Traumatic Spinal Cord Injury In Rats Research Articles

Hydrogen Sulfide Improves Functional Recovery in Rat Traumatic Spinal Cord Injury Model by Inducing Nuclear Translocation of NF-E2-Related Factor 2.

Hydrogen sulfide (H2S), an important gaseous messenger, is known to have neuroprotective effects in many neurological disorders. This study examined the neuroprotective effects and the associated mechanisms of H2S in the model Sprague-Dawley (SD) rats with spinal cord injury (SCI). We found that H2S showed neuroprotective effects in SCI model rats, improved the symptoms of neurological impairment, reduced the secretion of inflammatory factors, nerve cell apoptosis, and endoplasmic reticulum (ER), and oxidative stresses. Moreover, these effects were produced by activation of nuclear factor-erythroid 2-related factor 2 (Nrf2) protein. Our results suggest that H2S supplementation could be a potential therapeutic strategy to promote SCI recovery.

Tetrahydropalmatine reduces cell death and improves functional recovery after traumatic spinal cord injury in ratsTetrahydropalmatine reduces cell death and improves functional recovery after traumatic spinal cord injury in rats

Purpose: To investigate the effectiveness of tetrahydropalmatine (THP) in the treatment of spinal cord injury (SCI) in rats.
 Methods: Adult Sprague Dawley rats were divided into 3 groups: normal control group, SCI group, and SCI group treated with THP (100 mg kg-1). The effect of THP on spinal cord water content, levels of inflammatory mediators, oxidative stress and apoptosis were determined. Locomotor activity in rats was measured using Basso, Beattie and Bresnahan (BBB) scores. Various oxidative stress markers as well as cytokine levels (NF-ĸB, IL-6, IL-1β and TNF-α were determined. Apoptotic index was measured using TUNEL assay.
 Results: After 72 h of treatment with THP, BBB scores in SCI group of rats significantly increased from 4.19 ± 0.41 to 8.89 ± 0.47 (p < 0.05). Tunel assay revealed a higher apoptotic index (42.50 ± 3.19) in the tissues of SCI rats than in SCI rats treated with THP (31.48 ± 1.19, p < 0.01). Expressions of inflammatory cytokines were significantly upregulated in SCI rats. However, THP administration resulted in significant downregulation of the expressions (p < 0.01).
 Conclusion: These results indicate that THP attenuates traumatic SCI in rats via modulation of the levels of anti-inflammatory mediators. Thus, THP has a promising potential for the management of SCI.

Inhibition of leucine-rich repeats and calponin homology domain containing 1 accelerates microglia-mediated neuroinflammation in a rat traumatic spinal cord injury model

BackgroundSpinal cord injury (SCI) triggers the primary mechanical injury and secondary inflammation-mediated injury. Neuroinflammation-mediated insult causes secondary and extensive neurological damage after SCI. Microglia play a pivotal role in the initiation and progression of post-SCI neuroinflammation.MethodsTo elucidate the significance of LRCH1 to microglial functions, we applied lentivirus-induced LRCH1 knockdown in primary microglia culture and tested the role of LRCH1 in microglia-mediated inflammatory reaction both in vitro and in a rat SCI model.ResultsWe found that LRCH1 was downregulated in microglia after traumatic SCI. LRCH1 knockdown increased the production of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6 after in vitro priming with lipopolysaccharide and adenosine triphosphate. Furthermore, LRCH1 knockdown promoted the priming-induced microglial polarization towards the pro-inflammatory inducible nitric oxide synthase (iNOS)-expressing microglia. LRCH1 knockdown also enhanced microglia-mediated N27 neuron death after priming. Further analysis revealed that LRCH1 knockdown increased priming-induced activation of p38 mitogen-activated protein kinase (MAPK) and Erk1/2 signaling, which are crucial to the inflammatory response of microglia. When LRCH1-knockdown microglia were adoptively injected into rat spinal cords, they enhanced post-SCI production of pro-inflammatory cytokines, increased SCI-induced recruitment of leukocytes, aggravated SCI-induced tissue damage and neuronal death, and worsened the locomotor function.ConclusionOur study reveals for the first time that LRCH1 serves as a negative regulator of microglia-mediated neuroinflammation after SCI and provides clues for developing novel therapeutic approaches against SCI.

MAP‑1B, PACS‑2 and AHCYL1 are regulated by miR‑34A/B/C and miR‑449 in neuroplasticity following traumatic spinal cord injury in rats: Preliminary explorative results from microarray data.

Spinal cord injury (SCI) is a specific type of damage to the central nervous system causing temporary or permanent changes in its function. The present aimed to identify the genetic changes in neuroplasticity following SCI in rats. The GSE52763 microarray dataset, which included 15 samples [3 sham (1 week), 4 injury only (1 week), 4 injury only (3 weeks), 4 injury + treadmill (3 weeks)] was downloaded from the Gene Expression Omnibus database. An empirical Bayes linear regression model in limma package was used to identify the differentially expressed genes (DEGs) in injury vs. sham and treadmill vs. non-treadmill comparison groups. Subsequently, time series and enrichment analyses were performed using pheatmap and clusterProfile packages, respectively. Additionally, protein-protein interaction (PPI) and transcription factor (TF)-microRNA (miRNA)-target regulatory networks were constructed using Cytoscape software. In total, 159 and 105 DEGs were identified in injury vs. sham groups and treadmill vs. non-treadmill groups, respectively. There were 40 genes in cluster 1 that presented increased expression levels in the injury (1 week/3 weeks) groups compared with the sham group, and decreased expression levels in the injury + treadmill group compared with the injury only groups; conversely, 52 genes in cluster 2 exhibited decreased expression levels in the injury (1 week/3 weeks) groups compared with the sham group, and increased expression levels in the injury + treadmill group compared with the injury only groups. Enrichment analysis indicated that clusters 1 and 2 were associated with immune response and signal transduction, respectively. Furthermore, microtubule associated protein 1B, phosphofurin acidic cluster sorting protein 2 and adenosylhomocysteinase-like 1 exhibited the highest degrees in the regulatory network, and were regulated by miRNAs including miR-34A, miR-34B, miR-34C and miR-449. These miRNAs and their target genes may serve important roles in neuroplasticity following traumatic SCI in rats. Nevertheless, additional in-depth studies are required to confirm these data.

Differential Expression Profiles and Functional Predication of Circular Ribonucleic Acid in Traumatic Spinal Cord Injury of Rats.

Recent studies indicate that circular ribonucleic acids (circRNAs) are involved in a variety of human diseases. The roles of circRNAs in traumatic spinal cord injury (SCI) remain unknown, however. We performed RNA-seq to analyze the circRNA expression profile in rat spinal cord after SCI and to investigate the relevant mechanisms. In all, 150 circRNAs were significantly differentially expressed in rat spinal cord after SCI by a fold-change ≥2 and p value ≤0.05. Among these, 99 circRNAs were upregulated, while 51 were downregulated. Gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway analyses, and circRNA/miocroRNA (miRNA) interaction networks were conducted to predict the potential roles of circRNAs in the process of SCI. In addition, the expression levels of six selected circRNAs were verified successfully by quantitative real-time polymerase chain reaction. Further study identified circRNA_07079 and circRNA_01282 as being associated with SCI, and they may participate in the pathophysiology of SCI through circRNA-targeted miRNA-messenger RNA axis. In summary, the results of our study revealed the expression profiles and potential functions of differentially expressed circRNAs in traumatic SCI in rats; this may provide new clues for studying the mechanisms underlying SCI and also present novel molecular targets for clinical therapy of SCI.

Identification of crucial genes associated with rat traumatic spinal cord injury.

The aim of the present study was to investigate the key genes associated with traumatic spinal cord injuries (TSCI). The dataset GSE52763 was downloaded from the Gene Expression Omnibus, for which lumbar spinal cord samples were obtained from rats at 1 and 3 weeks following contusive spinal cord injury and 1 week subsequent to a sham laminectomy, and used to identify differentially expressed genes (DEGs). Functional enrichment analysis, co-expression analysis and transcription factor (TF) identification were performed for DEGs common to the 1 and 3 week injury samples. In total, 234 upregulated and 51 downregulated DEGs were common to the 1 and 3 week injury samples. The upregulated DEGs were significantly enriched in Gene Ontology terms concerning immunity (e.g. Itgal and Ccl2) and certain pathways, including natural killer cell mediated cytotoxicity [e.g. Ras-related C3 botulinum toxin substrate 2 (Rac2) and TYRO protein tyrosine kinase binding protein (Tyrobp)]. The downregulated DEGs were highly enriched in female gonad development [e.g. progesterone receptor (Pgr)], and the steroid biosynthesis pathway. A total of 139 genes had co-expression associations and the majority of them were upregulated genes. The upregulated co-expressed genes were predominantly enriched in biological regulation, including TGFB induced factor homeobox 1 (Tgif1) and Rac2. The downregulated co-expressed genes were enriched in anatomical structure development (e.g. Dnm3). A total of 92 co-expressed genes composed the protein-protein interaction network. Additionally, 9 TFs (e.g. Pgr and Tgif1) were identified from the DEGs. It was hypothesized that the genes including Tgif1, Rac2, Tyrobp, and Pgr may be closely associated with TSCI.

Protective effect of geraniol inhibits inflammatory response, oxidative stress and apoptosis in traumatic injury of the spinal cord through modulation of NF-κB and p38 MAPK.

Geraniol is a type of monoterpenoid with a rose scent and a slightly sweet flavor. It is found in the volatile oil of various plants, and has anti-inflammatory and anti-oxidant effects. The present study aimed to investigate the protective effect of geraniol in inhibiting the inflammatory response, oxidative stress and apoptosis in traumatic spinal cord injury (SCI), as well as to analyze the mechanism underlying its effect. Adult male Sprague-Dawley rats were induced to traumatic SCI through a surgical procedure and were defined as the SCI model group. SCI or normal rats were then administered 250 mg/kg/day geraniol for 4 weeks. The Basso, Beattie and Bresnahan (BBB) test and the spinal cord water content were used to analyze the effect of geraniol against traumatic SCI in rats. The inflammatory response, oxidative stress, and caspase-9 and -3 activities were measured using commercial ELISA kits. In addition, the associated mechanism was analyzed, using western blot analysis to determine the protein expression levels of nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). The results of the present study demonstrated that BBB scores were significantly increased and the spinal cord water content was significantly inhibited in SCI rats after 3 weeks of geraniol treatment. Furthermore, the inflammatory response, oxidative stress, and the caspase-9 and -3 activities were significantly suppressed upon treatment with geraniol. Finally, the mechanism of geraniol against traumatic SCI downregulated the NF-κB and p38 MAPK pathways in SCI rats. Therefore, the protective effect of geraniol is suggested to inhibit the inflammatory response, oxidative stress and apoptosis in traumatic SCI through the modulation of NF-κB and p38 MAPK.

Transplantation of cryopreserved rat fetal neural cells in suspension and in multicellular aggregates into rats with spinal cord injury

Today cell transplantation is one of the promising approaches of spinal cord injuries treatment. The aim of the work was to study the effect of cryopreserved fetal neural cell transplantation in suspensions and cell aggregates for motor activity recovery of rats with experimental spinal cord injury.Materials and methods. Cells were isolated from the brain tissue of rat fetuses 15-16 days of gestation. The formation of aggregates was performed during short-term cultivation at a concentration of 8·106cells/mL in medium with 10 % adult rat serum. Cell transplantation was performed into the damaged area of spinal cord in aggregates or suspension. To fix transplanted cells in the damaged area we used alginate gel.Results. Transplantation of cryopreserved fetal neural cells in alginate gel had the positive effect on dynamics of rats’ motor activity recovery. That was manifested in the extensive mobility of three joints of one limb and the limited mobility of two joints of the other with simultaneous recovery of the sensitivity of the hind limbs.Conclusion. Cryopreserved fetal neural cells aggregates had a high therapeutic potential on rat traumatic spinal cord injury compared with cell suspension by improving the structure of forming nervous tissue and significantly increasing the rate of hind limb function recovery.

Effect of adenovirus-mediated RNA interference of IL-1β expression on spinal cord injury in rats.

We introduced an adenoviral vector expressing interleukin-1β (IL-1β) small-hairpin RNA (shRNA) into the injured spinal cords to evaluate the therapeutic potential of IL-1β downregulation in a rat model of spinal cord injury (SCI). The purpose of this study was to investigate the possible protective effects of the IL-1β downregulation on traumatic SCI in rats. Department of Orthopedic Surgery, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, People's Republic of China. An adenoviral shRNA targeting IL-1β was constructed and injected at the T12 section 7 days before SCI. The rats' motor functions were evaluated by the Basso-Beattie-Bresnahan (BBB) rating scale. Immunofluorescence, enzyme-linked immunosorbent assay, flow-cytometric analysis and western blots were also performed. Animals downregulating IL-1β had significantly better recovery of locomotor function and less neuronal loss after SCI. In addition, IL-1β downregulation significantly decreased tumor necrosis factor-alpha (TNF-α) level and Bax expression, reduced the activity of caspase-3 and increased Bcl-2 expression after SCI. This study demonstrated that the IL-1β downregulation may have potential therapeutic benefits for both reducing secondary damages and improving the outcomes after traumatic SCI.

Lipopolysaccharide preconditioning attenuates neuroapoptosis and improves functional recovery through activation of Nrf2 in traumatic spinal cord injury rats

The previous studies suggested that low-dose lipopolysaccharide (LPS) provides neuroprotection against subsequent challenge with ischemic/reperfusion injury in the brain. But there were few reports about the neuroprotective effects of low-dose LPS against spinal cord injury (SCI). In this study, we evaluated the effect of low-dose LPS preconditioning on neuroapoptosis status after traumatic SCI (TSCI), using a standardized contusion model (NYU, New York University, impactor). SCI-induced rats were randomly divided into three groups: sham operation, control (receiving only normal saline) and LPS preconditioning (0.2 mg/kg, ip; 72 hours before injury). Neurologic function was assessed by the Basso, Beattie and Bresnahan (BBB) score at 6, 12, 24, 48 and 72 hours after TSCI. Rats were sacrificed at 72 hours postinjury. Histological changes were studied using Nissl staining. Apoptotic neural cells were assessed using the TdT-mediated dUTP Nick End Labeling (TUNEL) assay. Nuclear factor erythroid 2-related factor 2 (Nrf2) and caspase-3 were detected with immunohistochemistry and Western blot. LPS preconditioning reduced neuron apoptosis, improved neurologic outcome and actived Nrf2 expression. Moreover, Histological changes and the number of apoptotic cells were correlated with Nrf2 expression after the rats suffered the SCI. Our results suggest that LPS preconditioning exerted a neuroprotective effect against TSCI in rats, and activation of Nrf2 was believed to be one of the contributing mechanisms.

Peroxisome proliferator-activated receptor-γ agonist rosiglitazone reduces secondary damage in experimental spinal cord injury

To investigate the neuroprotective effects of rosiglitazone in a rat traumatic spinal cord injury (SCI) model. Adult Sprague-Dawley rats (n = 12/group) underwent laminectomy (sham), SCI, SCI and rosiglitazone treatment (2 mg/kg twice daily for 7 days), or SCI and saline injection (vehicle). SCI was induced via dural application of an aneurysm clip. Spinal cord apoptosis and levels of tumour necrosis factor-α (TNFα), interleukin (IL)-1β, myeloperoxidase (MPO) and the apoptosis-associated proteins B-cell leukaemia/lymphoma 2 (Bcl-2) and Bcl-2 associated X protein (Bax) were examined 24 h after SCI. Locomotor function was evaluated 3, 7, 10, 14 and 21 days after SCI. At 24 h after SCI, apoptosis and TNFα, IL-1β and MPO concentrations were significantly lower in the rosiglitazone group than in the vehicle and SCI groups. SCI resulted in an increase in Bax and a decrease in Bcl-2, which was reversed by rosiglitazone treatment. Rats in the rosiglitazone group had significantly better functional recovery than those in the vehicle and SCI groups. Rosiglitazone significantly improved functional recovery, probably via attenuation of the local inflammatory reaction and reduced apoptosis.

The Effect of Irradiation and Methylprednisolone in Spinal Cord Injured Rats

This study investigated the outcome of combined therapy with irradiation and methylprednisolone (MP) after a traumatic spinal cord injury (SCI). To evaluate the neurologic outcomes as well as the antiapoptotic and anti-inflammatory effects on traumatic SCI in rats after combined therapy. Although irradiation carries the risk of secondary SCI, it has been effective for the regeneration of the axons of nerve cells by reducing gliosis. Thus, to minimize apoptosis and irradiation risks after SCI, this study investigated the effects of steroid injections before irradiation. Thirty-two rats were used for the experimental procedure. After a traumatic SCI, they were divided into 4 groups of 8 rats each: (1) a control group that only had rats with a SCI (Group 1); (2) a group that received MP at 30 minutes, 6 hours and 24 hours, and then received irradiation 2 days after the SCI (Group 2); (3) a group that received MP at 30 minutes, and irradiation 2 days after the SCI (Group 3); and (4) a group that received irradiation 2 days after the traumatic SCI (Group 4). The degree of recovery using the inclined plane climbing test was greatest in Group 2, followed by Group 3, Group 4, and Group 1. The cavitation lesions, Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling -positive apoptosis, glial fibrillary acidic protein-positive astrocyte count, and CC-1-positive oligodendrocyte count significantly decreased in the irradiated groups (Groups 2, 3, 4) compared to the control group (Group 1). In particular, they decreased considerably more in the group that received MP 3 times (Group 2) compared to the group that received MP only once (Group 3). These results suggest that the combined therapy was effective and might provide synergistic effects for neurologic recovery after a traumatic SCI.

Spatiotemporal CCR1, CCL3(MIP-1α), CXCR4, CXCL12(SDF-1α) expression patterns in a rat spinal cord injury model of posttraumatic neuropathic pain

Central neuropathic pain is a frequent challenging complication after spinal cord injury (SCI), and specific therapeutic approaches remain elusive. The purpose of the present investigations was to identify potential key mediators of these pain syndromes by analyzing detailed expression profiles of important chemokines in an experimental SCI paradigm of posttraumatic neuropathic pain in rats. Expression of CCR1, CCL3(MIP-1α), CXCR4, and CXCL12(SDF-1α) was investigated in parallel with behavioral testing for mechanical and thermal nociceptive thresholds after standardized SCI; 100-kdyn (moderate injury) and 200-kdyn (severe injury) force-defined thoracic spinal cord contusion lesions were applied via an Infinite Horizon Impactor at the T-9 level. Sham controls received laminectomies. Hindlimb locomotor function as well as mechanical and thermal sensitivities were monitored weekly by standardized behavioral testing after SCI. Chemokine expression was analyzed by real-time reverse transcriptase polymerase chain reaction in the early (7 days postoperatively) and late (42 days postoperatively) time courses after SCI, and immunohistochemical analysis (anatomical and quantitative) was performed 2, 7, 14, and 42 days after lesioning. Double staining with cellular markers and pain-related peptides (substance P and CGRP) or receptors (TRPV-1, TRPV-2, VRL-1, and TLR-4) was performed. Based on data obtained from behavioral testing, quantified immunohistochemical chemokine expressions in individual animals were correlated with the respective mechanical and thermal sensitivity thresholds 6 weeks after SCI. After 200-kdyn lesions, the animals exhibited prolonged reduction in their nociceptive thresholds, while 100-kdyn groups showed pain-related behaviors only in the early time course after SCI. Investigated chemokines were widely induced after SCI, involving cervical, thoracic, and lumbar spinal cord levels far beyond the lesion core. CCR1 and CCL3 were induced significantly in the dorsal horns 2 days after lesioning and remained at high levels after SCI with significantly higher intensities after 200-kdyn than 100-kdyn contusions. CXCR4 and CXCL12 levels continuously increased from 2 to 42 days after moderate and severe lesions. Additionally, chemokines were induced significantly in dorsal columns, with highest density levels 42 days after 200-kdyn lesions. In dorsal horns, CCR1 was coexpressed with TRPV-1 while CXCR4 and CXCL12 were partially coexpressed with substance P and CGRP. In dorsal columns, CCL3/CCR1 colabeled with GFAP, TRPV-2, TRPV-1, TLR-4; CXCR4/CXCL12 coexpressed with GFAP, CD68/ED1, and TLR4. Chemokine immunoreactivity density levels, especially CCL3 and its receptor, correlated in part significantly with nociceptive thresholds. The authors report lesion grade-dependent upregulation of different chemokines/chemokine receptors after spinal cord contusion lesions in pain-processing spinal cord regions in a clinically relevant model of traumatic SCI in rats. Prolonged chemokine induction further correlated with below-level pain development in the delayed time course after severe SCI and was coexpressed with pain-associated peptides and receptors, suggesting that chemokines play a crucial role in chronic central pain mechanisms after SCI.

Evaluation of protective effects of the alpha lipoic acid after spinal cord injury: An animal study

Purpose Many of the hypotheses have been suggested to explain the mechanism of the secondary effects of traumatic spinal cord injury (TSCI) as follows: ischaemia/reperfusion disability theory, free radicals theory, exitotoxicity theory, immunological destruction theory, apoptosis theory. Recently, free radicals, lipid peroxidation reactions and apoptosis theories have been much more accepted than others. In this study, possible protective effects of the alpha lipoic acid were evaluated in the traumatic spinal cord of rats. Methods Using a well characterised weight drop technique, spinal cord contusions were formed to 48 Wistar albino rats at thoracal 8–10 level. After alpha lipoic acid and methylprednisolone were administered intraperitoneally, the spinal cord tissues were harvested for histopathological and biochemical studies. Results Histopathological examination results showed that neither methylprednisolone nor alpha lipoic acid can play an act to decrease or block the neural tissue destruction and necrosis in hyperacute and subacute stage of the TSCI in rats. Biochemical study results showed that alpha lipoic acid was much more decreased the lipid peroxidation levels than methylprednisolone in subacute stage. However, none of the agents was changed the myeloperoxidation level in subacute stage. Interpretation Alpha lipoic acid and methylprednisolone administrations did not alter the onset or degree of necrosis at the zone of the TSCI in rats. On the other hand, alpha lipoic acid is more effective than methylprednisolone treatment for the prevention of lipid peroxidation after spinal cord injury.

Agmatine improves locomotor function and reduces tissue damage following spinal cord injury.

Clinically effective drug treatments for spinal cord injury (SCI) remain unavailable. Agmatine, an NMDA receptor antagonist and inhibitor of nitric oxide synthase (NOS), is an endogenous neuromodulator found in the brain and spinal cord. Evidence is presented that agmatine significantly improves locomotor function and reduces tissue damage following traumatic SCI in rats. The results suggest the importance of future therapeutic strategies encompassing the use of single drugs with multiple targets for the treatment of acute SCI. The therapeutic targets of agmatine (NMDA receptor and NOS) have been shown to be critically linked to the pathophysiological sequelae of CNS injury and this, combined with the non-toxic profile, lends support to agmatine being considered as a potential candidate for future clinical applications.

Effects of BW755C, a mixed cyclo-oxygenase-lipoxygenase inhibitor, following traumatic spinal cord injury in rats

BW755C is an inhibitor of both cyclo-oxygenase and lipoxygenase, which has been found to have protective effects after myocardial ischemia in dogs. Impact injury to the spinal cord is associated with tissue ischemia as well as with the accumulation of eicosanoids. In the present studies we evaluated the effects of BW755C after traumatic spinalcord injury in rats. Drug treatment reduced thromboxane B 2 levels and improved neurological recovery as compared to treatment with equal-volume physiological saline. The findings suggest that this drug or related compounds may be useful for the treatment of clinical spinal cord injury.