OBJECTIVE: To investigate the effects of removing microglia from spinal cord on nerve repair and functional recovery after spinal cord injury (SCI) in mice. METHODS: Thirty-nine 6-week-old female C57BL/6 mice were randomly divided into control group ( n=12), SCI group ( n=12), and PLX3397+SCI group ( n=15). The PLX3397+SCI group received continuous feeding of PLX3397, a colony-stimulating factor 1 receptor inhibitor, while the other two groups were fed a standard diet. After 14 days, both the SCI group and the PLX3397+SCI group were tested for ionized calcium binding adapter molecule 1 (Iba1) to confirm that the PLX3397+SCI group had completely depleted the spinal cord microglia. The SCI model was then prepared by clamping the spinal cord in both the SCI group and the PLX3397+SCI group, while the control group underwent laminectomy. Preoperatively and at 1, 3, 7, 14, 21, and 28 days postoperatively, the Basso Mouse Scale (BMS) was used to assess the hind limb function of mice in each group. At 28 days, a footprint test was conducted to observe the gait of the mice. After SCI, spinal cord tissue from the injury site was taken, and Iba1 immunofluorescence staining was performed at 7 days to observe the aggregation and proliferation of microglia in the spinal cord. HE staining was used to observe the formation of glial scars at the injury site at 28 days; glial fibrillary acidic protein (GFAP) immunofluorescence staining was applied to astrocytes to assess the extent of the injured area; neuronal nuclei antigen (NeuN) immunofluorescence staining was used to evaluate neuronal survival. And 5-hydroxytryptamine (5-HT) immunofluorescence staining was performed to assess axonal survival at 60 days. RESULTS: All mice survived until the end of the experiment. Immunofluorescence staining revealed that the microglia in the spinal cord of the PLX3397+SCI group decreased by more than 95% compared to the control group after 14 days of continuous feeding with PLX3397 ( P<0.05). Compared to the control group, the BMS scores in the PLX3397+SCI group and the SCI group significantly decreased at different time points after SCI ( P<0.05). Moreover, the PLX3397+SCI group showed a further decrease in BMS scores compared to the SCI group, and exhibited a dragging gait. The differences between the two groups were significant at 14, 21, and 28 days ( P<0.05). HE staining at 28 days revealed that the SCI group had formed a well-defined and dense gliotic scar, while the PLX3397+SCI group also developed a gliotic scar, but with a more blurred and loose boundary. Immunofluorescence staining revealed that the number of microglia near the injury center at 7 days increased in the SCI group than in the control group, but the difference between groups was not significant ( P>0.05). In contrast, the PLX3397+SCI group showed a significant reduction in microglia compared to both the control and SCI groups ( P<0.05). At 28 days after SCI, the area of spinal cord injury in the PLX3397+SCI group was significantly larger than that in SCI group ( P<0.05); the surviving neurons significantly reduced compared with the control group and SCI group ( P<0.05). The axonal necrosis and retraction at 60 days after SCI were more obvious. CONCLUSION The removal of microglia in the spinal cord aggravate the tissue damage after SCI and affecte the recovery of motor function in mice, suggesting that microglia played a neuroprotective role in SCI.
Animals ; Spinal Cord Injuries/surgery* ; Microglia/pathology* ; Female ; Mice ; Mice, Inbred C57BL ; Nerve Regeneration/drug effects* ; Spinal Cord/pathology* ; Pyrroles/administration & dosage* ; Aminopyridines/administration & dosage* ; Recovery of Function ; Disease Models, Animal ; Calcium-Binding Proteins/metabolism* ; Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/antagonists & inhibitors* ; Microfilament Proteins/metabolism* ; Glial Fibrillary Acidic Protein/metabolism*

OBJECTIVE: To preliminarily investigate the effects and mechanism of action of Yishen Yangsui Formula (, YSYSF)on the recovery of neurological function in rats with degenerative cervical myelopathy. METHODS: Fifty adult SD female rats were randomly divided into control group, sham group, model group, YSYSF group and positive drug group by using randomized numerical table method. In the model group, YSYSF group and positive drug group, polyvinyl alcohol acrylamide interpenetrating network hydrogel(water-absorbent swelling material) was used to construct a rat spinal cord chronic compression model. The sham group was implanted with the water-absorbent swelling material and then removed without causing spinal cord compression. The control group, the sham group and the model group were given equal amounts of saline by gavage, the group of YSYSF was given Chinese herbal medicine soup by gavage 9.1 g·kg^-1 once a day, and the positive drug group was given tetrahexylsalicylglucoside sodium monosialate ganglioside by intraperitoneal injection 4.2 mg·kg^-1 once a day. The motor function of the rats was assessed by the BBB method after 1, 3, 7, and 14 d of drug administration. The spinal cord tissues were taken from rats executed 14 d after drug administration, and the morphological changes of the spinal cord compression site were observed by HE staining, and the expression levels of Caspase-1, GSDMD, NLRP3, PYCARD, IL-1β, and IL-18 were detected in the area of spinal cord injury by Western blot method. RESULTS: The BBB scores of the control group and the sham group were normal at all time points after modeling, which were higher than the BBB scores of the model group, the YSYSF, and the positive drug group (P<0.05). From the 3rd day after gavage, at all time points, the BBB scores of rats in the YSYSF group and the positive drug group were higher than those of rats in the model group (P<0.05). The staining pattern of HE spinal cord tissue was normal in the control group and the sham group, and the HE spinal cord in the model group was severely damaged with a large number of neuron deaths, whereas the damage to the spinal cord and neuron cells was reduced in the YSYSF group and the positive drug group. The expression levels of caspase-1, GSDMD, NLRP3, PYCARD, IL-1β and IL-18 in the spinal cord of the model group were significantly higher than those of the sham group (P<0.0001), and the expression levels of caspase-1, GSDMD, NLRP3, PYCARD, IL-1β, and IL-18 in the YSYSF group and the drug group were significantly lower than those in the model group (P<0.05). CONCLUSION YSYSF can improve the motor function of rats with degenerative cervical spinal cord disease, alleviate the pathological changes, and promote the recovery of spinal cord neurological function. The specific mechanism may be related to the inhibition of the activation of inflammatory vesicles NLRP3 and PYCARD, the reduction of the release of inflammatory factors IL-1β and IL-18, the reduction of the expression of caspase-1 and GSDMD, the reduction of cellular death, and the inhibition of inflammatory response.
Animals ; Female ; Drugs, Chinese Herbal/administration & dosage* ; Rats ; Rats, Sprague-Dawley ; Pyroptosis/drug effects* ; Spinal Cord/pathology* ; NLR Family, Pyrin Domain-Containing 3 Protein ; Spinal Cord Diseases/drug therapy* ; Interleukin-1beta/metabolism*

PURPOSE: The secondary damage of spinal cord injury (SCI) starts from the collapse of the blood spinal cord barrier (BSCB) to chronic and devastating neurological deficits. Thereby, the retention of the integrity and permeability of BSCB is well-recognized as one of the major therapies to promote functional recovery after SCI. Previous studies have demonstrated that activation of hypoxia inducible factor-1α (HIF-1α) provides anti-apoptosis and neuroprotection in SCI. Endogenous HIF-1α, rapidly degraded by prolylhydroxylase, is insufficient for promoting functional recovery. Dimethyloxalylglycine (DMOG), a highly selective inhibitor of prolylhydroxylase, has been reported to have a positive effect on axon regeneration. However, the roles and underlying mechanisms of DMOG in BSCB restoration remain unclear. Herein, we aim to investigate pathological changes of BSCB restoration in rats with SCI treated by DOMG and evaluate the therapeutic effects of DMOG. METHODS: The work was performed from 2022 to 2023. In this study, Allen's impact model and human umbilical vein endothelial cells were employed to explore the mechanism of DMOG. In the phenotypic validation experiment, the rats were randomly divided into 3 groups: sham group, SCI group, and SCI + DMOG group (10 rats for each). Histological analysis via Nissl staining, Basso-Beattie-Bresnahan scale, and footprint analysis was used to evaluate the functional recovery after SCI. Western blotting, TUNEL assay, and immunofluorescence staining were employed to exhibit levels of tight junction and adhesion junction of BSCB, HIF-1α, cell apoptosis, and endoplasmic reticulum (ER) stress. The one-way ANOVA test was used for statistical analysis. The difference was considered statistically significant at p < 0.05. RESULTS: In this study, we observed the expression of HIF-1α reduced in the SCI model. DMOG treatment remarkably augmented HIF-1α level, alleviated endothelial cells apoptosis and disruption of BSCB, and enhanced functional recovery post-SCI. Besides, the administration of DMOG offset the activation of ER stress induced by SCI, but this phenomenon was blocked by tunicamycin (an ER stress activator). Finally, we disclosed that DMOG maintained the integrity and permeability of BSCB by inhibiting ER stress, and inhibition of HIF-1α erased the protection from DMOG. CONCLUSIONS Our findings illustrate that the administration of DMOG alleviates the devastation of BSCB and HIF-1α-induced inhibition of ER stress.
Spinal Cord Injuries/pathology* ; Animals ; Apoptosis/drug effects* ; Amino Acids, Dicarboxylic/therapeutic use* ; Recovery of Function/drug effects* ; Rats ; Rats, Sprague-Dawley ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Male ; Spinal Cord/blood supply*

OBJECTIVE: To illustrate the role of dehydrocorydaline (DHC) in chronic constriction injury (CCI)-induced neuropathic pain and the underlying mechanism. METHODS: C57BL/6J mice were randomly divided into 3 groups by using a random number table, including sham group (sham operation), CCI group [intrathecal injection of 10% dimethyl sulfoxide (DMSO)], and CCI+DHC group (intrathecal injection of DHC), 8 mice in each group. A CCI mouse model was conducted to induce neuropathic pain through ligating the right common sciatic nerve. On day 14 after CCI modeling or sham operation, mice were intrathecal injected with 5 µL of 10% DMSO or 10 mg/kg DHC (5 µL) into the 5th to 6th lumbar intervertebral space (L5-L6). Pregnant ICR mice were sacrificed for isolating primary spinal neurons on day 14 of embryo development for in vitro experiment. Pain behaviors were evaluated by measuring the paw withdrawal mechanical threshold (PWMT) of mice. Immunofluorescence was used to observe the activation of astrocytes and microglia in mouse spinal cord. Protein expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), phosphorylation of N-methyl-D-aspartate receptor subunit 2B (p-NR2B), and NR2B in the spinal cord or primary spinal neurons were detected by Western blot. RESULTS: In CCI-induced neuropathic pain model, mice presented significantly decreased PWMT, activation of glial cells, overexpressions of iNOS, TNF-α, IL-6, and higher p-NR2B/NR2B ratio in the spinal cord (P<0.05 or P<0.01), which were all reversed by a single intrathecal injection of DHC (P<0.05 or P<0.01). The p-NR2B/NR2B ratio in primary spinal neurons were also inhibited after DHC treatment (P<0.05). CONCLUSION An intrathecal injection of DHC relieved CCI-induced neuropathic pain in mice by inhibiting the neuroinflammation and neuron hyperactivity.
Animals ; Neuralgia/etiology* ; Mice, Inbred C57BL ; Analgesics/pharmacology* ; Neuroinflammatory Diseases/pathology* ; Constriction ; Male ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Nitric Oxide Synthase Type II/metabolism* ; Mice, Inbred ICR ; Microglia/pathology* ; Spinal Cord/drug effects* ; Female ; Mice ; Tumor Necrosis Factor-alpha/metabolism* ; Disease Models, Animal ; Constriction, Pathologic/complications* ; Interleukin-6/metabolism* ; Astrocytes/metabolism* ; Chronic Disease ; Neurons/metabolism*

OBJECTIVE: To investigate whether Buyang Huanwu Decoction (BYHWD) had a good curative effect on the neuroprotection of red nucleus neurons after spinal cord injury (SCI) and the possible molecular mechanism. METHODS: Ninety male Sprague-Dawley rats were divided into 5 groups (n=18 per group) according to a random number table, including the control, model, low- (12.78 g/kg, BL group), medium- (25.65 g/kg, BM group), and high-dose BYHWD groups (51.30 g/kg, BH group). A rubrospinal tract transection model in rats was established, and different doses of BYHWD were intragastrically administrated for 4 weeks. The forelimb locomotor function was recorded using the spontaneous vertical exploration test. Cyclic adenosine monophosphate (cAMP) level in red nucleus was detected through an enzyme-linked immunosorbent assay. The morphology and number of red nucleus neurons were observed using Nissl's staining and axonal retrograde tracing by Fluoro-Gold (FG). The expression of cAMP-dependent protein kinase A (PKA), nuclear factor kappa-B (NF-κB) p65, and brain-derived neurotrophic factor (BDNF) in red nucleus were detected using immunohistochemistry and quantitative real-time polymerase chain reaction. RESULTS: Compared with the control group, the utilization rate of bilateral forelimbs, unilateral right forelimbs, proportion of FG-labeled positive neurons, cAMP level, protein expressions of PKA and BDNF, and BDNF mRNA expression were significantly decreased in the model group (P<0.01), while NF-κB p65 was increased in the model group (P<0.01). Compared with the model group, the utilization rate of bilateral forelimbs and unilateral right forelimbs were significantly higher in the BL, BM and BH groups (P<0.01), the proportion of FG-labeled positive neurons, cAMP level, protein expressions of PKA and BDNF and BDNF mRNA expression in all BYHWD groups were increased (P<0.05 or P<0.01), while NF-κB p65 were decreased in all BYHWD groups (P<0.05 or P<0.01). CONCLUSIONS BYHWD possesses a sound neuroprotective effect on red nucleus neurons after SCI, and the efficacy was dose-related. The mechanism may be related to regulating the cAMP/PKA/NF-κ B p65 signaling pathway, finally promoting expression of BDNF.
Animals ; Spinal Cord Injuries/pathology* ; Drugs, Chinese Herbal/therapeutic use* ; Rats, Sprague-Dawley ; Male ; Cyclic AMP/metabolism* ; Transcription Factor RelA/metabolism* ; Cyclic AMP-Dependent Protein Kinases/metabolism* ; Signal Transduction/drug effects* ; Brain-Derived Neurotrophic Factor/genetics* ; Red Nucleus/metabolism* ; Recovery of Function/drug effects* ; Neurons/metabolism* ; Rats

OBJECTIVES: To investigate the effect of monotropein on motor function recovery of mice with spinal cord injury (SCI) and explore the underlying mechanism. METHODS: Forty-five adult female C57BL/6 mice were randomized equally into sham operation group, SCI group, and SCI group with daily intraperitoneal monotropein injection. The mice in the former two groups received daily saline injections. Motor function of the mice was evaluated using BMS scores, slant plate test, and footprint analyses. Pathological changes and neuronal counts in the spinal cord were observed using HE, LFB, and Nissl staining. The biological functions of monotropein were explored using GO and KEGG enrichment analyses. NeuN/cleaved caspase-3 immunofluorescence assay and Western blotting were used to detect neuronal apoptosis in the spinal cord of the mice. In cultured HT22 cells, the effect of monotropein on TNF-α-induced cell apoptosis was evaluated using TUNEL staining and Western blotting. In monotropein-treated HT22 cells and SCI mice, the changes in the PI3K/AKT pathway were examined, and the effect of a PI3K/AKT pathway activator (IGF-1) on HT22 cell apoptosis and motor function recovery of SCI mice were observed. RESULTS: SCI mice with monotropein treatment showed significantly improved motor functions with reduced SCI areas and increased myelin retention and neuron counts in the spinal cord. Bioinformatics analysis suggested a role of PI3K/AKT signaling pathway in mediating the anti-apoptotic effects of monotropein. In SCI mice, monotropein obviously reduced apoptotic neurons, decreased expressions of cleaved caspase-3 and Bax and increased Bcl-2 expression in the spinal cord. In HT22 cells, monotropein significantly inhibited TNF-α-induced apoptosis and PI3K/AKT pathway activation. Treatment with IGF-1 obviously increased apoptosis of HT22 cells and exacerbated locomotor dysfunction in SCI mice. CONCLUSIONS Monotropein promotes motor function recovery in SCI mice by reducing neuronal apoptosis possibly by inhibiting the PI3K/AKT signaling pathway.
Animals ; Spinal Cord Injuries/metabolism* ; Apoptosis/drug effects* ; Signal Transduction/drug effects* ; Mice, Inbred C57BL ; Mice ; Proto-Oncogene Proteins c-akt/metabolism* ; Female ; Phosphatidylinositol 3-Kinases/metabolism* ; Neurons/pathology* ; Recovery of Function

Astrocytes in the spinal dorsal horn (SDH) exhibit diverse reactive phenotypes under neuropathic conditions, yet the mechanisms driving this diversity and its implications in chronic pain remain unclear. Here, we report that spared nerve injury (SNI) induces marked upregulation of both complement component 3 (C3⁺, A1-like) and S100 calcium-binding protein A10 (S100A10⁺, A2-like) astrocyte subpopulations in the SDH, with elevated microglial cytokines including interleukin-1α, tumor necrosis factor-α, and complement component 1q. Transcriptomic, immunohistochemical, and Western blot analyses reveal co-activation of multiple reactive astrocyte states over a unidirectional shift toward an A1-like phenotype. Fibroblast growth factor 8 (FGF8), a neuroprotective factor via FGFR3, mitigated microglia-induced C3⁺ astrocyte reactivity in vitro and suppressed spinal C3 expression and mechanical allodynia following intrathecal administration in SNI mice. These findings reveal a microglia-astrocyte signaling axis that promotes A1 reactivity and position FGF8 as a promising therapeutic candidate for neuropathic pain by modulating astrocyte heterogeneity.
Animals ; Astrocytes/drug effects* ; Neuralgia/pathology* ; Receptor, Fibroblast Growth Factor, Type 3/metabolism* ; Signal Transduction/physiology* ; Male ; Mice ; Microglia/drug effects* ; Fibroblast Growth Factor 8/pharmacology* ; Mice, Inbred C57BL ; Hyperalgesia/drug therapy* ; Spinal Cord/drug effects* ; Complement C3/metabolism* ; Spinal Cord Dorsal Horn/metabolism*

Objective To investigate the effects of sakuranetin (SK) on motor functions in the mouse model of spinal cord injury (SCI) and decipher the mechanism. Methods Fifty-four C57BL/6J mice were randomized into sham,SCI,and SK groups.The mice in the sham group underwent only laminectomy at T9,while those in the SCI and SK groups were subjected to spinal cord contusion injury at T9.Behavioral tests were conducted at different time points after surgery to evaluate the motor functions of mice in each group.The pathological changes in the tissue were observed to assess the extent of SCI in each group.The role and mechanism of SK in SCI were predicted by gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses.Reverse transcription real-time fluorescence quantitative PCR,ELISA,and immunofluorescence were employed to evaluate the inflammation and activation of microglia in SCI mice.BV2 cells in vitro were classified into control (Con),lipopolysaccharide (LPS),and LPS+SK groups.The effects of SK intervention on the release of inflammatory cytokines and the activation of BV2 cells were evaluated.Furthermore,the phosphatidylinositol-3-kinase(PI3K)/protein kinase B (AKT) signaling pathway activator insulin-like growth factor-1 (IGF-1) was used to treat the SK-induced BV2 cells in vitro (SK+IGF-1 group),and SK was used to treat the IGF-1-induced BV2 cells in vitro (IGF-1+SK group).Western blotting was conducted for molecular mechanism validation. Results Behavioral tests and histological staining results showed that compared with the SCI group,the SK group exhibited improved motor abilities and reduced area of damage in the spinal cord tissue (all P<0.001).The GO enrichment analysis predicted that SK may be involved in the inflammation following SCI.The KEGG enrichment analysis predicted that SK regulated the PI3K/Akt pathway to exert the neuroprotective effect.The results from in vitro and in vivo experiments showed that SK lowered the levels of tumor necrosis factor-α,interleukin-6,and interleukin-1β and inhibited the activation of microglia (all P<0.05).The results of Western blotting showed that SK down-regulated the phosphorylation levels of PI3K and Akt (all P<0.001) and inhibited the IGF-1-induced elevation of PI3K and Akt phosphorylation levels (all P<0.001).Conversely,IGF-1 had the opposite effects (P=0.001,P<0.001).The results of reverse transcription real-time fluorescence quantitative PCR,ELISA,and immunofluorescence showed that the SK+IGF-1 group had higher levels of inflammatory cytokines and more activated microglia than the SK group(all P<0.05). Conclusion SK may suppress the activation of the PI3K/Akt pathway to inhibit the inflammation mediated by SCI-induced activation of microglia,ameliorate the pathological damage of the spinal cord tissue,and promote the recovery of motor functions in SCI mice.
Animals ; Spinal Cord Injuries/pathology* ; Mice ; Microglia/metabolism* ; Mice, Inbred C57BL ; Neuroinflammatory Diseases/pathology* ; Signal Transduction/drug effects* ; Phosphatidylinositol 3-Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Male ; Inflammation ; Lipopolysaccharides ; Insulin-Like Growth Factor I/metabolism* ; Disease Models, Animal

Recent studies have shown that the chemokine receptor CXCR3 and its ligand CXCL10 in the dorsal root ganglion mediate itch in experimental allergic contact dermatitis (ACD). CXCR3 in the spinal cord also contributes to the maintenance of neuropathic pain. However, whether spinal CXCR3 is involved in acute or chronic itch remains unclear. Here, we report that Cxcr3 mice showed normal scratching in acute itch models but reduced scratching in chronic itch models of dry skin and ACD. In contrast, both formalin-induced acute pain and complete Freund's adjuvant-induced chronic inflammatory pain were reduced in Cxcr3 mice. In addition, the expression of CXCR3 and CXCL10 was increased in the spinal cord in the dry skin model induced by acetone and diethyl ether followed by water (AEW). Intrathecal injection of a CXCR3 antagonist alleviated AEW-induced itch. Furthermore, touch-elicited itch (alloknesis) after compound 48/80 or AEW treatment was suppressed in Cxcr3 mice. Finally, AEW-induced astrocyte activation was inhibited in Cxcr3 mice. Taken together, these data suggest that spinal CXCR3 mediates chronic itch and alloknesis, and targeting CXCR3 may provide effective treatment for chronic pruritus.
Acetamides ; therapeutic use ; Animals ; Chemokine CXCL10 ; metabolism ; Chloroquine ; toxicity ; Chronic Disease ; Cyclopropanes ; adverse effects ; Dehydration ; complications ; Dinitrofluorobenzene ; adverse effects ; Disease Models, Animal ; Formaldehyde ; toxicity ; Freund's Adjuvant ; toxicity ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Motor Activity ; drug effects ; Pain ; chemically induced ; Pruritus ; chemically induced ; pathology ; Pyrimidines ; therapeutic use ; Receptors, CXCR3 ; antagonists & inhibitors ; genetics ; metabolism ; Skin ; pathology ; Spinal Cord ; drug effects ; metabolism ; pathology ; Time Factors ; p-Methoxy-N-methylphenethylamine ; toxicity

Peripheral itch stimuli are transmitted by sensory neurons to the spinal cord dorsal horn, which then transmits the information to the brain. The molecular and cellular mechanisms within the dorsal horn for itch transmission have only been investigated and identified during the past ten years. This review covers the progress that has been made in identifying the peptide families in sensory neurons and the receptor families in dorsal horn neurons as putative itch transmitters, with a focus on gastrin-releasing peptide (GRP)-GRP receptor signaling. Also discussed are the signaling mechanisms, including opioids, by which various types of itch are transmitted and modulated, as well as the many conflicting results arising from recent studies.
Action Potentials ; drug effects ; Analgesics, Opioid ; pharmacology ; Animals ; Humans ; Pruritus ; metabolism ; pathology ; Sensory Receptor Cells ; metabolism ; Spinal Cord ; pathology ; Synaptic Transmission ; physiology