Tetramethylpyrazine-loaded electroconductive hydrogels promote tissue repair after spinal cord injury by protecting the blood-spinal cord barrier and neurons.

Spinal cord injury (SCI) usually induces profound microvascular dysfunction. It disrupts the integrity of the blood-spinal cord barrier (BSCB), which could trigger a cascade of secondary pathological events that manifest as neuronal apoptosis and axonal demyelination. These events can further lead to irreversible neurological impairments. Thus, reducing the permeability of the BSCB and maintaining its substructural integrity are essential to promote neuronal survival following SCI. Tetramethylpyrazine (TMP) has emerged as a potential protective agent for treating the BSCB after SCI. However, its therapeutic potential is hindered by challenges in the administration route and suboptimal bioavailability, leading to attenuated clinical outcomes. To address this challenge, traditional Chinese medicine, TMP, was used in this study to construct a drug-loaded electroconductive hydrogel for synergistic treatment of SCI. A conductive hydrogel combined with TMP demonstrates good electrical and mechanical properties as well as superior biocompatibility. Furthermore, it also facilitates sustained local release of TMP at the implantation site. Furthermore, the TMP-loaded electroconductive hydrogel could suppress oxidative stress responses, thereby diminishing endothelial cell apoptosis and the breakdown of tight junction proteins. This concerted action repairs BSCB integrity. Concurrently, myelin-associated axons and neurons are protected against death, which meaningfully restore neurological functions post spinal cord injury. Hence, these findings indicate that combining the electroconductive hydrogel with TMP presents a promising avenue for potentiating drug efficacy and synergistic repair following SCI.

Celastrol inhibits oligodendrocyte and neuron ferroptosis to promote spinal cord injury recovery.

BACKGROUND: Spinal cord injury (SCI) is a traumatic injury to the central nervous system and can cause lipid peroxidation in the spinal cord. Ferroptosis, an iron-dependent programmed cell death, plays a key role in the pathophysiology progression of SCI. Celastrol, a widely used antioxidant drug, has potential therapeutic value for nervous system. PURPOSE: To investigate whether celastrol can be a reliable candidate for ferroptosis inhibitor and the molecular mechanism of celastrol in repairing SCI by inhibiting ferroptosis. METHODS: First, a rat SCI model was constructed, and the recovery of motor function was observed after treatment with celastrol. The regulatory effect of celastrol on ferroptosis pathway Nrf2-xCT-GPX4 was detected by Western blot and immunofluorescence. Finally, the ferroptosis model of neurons and oligodendrocytes was constructed in vitro to further verify the mechanism of inhibiting ferroptosis by celastrol. RESULTS: Our results demonstrated that celastrol promoted the recovery of spinal cord tissue and motor function in SCI rats. Further in vitro and in vivo studies showed that celastrol significantly inhibited ferroptosis in neurons and oligodendrocytes and reduced the accumulation of ROS. Finally, we found that celastrol could inhibit ferroptosis by up-regulating the Nrf2-xCT-GPX4 axis to repair SCI. CONCLUSION: Celastrol effectively inhibits ferroptosis after SCI by upregulating the Nrf2-xCT-GPX4 axis, reducing the production of lipid ROS, protecting the survival of neurons and oligodendrocytes, and improving the functional recovery.

The analgesic properties of Yu-Xue-Bi tablets in the inflammatory pain mice: By the inhibition of CCL3-mediated macrophage transmigration into the spinal cord.

ETHNOPHARMACOLOGICAL RELEVANCE: Until now, inflammatory pain, especially ones with central sensitization in the spinal cord, is far from effectively treated. Yu-Xue-Bi Tablets (YXB) is a patented medicine, which has been widely applied for inflammatory pain. However, its therapeutic characteristics and mechanism remain unknown. AIM OF THE STUDY: This study is designed to evaluate the analgesic characteristics and explore the underlying mechanism of YXB in the inflammatory pain model induced by Complete Freund's Adjuvant (CFA). MATERIALS AND METHODS: The analgesic effects were measured by Von Frey test. The expression of calcitonin gene-related peptide (CGRP) was quantified by immunofluorescence. The expression of immune factors was analyzed via Luminex assay. The further quantifications of C-C Motif chemokine ligand 3 (CCL3) were verified by Enzyme-linked immunosorbent assay (ELISA). The transmigration of macrophage and activation of microglia were evaluated by immunofluorescence. Spinal injections of purified CCL3, CCR1 antagonist (J113863) and CCR5 antagonist (Maraviroc) were used to clarify roles of CCL3 assumed in the pharmacological mechanism of YXB. RESULTS: In CFA mice, YXB ameliorated the mechanical allodynia in dose and time dependent way, suppressed the central sensitization in dose dependent way. In the L5 spinal cord, YXB downregulated the expression of macrophage M1 pro-inflammatory factors TNFRI and CCL3, inhibited the transmigration of circulating macrophage and the activation of microglia. Purified CCL3 led to the transmigration of macrophage, activation of microglia, central sensitization, and mechanical allodynia in the Sham mice. Inhibitors of CCR1 and CCR5 attenuated above symptoms in CFA mice. Purified CCL3 blocked YXB mediated down regulation of CCL3, inhibition of macrophage transmigration, but not activation of microglia. CONCLUSION: YXB exerts the analgesic effects by inhibiting CCL3-mediated peripheral macrophage transmigrate into spinal cord. This study provided a novel approach for inflammatory pain treatment and new insight into the pharmacological action of YXB.

The effect of Iridoids effective fraction of Valeriana jatamansi Jones on movement function in rats after acute cord injury and the related mechanism.

OBJECTIVES: Spinal cord injury (SCI) is a disastrous central nervous system (CNS) disorder, which was intimately associated with oxidative stress. Studies have confirmed that Iridoids Effective Fraction of Valeriana jatamansi Jones (IEFV) can scavenge reactive oxygen species. This study aimed to confirm the efficacy of IEFV in ameliorating SCI. METHODS: For establish the SCI model, the Sprague-Dawley rats underwent a T10 laminectomy with transient violent oppression by aneurysm clip. Then, the rats received IEFV intragastrically for 8 consecutive weeks to evaluate the protective effect of IEFV on motor function, oxidative stress, inflammation and neurotrophic factors in SCI rats. RESULTS: Basso, Beattie and Bresnahan scores, hematoxylin and eosin (H&E) staining and transmission electron microscopy experiments found IEFV protected motor function and alleviated neuron damage. Meanwhile, IEFV treatment decreased the release of malondialdehyde, interleukin-6 (IL-6), cyclooxygenase-2 and tumor necrosis factor-α. Moreover, IEFV treatment elevated the expression levels of brain-derived neurotrophic factor and nerve growth factor of SCI rats. Finally, administration of IEFV significantly inhibited the expression of p-p65 and toll-like receptor 4 (TLR4). CONCLUSIONS: This study suggests that IEFV could attenuate the oxidative stress and inflammatory response of the spinal cord after SCI, which was associated with inhibition of the TLR4/nuclear factor-kappaB signaling pathway.

Nobiletin attenuates inflammation via modulating proinflammatory and antiinflammatory cytokine expressions in an autoimmune encephalomyelitis mouse model.

The aim of this study is to investigate the potential preventive and therapeutic effects of nobiletin by evaluating the expression of cytokines associated with inflammatory reactions in an autoimmune encephalomyelitis mouse model. A total of 60 male C57BL/6 mice aged between 8 and 10 weeks were used. Mice were divided into six groups (n = 10 mice per group): control, EAE, low-prophylaxis, high-prophylaxis, low-treatment and high-treatment. Experimental autoimmune encephalomyelitis (EAE) was induced by myelin oligodendrocyte glycoprotein (MOG) and pertussis toxin. Nobiletin was administered in low (25 mg/kg) and high (50 mg/kg) doses, intraperitoneally. The prophylactic and therapeutic effects of nobiletin on brain tissue and spinal cord were evaluated by expression of interleukin-1 beta (IL-1ß), tumor necrosis factor-alpha (TNF-α), interferon gamma (IFNγ), IL-6, IL-10 and transforming growth factor-beta (TGF-ß) using immunohistochemistry and real-time polymerase chain reaction (RT-PCR). Prophylactic and therapeutic use of nobiletin inhibited EAE-induced increase of TNF-α, IL-1ß and IL-6 activities to alleviate inflammatory response in brain and spinal cord. Moreover, nobiletin supplement dramatically increased the IL-10, TGF-ß and IFNγ expressions in prophylaxis and treatment groups compared with the EAE group in the brain and spinal cord. The results obtained from this study show that prophylactic and therapeutic nobiletin modulates expressions of proinflammatory and antiinflammatory cytokines in brain and spinal cord dose-dependent manner in EAE model. These data demonstrates that nobiletin has a potential to attenuate inflammation in EAE mouse model. These experimental findings need to be supported by clinical studies.

Diffusion weighted imaging as a biomarker of retinoic acid induced myelomeningocele.

Neural tube defects are a common congenital anomaly involving incomplete closure of the spinal cord. Myelomeningocele (MMC) is a severe form in which there is complete exposure of neural tissue with a lack of skin, soft tissue, or bony covering to protect the spinal cord. The all-trans retinoic acid (ATRA) induced rat model of (MMC) is a reproducible, cost-effective means of studying this disease; however, there are limited modalities to objectively quantify disease severity, or potential benefits from experimental therapies. We sought to determine the feasibility of detecting differences between MMC and wild type (WT) rat fetuses using diffusion magnetic resonance imaging techniques (MRI). Rat dams were gavage-fed ATRA to produce MMC defects in fetuses, which were surgically delivered prior to term. Average diffusion coefficient (ADC) and fractional anisotropy (FA) maps were obtained for each fetus. Brain volumes and two anatomically defined brain length measurements (D1 and D2) were significantly decreased in MMC compared to WT. Mean ADC signal was significantly increased in MMC compared to WT, but no difference was found for FA signal. In summary, ADC and brain measurements were significantly different between WT and MMC rat fetuses. ADC could be a useful complementary imaging biomarker to current histopathologic analysis of MMC models, and potentially expedite therapeutic research for this disease.

Pain-relieving effects of Lawsonia inermis on neuropathic pain induced by chronic constriction injury.

The aim of this study was to determine the role of Lawsonia inermis (L. inermis) extract in the chronic constriction injury (CCI)-induced neuropathic pain. Following CCI surgery, L. inermis extract (250 mg/kg and 500 mg/kg) and gabapentin (100 mg/kg) were administered intraperitoneally for 14 consecutive days. Heat hyperalgesia and allodynia were assessed by radiant heat, aceton drop, and von frey filament tests, respectively. Rat pain behaviors were evaluated on -1sh, 3rd, 5th, 7th, 10th and 14th days post CCI surgery. At the end of the study, the spinal levels of malondialdehyde (MDA), total thiol, IL1-ß, and TNF-α were estimated. Treatment of L. inermis extract reversed the decreased level of thiol and the elevation of MDA level in the spinal cord of CCI rats. Besides, L. inermis extract treatment decreased the elevation of inflammatory markers including IL1-ß, and TNF-α in the spinal cord of CCI rats. These results indicated that L. inermis has potential neuroprotective effects against CCI induced neuropathic pain due to its anti-oxidant, and anti-inflammatory effects.

Daphnetin inhibits spinal glial activation via Nrf2/HO-1/NF-κB signaling pathway and attenuates CFA-induced inflammatory pain.

Daphnetin (7, 8-dihydroxycoumarin, DAPH), a coumarin derivative isolated from Daphne odora var., recently draws much more attention as a promising drug candidate to treat neuroinflammatory diseases due to its protective effects against neuroinflammation. However, itscontribution to chronic inflammatory pain is largely unknown. In the current work, we investigated the effects of DAPH in a murine model of inflammatory pain induced by complete Freund's adjuvant (CFA) and its possible underlying mechanisms. Our results showed that DAPH treatment significantly attenuated mechanical allodynia provoked by CFA. A profound inhibition of spinal glial activation, followed by attenuated expression levels of spinal pro-inflammatory cytokines, was observed in DAPH-treated inflammatory pain mice. Further study demonstrated that DAPH mediated negative regulation of spinal NF-κB pathway, as well as its preferential activation of Nrf2/HO-1 signaling pathway in inflammatory pain mice. This study, for the first time, indicated that DAPH might preventthe development of mechanical allodynia in mice with inflammatory pain. And more importantly, these data provide evidence for the potential application of DAPH in the treatment of chronic inflammatory pain.

The role of chronic muscle (in)activity on carnosine homeostasis: a study with spinal cord-injured athletes.

To examine the role of chronic (in)activity on muscle carnosine (MCarn) and how chronic (in)activity affects MCarn responses to ß-alanine supplementation in spinal cord-injured athletes, 16 male athletes with paraplegia were randomized (2:1 ratio) to receive ß-alanine (n = 11) or placebo (PL, n = 5). They consumed 6.4 g/day of ß-alanine or PL for 28 days. Muscle biopsies of the active deltoid and the inactive vastus lateralis (VL) were taken before and after supplementation. MCarn in the VL was also compared with the VL of a group of individuals without paraplegia (n = 15). MCarn was quantified in whole muscle and in pools of individual fibers by high-performance liquid chromatography. MCarn was higher in chronically inactive VL vs. well-trained deltoid (32.0 ± 12.0 vs. 20.5 ± 6.1 mmol/kg DM; P = 0.018). MCarn was higher in inactive vs. active VL (32.0 ± 12.0 vs. 21.2 ± 7.5 mmol/kg DM; P = 0.011). In type-I fibers, MCarn was significantly higher in the inactive VL than in the active deltoid (38.3 ± 4.7 vs. 27.3 ± 11.8 mmol/kg DM, P = 0.014). MCarn increased similarly between inactive VL and active deltoid in the ß-alanine group (VL: 68.9 ± 55.1%, P = 0.0002; deltoid: 90.5 ± 51.4%, P < 0.0001), with no changes in the PL group. MCarn content was higher in the inactive VL than in the active deltoid and the active VL, but this is probably a consequence of fiber type shift (type I to type II) that occurs with chronic inactivity. Chronically inactive muscle showed an increase in MCarn after BA supplementation equally to the active muscle, suggesting that carnosine accretion following ß-alanine supplementation is not influenced by muscle inactivity.

Chaiqin chengqi decoction ameliorates acute pancreatitis in mice via inhibition of neuron activation-mediated acinar cell SP/NK1R signaling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Chaiqin chengqi decoction (CQCQD) and its derivatives have been widely used in China for the early management of patients with acute pancreatitis (AP). Numerous studies demonstrate the anti-inflammatory and anti-oxidative effects of CQCQD and derivatives, but whether these effects can be attributed to suppressing neurogenic inflammation, has never been studied. AIM OF THE STUDY: To investigate the effects of CQCQD on substance P (SP)-neurokinin 1 receptor (NK1R) based neurogenic inflammation in an experimental AP model. MATERIAL AND METHODS: For AP patients on admission, pain score was accessed by visual analog scale (VAS); the levels of serum SP and expressions of pancreatic SP and NK1R were also determined. For in vivo study, mice received 7 intraperitoneal injections of cerulein (50 µg/kg) at hourly intervals to induce AP, whilst controls received normal saline injections. In the treatment groups, CQCQD (10 g/kg, 200 µl) was intragastrically given at the third, fifth, and seventh of the cerulein injection or the NK1R antagonist CP96345 (5 mg/kg) was intraperitoneally injected 30 min before the first cerulein administration. The von Frey test was performed to evaluate pain behavior. Animals were sacrificed at 12 h from the first cerulein/saline injection for severity assessment. Pharmacology network analysis was used to identify active ingredients of CQCQD for AP and pain. In vitro, freshly isolated pancreatic acinar cells were pre-treated with CQCQD (5 mg/ml), CP96345 (1 µM), or selected active compounds of CQCQD (12.5, 25, and 50 µM) for 30 min, followed by SP incubation for another 30 min. RESULTS: The VAS score as well as the levels of serum SP and expressions of pancreatic SP-NK1R were up-regulated in moderately severe and severe patients compared with those with mild disease. CQCQD, but not CP96345, consistently and significantly ameliorated pain, pancreatic necrosis, and systemic inflammation in cerulein-induced AP as well as inhibited NK1R internalization of pancreatic acinar cells. These effects of CQCQD were associated with reduction of pancreatic SP-NK1R and neuron activity in pancreas, dorsal root ganglia, and spinal cord. Baicalin, emodin, and magnolol, the top 3 active components of CQCQD identified via pharmacology network analysis, suppressed NK1R internalization and NF-κB signal pathway activation in isolated pancreatic acinar cells. CONCLUSIONS: CQCQD ameliorated cerulein-induced AP and its associated pain via inhibiting neuron activation-mediated pancreatic acinar cell SP-NK1R signaling pathways and its active compounds baicalin, emodin, and magnolol contributed to this effect.

Berberine alleviates visceral hypersensitivity in rats by altering gut microbiome and suppressing spinal microglial activation.

Accumulating evidence shows that agents targeting gut dysbiosis are effective for improving symptoms of irritable bowel syndrome (IBS). However, the potential mechanisms remain unclear. In this study we investigated the effects of berberine on the microbiota-gut-brain axis in two rat models of visceral hypersensitivity, i.e., specific pathogen-free SD rats subjected to chronic water avoidance stress (WAS) and treated with berberine (200 mg· kg-1 ·d-1, ig, for 10 days) as well as germ-free (GF) rats subjected to fecal microbiota transplantation (FMT) from a patient with IBS (designated IBS-FMT) and treated with berberine (200 mg· kg-1 ·d-1, ig, for 2 weeks). Before the rats were sacrificed, visceral sensation and depressive behaviors were evaluated. Then colonic tryptase was measured and microglial activation in the dorsal lumbar spinal cord was assessed. The fecal microbiota was profiled using 16S rRNA sequencing, and short chain fatty acids (SCFAs) were measured. We showed that berberine treatment significantly alleviated chronic WAS-induced visceral hypersensitivity and activation of colonic mast cells and microglia in the dorsal lumbar spinal cord. Transfer of fecal samples from berberine-treated stressed donors to GF rats protected against acute WAS. FMT from a patient with IBS induced visceral hypersensitivity and pro-inflammatory phenotype in microglia, while berberine treatment reversed the microglial activation and altered microbial composition and function and SCFA profiles in stools of IBS-FMT rats. We demonstrated that berberine did not directly influence LPS-induced microglial activation in vitro. In both models, several SCFA-producing genera were enriched by berberine treatment, and positively correlated to the morphological parameters of microglia. In conclusion, activation of microglia in the dorsal lumbar spinal cord was involved in the pathogenesis of IBS caused by dysregulation of the microbiota-gut-brain axis, and the berberine-altered gut microbiome mediated the modulatory effects of the agent on microglial activation and visceral hypersensitivity, providing a potential option for the treatment of IBS.

Anti-nociceptive effects of Sedum Lineare Thunb. on spared nerve injury-induced neuropathic pain by inhibiting TLR4/NF-κB signaling in the spinal cord in rats.

Neuropathic pain is still a critical public health problem worldwide. Thereby, the search for novel and more effective strategies against neuropathic pain is urgently considered. It is known that neuroinflammation plays a crucial role in the pathogenesis of neuropathic pain. SedumLineare Thunb. (SLT), a kind of Chinese herb originated from the whole grass of Crassulaceae plant, was reported to possess anti-inflammatory activity. However, whether SLT has anti-nociceptive effect on neuropathic pain and its possible underlying mechanisms remains poorly elucidated. In this study, a rat model of neuropathic pain induced by spared nerve injury (SNI)was applied. SLT (p.o.) was administered to SNI rats once every day lasting for 14 days. Pain-related behaviors were assessed by using paw withdrawal threshold (PWT) and CatWalk gait parameters. Expression levels of inflammatory mediators and pain-related signaling molecules in the spinal cord were detected using western blotting assay. The results revealed that SLT (30, 100, and 300 mg/kg, p.o.) treatment for SNI rats ameliorated mechanical hypersensitivity in a dose-dependent manner. Application of SLT at the most effective dose of 100 mg/kg to SNI rats not only significantly blocked microglial activation, but also markedly reduced the protein levels of spinal HMGB1, TLR4, MyD88, TRAF6, IL-1ß, IL-6, and TNF-α, along with an enhancement in gait parameters. Furthermore, SLT treatment dramatically inhibited the phosphorylation levels of both IKK and NF-κB p65 but obviously improved both IκB and IL-10 protein expression in the spinal cord of SNI rats. Altogether, these data suggested that SLT could suppress spinal TLR4/NF-κB signaling pathway in SNI rats, which might at least partly contribute to its anti-nociceptive action, indicating that SLT may serveas a potential therapeutic agent for neuropathic pain.

Effect of Propolis on Neurological Recovery After Experimental Spinal Cord Injury.

AIM: To examine the effect of propolis on the healing process in terms of both electrophysiological and ultrastructural parameters in a rat model of experimental spinal cord injury. MATERIAL AND METHODS: Thirty rats were divided into control, spinal cord trauma, and treated trauma groups with 10 rats per group. The rats were sacrificed after 10 days. Before sacrifice, all rats were neurologically assessed by electrophysiological monitoring, and immediately after sacrifice, the spinal cord was examined ultrastructurally by transmission electron microscopy (TEM). RESULTS: According to the electrophysiological examination, the treatment group was statistically significantly different from the trauma group. However, no statistically significant difference was found between the control and treatment groups. In terms of the TEM examination, the treatment group was significantly different from the trauma group. CONCLUSION: In this study, propolis was administered just before the induction of trauma, and the findings suggest that the use of propolis has a positive effect on the healing process. This implies that in order to prevent postoperative deficits, this treatment may be preferably applied before spinal cord surgery for trauma.

Preclinical Nanomedicines for Polyglutamine-Based Neurodegenerative Diseases.

Polyglutamine (polyQ) diseases, such as Huntington's disease and several types of spinocerebellar ataxias, are dominantly inherited progressive neurodegenerative disorders and characterized by the presence of expanded CAG trinucleotide repeats in the respective disease locus of the patient genomes. Patients with polyQ diseases currently need to rely on symptom-relieving treatments because disease-modifying therapeutic interventions remain scarce. Many disease-modifying therapeutic agents are now under clinical testing for treating polyQ diseases, but their delivery to the brain is often too invasive (e.g., intracranial injection) or inefficient, owing to in vivo degradation and clearance by physiological barriers (e.g., oral and intravenous administration). Nanoparticles provide a feasible solution for improving drug delivery to the brain, as evidenced by an increasing number of preclinical studies that document the efficacy of nanomedicines for polyQ diseases over the past 5-6 years. In this review, we present the pathogenic mechanisms of polyQ diseases, the common animal models of polyQ diseases for evaluating the efficacy of nanomedicines, and the common administration routes for delivering nanoparticles to the brain. Next, we summarize the recent preclinical applications of nanomedicines for treating polyQ diseases and improving neurological conditions in vivo, placing emphasis on antisense oligonucleotides, small peptide inhibitors, and small molecules as the disease-modifying agents. We conclude with our perspectives of the burgeoning field of "nanomedicines for polyQ diseases", including the use of inorganic nanoparticles and potential drugs as next-generation nanomedicines, development of higher-order animal models of polyQ diseases, and importance of "brain-nano" interactions.

Total flavonoids of astragalus attenuates experimental autoimmune encephalomyelitis by suppressing the activation and inflammatory responses of microglia via JNK/AKT/NFκB signaling pathway.

BACKGROUND: Microglia-mediated neuroinflammation is one of the most prominent characteristics of multiple sclerosis (MS), a chronic demyelination disease. As one of the main active ingredients in Astragali radix, total flavonoids of Astragalus (TFA) has multiple pharmacological effects such as immunomodulation, anti-inflammation and and anti-tumor. However, little is known about whether TFA could inhibit microglia-mediated neuroinflammation in MS. PURPOSE: This study was aimed to elucidate whether TFA could inhibit microglia-mediated neuroinflammation in MS. STUDY DESIGN: In the present study, we explored the protective effect of TFA on experimental autoimmune encephalomyelitis (EAE), an animal model of MS, in mice for the first time, and discussed its mechanism from the aspect of anti-microglia-mediated neuroinflammation. METHODS: The mice received oral administration of TFA (25 and 50 mg/kg) daily from two days before immunization and continued until day 21 post-immunization. The effect of TFA on EAE in mice and its mechanism were investigated by ELISA, Western blot, real-time PCR, luciferase reporter assay, histopathology and immunohistochemistry. RESULTS: TFA were shown to alleviate the severity of EAE in mice. It inhibited the excessive activation of microglia both in spinal cords of EAE mice and in LPS-stimulated BV-2 cells, evidenced by weakening the production of inflammatory mediators such as NO, TNF-α, IL-6, and IL-1ß markedly at either protein or mRNA level. Further study demonstrated that TFA repressed the phosphorylation, nuclear translocation and transcriptional activity of NFκB, and inhibited the activation of AKT and JNK signaling in BV-2 cells induced by LPS. The agonists of AKT and JNK, anisomycin and SC79, could partly abolish the inhibitory effect of TFA on the production of inflammatory mediators in BV-2 cells induced by LPS. CONCLUSIONS: Taken together, our results clarified that TFA inhibited microglia-mediated inflammation in EAE mice probably through deactivating JNK/AKT/NFκB signaling pathways. The novel findings may lay a theoretical foundation for the clinical application of TFA in the treatment of MS.

Go-sha-jinki-Gan Alleviates Inflammation in Neurological Disorders via p38-TNF Signaling in the Central Nervous System.

Go-sha-jinki-Gan (GJG) is a traditional Japanese herbal medicine. In clinical practice, GJG is effective against neuropathic pain and hypersensitivity induced by chemotherapy or diabetes. In our previous study using a chronic constriction injury mouse model, we showed that GJG inhibited microglia activation by suppressing the expression of tumor necrosis factor-α (TNF-α) and p38 mitogen-activated protein kinase (p38 MAPK) in the peripheral nervous system. To investigate whether GJG can suppress inflammation in the central nervous system (CNS) in the context of neurological disorders, we examined the effect of GJG on the activation of resident glial cells and on p38-TNF signaling in two mouse models of neurological disorders: the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis and the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease. GJG administration relieved the severity of clinical EAE symptoms and MPTP-induced inflammation by decreasing the number of microglia and the production of TNF-α in the spinal cord of EAE mice and the substantia nigra of MPTP-treated mice. Accordingly, GJG suppressed the phosphorylation of p38 in glial cells of these two mouse models. We conclude that GJG attenuates inflammation of the CNS by suppressing glial cell activation, followed by a decrease in the production of TNF-α via p38-TNF signaling.

Raloxifene is a Female-specific Proteostasis Therapeutic in the Spinal Cord.

Several neurodegenerative disorders are characterized by proteasome dysfunctions leading to protein aggregations and pathogenesis. Since we showed that estrogen receptor alpha (ERα) activates the proteasome, drugs able to stimulate ERα in the central nervous system (CNS) could hold potential for therapeutic intervention. However, the transcriptional effects of selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, can be tissue specific. A direct comparison of the effects of different SERMs on gene transcription in the CNS has never been performed. Here, we report an RNA-seq analysis of the spinal cord treated with estrogen, tamoxifen, or raloxifene. We find stark SERM and sex-specific differences in gene expression profiles in the spinal cord. Notably, raloxifene, but not estrogen or tamoxifen, modulates numerous deubiquitinating enzymes, proteasome subunits and assembly factors, and these effects translate into decreased protein aggregates. In the SOD1-G93A mouse model of amyotrophic lateral sclerosis, we found that even a low dose of raloxifene causes a significant decrease in mutant SOD1 aggregates in the spinal cord, accompanied by a delay in the decline of muscle strength in females, but not in males. These results strongly indicate SERM-selective as well as sex-specific effects, and emphasize the importance of sex as a biological variable to be considered for the careful selection of specific SERM for use in clinical trials for neurodegenerative diseases.

Protective Effects of Curcumin Against Paclitaxel-Induced Spinal Cord and Sciatic Nerve Injuries in Rats.

Paclitaxel (PTX) is an antineoplastic agent commonly used in the treatment of solid tumors and is known to cause dose-limiting peripheral neurotoxicity. This study was performed to evaluate the protective effect of curcumin (CUR) against PTX-induced spinal cord and sciatic nerve injuries in rats. The rats were administered PTX (2 mg/kg, BW) intraperitoneally for the first 5 consecutive days followed by administration of CUR (100 and 200 mg/kg, BW daily in corn oil) orally for 10 days. Our results showed that CUR significantly reduced mRNA expression levels of NF-κB, TNF-α, IL-6, iNOS and GFAP whereas caused an increase in levels of Nrf2, HO-1 and NQO1 in the spinal cord and sciatic nerve of PTX-induced rats. In addition, CUR suppressed the activation of apoptotic and autophagic pathways by increasing Bcl-2 and Bcl-xL, and decreasing p53, caspase-3, Apaf-1, LC3A, LC3B and beclin-1 mRNA expression levels. The results showed that CUR also maintained the spinal cord and sciatic nerve histological architecture and integrity by both LFB staining and H&E staining. Immunohistochemical expressions of 8-OHdG, caspase-3 and LC3B in the PTX-induced spinal cord tissue were decreased after administration of CUR. Taken together, our findings demonstrated that CUR has protective effects on PTX-induced spinal cord and sciatic nerve injuries in rats.

Aqueous leaf extract from Luehea divaricata Mart. Modulates oxidative stress markers in the spinal cord of rats with neuropathic pain.

ETHNOPHARMACOLOGICAL RELEVANCE: Reactive oxygen species (ROS) play an important role in neuropathic pain (i.e., pain caused by lesion or disease of the somatosensory system). We showed previously that the aqueous extract prepared from Luehea divaricata leaves, a plant explored by native ethnic groups of Brazil to treat different pathologic conditions, exhibits good antioxidant activity and induces analgesia in rats with neuropathic pain (J Ethnopharmacol, 2020; 256:112761. doi: 10.1016/j.jep.2020.112761). The effect was comparable to that of gabapentin, a drug recommended as first-line treatment for neuropathic pain. However, increasing evidence has indicated the need to accurately determine the oxidative stress level of an individual before prescribing supplemental antioxidants. AIM OF THE STUDY: This study assessed the effects of the oral administration of aqueous extract from leaves of L. divaricata on the sciatic functional index (SFI) and spinal-cord pro-oxidant and antioxidant markers of rats with neuropathic pain. MATERIALS AND METHODS: Placement of four loose chromic thread ligatures around the sciatic nerve produced chronic constriction injury (CCI) of the sciatic nerve, a commonly employed animal model to study neuropathic pain. Aqueous extract from leaves of L. divaricata (100, 300, 500 and 1000 mg/kg), gabapentin (50 mg/kg) and aqueous extract (500 mg/kg) + gabapentin (30 mg/kg) were administrated per gavage daily for 10 or 35 days post-CCI. Antinociception was assessed using the von Frey test while SFI showed functional recovery post-nerve lesion throughout the experimental period. At days 10 and 35 post-surgery, the lumbosacral spinal cord and a segment of the injured sciatic nerve were dissected out and used to determine lipid hydroperoxide levels and total antioxidant capacity (TAC). The spinal cord was also used to determine superoxide anion generation (SAG), hydrogen peroxide (H2O2) levels and total thiol content. RESULTS: As expected, the extract, gabapentin and extract + gabapentin induced antinociception in CCI rats. While no significant functional recovery was found at 10 days post-CCI, a significant recovery was found in SFI of extract-treated CCI rats at 21 and 35 days post-CCI. A significant functional recovery was found already at day 10 post-CCI in gabapentin and gabapentin + extract-treated CCI rats. The extract treatment prevented increases in lipid hydroperoxides levels and TAC in injured sciatic nerve, which were found in this tissue of vehicle-treated rats at 10 days post-CCI. Extract also prevented an increase in SAG, H2O2 and lipid hydroperoxides levels in the spinal cord, which were elevated in this tissue of vehicle-treated rats at 10 and 35 days post-CCI. Extract also prevented a decrease in total thiol content and an increase in TAC in the spinal cord of CCI rats in these same time periods. CONCLUSIONS: Aqueous extract from L. divaricata leaves was demonstrated, for the first time, to improve SFI and modulate oxidative stress markers in injured sciatic nerve and spinal cord of CCI rats. Thus, the antinociceptive effect of the extract involves modulation of oxidative stress markers in injured sciatic nerve and spinal cord.

Selenium-Doped Carbon Quantum Dots Efficiently Ameliorate Secondary Spinal Cord Injury via Scavenging Reactive Oxygen Species.

BACKGROUND: The excess production of reactive oxygen species (ROS) after traumatic spinal cord injury (TSCI) has been identified as a leading cause of secondary injury, which can significantly exacerbate acute damage in the injured spinal cord. Thus, scavenging of ROS has emerged as an effective route to ameliorate secondary spinal cord injury. PURPOSE: Selenium-doped carbon quantum dots (Se-CQDs) with the ability to scavenge reactive oxygen species were prepared and used for efficiently ameliorating secondary injury in TSCI. METHODS: Water-soluble Se-CQDs were easily synthesized via hydrothermal treatment of l-selenocystine. The chemical structure, size, and morphology of the Se-CQDs were characterized in detail. The biocompatibility and protective effects of the Se-CQDs against H2O2-induced oxidative damage were investigated in vitro. Moreover, the behavioral test, bladder function, histological observation, Western blot were used to investigate the neuroprotective effect of Se-CQDs in a rat model of contusion TSCI. RESULTS: The obtained Se-CQDs exhibited good biocompatibility and remarkable protective effect against H2O2-induced oxidative damage in astrocytes and PC12 cells. Moreover, Se-CQDs displayed marked anti-inflammatory and anti-apoptotic activities, which thereby reduced the formation of glial scars and increased the survival of neurons with unscathed myelin sheaths in vivo. As a result, Se-CQDs were capable of largely improving locomotor function of rats with TSCI. CONCLUSION: This study suggests that Se-CQDs can be used as a promising therapeutic platform for ameliorating secondary injury in TSCI.