Electroacupuncture inhibits dendritic spine remodeling through the srGAP3-Rac1 signaling pathway in rats with SNL.

Previous studies have shown that peripheral nerve injury can lead to abnormal dendritic spine remodeling in spinal dorsal horn neurons. Inhibition of abnormal dendritic spine remodeling can relieve neuropathic pain. Electroacupuncture (EA) has a beneficial effect on the treatment of neuropathic pain, but the specific mechanism remains unclear. Evidence has shown that slit-robo GTPase activating protein 3 (srGAP3) and Rho GTPase (Rac1) play very important roles in dendritic spine remodeling. Here, we used srGAP3 siRNA and Rac1 activator CN04 to confirm the relationship between SrGAP3 and Rac1 and their roles in improving neuropathic pain with EA. Spinal nerve ligation (SNL) was used as the experimental model, and thermal withdrawal latency (TWL), mechanical withdrawal threshold (MWT), Western blotting, immunohistochemistry and Golgi-Cox staining were used to examine changes in behavioral performance, protein expression and dendritic spines. More dendritic spines and higher expression levels of srGAP3 were found in the initial phase of neuropathic pain. During the maintenance phase, dendritic spines were more mature, which was consistent with lower expression levels of srGAP3 and higher expression levels of Rac1-GTP. EA during the maintenance phase reduced the density and maturity of dendritic spines of rats with SNL, increased the levels of srGAP3 and reduced the levels of Rac1-GTP, while srGAP3 siRNA and CN04 reversed the therapeutic effects of EA. These results suggest that dendritic spines have different manifestations in different stages of neuropathic pain and that EA may inhibit the abnormal dendritic spine remodeling by regulating the srGAP3/Rac1 signaling pathway to alleviate neuropathic pain.

Electroacupuncture may alleviate neuropathic pain via suppressing P2X7R expression.

Neuropathic pain is a severe problem that is difficult to treat clinically. Reducing abnormal remodeling of dendritic spines/synapses and increasing the anti-inflammatory effects in the spinal cord dorsal horn are potential methods to treat this disease. Previous studies have reported that electroacupuncture (EA) could increase the pain threshold after peripheral nerve injury. However, the underlying mechanism is unclear. P2X7 receptors (P2X7R) mediate the activation of microglia and participate in the occurrence and development of neuropathic pain. We hypothesized that the effects of EA on relieving pain may be related to the downregulation of the P2X7R. Spinal nerve ligation (SNL) rats were used as a model in this experiment, and 2'(3')-O-(4-benzoyl)benzoyl ATP (BzATP) was used as a P2X7R agonist. We found that EA treatment decreased dendritic spine density, inhibited synaptic reconstruction and reduced inflammatory response, which is consistent with the decrease in P2X7R expression as well as the improved neurobehavioral performance. In contrast to the beneficial effects of EA, BzATP enhanced abnormal remodeling of dendritic spines/synapses and inflammation. Furthermore, the EA-mediated positive effects were reversed by BzATP, which is consistent with the increased P2X7R expression. These findings indicated that EA improves neuropathic pain by reducing abnormal dendritic spine/synaptic reconstruction and inflammation via suppressing P2X7R expression.

Spatiotemporal multi-omics: exploring molecular landscapes in aging and regenerative medicine.

Aging and regeneration represent complex biological phenomena that have long captivated the scientific community. To fully comprehend these processes, it is essential to investigate molecular dynamics through a lens that encompasses both spatial and temporal dimensions. Conventional omics methodologies, such as genomics and transcriptomics, have been instrumental in identifying critical molecular facets of aging and regeneration. However, these methods are somewhat limited, constrained by their spatial resolution and their lack of capacity to dynamically represent tissue alterations. The advent of emerging spatiotemporal multi-omics approaches, encompassing transcriptomics, proteomics, metabolomics, and epigenomics, furnishes comprehensive insights into these intricate molecular dynamics. These sophisticated techniques facilitate accurate delineation of molecular patterns across an array of cells, tissues, and organs, thereby offering an in-depth understanding of the fundamental mechanisms at play. This review meticulously examines the significance of spatiotemporal multi-omics in the realms of aging and regeneration research. It underscores how these methodologies augment our comprehension of molecular dynamics, cellular interactions, and signaling pathways. Initially, the review delineates the foundational principles underpinning these methods, followed by an evaluation of their recent applications within the field. The review ultimately concludes by addressing the prevailing challenges and projecting future advancements in the field. Indubitably, spatiotemporal multi-omics are instrumental in deciphering the complexities inherent in aging and regeneration, thus charting a course toward potential therapeutic innovations.

Electroacupuncture alleviates neuropathic pain caused by SNL by promoting M2 microglia polarization through PD-L1.

As a common clinical disease, neuropathic pain is difficult to be cured with drugs. The occurrence and progression of pain is closely related to the response of spinal microglia. Aspartof the regulation of microglialactivity,PD-L1 playsacriticalrole. Loss of PD-L1 promoted the polarization of M1-like microglia. Increased expression of PD-L1 promoted M2-like polarization. Electroacupuncture has a significant analgesic effect in clinical practice, but its specific mechanism remains to be further explored. In this study, we verified the role of PD-L1 in EA analgesia and the underlying molecular mechanism through spinal nerve ligation (SNL) in rats and lipopolysaccharide (LPS)-treated BV2 microglial cells. Forbehavioralstudiesofrats,mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured, and spinal cord neuros were examined under transmission electron microscopyto determine changes to their myelin structure. The expression levels of PD-L1 and M1/M2-specific markers in rat spinal cord and BV2 microglial cells were measured by enzyme-linked immunosorbent assay, flow cytometry, immunofluorescence staining and Western blot analysis. Our study showed that EA increased the pain threshold, reduced the destruction of myelin structure, promoted the expression of PD-L1 and PD-1, inhibited the MAPK signaling pathway, and promoted the conversion of microglial polarization from the M1 phenotype to the M2 phenotype in SNL rats. PD-L1 knockdown reversed these effects of EA. In addition, PD-L1 knockdown activated the MAPK signaling pathway, promoted microglial polarization to the M1 phenotype, decreased the expression of anti-inflammatory mediators and increased the expression of proinflammatory factors in LPS-stimulated BV2 microglial cells. Our results showed that EA may regulate the excitability of primary afferent neurons through PD-L1 and then inhibit the MAPK signaling pathway to promote the transformation of activated M1 microglia into M2 microglia, reduce inflammatory reactions, and finally achieve analgesic effects. A therapy targeting PD-L1 may be an effective strategy for treating neuropathic pain.

Electroacupuncture suppresses spinal nerve ligation-induced neuropathic pain via regulation of synaptic plasticity through upregulation of basic fibroblast growth factor expression.

BACKGROUND: Improving synaptic plasticity is a good way to alleviate neuropathic pain. Electroacupuncture (EA) is currently used worldwide to treat this disease, but its specific mechanisms of action need further investigation. Evidence has suggested that basic fibroblast growth factor (bFGF) plays an important role in promoting nerve regeneration and can promote the expression of vascular endothelial growth factor (VEGF). OBJECTIVE: In this study, we examined the effects of EA on synaptic plasticity and its underlying mechanism. METHODS: A spinal nerve ligation (SNL) rat model was established. NSC37204 (a specific inhibitor of bFGF) was used to determine the relationship between bFGF and putative EA-mediated improvements in synaptic plasticity. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were assessed to evaluate hyperalgesia in rats with SNL. Tissue morphology was detected by hematoxylin-eosin (HE) and Nissl staining, while neural plasticity and its molecular mechanisms were examined by Western blotting, quantitative real-time polymerase chain reaction (qPCR), dual-label immunohistochemistry and transmission electron microscopy. RESULTS: We found that EA improved synaptic plasticity, consistent with higher levels of expression of bFGF and VEGF. Contrary to the beneficial effects of EA, NSC37204 promoted synaptic reconstruction. Furthermore, EA-induced improvements in the neurobehavioral state and improved synaptic plasticity were blocked by NSC37204, consistent with lower expression levels of bFGF and VEGF. CONCLUSION: These findings indicate that EA suppresses SNL-induced neuropathic pain by improving synaptic plasticity via upregulation of bFGF expression.

Water Treadmill Training Ameliorates Neurite Outgrowth Inhibition Associated with NGR/RhoA/ROCK by Inhibiting Astrocyte Activation following Spinal Cord Injury.

Spinal cord injury (SCI) often results in damage to or degeneration of axons. Crosstalk between astrocytes and neurons plays a pivotal role in neurite outgrowth following SCI. Rehabilitative training is a recognized method for the treatment of SCI, but the specific mechanism underlying its effect on axonal outgrowth in the central nervous system (CNS) has not yet been determined. A total of 190 adult male SD rats weighing 200-250 g were randomly divided into eight groups for use as animal models of SCI. Rats were subjected to water treadmill training (TT) for 7 or 14 d. The Basso-Beattie-Bresnahan (BBB) motor function scale, hematoxylin-eosin (HE) staining, Nissl staining, Western blotting, and immunofluorescence were used to measure tissue morphology and the degree of neurological deficit and to determine quantitative expression and accurate localization of the corresponding proteins. We found that TT decreased tissue structure damage and improved functional recovery. TT also promoted the regeneration of neurons and reduced SCI-induced apoptosis SCI around the lesion, as well as significantly increasing the expression of GAP43 and NF200 after SCI. In addition, TT significantly inhibited the injury-induced increase in the expression of proinflammatory factors. Moreover, TT reduced the activation of astrocytes and microglia, accompanied by the reduced expression of C3d and increased expression of S100A10. Finally, TT effectively reduced the level of chondroitin sulfate proteoglycan (CSPG) surrounding the lesion and inhibited the NGR/RhoA/ROCK signaling pathway in neurons after SCI. Overall, we found that TT played a novel role in recovery from SCI by promoting axonal outgrowth associated with NGR/RhoA/ROCK signaling by inhibiting astrocyte activation after SCI.

Electroacupuncture pre-treatment alleviates sepsis-induced cardiac inflammation and dysfunction by inhibiting the calpain-2/STAT3 pathway.

Electroacupuncture (EA) has both anti-inflammatory and cardio-protective effects. Activation of calpain pathway is involved in several myocardiopathy. In sepsis, the role of calpain-2-regulated STAT3 in cardio-protective mechanism of electroacupuncture remains unclear. In this study, we aimed to elucidate the mechanism by which electroacupuncture reduces cardiac inflammation and apoptosis and improves cardiac function during sepsis. Electroacupuncture pretreatment for 7 days was applied in septic cardiomyopathy model induced by lipopolysaccharide (LPS). lipopolysaccharide-induced sepsis was associated with a dramatically systemic inflammation and cardiac dysfunction, which was alleviated by electroacupuncture pre-treatment. Lipopolysaccharide resulted in increases of pro-inflammatory factors (TNF-α,IL1ßand IL-6) and apoptosis (TUNEL staining and BAX/Bcl2) via activation of calpain-2/STAT3 pathway.Electroacupuncture pre-treatment inhibited LPS-induced activation of cardiac calpain-2/STAT3 signalling and ameliorated inflammatory and apoptosis. Additionally, inhibition of calpain-2 expression using the corresponding siRNA decreased the Phosphorylation of STAT3,pro-inflammatory factors and apoptosis in lipopolysaccharide- treated cardiomyocytes, confirming that calpain-2 activated p-STAT3 participate in septic cardiomyopathy. Furthermore, suppression of STAT3 by stattic enhanced anti-inflammatory and anti-apoptosis effects of electroacupuncture. These findings reveal mechanisms of electroacupuncture preconditioning protection against cardiac inflammation and apoptosis in sepsis mouse via calpain-2/STAT3 pathway and may provide novel targets for clinical treatments of the sepsis-induced cardiac dysfunction.

Water treadmill training protects the integrity of the blood-spinal cord barrier following SCI via the BDNF/TrkB-CREB signalling pathway.

Following spinal cord injury (SCI), destruction of the blood-spinal cord barrier (BSCB) leads to increased microvascular permeability and tissue oedema. The BSCB, formed by a dense network of tight junctions (TJs) and adhesion junctions (AJs) is considered a therapeutic target. Most studies have focused on the effect of drug therapy on the neurovascular system after SCI, ignoring the protection and functional recovery of the vascular system by exercise training. Previously, we indicated that water treadmill training (TT) has a protective effect on the BSCB after SCI, but the specific molecular mechanism of the effect of TT on BSCB is still not clear. In this study, we used a specific inhibitor of TrkB (ANA-12) to explore whether the BDNF/TrkB-CREB signalling pathway is involved in TT-mediated BSCB protection after SCI. A New York University (NYU) impactor was used to establish the SCI model. Rats in the SI (Sham + ANA-12), IM (SCI + ANA-12) and ITM (SCI + TT + ANA-12) groups were injected with ANA-12 (0.5 mg/kg) daily, and rats in TM (SCI + TT) and ITM (SCI + TT + ANA-12) groups were treated with water TT for 7 or 14 d. The degree of neurological deficit, water content, BSCB permeability, protein expression and ultrastructure of vascular endothelial cells were assessed by the Basso-Beattie-Bresnahan (BBB) motor rating scale, Evans blue (EB), Western blot (WB) experiments, immunofluorescence and transmission electron microscopy (TEM). Our results suggest that TT upregulates the BDNF/TrkB-CREB signalling pathway following SCI. The BDNF/TrkB-CREB signalling pathway is involved in the protection of the BSCB. Application of the inhibitor blocked the protective effect of TT on the BSCB. We concluded that TT ameliorated SCI-induced BSCB impairment by upregulating the BDNF/TrkB-CREB signalling pathways.

Electroacupuncture improves neuronal plasticity through the A2AR/cAMP/PKA signaling pathway in SNL rats.

Improvements in neuronal plasticity are considered to be conducive to recovery from neuropathic pain. Electroacupuncture (EA) is regarded as an effective rehabilitation method for neuropathic pain. However, the effects and potential mechanism associated with EA-induced repair of hyperesthesia are not fully understood. Evidence has suggested that the adenosine A2A receptor (A2AR) and the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway play an important role in improving neuropathic pain. Here, we examined the function of EA in promoting neuronal plasticity in spinal nerve ligation (SNL) rats. The A2AR antagonist SCH58261, A2AR agonist 2-p-(2-carboxyethyl)phenethylamino-50-N-ethylcarboxamido adenosine HCl (CGS21680) and A2AR siRNA were used to confirm the relationship between A2AR and the cAMP/PKA pathway as well as the effects of A2AR on EA-induced improvements in neurobehavioral state and neuronal plasticity. Mechanical withdrawal threshold (MWT), thermal withdrawal latency (TWL), HE staining, Western blotting, RT-PCR, immunofluorescence, enzyme-linked immunosorbent assay, Nissl staining, silver staining, Golgi-Cox staining and transmission electron microscopy were used to evaluate the changes in neurobehavioral performance, protein expression, neuronal structure and dendrites/synapses. The results showed that EA and CGS21680 improved the behavioral performance, neuronal structure and dendritic/synaptic morphology of SNL rats, consistent with higher expression levels of A2AR, cAMP and PKA. In contrast to the positive effects of EA, SCH58261 inhibited dendritic growth and promoted dendritic spine/synaptic remodeling. In addition, the EA-induced improvement in neuronal plasticity was inhibited by SCH58261 and A2AR siRNA, consistent with lower expression levels of A2AR, cAMP and PKA, and worse behavioral performance. These results indicate that EA suppresses SNL-induced neuropathic pain by improving neuronal plasticity via upregulating the A2AR/cAMP/PKA signaling pathway.

Electroacupuncture effects on the P2X4R pathway in microglia regulating the excitability of neurons in the substantia gelatinosa region of rats with spinal nerve ligation.

Electroacupuncture (EA) has been used to treat neuropathic pain induced by peripheral nerve injury (PNI) by applying an electrical current to acupoints with acupuncture needles. However, the mechanisms by which EA treats pain remain indistinct. High P2X4 receptor (P2X4R) expression levels demonstrate a notable increase in hyperactive microglia in the ipsilateral spinal dorsal horn following PNI. In order to demonstrate the possibility that EA analgesia is mediated in part by P2X4R in hyperactive microglia, the present study performed mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests in male Sprague­Dawley rats that had undergone spinal nerve ligation (SNL). The expression levels of spinal P2X4R were determined using reverse transcription­quantitative PCR, western blotting analysis and immunofluorescence staining. Furthermore, spontaneous excitatory postsynaptic currents (sEPSCs) were recorded using whole­cell patch clamp to demonstrate the effect of EA on synaptic transmission in rat spinal substantia gelatinosa (SG) neurons. The results of the present study demonstrated that EA increased the MWT and TWL and decreased overexpression of P2X4R in hyperactive microglia in SNL rats. Moreover, EA attenuated the frequency of sEPSCs in SG neurons in SNL rats. The results of the present study indicate that EA may mediate P2X4R in hyperactive spinal microglia to inhibit nociceptive transmission of SG neurons, thus relieving pain in SNL rats.

Water treadmill training attenuates blood-spinal cord barrier disruption in rats by promoting angiogenesis and inhibiting matrix metalloproteinase-2/9 expression following spinal cord injury.

BACKGROUND: The permeability of the blood-spinal cord barrier (BSCB) is mainly determined by junction complexes between adjacent endothelial cells (ECs), including tight junctions (TJs) and adherens junctions (AJs), which can be severely damaged after spinal cord injury (SCI). Exercise training is a recognized method for the treatment of SCI. The destruction of the BSCB mediated by matrix metalloproteinases (MMPs) leads to inflammation, neurotoxin production, and neuronal apoptosis. The failure of new blood vessels to effectively regenerate is also an important cause of delayed recovery after SCI. For the first time, we introduced water treadmill training (TT) to help SCI rats successfully exercise and measured the effects of TT in promoting recovery after SCI and the possible mechanisms involved. METHODS: Sprague-Dawley (200-250 g) rats were randomly divided into the following three groups: sham operated, SCI, and SCI + TT. Animals were sacrificed at 7 or 14 days post-surgery. The degree of neurological deficit, tissue morphology and BSCB permeability were assessed by the Basso-Beattie-Bresnahan (BBB) motor function scale and appropriate staining protocols, and apoptosis, protein expression and vascular EC ultrastructure were assessed by TUNEL staining, Western blotting, immunofluorescence and transmission electron microscopy (TEM). RESULTS: Our experiments showed that TT reduced permeability of the BSCB and decreased structural tissue damage. TT significantly improved functional recovery when compared with that in the SCI group; TJ and AJ proteins expression increased significantly after TT, and training reduced apoptosis induced by SCI. TT could promote angiogenesis, and MMP-2 and MMP-9 expression was significantly inhibited by TT. CONCLUSIONS: The results of this study indicate that TT promotes functional recovery for the following reasons: TT (1) protects residual BSCB structure from further damage, (2) promotes vascular regeneration, and (3) inhibits MMP-2/9 expression to mitigate BSCB damage.

Effects of electroacupuncture at different acupoints on the histomorphology of neurogenic bladder and the expression of hyperpolarization-activated cyclic nucleotide-gated channels in interstitial cells of Cajal in a rat model of suprasacral spinal cord injury.

BACKGROUND: To investigate the effects of electroacupuncture at different acupoints on the histomorphology of neurogenic bladder and the expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in interstitial cells of Cajal (ICC) in a rat model of suprasacral spinal cord injury (SCI). METHODS: A incomplete suprasacral SCI rat model was induced using a MASCIS impactor. Rats were randomly divided into a sham operation group, SCI model group, Ciliao treatment group or Guanyuan treatment group. The histomorphology of bladder cells was observed after hematoxylin and eosin (H&E) staining of bladder tissue sections. The expression of HCN channel proteins in ICC cells was detected by western blot and immunofluorescence, and HCN channel mRNA expression was measured using real-time PCR. RESULTS: In terms of histomorphology, the level of bladder cells after SCI increased significantly, and marked inflammation and edema were observed. Electroacupuncture treatment at the Ciliao acupoint significantly reduced inflammation and edema, whilst electroacupuncture treatment at the Guanyuan point partially reduced inflammation and edema. In terms of HCN channel protein and mRNA expression, western blotting, immunofluorescence and real-time PCR all confirmed that HCN channel expression after SCI was significantly upregulated, while electroacupuncture treatment at the Ciliao and Guanyuan acupoints inhibited HCN channel expression. CONCLUSIONS: Electroacupuncture treatment at the Ciliao acupoint significantly reduced histomorphological abnormalities in ICCs, and inhibited the expression of HCN channel proteins after SCI.

Acupoint application inhibits nerve growth factor and attenuates allergic inflammation in allergic rhinitis model rats.

BACKGROUND: Acupoint application therapy (AAT) has been widely used to treat allergic inflammation induced by allergic rhinitis (AR). The therapeutic effect of acupoint application is obvious. But the underlying therapeutic mechanism is still indistinct. Nerve growth factor (NGF) expression showed a dramatic rise in nasal mucosa tissue after AR, and allergic inflammation also increased significantly. To demonstrate how AAT can improve allergic inflammation by down-regulating the expression of NGF, AR rat models were established by intraperitoneal injection of ovalbumin (OVA) and nasal drops in SD rats. The number of nasal rubbing, sneezing and the degree of runny nose were observed and the symptoms were scored by behavioral symptom scoring method within 3 min. The expression levels of NGF and its downstream key proteins, such as IL-4, IL-5, IL-13, IgE and IFN-γ were determined by q-PCR, Western blot analysis, ELISA and immunofluorescence staining. Furthermore, H&E staining and toluidine blue staining were used to observe the pathological structure of nasal mucosa and mast cells in nasal mucosa, and the ultrastructure of nasal mucosa was observed by electron microscopy. RESULTS: Our data demonstrated that acupoint application significantly reduced the score of behavioral symptoms, and decreased the expression levels of NGF and its downstream key proteins, including IL-4, IL-5, IL-13, IgE, as well as promoting the expression level of IFN-γ in nasal mucosa tissue in AR rats. Thus, the activation of IgE and viability of mast cells was inhibited. CONCLUSION: Our findings suggest that AAT can attenuate allergic inflammation by inhibiting the expression of NGF and its downstream pathway.

Effect of electroacupuncture on the expression of P2 × 4, GABAA γ 2 and long-term potentiation in spinal cord of rats with neuropathic pain.

OBJECTIVE: To observe the impacts of electroacupuncture (EA) stimulation at "Zusanli and Kunlun Points" on spinal dorsal horn microglia activation in L5 spinal nerve ligation (SNL) rats and BNDF, P2 × 4 and GABAAγ2, and the changes in spinal dorsal horn synaptic plasticity in model rats. METHODS: Adult male SD rats (180-220 g) were selected and randomly divided into 6 groups, including the sham group, the SNL group, the SNL + EA group, the SNL+5-BDBD group, the SNL + EA + 5-BDBD group and the SNL + FEA group. The changes in the Iba-1, BDNF, P2 × 4 and GABAAγ2 in the spinal cord of rats were observed by Western blotting, immunofluorescence, RT-PCR and other techniques; the long-term changes in the potential after the excitatory synapse of the spinal dorsal horn in rats were observed by in vivo electrophysiological technique. RESULTS: After 7 days of intervention, the fluorescence intensity (FI) of P2 × 4 and Iba-1 in the SNL + EA group was lower than that in the SNL group and higher than that in the sham group(P < 0.01), but the FI of GABAAγ2 was higher than that in the SNL group(P < 0.01); the expression of Iba-1, BDNF and P2 × 4 proteins in the SNL + EA group, the SNL+5-BDBD group and the SNL + EA + 5-BDBD group was significantly lower than that in the SNL + FEA group(P < 0.05), but the expression of GABAAγ2 protein was higher (P < 0.05); after treatment with EA, the expression levels of Iba-1 mRNA and P2 × 4 mRNA in the SNL + EA group were lower than those in the SNL group(P < 0.01), but the expression levels of GABAAγ2 mRNA were higher (P < 0.01). Meanwhile, long-term potentiation changes could not be induced in the SNL + EA group. CONCLUSION: The EA stimulation at "Zusanli" and "Kunlun" points can improve the pain threshold of rats with neuropathic pain (NP), inhibit the excitatory postsynaptic potential (EPSP), and weaken the excitatory transmission efficiency between synapses during NP.

Hyperbaric oxygen therapy reduces apoptosis and dendritic/synaptic degeneration via the BDNF/TrkB signaling pathways in SCI rats.

Spinal cord injury (SCI) is a serious neurological disease without efficacious drugs. Anti-apoptosis and suppressing dendritic/synaptic degeneration in the anterior horn are essential targets after SCI. Previous studies found that hyperbaric oxygen therapy (HBOT) significantly protected rats after SCI. However, its potential effects and mechanisms remain unknown. The BDNF/TrkB signaling pathways evidently contribute to the SCI recovery. Currently, we mainly investigate the potential effects and mechanism of HBOT on anti-apoptosis and ameliorating impaired dendrites, dendritic spines and synapses after SCI. Establish SCI model and randomly divide rats into 5 groups. After SCI, rats were subjected to HBOT. ANA-12 is the specific inhibitor of BDNF/TrkB signal pathway. Changes in neurological deficit, neuronal morphology, apoptosis, protein expression and dendrite/synapse were examined by Basso-Beattie-Bresnahan (BBB) locomotor rating scale, Hematoxylin-eosin (HE) and Nissl staining, TUNEL staining, RT-PCR, Western blot, immunofluorescence and Golgi-Cox staining. We found HBOT suppressed dendritic/synaptic degeneration and alleviated apoptosis, consistent with the increase of BDNF and TrkB expression and improved neurological recovery. In contrast to the positive effects of HBOT, inhibitor increased degeneration and apoptosis. Moreover, we observed that these HBOT-mediated protective effects were significantly inhibited by inhibitor, consistent with the lower expression of BDNF/TrkB and worse neurobehavioral state. These findings suggest that hyperbaric oxygen therapy ameliorates spinal cord injury-induced neurological impairment by anti-apoptosis and suppressing dendritic/synaptic degeneration via upregulating the BDNF/TrkB signaling pathways.

Electroacupuncture inhibits dendritic spine remodeling through the srGAP3-Rac1 signaling pathway in rats with SNL

Previous studies have shown that peripheral nerve injury can lead to abnormal dendritic spine remodeling in spinal dorsal horn neurons. Inhibition of abnormal dendritic spine remodeling can relieve neuropathic pain. Electroacupuncture (EA) has a beneficial effect on the treatment of neuropathic pain, but the specific mechanism remains unclear. Evidence has shown that slit-robo GTPase activating protein 3 (srGAP3) and Rho GTPase (Rac1) play very important roles in dendritic spine remodeling. Here, we used srGAP3 siRNA and Rac1 activator CN04 to confirm the relationship between SrGAP3 and Rac1 and their roles in improving neuropathic pain with EA. Spinal nerve ligation (SNL) was used as the experimental model, and thermal withdrawal latency (TWL), mechanical withdrawal threshold (MWT), Western blotting, immunohistochemistry and Golgi-Cox staining were used to examine changes in behavioral performance, protein expression and dendritic spines. More dendritic spines and higher expression levels of srGAP3 were found in the initial phase of neuropathic pain. During the maintenance phase, dendritic spines were more mature, which was consistent with lower expression levels of srGAP3 and higher expression levels of Rac1-GTP. EA during the maintenance phase reduced the density and maturity of dendritic spines of rats with SNL, increased the levels of srGAP3 and reduced the levels of Rac1-GTP, while srGAP3 siRNA and CN04 reversed the therapeutic effects of EA. These results suggest that dendritic spines have different manifestations in different stages of neuropathic pain and that EA may inhibit the abnormal dendritic spine remodeling by regulating the srGAP3/Rac1 signaling pathway to alleviate neuropathic pain.