Nrf2 signaling in the oxidative stress response after spinal cord injury

Low-Dose Lipopolysaccharide Alleviates Neuronal Apoptosis and Oxidative Stress in Rats with Spinal Cord Injury by Inducing Nrf2 m6A Methylation Modification via Suppressing ALKBH5

This work reported the neuronal protection of low-dose lipopolysaccharide (LD-LPS) after spinal cord injury (SCI). SCI rat model was constructed, after adenovirus-mediated ALKBH5 vectors and shRNA transfection and LD-LPS pre-treatment. Hematoxylin and eosin, Nissl, TUNEL staining of spinal cord tissues were adopted to monitor pathological changes, neuronal survival and apoptosis. PC12 cells transfected with ALKBH5 vectors and ALKBH5/Nrf2 siRNAs were treated by LD-LPS, followed by oxygen and glucose deprivation/reoxygenation (OGD/R). Cell viability and apoptosis were assessed by cell counting kit-8 and TUNEL assays. Neuronal oxidative stress was evaluated by appraising MDA and SOD levels. ALKBH5 and Nrf2 expression was monitored through immunohistochemistry, Western blot and qRT-PCR. Methylated RNA immunoprecipitation assay and Dot-blot experiment were for Nrf2 m6A modification detection, while RNA pull-down assay was for the binding validation between ALKBH5 and Nrf2. In rats with SCI, LD-LPS relieved spinal cord tissue damage and neuronal apoptosis; enhanced neuronal survival; decreased MDA content; elevated SOD activity; down-regulated ALKBH5; up-regulated Nrf2; and facilitated Nrf2 m6A methylation. These above influences by LD-LPS were eliminated by ALKBH5. Similar results were found in the OGD/R-induced PC12 cells after LD-LPS treatment. ALKBH5 significantly blocked Nrf2 m6A methylation, and pulled down Nrf2 protein. In the OGD/R-induced PC12 cells, the repressed oxidative stress and apoptosis by ALKBH5 silencing was abrogated by Nrf2 knockdown. LD-LPS might alleviate neuronal apoptosis and oxidative stress after SCI by facilitating Nrf2 m6A methylation via reducing ALKBH5. It was proposed to be a novel strategy for SCI treatment.

Teriparatide mitigates oxidative stress following spinal cord injury and enhances neurological recovery via the Nrf2/HO-1 signaling pathway

Introduction

Spinal Cord Injury (SCI) represents a devastating form of central nervous system trauma, where oxidative stress plays a critical role in the ensuing pathology. Targeting oxidative stress presents a viable therapeutic avenue. Teriparatide, a synthetic analog of parathyroid hormone, is conventionally utilized for osteoporosis and bone defect management. Emerging evidence suggests teriparatide's potential in modulating oxidative stress in ischemic stroke, yet its efficacy in SCI remains underexplored.

Methods

We investigated the neuroprotective effects of teriparatide in a rat spinal cord injury (SCI) model. Teriparatide was administered to animals post-injury, and functional recovery was assessed using the open field test and Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Molecular analyses included evaluation of Nrf2 pathway activation and antioxidant protein expression via immunofluorescence, Western blot, and ELISA. Additionally, glutathione peroxidase (GSH-PX) activity and malondialdehyde (MDA) levels were measured using commercial assay kits.

Results

We obtained two significant results: Firstly, teriparatide treatment significantly enhanced motor function recovery post-SCI. Secondly, teriparatide upregulated Nrf2 expression, which subsequently increased the production of the antioxidant proteins HO-1 and SOD2, reduced MDA levels in spinal tissues, and boosted GSH-PX activity.

Conclusion

Our findings demonstrate that teriparatide activates the Nrf2/HO-1 antioxidant pathway, effectively mitigating oxidative damage in SCI. This repositioning of an FDA-approved osteoporosis drug presents a clinically translatable strategy for neuroprotection.

Nitroxidative Stress, Cell-Signaling Pathways, and Manganese Porphyrins: Therapeutic Potential in Neuropathic Pain

Neuropathic pain, a debilitating condition arising from somatosensory system damage, significantly impacts quality of life, leading to anxiety, self-mutilation, and depression. Oxidative and nitrosative stress, an imbalance between reactive oxygen and nitrogen species (ROS/RNS) and antioxidant defenses, plays a crucial role in its pathophysiology. While reactive species are essential for physiological functions, excessive levels can cause cellular component damage, leading to neuronal dysfunction and pain. This review highlights the complex interactions between reactive species, antioxidant systems, cell signaling, and neuropathic pain. We discuss the physiological roles of ROS/RNS and the detrimental effects of oxidative and nitrosative stress. Furthermore, we explore the potential of manganese porphyrins, compounds with antioxidant properties, as promising therapeutic agents to mitigate oxidative stress and alleviate neuropathic pain by targeting key cellular pathways involved in pain. Further research is needed to fully understand their therapeutic potential in managing neuropathic pain in human and non-human animals.

The Impact of Nuclear Factor Kappa B on the Response of Microglia in Spinal Cord Injuries

Spinal cord injury (SCI) results in both primary and secondary damage, each contributing to the overall injury and its consequences. Following SCI, microglia, the resident immune cells of the central nervous system (CNS), undergo a series of complex responses that contribute to the pathophysiology of the injury. In the context of SCI, nuclear factor kappa B (NF-kB) emerged as a critical mediator in the regulation of inflammatory responses following SCI. The aim of this review is to provide a comprehensive understanding of the involvement of NF-kB in the response of microglia following SCI. The PUBMED database was searched using the following keywords: NF-kB AND microglia AND spinal cord injury. Clinical and experimental studies evaluating the role of NF-kB in the response of microglia following SCI were included. Systematic reviews, case reports, research protocols, conference articles, and studies in languages other than English were excluded. The final analysis included 52 studies. NF-kB signaling exerts profound effects on the microglial response following SCI, influencing the inflammatory milieu, tissue damage, and potential for repair and recovery. Deactivation of the NF-kB signaling pathway suppresses the production of proinflammatory mediators in microglia, after SCI. Moreover, NF-kB suppression has neuroprotective effects, as it mitigates neuronal apoptosis and facilitates the M2 microglial phenotype, alleviating tissue damage after SCI. Moreover, several microRNAs play a crucial role in regulating gene expression post-transcriptionally and have emerged as key regulators in microglia activation after SCI. Overall, the role of NF-kB in the response of microglia to SCI is complex and context-dependent. While NF-kB activation is involved in initiating and propagating the inflammatory response following SCI, it also plays a role in tissue repair and regeneration. Thus, modulating NF-kB signaling in microglia represents a potential therapeutic target for attenuating inflammation and promoting neuroprotection and tissue repair in SCI.

Nrf2 Signaling Pathway: Focus on Oxidative Stress in Spinal Cord Injury

Spinal cord injury (SCI) is a serious, disabling injury to the central nervous system that can lead to motor, sensory, and autonomic dysfunction below the injury plane. SCI can be divided into primary injury and secondary injury according to its pathophysiological process. Primary injury is irreversible in most cases, while secondary injury is a dynamic regulatory process. Secondary injury involves a series of pathological events, such as ischemia, oxidative stress, inflammatory events, apoptotic pathways, and motor dysfunction. Among them, oxidative stress is an important pathological event of secondary injury. Oxidative stress causes a series of destructive events such as lipid peroxidation, DNA damage, inflammation, and cell death, which further worsens the microenvironment of the injured site and leads to neurological dysfunction. The nuclear factor erythrocyte 2-associated factor 2 (Nrf2) is considered to be a key pathway of antioxidative stress and is closely related to the pathological process of SCI. Activation of this pathway can effectively inhibit the oxidative stress process and promote the recovery of nerve function after SCI. Therefore, the Nrf2 pathway may be a potential therapeutic target for SCI. This review deeply analyzed the generation of oxidative stress in SCI, the role and mechanism of Nrf2 as the main regulator of antioxidant stress in SCI, and the influence of cross-talk between Nrf2 and related pathways that may be involved in the pathological regulation of SCI on oxidative stress, and summarized the drugs and other treatment methods based on Nrf2 pathway regulation. The objective of this paper is to provide evidence for the role of Nrf2 activation in SCI and to highlight the important role of Nrf2 in alleviating SCI by elucidating the mechanism, so as to provide a theoretical basis for targeting Nrf2 pathway as a therapy for SCI.

4-amino-3-(phenylselanyl) benzenesulfonamide attenuates intermittent cold stress-induced fibromyalgia in mice: Targeting to the Nrf2-NFκB axis

Stress is widely recognized as the primary environmental factor associated with chronic pain conditions, including fibromyalgia. A recent study demonstrated the potential antinociceptive effects of 4-amino-3-(phenylselanyl) benzenesulfonamide (4-APSB) in acute nociceptive animal models due to its antioxidant and anti-inflammatory properties. However, the efficacy of 4-APSB in managing chronic painful conditions, such as fibromyalgia, has not been explored so far. This study investigated the pharmacological effects of 4-APSB in an experimental model of fibromyalgia induced by intermittent cold stress (ICS). Male and female mice were divided into Control, ICS, 4-APSB, and ICS + 4-APSB. After the ICS, the animals were treated with 4-APSB (1 mg kg-1) or vehicle by the intragastric route until the tenth day. The behavioral tasks were performed on days 5, 8, and 10. The findings showed a negative correlation between paw withdrawal threshold and Nrf2 or NFκB mRNA expression levels caused by ICS exposure. The 4-APSB suppressed the nociceptive signs and a depressive like-phenotype in male and female mice exposed to ICS. 4-APBS normalized the elevated levels of TBARS and the up-regulation of Nrf2 and NFκB expression in the cerebral cortex of ICS-exposed mice. This compound also modulated the oxidative stress in the spinal cord of female mice. The 4-APSB attenuated the inhibition of Na+, K+ - ATPase activity in the central nervous system (CNS) of female mice exposed to ICS. 4-APSB attenuated behavioral and redox imbalance triggered by the ICS model in male and female mice, suggesting its beneficial effects for treating fibromyalgia in both sexes.

The prospective therapeutic benefits of sesamol: neuroprotection in neurological diseases

Oxidative stress is recognized as a critical contributor to the advancement of neurological diseases, thereby rendering the alleviation of oxidative stress a pivotal strategy in the therapeutic management of such conditions. Sesamol, the principal constituent of sesame oil, has been the subject of extensive research due to its significant antioxidant properties, especially its ability to effectively counteract oxidative stress within the central nervous system and confer neuroprotection. While sesamol demonstrates potential in the treatment and prevention of neurological diseases, its modulation of oxidative stress is complex and not yet fully understood. This review delves into the neuroprotective effects arising from sesamol's antioxidant properties, analyzing how its antioxidative capabilities impact neurological diseases. It provides a theoretical foundation and unveils potential novel therapeutic applications of sesamol in the treatment of neurological disorders through the modulation of oxidative stress.

Study of the Effect of Methyl Eugenol on Gastric Damage Produced by Spinal Cord Injury Model in the Rat

Traumatic spinal cord injury (SCI) is a serious medical condition that places patients at high risk of developing gastric ulceration and gastrointestinal bleeding. One preventative strategy involves the use of omeprazole; however, its chronic use is associated with adverse effects, highlighting the need for alternative therapies. This study evaluated the protective effects of methyl eugenol (ME) on gastric mucosal damage in a rat model of SCI. ME was administered orally at doses of 30, 100, and 177 mg/kg in SCI induced at the T9 level, alongside diclofenac or ketorolac (30 mg/kg each). The enzymatic activity of superoxide dismutase, catalase, and glutathione peroxidase was assessed, and the levels of total glutathione and malondialdehyde were determined using biochemical kits. Additionally, stomach histological sections were analyzed. ME exhibited dose-dependent gastroprotective effects, with maximal protection observed at 177 mg/kg in the presence of diclofenac (9.78 ± 2.16 mm2) or ketorolac (12.49 ± 2.17 mm2). A histological analysis confirmed these findings. In conclusion, methyl eugenol protects the gastric mucosa from SCI-induced damage, with glutathione peroxidase and catalase playing key roles in its mechanism of gastroprotection.

Compound 7 regulates microglia polarization and attenuates radiation-induced myelopathy via the Nrf2 signaling pathway in vivo and in vitro studies

BACKGROUND

Radiation-induced myelopathy (RM) is a significant complication of radiotherapy with its mechanisms still not fully understood and lacking effective treatments. Compound 7 (C7) is a newly identified, potent, and selective inhibitor of the Keap1-Nrf2 interaction. This study aimed to explore the protective effects and mechanisms of C7 on RM in vitro and in vivo.

METHODS

Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), reactive oxygen species (ROS) and mitochondrial polarization, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, genetic editing techniques, locomotor functions, and tissue staining were employed to explore the protective effects and underlying mechanisms of C7 in radiation-induced primary rat microglia and BV2 cells, as well as RM rat models.

RESULTS

In this study, we found that C7 inhibited the production of pro-inflammation cytokines and oxidative stress induced by irradiation in vitro. Further, the data revealed that radiation worsened the locomotor functions in rats, and C7 significantly improved histological and functional recovery in RM rats. Mechanically, C7 activated Nrf2 signaling and promoted the microglia transformation from M1 to M2 phenotype.

CONCLUSION

C7 could ameliorate RM by boosting Nrf2 signaling and promoting M2 phenotype microglia polarization in vitro and in vivo.

Microenvironments‐Modulated Biomaterials Enhance Spinal Cord Injury Therapy

Spinal cord injury (SCI) results from various causes, including sports‐related incidents, degenerative cervical myelopathy, traffic accidents, and falls. SCI typically leads to sensory and motor dysfunction and even paralysis. Current treatments for SCI include systemic administration of high‐dose steroids and surgical decompression and stabilization. However, excessive use of glucocorticoids may increase susceptibility to infections and systemic bleeding. The long‐term effect of surgery intervention remains unclear, with ongoing debates regarding its timing, efficacy, and safety. Therefore, innovative approaches are urgently needed to alleviate secondary injuries and promote spinal recovery. One emerging therapeutic approach for SCI is modulating the microenvironments to achieve neuroprotection and neurogenesis during recovery. Several biomaterials with favorable physicochemical properties have been developed to enhance therapeutic effects by regulating microenvironments. This Review first discusses the pathology of SCI microenvironments and then introduces biomaterials‐based regulatory strategies targeting various microenvironmental components, including anti‐inflammation, anti‐oxidation, reduction of excitotoxicity, revascularization, neurogenesis, and scar density reduction. Additionally, the research and clinical application prospects for microenvironment regulation are presented.

Promotion of nerve regeneration and motor function recovery in SCI rats using LOCAS-iPSCs-NSCs

BACKGROUND

Spinal cord injury (SCI) is a severe traumatic spinal condition with a poor prognosis. In this study, a scaffold called linearly ordered collagen aggregates (LOCAS) was created and loaded with induced pluripotent stem cells (iPSCs)-derived neural stem cells (NSCs) from human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) to treat SCI in a rat model.

METHODS

The rats underwent a complete transection SCI resulting in a 3-mm break at either the T9 or T10 level of the spinal cord.

RESULTS

Scanning electron microscope analysis revealed a uniform pore structure on the coronal plane of the scaffold. The LOCAS had a porosity of 88.52% and a water absorption of 1161.67%. Its compressive modulus and stress were measured at 4.1 MPa and 205 kPa, respectively, with a degradation time of 10 weeks. After 12 weeks, rats in the LOCAS-iPSCs-NSCs group exhibited significantly higher BBB scores (8.6) compared to the LOCAS-iPSCs-NSCs group (5.6) and the Model group (4.2). The CatWalk analysis showed improved motion trajectory, regularity index (RI), and swing speed in the LOCAS-iPSCs-NSCs group compared to the other groups. Motor evoked potentials latency was lower and amplitude was higher in the LOCAS-iPSCs-NSCs group, indicating better neural function recovery. Histological analysis demonstrated enhanced neuronal differentiation of NSCs and nerve fiber regeneration promoted by LOCAS-iPSCs-NSCs, leading to improved motor function recovery in rats. The LOCAS scaffold facilitated ordered neurofilament extension and guided nerve regeneration.

CONCLUSIONS

The combination of LOCAS and iPSCs-NSCs demonstrated a positive therapeutic impact on motor function recovery and tissue repair in rats with SCI. This development offers a more resilient bionic microenvironment and presents novel possibilities for clinical SCI repair.

Hypoxic-preconditioned mesenchymal stem cell-derived small extracellular vesicles inhibit neuronal death after spinal cord injury by regulating the SIRT1/Nrf2/HO-1 pathway

Background

Oxidative stress and apoptosis of neurons significantly contribute to the pathophysiological cascade of spinal cord injury (SCI). However, the role of hypoxic-preconditioned mesenchymal stem cell-derived small extracellular vesicles (H-sEVs) in promoting SCI repair remains unclear. Hence, the present study aims to investigate the regulatory effects of H-sEVs on neuronal oxidative stress and apoptotic responses following SCI.

Methods

The administration of H-sEVs of SCI rats was assessed using behavioral evaluations such as Basso-Beattie-Bresnahan (BBB) scores, neuroelectrophysiological monitoring, and Catwalk gait analysis. Indices of oxidative stress (including superoxide dismutase [SOD], total antioxidant capacity [T-AOC], and malondialdehyde [MDA]) were measured. Neuronal survival was evaluated through Nissl staining, while the expression level of sirtuin 1 (SIRT1) was examined using immunohistochemical staining. Additionally, histological evaluation of lesion size was performed using hematoxylin-eosin (HE) staining. Tunel cell apoptosis staining and analysis of apoptosis-associated proteins (B-cell lymphoma-2 [Bcl2] and BCL2-Associated X [Bax]) were conducted through immunofluorescence staining and western blot, respectively. Furthermore, the model of oxidative stress was established using PC12 cells, and apoptosis levels were assessed via flow cytometry and western blot analysis. Importantly, to ascertain the critical role of SIRT1, we performed SIRT1 knockout experiments in PC12 cells using lentivirus transfection, followed by western blot.

Results

Using those behavioral evaluations, we observed significant functional improvement after H-sEVs treatment. Nissl staining revealed that H-sEVs treatment promoted neuronal survival. Moreover, we found that H-sEVs effectively reduced oxidative stress levels after SCI. HE staining demonstrated that H-sEVs could reduce lesion area. Immunohistochemical analysis revealed that H-sEVs enhanced SIRT1 expression. Furthermore, Tunel cell apoptosis staining and western blot analysis of apoptosis-related proteins confirmed the anti-apoptotic effects of H-sEVs. The PC12 cells were used to further substantiate the neuroprotective properties of H-sEVs by significantly inhibiting neuronal death and attenuating oxidative stress. Remarkably, SIRT1 knockout in PC12 cells reversed the antioxidant stress effects induced by H-sEVs treatment. Additionally, we elucidated the involvement of the downstream Nrf2/HO-1 signaling pathway.

Conclusion

Our study provides valuable insights into the effects of H-sEVs on neuronal oxidative stress and apoptosis after SCI. These findings underscore the potential clinical significance of H-sEVs-based therapies for SCI.

The effects of hyaluronan and proteoglycan link protein 1 (HAPLN1) in ameliorating spinal cord injury mediated by Nrf2

Excessive inflammatory response and oxidative stress (OS) play an important role in the pathogenesis of spinal cord injury (SCI). Balance of inflammation and prevention of OS have been considered an effective strategy for the treatment of SCI. Hyaluronan and proteoglycan link protein 1 (HAPLN1), also known as cartilage link protein, has displayed a wide range of biological and physiological functions in different types of tissues and cells. However, whether HAPLN1 regulates inflammation and OS during SCI is unknown. Therefore, we aimed to examine whether HAPLN1 can have a protective effect on SCI. In this study, both in vitro and in vivo SCI models were established. Nissl staining and terminal deoxynucleotidyl transferase dUTP nick end labeling staining assays were used. Western blotting and enzyme-linked immunosorbent assay were employed to assess the expression of proteins. Our results demonstrate that the administration of HAPLN1 promoted the recovery of motor neurons after SCI by increasing the Basso mouse scale score, increasing the numbers of motor neurons, and preventing apoptosis of spinal cord cells. Additionally, HAPLN1 mitigated OS in spinal cord tissue after SCI by increasing the content of superoxide dismutase SOD and the activity of glutathione peroxidase but reducing the levels of malondialdehyde. Importantly, we found that HAPLN1 stimulated the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway and stimulated the expression of heme oxygenase-1 and nicotinamide adenine dinucleotide phosphate quinone oxidoreductase-1, which mediated the attenuation of HAPLN1 in activation of the NOD-like receptor protein 3 (NLRP3) inflammasome by reducing the levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, and interleukin-1β. Correspondingly, in vitro experiments show that the presence of HAPLN1 suppressed the NLRP3 inflammasome and prevented cell injury against H2O2 in PC12 cells. These effects were mediated by the Nrf2/ARE pathway, and inhibition of Nrf2 with ML385 abolished the beneficial effects of HAPLN1. Based on these findings, we conclude that HAPLN1 inhibits the NLRP3 inflammasome through the stimulation of the Nrf2/ARE pathway, thereby suppressing neuroinflammation, enhancing motor neuronal survival, and improving the recovery of nerve function after SCI.

Research progress on the inhibition of oxidative stress by teriparatide in spinal cord injury

Spinal cord injury (SCI) is currently a highly disabling disease, which poses serious harm to patients and their families. Due to the fact that primary SCI is caused by direct external force, current research on SCI mainly focuses on the treatment and prevention of secondary SCI. Oxidative stress is one of the important pathogenic mechanisms of SCI, and intervention of oxidative stress may be a potential treatment option for SCI. Teriparatide is a drug that regulates bone metabolism, and recent studies have found that it has the ability to counteract oxidative stress and is closely related to SCI. This article summarizes the main pathological mechanisms of oxidative stress in SCI, as well as the relationship between them with teriparatide, and explores the therapeutic potential of teriparatide in SCI.

Oxidative stress following spinal cord injury: From molecular mechanisms to therapeutic targets

Spinal cord injury (SCI) is a medical condition that results from severe trauma to the central nervous system; it imposes great psychological and economic burdens on affected patients and their families. The dynamic balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining normal cellular physiological functions. As important intracellular signaling molecules, ROS regulate numerous physiological activities, including vascular reactivity and neuronal function. However, excessive ROS can cause damage to cellular macromolecules, including DNA, lipids, and proteins; this damage eventually leads to cell death. This review discusses the mechanisms of oxidative stress in SCI and describes some signaling pathways that regulate oxidative injury after injury, with the aim of providing guidance for the development of novel SCI treatment strategies.

Nanodelivery of histamine H3 receptor inverse agonist BF-2649 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury

Military personnel are often victims of spinal cord injury resulting in lifetime disability and decrease in quality of life. However, no suitable therapeutic measures are still available to restore functional disability or arresting the pathophysiological progression of disease in victims for leading a better quality of life. Thus, further research in spinal cord injury using novel strategies or combination of available neuroprotective drugs is urgently needed for superior neuroprotection. In this regard, our laboratory is engaged in developing TiO2 nanowired delivery of drugs, antibodies and enzymes in combination to attenuate spinal cord injury induced pathophysiology and functional disability in experimental rodent model. Previous observations show that histamine antagonists or antioxidant compounds when given alone in spinal cord injury are able to induce neuroprotection for short periods after trauma. In this investigation we used a combination of histaminergic drugs with antioxidant compound H-290/51 using their nanowired delivery for neuroprotection in spinal cord injury of longer duration. Our observations show that a combination of H3 receptor inverse agonist BF-2549 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury. These observations suggests that histamine receptors are involved in the pathophysiology of spinal cord injury and induce superior neuroprotection in combination with an inhibitor of lipid peroxidation H-290/51, not reported earlier. The possible mechanisms and significance of our findings in relation to future clinical approaches in spinal cord injury is discussed.

Exploring microglia and their phenomenal concatenation of stress responses in neurodegenerative disorders

Neuronal cells are highly functioning but also extremely stress-sensitive cells. By defending the neuronal cells against pathogenic insults, microglial cells, a unique cell type, act as the frontline cavalry in the central nervous system (CNS). Their remarkable and unique ability to self-renew independently after their creation is crucial for maintaining normal brain function and neuroprotection. They have a wide range of molecular sensors that help maintain CNS homeostasis during development and adulthood. Despite being the protector of the CNS, studies have revealed that persistent microglial activation may be the root cause of innumerable neurodegenerative illnesses, including Alzheimer's disease (AD), Parkinson's disease (PD), and Amyloid Lateral Sclerosis (ALS). From our vigorous review, we state that there is a possible interlinking between pathways of Endoplasmic reticulum (ER) stress response, inflammation, and oxidative stress resulting in dysregulation of the microglial population, directly influencing the accumulation of pro-inflammatory cytokines, complement factors, free radicals, and nitric oxides leading to cell death via apoptosis. Recent research uses the suppression of these three pathways as a therapeutic approach to prevent neuronal death. Hence, in this review, we have spotlighted the advancement in microglial studies, which focus on their molecular defenses against multiple stresses, and current therapeutic strategies indirectly targeting glial cells for neurodevelopmental diseases.

Neuroprotective mechanism of Ajugarin-I against Vincristine-Induced neuropathic pain via regulation of Nrf2/NF-κB and Bcl2 signalling

Vincristine (VCR) is a well-known chemotherapeutic agent that frequently triggers neuropathic pain. Ajugarin-I (Aju-I) isolated from Ajuga bracteosa exerts antioxidant, anti-inflammatory, and neuroprotective properties. The present study was designed to investigate the ameliorative potential of Aju-I against VCR-induced neuropathic pain and explored the underlying mechanism involved. The neuroprotective potential of Aju-I was first confirmed against hydrogen peroxide (H₂O₂)-induced cytotoxicity and oxidative stress in PC12 cells. For neuropathic pain induction, vincristine was given intraperitoneally (i.p.) into adult male albino mice (BALB/c) of the same age (8-12 weeks old) for 10 days (days 1-10). Aju-I (1 and 5 mg/kg) doses were administered from day 11 to 21 intraperitoneally (i.p.) after the neuropathic induction. Initially, behavioral tests such as thermal hyperalgesia, mechanical allodynia, and cold allodynia were performed to investigate the antinociceptive potential of Ajugarin-I (1 and 5 mg/kg, b.w). The nuclear factor-erythroid factor 2-related factor 2(Nrf2), nuclear factor-κB (NF-κB), BCL2-associated × protein (Bax), and B-cell-lymphoma-2 (Bcl-2) signaling proteins were determined by immunohistochemistry and western blot. Additionally, inflammatory cytokines, antioxidant, and oxidative stress parameters were also measured in the spinal cord and sciatic nerve. The behavioral results demonstrated that Aju-I (5 mg/kg) markedly alleviated VCR-induced neuropathic pain behaviors including hyperalgesia and allodynia. It reversed the histological alterations caused by VCR in the sciatic nerve, spinal cord, and brain. It significantly alleviated oxidative stress and inflammation by regulating the immunoreactivity of Nrf2/NF-κB signaling. It suppressed apoptosis by regulating the immunoreactivity of Bcl-2/Bax and Caspase-3. The flow cytometry and comet analysis also confirmed its anti-apoptotic potential. It considerably improved the antioxidant status and mitigated VCR-induced inflammatory cytokines. High-performance liquid chromatography (HPLC) analysis indicated that Aju-I crosses the blood-brain barrier (BBB) and penetrated the brain tissue. These findings suggest that Aju-I treatment inhibited vincristine-induced neuropathy via regulation of Nrf2/NF-κB and Bcl2 signaling.

Photobiomodulation augments the effects of mitochondrial transplantation in the treatment of spinal cord injury in rats by facilitating mitochondrial transfer to neurons via Connexin 36

Mitochondrial transplantation is a promising treatment for spinal cord injury (SCI), but it has the disadvantage of low efficiency of mitochondrial transfer to targeted cells. Here, we demonstrated that Photobiomodulation (PBM) could promote the transfer process, thus augmenting the therapeutic effect of mitochondrial transplantation. In vivo experiments, motor function recovery, tissue repair, and neuronal apoptosis were evaluated in different treatment groups. Under the premise of mitochondrial transplantation, the expression of Connex36 (Cx36), the trend of mitochondria transferred to neurons, and its downstream effects, such as ATP production and antioxidant capacity, were evaluated after PBM intervention. In in vitro experiments, dorsal root ganglia (DRG) were cotreated with PBM and 18β-GA (a Cx36 inhibitor). In vivo experiments showed that PBM combined with mitochondrial transplantation could increase ATP production and reduce oxidative stress and neuronal apoptosis levels, thereby promoting tissue repair and motor function recovery. In vitro experiments further verified that Cx36 mediated the transfer of mitochondria into neurons. PBM could facilitate this progress via Cx36 both in vivo and in vitro. The present study reports a potential method of using PBM to facilitate the transfer of mitochondria to neurons for the treatment of SCI.

AMPK-Nrf2 Signaling Pathway in Phrenic Motoneurons following Cervical Spinal Cord Injury

High spinal cord injuries (SCI) induce the deafferentation of phrenic motoneurons, leading to permanent diaphragm paralysis. This involves secondary injury associated with pathologic and inflammatory processes at the site of injury, and at the level of phrenic motoneurons. In the present study, we evaluated the antioxidant response in phrenic motoneurons involving the AMPK-Nrf2 signaling pathway following C2 spinal cord lateral hemi-section in rats. We showed that there is an abrupt reduction in the expression of phosphorylated AMPK and Nrf2 at one hour post-injury in phrenic motoneurons. A rebound is then observed at one day post-injury, reflecting a return to homeostasis condition. In the total spinal cord around phrenic motoneurons, the increase in phosphorylated AMPK and Nrf2 occurred at three days post-injury, showing the differential antioxidant response between phrenic motoneurons and other cell types. Taken together, our results display the implication of the AMPK-Nrf2 signaling pathway in phrenic motoneurons’ response to oxidative stress following high SCI. Harnessing this AMPK-Nrf2 signaling pathway could improve the antioxidant response and help in spinal rewiring to these deafferented phrenic motoneurons to improve diaphragm activity in patients suffering high SCI.