglion neurons after sciatic nerve transection. These data demonstrate that mi-croRNA-214 is located and differentially expressed in dorsal root ganglion primary neurons and may participate in regulating the gene expression of Slit-Robo GTPase-activating protein 3 after sciatic nerve transection.

Edaravone promotes functional recovery after mechanical peripheral nerve injury

Edaravone has been shown to reduce ischemia/reperfusion-induced peripheral nerve injury. However, the therapeutic effect of edaravone on peripheral nerve injury caused by mechanical factors is unknown. In the present study, we established a peripheral nerve injury model by crushing the sciatic nerve using hemostatic forceps, and then administered edaravone 3 mg/kg intraperitoneally. The sciatic functional index and superoxide dismutase activity of the sciatic nerve were increased, and the malondialdehyde level was decreased in animals in the edaravone group compared with those in the model group. Bcl-2 expression was increased, but Bax expres- sion was decreased in anterior horn cells of the L4-6 spinal cord segments. These results indicated that edaravone has a neuroprotective effect following peripheral nerve injury caused by mechan- ical factors through alleviating free radical damage to cells and inhibiting lipid peroxidation, as well as regulating apoptosis-related protein expression.

Stress and strain analysis on the anastomosis site sutured with either epineurial or perineurial sutures after simulation of sciatic nerve injury

The magnitude of tensile stress and tensile strain at an anastomosis site under physiological stress is an important factor for the success of anastomosis following suturing in peripheral nerve injury treatment. Sciatic nerves from fresh adult cadavers were used to create models of sciatic nerve injury. The denervated specimens underwent epineurial and perineurial suturing. The elastic modulus （40.96 ＋ 2.59 MPa） and Poisson ratio （0.37 ＋ 0.02） of the normal sciatic nerve were measured by strain electrical measurement. A resistance strain gauge was pasted on the front, back left, and right of the edge of the anastomosis site after suturing. Strain electrical measurement results showed that the stress and strain values of the sciatic nerve following perineurial suturing were lower than those following epineurial suturing. Scanning electron microscopy revealed that the sciatic nerve fibers were disordered following epineurial compared with perineurial suturing. These results indicate that the effect of perineurial suturing in sciatic nerve injury repair is better than that of epineurial suturing.

Temporal changes in the spinal cord transcriptome after peripheral nerve injury

Peripheral nerve injury may trigger changes in mRNA levels in the spinal cord.Finding key mRNAs is important for improving repair after nerve injury.This study aimed to investigate changes in mRNAs in the spinal cord following sciatic nerve injury by transcriptomic analysis.The left sciatic nerve denervation model was established in C57 BL/6 mice.The left L4–6 spinal cord segment was obtained at 0,1,2,4 and 8 weeks after severing the sciatic nerve.mRNA expression profiles were generated by RNA sequencing.The sequencing results of spinal cord mRNA at 1,2,4,and 8 weeks after severing the sciatic nerve were compared with those at 0 weeks by bioinformatic analysis.We identified 1915 differentially expressed mRNAs in the spinal cord,of which 4,1909,and 2 were differentially expressed at 1,4,and 8 weeks after sciatic nerve injury,respectively.Sequencing results indicated that the number of differentially expressed mRNAs in the spinal cord was highest at 4 weeks after sciatic nerve injury.These mRNAs were associated with the cellular response to lipid,ATP metabolism,energy coupled proton transmembrane transport,nuclear transcription factor complex,vacuolar proton-transporting V-type ATPase complex,inner mitochondrial membrane protein complex,tau protein binding,NADH dehydrogenase activity and hydrogen ion transmembrane transporter activity.Of these mRNAs,Sgk1,Neurturin and Gpnmb took part in cell growth and development.Pathway analysis showed that these mRNAs were mainly involved in aldosterone-regulated sodium reabsorption,oxidative phosphorylation and collecting duct acid secretion.Functional assessment indicated that these mRNAs were associated with inflammation and cell morphology development.Our findings show that the number and type of spinal cord mRNAs involved in changes at different time points after peripheral nerve injury were different.The number of differentially expressed mRNAs in the spinal cord was highest at 4 weeks after sciatic nerve injury.These results provide reference data for finding new targets for the treatment of peripheral nerve injury,and for further gene therapy studies of peripheral nerve injury and repair.The study procedures were approved by the Ethics Committee of the Peking University People's Hospital(approval No.2017 PHC004)on March 5,2017.

Platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury

The effect of platelet-rich plasma on nerve regeneration remains controversial.In this study,we established a rabbit model of sciatic nerve small-gap defects with preserved epineurium and then filled the gaps with platelet-rich plasma.Twenty-eight rabbits were divided into the following groups(7 rabbits/group):model,low-concentrati on PRP(2.5-3.5-fold concentration of whole blood platelets),medium-concentration PRP(4.5-6.5-fold concentration of whole blood platelets),and high-concentration PRP(7.5-8.5-fold concentration of whole blood platelets).Electrophysiological and histomorphometrical assessments and proteomics analysis we re used to evaluate regeneration of the sciatic nerve.Our results showed that platelet-rich plasma containing 4.5-6.5-and 7.5-8.5-fold concentrations of whole blood platelets promoted repair of sciatic nerve injury.Proteomics analysis was performed to investigate the possible mechanism by which platelet-rich plasma promoted nerve regeneration.Proteomics analysis showed that after sciatic nerve injury,platelet-rich plasma increased the expression of integrin subunitβ-8(ITGB8),which participates in angiogenesis,and differentially expressed proteins were mainly enriched in focal adhesion pathways.Additionally,two key proteins,ribosomal protein S27 a(RSP27 a)and ubiquilin 1(UBQLN1),which were selected after protein-protein interaction analysis,are involved in the regulation of ubiquitin levels in vivo.These data suggest that platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury by affecting angiogenesis and intracellular ubiquitin levels.

Saikosaponin a increases interleukin-10 expression and inhibits scar formation after sciatic nerve injury

Nerve scarring after peripheral nerve injury can severely hamper nerve regeneration and functional recovery.Further,the anti-inflammatory cytokine,interleukin-10,can inhibit nerve scar formation.Saikosaponin a（SSa） is a monomer molecule extracted from the Chinese medicine,Bupleurum.SSa can exert anti-inflammatory effects in spinal cord injury and traumatic brain injury.However,it has not been shown whether SSa can play a role in peripheral nerve injury.In this study,rats were randomly assigned to three groups.In the sham group,the left sciatic nerve was directly sutured after exposure.In the sciatic nerve injury（SNI） ＋ SSa and SNI groups,the left sciatic nerve was sutured and continuously injected daily with SSa（10 mg/kg） or an equivalent volume of saline for 7 days.Enzyme linked immunosorbent assay results demonstrated that at 7 days after injury,interleukin-10 level was considerably higher in the SNI ＋ SSa group than in the SNI group.Masson staining and western blot assay demonstrated that at 8 weeks after injury,type I and III collagen content was lower and nerve scar formation was visibly less in the SNI ＋ SSa group compared with the SNI group.Simultaneously,sciatic functional index and nerve conduction velocity were improved in the SNI ＋ SSa group compared with the SNI group.These results confirm that SSa can increase the expression of the anti-inflammatory factor,interleukin-10,and reduce nerve scar formation to promote functional recovery of injured sciatic nerve.

Bacterial melanin promotes recovery after sciatic nerve injury in rats

Bacterial melanin, obtained from the mutant strain of Bacillus Thuringiensis, has been shown to promote recovery after central nervous system injury. It is hypothesized, in this study, that bacterial melanin can promote structural and functional recovery after peripheral nerve injury. Rats subjected to sciatic nerve transection were intramuscularly administered bacterial melanin. The sciatic nerve transected rats that did not receive intramuscular administration of bacterial melanin served as controls. Behavior tests showed that compared to control rats, the time taken for instrumental conditioned reflex recovery was significantly shorter and the ability to keep the balance on the rotating bar was significantly better in bacterial melanin-treated rats. Histomor- phological tests showed that bacterial melanin promoted axon regeneration after sciatic nerve injury. These findings suggest that bacterial melanin exhibits neuroprotective effects on injured sciatic nerve, contributes to limb motor function recovery, and therefore can be used for rehabil- itation treatment of peripheral nerve injury.

Negative regulation of gamma-aminobutyric acid type A receptor on free calcium ion levels following facial nerve injury

Previous studies have demonstrated that muscarinic, and nicotinic receptors increase free Ca2＋ levels in the facial nerve nucleus via various channels following facial nerve injury. However, intracellular Ca2＋ overload can trigger either necrotic or apoptotic cell death. Gamma-aminobutyric acid （GABA）, an important inhibitory neurotransmitter in the central nervous system, exists in the facial nerve nucleus. It is assumed that GABA negatively regulates free Ca2＋ levels in the facial nerve nucleus. The present study investigated GABA type A （GABAA） receptor expression in the facial nerve nucleus in a rat model of facial nerve injury using immunohistochemistry and laser confocal microscopy, as well as the regulatory effects of GABAA receptor on nicotinic receptor response following facial nerve injury. Subunits α1, α3, α5, β1, β2, δ, and γ3 of GABAA receptors were expressed in the facial nerve nucleus following facial nerve injury. In addition, GABAA receptor expression significantly inhibited the increase in nicotinic receptor-mediated free Ca2＋ levels in the facial nerve nucleus following facial nerve injury in a concentration-dependent fashion. These results suggest that GABAA receptors exhibit negative effects on nicotinic receptor responses following facial nerve injury.

FOXO3a as a sensor of unilateral nerve injury in sensory neurons ipsilateral, contralateral and remote to injury

Emerging evidence supports that the stress response to peripheral nerve injury extends beyond the injured neuron,with alterations in associated transcription factors detected both locally and remote to the lesion.Stress-induced nuclear translocation of the transcription factor forkhead class box O3a(FOXO3a)was initially linked to activation of apoptotic genes in many neuronal subtypes.However,a more complex role of FOXO3a has been suggested in the injury response of sensory neurons,with the injured neuron expressing less FOXO3a.To elucidate this response and test whether non-injured sensory neurons also alter FOXO3a expression,the temporal impact of chronic unilateral L4–6 spinal nerve transection on FOXO3a expression and nuclear localization in adult rat dorsal root ganglion neurons ipsilateral,contralateral or remote to injury relative to na?ve controls was examined.In na?ve neurons,high cytoplasmic and nuclear levels of FOXO3a colocalized with calcitonin gene related peptide,a marker of the nociceptive subpopulation.One hour post-injury,an acute increase in nuclear FOXO3a in small size injured neurons occurred followed by a significant decrease after 1,2 and 4 days,with levels increasing toward pre-injury levels by 1 week post-injury.A more robust biphasic response to the injury was observed in uninjured neurons contralateral to and those remote to injury.Nuclear levels of FOXO3a peaked at 1 day,decreased by 4 days,then increased by 1 week post-injury,a response mirrored in C4 dorsal root ganglion neurons remote to injury.This altered expression contralateral and remote to injury supports that spinal nerve damage has broader systemic impacts,a response we recently reported for another stress transcription factor,Luman/CREB3.The early decreased expression and nuclear localization of FOXO3a in the injured neuron implicate these changes in the cell body response to injury that may be protective.Finally,the broader systemic changes support the existence of stress/injury-induced humeral factor(s)influencing transcriptional and potentially behavioral changes in uninjured dorsal root ganglion neurons.Approval to conduct this study was obtained from the University of Saskatchewan Animal Research Ethics Board(protocol#19920164).

Label-free quantitative proteomics analysis models in vivo and in vitro reveal key proteins and potential roles in sciatic nerve injury

Background:The underlying mechanism of sciatic nerve injury(SNI)is a common motor functional disorder,necessitates further research.Methods:A rat model of SNI was established,with the injury group subjected to compressive injury of the right sciatic nerve exposed at the midpoint of the thigh and the sham surgery group undergoing the same surgical procedure.An oxygen-glucose deprivation model was employed to simulate in vitro SNI in PC12 cells.Following data acquisition and quality control,differentially expressed proteins(DEPs)in each model were identified through differential analysis,and enrichment analysis was used to explore the potential functions and pathways of the DEPs.Venn diagrams were drawn,and DEPs from both in vivo and in vitro SNI models were imported into the STRING database to construct a protein-protein interaction network and screen for hub proteins.Results:After the peptide segments obtained from rat nerve blockade and PC12 cells met quality requirements,258 DEPs were identified in rat nerve samples,and 119 DEPs were screened in PC12 cells.Enrichment analysis revealed that DEPs in the rat model were predominantly concentrated in biological functions such as myogenic cell proliferation and signaling related to lipid and energy metabolism.DEPs in the in vitro model were mainly enriched in biological processes such as phagocytosis and were associated with lipid transport and metabolism.Two hub proteins,amyloid precursor protein(APP)and fibronectin 1(FN1),were identified through MCC,MCODE,and Degree scoring.Both PC12 cells and external validation sets showed relatively higher expression of APP and FN1 in injured samples.Results of gene set enrichment analysis indicated that these two proteins were associated with metabolic pathways,such as biosynthesis of glycosaminoglycan chondroitin sulfate and biosynthesis of unsaturated fatty acids.Conclusion:APP and FN1 are potential key molecules involved in SNI and are associated with various metabolic pathways in nerve repair.These findings provide a theoretical basis for the development of therapeutic targets for SNI.