Dantrolene can reduce secondary damage after spinal cord injury

Repair of spinal cord injury by bone marrow mesenchymal stem cell-derived exosomes: a systematic review and meta-analysis based on rat models

Objective

This study aims to systematically evaluate the efficacy of bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exo) in improving spinal cord injury (SCI) to mitigate the risk of translational discrepancies from animal experiments to clinical applications.

Methods

We conducted a comprehensive literature search up to March 2024 using PubMed, Embase, Web of Science, and Scopus databases. Two researchers independently screened the literature, extracted data, and assessed the quality of the studies. Data analysis was performed using STATA16 software.

Results

A total of 30 studies were included. The results indicated that BMSCs-Exo significantly improved the BBB score in SCI rats (WMD = 3.47, 95% CI [3.31, 3.63]), inhibited the expression of the pro-inflammatory cytokine TNF-α (SMD = -3.12, 95% CI [-3.57, -2.67]), and promoted the expression of anti-inflammatory cytokines IL-10 (SMD = 2.76, 95% CI [1.88, 3.63]) and TGF-β (SMD = 3.89, 95% CI [3.02, 4.76]). Additionally, BMSCs-Exo significantly reduced apoptosis levels (SMD = -4.52, 95% CI [-5.14, -3.89]), promoted the expression of axonal regeneration markers NeuN cells/field (SMD = 3.54, 95% CI [2.65, 4.42]), NF200 (SMD = 4.88, 95% CI [3.70, 6.05]), and the number of Nissl bodies (SMD = 1.89, 95% CI [1.13, 2.65]), and decreased the expression of astrogliosis marker GFAP (SMD = -5.15, 95% CI [-6.47, -3.82]). The heterogeneity among studies was primarily due to variations in BMSCs-Exo transplantation doses, with efficacy increasing with higher doses.

Conclusion

BMSCs-Exo significantly improved motor function in SCI rats by modulating inflammatory responses, reducing apoptosis, inhibiting astrogliosis, and promoting axonal regeneration. However, the presence of selection, performance, and detection biases in current animal experiments may undermine the quality of evidence in this study.

Dantrolene alleviates mitochondrial dysfunction and neuroinflammation in traumatic brain injury by modulating the NF-ĸβ/Akt pathway

Traumatic brain injury (TBI) triggers a bevy of changes including mitochondrial dysfunction, apoptosis, oxidative stress, neurobehavioural impairment, and neuroinflammation, among others. Dantrolene (DNT), a muscle relaxant which inhibits intracellular Ca2+ signaling from the ER, has been repurposed as a potential neuroprotective agent in various neurological diseases. However, there have been limited studies on whether it can mitigate TBI-induced deficits and restore impaired mitochondrial dynamics. This study sought to evaluate whether Dantrolene can potentially provide neuroprotection in an in vivo model of TBI. Male wistar rats subjected to TBI were treated with DNT (10 mg/kg) 1 h and 12 h post surgery. Animals were assessed 24 h post-TBI to evaluate neurobehavioural deficits and cerebral edema. We evaluated the protein expressions of apoptotic, autophagic, and neuroinflammatory markers by immunoblotting, as well as Mitochondrial Membrane Potential (MMP) and Reactive Oxygen Species (ROS) via Flow Cytometry to ascertain the effects of DNT on TBI. We further analysed immunofluorescence staining with Glial Fibrillary Acidic Protein (GFAP) and immunohistochemistry with NF-κβ to investigate neuroinflammation. H&E staining was also performed post-TBI. Our findings revealed DNT administration inhibits mitochondria-mediated apoptotis and reduces heightened oxidative stress. DNT treatment was also found to reverse neurobehavioural impairments and offer neuroprotection by preserving neuronal architechture. We also demonstrated that DNT inhibits neuronal autophagy and alleviates neuroinflammation following TBI by modulating the NF-κβ/Akt signaling pathway. Thus, our results suggest a novel application of DNT in ameliorating the multitude of deficits induced by TBI, thereby conferring neuroprotection.

Omega-conotoxin MVIIA reduces neuropathic pain after spinal cord injury by inhibiting N-type voltage-dependent calcium channels on spinal dorsal horn

Spinal cord injury (SCI) leads to the development of neuropathic pain. Although a multitude of pathological processes contribute to SCI-induced pain, excessive intracellular calcium accumulation and voltage-gated calcium-channel upregulation play critical roles in SCI-induced pain. However, the role of calcium-channel blockers in SCI-induced pain is unknown. Omega-conotoxin MVIIA (MVIIA) is a calcium-channel blocker that selectively inhibits N-type voltage-dependent calcium channels and demonstrates neuroprotective effects. Therefore, we investigated spinal analgesic actions and cellular mechanisms underlying the analgesic effects of MVIIA in SCI. We used SCI-induced pain model rats and conducted behavioral tests, immunohistochemical analyses, and electrophysiological experiments (in vitro whole-cell patch-clamp recording and in vivo extracellular recording). A behavior study suggested intrathecal MVIIA administration in the acute phase after SCI induced analgesia for mechanical allodynia. Immunohistochemical experiments and in vivo extracellular recordings suggested that MVIIA induces analgesia in SCI-induced pain by directly inhibiting neuronal activity in the superficial spinal dorsal horn. In vitro whole-cell patch-clamp recording showed that MVIIA inhibits presynaptic N-type voltage-dependent calcium channels expressed on primary afferent Aδ-and C-fiber terminals and suppresses the presynaptic glutamate release from substantia gelatinosa in the spinal dorsal horn. In conclusion, MVIIA administration in the acute phase after SCI may induce analgesia in SCI-induced pain by inhibiting N-type voltage-dependent calcium channels on Aδ-and C-fiber terminals in the spinal dorsal horn, resulting in decreased neuronal excitability enhanced by SCI-induced pain.

Regulation of the JAK/STAT signaling pathway in spinal cord injury: an updated review

Cytokines are involved in neural homeostasis and pathological processes associated with neuroinflammation after spinal cord injury (SCI). The biological effect of cytokines, including those associated with acute or chronic SCI pathologies, are the result of receptor-mediated signaling through the Janus kinases (JAKs) as well as the signal transducers and activators of transcription (STAT) DNA-binding protein families. Although therapies targeting at cytokines have led to significant changes in the treatment of SCI, they present difficulties in various aspects for the direct use by patients themselves. Several small-molecule inhibitors of JAKs, which may affect multiple pro-inflammatory cytokine-dependent pathways, as well as STATs, are in clinical development for the treatment of SCI. This review describes the current understanding of the JAK-STAT signaling in neuroendocrine homeostasis and diseases, together with the rationale for targeting at this pathway for the treatment of SCI.

Effects of intranasal dantrolene nanoparticles on brain concentration and behavior in PS19 tau transgenic mice

Background

Repurposing dantrolene as a potential disease-modifying treatment for Alzheimer's disease has been shown to be effective in amyloid transgenic mouse models but has not been examined in a model of tauopathy.

Objective

The effects of a nanoparticle intranasal formulation, the Eagle Research Formulation of Ryanodex (ERFR), in young adult and aged wild type and PS19 tau transgenic mice was investigated.

Methods

The bioavailability of intranasal ERFR was measured in 2 months and 9-12 month old C57BL/6J male mice. Mice received a single intranasal dose of ERFR and, after 20 min, blood and brain samples were collected. Dantrolene concentrations in the plasma and brain were analyzed by High Performance Liquid Chromatography. Animal behavior was examined in PS19 tau transgenic mice, with/without acrolein treatment to exacerbate cognitive deficits. Behavioral tests included cognition (cued and contextual fear conditioning, y-maze), motor function (rotarod), and olfaction (buried food test).

Results

Dantrolene concentration in the blood and brain decreased with age, though the decrease was greater in the blood resulting in a higher brain to blood concentration ratio. The behavioral assays showed no significant changes in cognition, olfaction or motor function in the PS19 mice compared to controls after chronic ERFR treatment even with acrolein treatment.

Conclusion

Our studies suggest that while we did not find PS19 mice to be a reliable Alzheimer animal model to test the therapeutic efficacy of dantrolene, the results suggest a potential for ERFR to be an effective chronic therapy for Alzheimer's disease and that further studies are indicated.

Comparative Study of Vasodilatation After Intra-arterial Nicardipine or Dantrolene Infusion in Animal Model of Cerebral Vasospasm

PURPOSE

Intra-arterial (IA) infusion of calcium channel blockers (CCBs) has been widely applied in treating medically refractory vasospasm; however, surprisingly little is known regarding their vasodilatory duration. This study was undertaken to compare attributes of nicardipine and dantrolene, focusing on efficacy and capacity for sustained vasodilation.

METHODS

In New Zealand white rabbits (N = 22), vasospasm was individually provoked through experimentally induced subarachnoid hemorrhage and confirmed via conventional angiography, grouping animals by IA-infused drug (nicardipine vs. dantrolene). Controls received normal saline. After chemoangioplasty, follow-up angiography was performed at intervals of 1-3 h for 6 h to compare vasospastic and dilated (i.e., treated) arterial diameters. Drug efficacy, duration of action, and changes in mean arterial pressure (relative to baseline) were analyzed by group.

RESULTS

Compared with controls, effective vasodilation was evident in both nicardipine and dantrolene test groups after IA infusion. Vasodilatory effects of nicardipine peaked at 1 h, returning to former vasospastic states at 3 h. In dantrolene recipients, vasodilation endured longer, lasting >6 h. Only the nicardipine group showed a significant 3‑h period of lowered blood pressure.

CONCLUSION

Unlike the vasodilatory action of a CCB, sustained for < 3 h after IA infusion, the effect of dantrolene endured for > 6 h. This outcome suggests that IA dantrolene infused alone or together with a conventional CCB infusion may be a new means of prolonging vasodilatory effect. Further research is needed to assess durations of IA-infused vasodilatory drug based on perfusion status.

Exosomes derived from bone marrow mesenchymal stem cells protect the injured spinal cord by inhibiting pericyte pyroptosis

Mesenchymal stem cell (MSC) transplantation is a promising treatment strategy for spinal cord injury, but immunological rejection and possible tumor formation limit its application. The therapeutic effects of MSCs mainly depend on their release of soluble paracrine factors. Exosomes are essential for the secretion of these paracrine effectors. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-EXOs) can be substituted for BMSCs in cell transplantation. However, the underlying mechanisms remain unclear. In this study, a rat model of T10 spinal cord injury was established using the impact method. Then, 30 minutes and 1 day after spinal cord injury, the rats were administered 200 μL exosomes via the tail vein (200 μg/mL; approximately 1 × 10⁶ BMSCs). Treatment with BMSC-EXOs greatly reduced neuronal cell death, improved myelin arrangement and reduced myelin loss, increased pericyte/endothelial cell coverage on the vascular wall, decreased blood-spinal cord barrier leakage, reduced caspase 1 expression, inhibited interleukin-1β release, and accelerated locomotor functional recovery in rats with spinal cord injury. In the cell culture experiment, pericytes were treated with interferon-γ and tumor necrosis factor-α. Then, Lipofectamine 3000 was used to deliver lipopolysaccharide into the cells, and the cells were co-incubated with adenosine triphosphate to simulate injury in vitro. Pre-treatment with BMSC-EXOs for 8 hours greatly reduced pericyte pyroptosis and increased pericyte survival rate. These findings suggest that BMSC-EXOs may protect pericytes by inhibiting pyroptosis and by improving blood-spinal cord barrier integrity, thereby promoting the survival of neurons and the extension of nerve fibers, and ultimately improving motor function in rats with spinal cord injury. All protocols were conducted with the approval of the Animal Ethics Committee of Zhengzhou University on March 16, 2019.

Ryanodine receptors mediate high intracellular Ca2+ and some myocyte damage following eccentric contractions in rat fast-twitch skeletal muscle

Eccentric contractions (ECC) facilitate cytosolic calcium ion (Ca2+) release from the sarcoplasmic reticulum (SR) and Ca2+ influx from the extracellular space. Ca2+ is a vital signaling messenger that regulates multiple cellular processes via its spatial and temporal concentration ([Ca2+]i) dynamics. We hypothesized that 1) a specific pattern of spatial/temporal intramyocyte Ca2+ dynamics portends muscle damage following ECC and 2) these dynamics would be regulated by the ryanodine receptor (RyR). [Ca2+]i in the tibialis anterior muscles of anesthetized adult Wistar rats was measured by ratiometric (i.e., ratio, R, 340/380 nm excitation) in vivo bioimaging with Fura-2 pre-ECC and at 5 and 24 h post-ECC (5 × 40 contractions). Separate groups of rats received RyR inhibitor dantrolene (DAN; 10 mg/kg ip) immediately post-ECC (+DAN). Muscle damage was evaluated by histological analysis on hematoxylin-eosin stained muscle sections. Compared with control (CONT, no ECC), [Ca2+]i distribution was heterogeneous with increased percent total area of high [Ca2+]i sites (operationally defined as R ≥ 1.39, i.e., ≥1 SD of mean control) 5 h post-ECC (CONT, 14.0 ± 8.0; ECC5h: 52.0 ± 7.4%, P < 0.01). DAN substantially reduced the high [Ca2+]i area 5 h post-ECC (ECC5h + DAN: 6.4 ± 3.1%, P < 0.01) and myocyte damage (ECC24h, 63.2 ± 1.0%; ECC24h + DAN: 29.1 ± 2.2%, P < 0.01). Temporal and spatially amplified [Ca2+]i fluctuations occurred regardless of DAN (ECC vs. ECC + DAN, P > 0.05). These results suggest that the RyR-mediated local high [Ca2+]i itself is related to the magnitude of muscle damage, whereas the [Ca2+]i fluctuation is an RyR-independent phenomenon.

Intranasal Dantrolene as a Disease-Modifying Drug in Alzheimer 5XFAD Mice

Background/Objective:

This study compares the effectiveness and safety of intranasal versus subcutaneous administration of dantrolene in 5XFAD Alzheimer’s disease (AD) mice.

Methods:

5XFAD and wild type (WT) B6SJLF1/J mice were treated with intranasal or subcutaneous dantrolene (5 mg/kg, 3×/wk), or vehicle. The early (ETG) and late (LTG) treatment groups began treatment at 2 or 6 months of age, respectively, and both treatment groups finished at12 months of age. Behavior was assessed for olfaction (buried food test), motor function (rotarod), and cognition (fear conditioning, Morris water maze). Liver histology (H & E staining) and function, synaptic proteins, and brain amyloid immunohistochemistry were examined. Plasma and brain dantrolene concentrations were determined in a separate cohort after intranasal or subcutaneous administration.

Results:

Intranasal dantrolene achieved higher brain and lower plasma concentrations than subcutaneous administration. Dantrolene administration at both approaches significantly improved hippocampal-dependent and -independent memory in the ETG, whereas only intranasal dantrolene improved cognition in the LTG. Dantrolene treatment had no significant change in the amyloid burden or synaptic proteins and no significant side effects on mortality, olfaction, motor, or liver functions in 5XFAD mice. Intranasal dantrolene treatment significantly ameliorated memory loss when it was started either before or after the onset of AD symptoms in 5XFAD mice.

Conclusions:

The long-term intranasal administration of dantrolene had therapeutic effects on memory compared to the subcutaneous approach even started after onset of AD symptoms, suggesting use as a disease-modifying drug, without significant effects on amyloid plaques, side effects, or mortality.

Time-Course Changes and Role of Autophagy in Primary Spinal Motor Neurons Subjected to Oxygen-Glucose Deprivation: Insights Into Autophagy Changes in a Cellular Model of Spinal Cord Ischemia

Spinal cord ischemia is a severe clinical complication induced by thoracoabdominal aortic surgery, severe trauma, or compression to the spinal column. As one of the most important functional cells in the spinal cord, spinal motor neurons (SMNs) suffer most during the process since they are vulnerable to ischemic injury due to high demands of energy. Previous researches have tried various animal models or organotypic tissue experiments to mimic the process and get to know the pathogenesis and mechanism. However, little work has been performed on the cellular model of spinal cord ischemia, which has been hampered by the inability to obtain a sufficient number of pure primary SMNs for in vitro study. By optimizing the isolation and culture of SMNs, our laboratory has developed an improved culture system of primary SMNs, which allows cellular models and thus mechanism studies. In the present study, by establishing an in vitro model of spinal cord ischemia, we intended to observe the dynamic time-course changes of SMNs and investigate the role of autophagy in SMNs during the process. It was found that oxygen-glucose deprivation (OGD) resulted in destruction of neural networks and decreased cell viability of primary SMNs, and the severity increased with the prolonging of the OGD time. The OGD treatment enhanced autophagy, which reached a peak at 5 h. Further investigation demonstrated that inhibition of autophagy exacerbated the injury, evidencing that autophagy plays a protective role during the process.

Significant reduction of vascular reactivity with dantrolene and nimodipine in diabetic rats: a potential approach to cerebral vasospasm management in diabetes

BACKGROUND

Diabetics have a higher risk of developing cerebral vasospasms (CVSPs) than non-diabetics. Current therapies are ineffective in reducing CVSPs, but a a combination of dantrolene and nimodipine may be a viable treatment. Considering the potentially harmful secondary effects of dantrolene, however, we evaluated the efficacy of 10 μM dantrolene compared to 50 μM dantrolene alone or in combination with 50 nM nimodipine.

METHODS

Dose-response curves for the phenylephrine (PHE)-induced contraction and acetylcholine (ACh)-induced relaxation were performed on aortic rings from diabetic and non-diabetic rats, before and after a 30-min incubation period with dantrolene (50 μM and 10 μM), alone or in combination with 50 nM nimodipine.

RESULTS

Whereas 50 μM dantrolene reduced PHE-induced contraction by 47% in diabetic rats and 29% in controls, 10 μM dantrolene failed to reduce this parameter in either group. Furthermore, 50 μM dantrolene reduced PHE-induced contraction by about 80% in both diabetic and controls when combined with nimodipine (N = 9, P < 0.05). The combination of 10 μM dantrolene and 50 nM nimodipine, however, was ineffective. Only 50 μM dantrolene improved endothelial dysfunction.

CONCLUSIONS

Improved endothelial-dependent relaxation and reduced vascular contractility with dantrolene are dose dependent. Thus, although dantrolene appears to be a promising alternative for the treatment of CVSPs when added to conventional therapies, careful titration should be performed to achieve a significant reduction in vascular hyperreactivity. Moreover, if our findings with rats are applicable to humans, the combined use of dantrolene and nimodipine at optimal doses may reduce CVSPs, especially in the diabetic population.

Coenzyme Q10 suppresses oxidative stress and apoptosis via activating the Nrf-2/NQO-1 and NF-κB signaling pathway after spinal cord injury in rats

Spinal cord injury (SCI) is one of the most devastating diseases that may cause paralysis, disability and irreversible loss of functions, which ultimately lead to permanent disabilities and a decrease in patient life expectancy. Coenzyme Q10 (CoQ10) is a lipid-soluble vitamin-like benzoquinone compound that can exert antioxidant and anti-apoptotic functions in a variety of diseases. However, the antioxidant and anti-apoptotic effects of CoQ10 in the treatment of SCI are still unknown. Therefore, we designed experiments to measure the changes in antioxidant capacity (glutathione (GSH), superoxide dismutase (SOD) and the end product of lipid peroxidation (MDA)) and apoptosis products (Bax, Bcl-2 and Caspase-3) to evaluate the protective effects of CoQ10 on SCI and investigated whether CoQ10 exerts its functions through the Nrf-2/NQO-1 and NF-κB signaling pathway. Our results showed that CoQ10 treatment could significantly decrease the levels of oxidative products (MDA) and increase the activities of antioxidant enzymes (SOD and GSH) against oxidative stress, as well as decrease the levels of pro-apoptotic proteins (Bax and Caspase-3) and increase the levels of anti-apoptotic proteins (Bcl-2) against apoptosis after SCI. We also observed that CoQ10 exerted beneficial effects through the Nrf-2/NQO-1 and NF-κB signaling pathway. These findings suggested that CoQ10 had a protective effect by decreasing oxidative stress and apoptosis after SCI. Thus, our data may provide a new approach wherein CoQ10 may be considered as a potential effective therapeutic for the treatment of SCI.

A Review on the Etiology and Management of Pediatric Traumatic Spinal Cord Injuries

CONTEXT

Pediatric traumatic spinal cord injury (SCI) is an uncommon presentation in the emergency department. Severe injuries are associated with devastating outcomes and complications, resulting in high costs to both the society and the economic system.

EVIDENCE ACQUISITION

The data on pediatric traumatic spinal cord injuries has been narratively reviewed.

RESULTS

Pediatric SCI is a life-threatening emergency leading to serious outcomes and high mortality in children if not managed promptly. Pediatric SCI can impose many challenges to neurosurgeons and caregivers because of the lack of large studies with high evidence level and specific guidelines in terms of diagnosis, initial management and of in-hospital treatment options. Several novel potential treatment options for SCI have been developed and are currently under investigation. However, research studies into this field have been limited by the ethical and methodological challenges.

CONCLUSION

Future research is needed to investigate the safety and efficacy of the recent uprising neurodegenerative techniques in SCI population. Owing to the current limitations, there is a need to develop novel trial methodologies that can overcome the current methodological and ethical limitations.

Neuroectodermal Stem Cells Grafted into the Injured Spinal Cord Induce Both Axonal Regeneration and Morphological Restoration via Multiple Mechanisms

Spinal cord contusion injury leads to severe loss of gray and white matter and subsequent deficit of motor and sensory functions below the lesion. In this study, we investigated whether application of murine clonal embryonic neuroectodermal stem cells can prevent the spinal cord secondary damage and induce functional recovery. Stem cells (NE-GFP-4C cell line) were grafted intraspinally or intravenously immediately or one week after thoracic spinal cord contusion injury. Control animals received cell culture medium or fibrin intraspinally one week after injury. Functional tests (Basso, Beattie, Bresnahan, CatWalk^®) and detailed morphological analysis were performed to evaluate the effects of grafted cells. Stem cells applied either locally or intravenously induced significantly improved functional recovery compared with their controls. Morphologically, stem cell grafting prevented the formation of secondary injury and promoted sparing of the gray and white matters. The transplanted cells integrated into the host tissue and differentiated into neurons, astrocytes, and oligodendrocytes. In intraspinally grafted animals, the corticospinal tract axons regenerated along the ventral border of the cavity and have grown several millimeters, even beyond the caudal end of the lesion. The extent of regeneration and functional improvement was inversely related to the amounts of chondroitin sulphate and ephrin-B2 molecules around the cavity and to the microglial and astrocytic reactions in the injured segment early after injury. The grafts produced glial cell derived neurotrophic factor, macrophage inflammatory protein-1a, interleukin (IL)-6 and IL-10 in a paracrine fashion for at least one week. Treating the grafted cords with neutralizing antibodies against these four factors through the use of osmotic pumps nearly completely abolished the effect of the graft. The non-significant functional improvement after function blocking is likely because the stem cell derivatives settled in the injured cord. These data suggest that grafted neuroectodermal stem cells are able to prevent the secondary spinal cord damage and induce significant regeneration via multiple mechanisms.

Time-dependent effects of dantrolene on motor evoked potentials in experimental spinal cord injuries

Objectives:Traumatic spinal cord injury (SCI) is a significant clinical problem with numerous secondary complications and perpetual deficits. No potent treatment is currently available to fully repair motor and other neurological functions. We studied the effects of dantrolene (DNT) at different time points, on the motor-evoked potentials (MEPs) and the apoptosis response in spinal cord injury. Methods:The study was conducted on a total of 38 rabbits divided into five main groups.These were group 1 (sham): only laminectomy (n = 6), group 2 (SCI): laminectomy and traumatic SCI (n = 8), group 3 (DNT 0h): just after the SCI, DNT 10 mg/kg I.P. (n = 8), group 4 (DNT 1h): 1 h after the SCI, DNT 10 mg/kg I.P. (n = 8), and group 5 (DNT 4h): 4 h after the SCI, DNT 10 mg/kg I.P. (n = 8). Results: DNT, which was administered as the treatment, had a therapeutic effect on the motor function. This effect was observed by recording neural transmission obtained via the Tarlov test and a transcranial magnetic stimulator by using the values of the MEPs. A significant decrease was histopathologically observed in the apoptotic cell count. Discussion: The electrophysiological efficacy of our model of trauma as SCI has been complemented with the significant differences between the control group and the SCI group. This creates a need for electrophysiological studies to be conducted in the future because effects, even at a minimum level, may play an important role in finding an applicable medicine for SCI.

Association of riluzole and dantrolene improves significant recovery after acute spinal cord injury in rats

BACKGROUND CONTEXT

Damage to the spinal cord can result in irreversible impairment or complete loss of motor, sensory, and autonomic functions. Riluzole and dantrolene have been shown to provide neuroprotection by reducing neuronal apoptosis after brain and spinal cord injury (SCI) in several animal models of neurologic disorders. As these drugs protect the injured spinal cord through different mechanisms, we investigated the cumulative effects of riluzole and dantrolene.

PURPOSE

This study aimed to investigate the neuroprotective efficacy of the combined administration of riluzole and dantrolene in experimental thoracic SCI.

STUDY DESIGN

Twenty-nine Wistar rats were laminectomized at T12 and divided in five groups. Rats in GI (n=6) underwent laminectomy alone and were treated with placebo. Rats in GII (n=6) underwent laminectomy followed by SCI and were treated with placebo. Rats in GIII (n=5) underwent laminectomy followed by SCI and were treated with riluzole and placebo 15 minutes and 1 hour after laminectomy, respectively. Rats in GIV (n=6) underwent laminectomy followed by SCI and were treated with placebo and dantrolene 15 minutes and 1 hour after laminectomy, respectively. Rats in GV (n=6) underwent laminectomy followed by SCI and were treated with riluzole and dantrolene 15 minutes and 1 hour after laminectomy, respectively. A compressive trauma was performed to induce SCI.

METHODS

Behavioral testing of hind limb function was performed using the Basso Beattie Bresnahan locomotor rating scale, which revealed significant recovery in the group treated with the association of riluzole and dantrolene compared with other groups. After euthanasia, the spinal cord was evaluated using light microscopy and immunochemistry with anti-NeuN and transferase dUTP nick-end-labeling (TUNEL) staining.

RESULTS

Animals treated with the association of riluzole and dantrolene showed a larger number of NeuN-positive neurons adjacent to the epicenter of injury (p≤.05). Furthermore, the TUNEL staining was similar between animals treated with riluzole and dantrolene and those that did not receive spinal cord trauma (p>.05).

CONCLUSIONS

These results showed that riluzole and dantrolene have a synergistic effect in neuroprotection after traumatic SCI by decreasing apoptotic cell death.

Synergistic Effects of Dantrolene and Nimodipine on the Phenylephrine-Induced Contraction and ACh-Induced Relaxation in Aortic Rings from Diabetic Rats

Diabetics have a higher risk of developing cerebral vasospasms (CVSP) than nondiabetics. The addition of the ryanodine receptor (RyR) blocker dantrolene to standard therapies reduces vasospasms in nondiabetics. Whether diabetics with CVSP also benefit from this drug, however, is unknown. We evaluated the effects of a 30 min incubation with dantrolene (50 μM), nimodipine (50 nM), and both drugs in combination, on phenylephrine- (PHE-) induced contraction and on acetylcholine- (ACh-) induced relaxation in aortic rings from streptozotocin (STZ) diabetic rats. Age-matched, nondiabetic rats served as controls. The oxidative stress markers malondialdehyde (MDA) and 4-hydroxyalkenal (4-HAE) were also evaluated in the presence and absence of dantrolene and nimodipine. The combination of these two drugs acted synergistically to reduce the PHE-induced contraction by 80% in both diabetics and controls. In contrast, it increased the E_max value for ACh-induced relaxation (from 56.46 ± 5.14% to 96.21 ± 7.50%; n = 6, P < 0.05), and it decreased MDA + 4-HAE values in diabetic rats only. These results suggest that the combination of dantrolene and nimodipine benefits both diabetics and nondiabetics by decreasing arterial tone synergistically.

Neuroprotective mechanisms of rutin for spinal cord injury through anti-oxidation and anti-inflammation and inhibition of p38 mitogen activated protein kinase pathway

Rutin has anti-inflammatory, antioxidant, anti-viral, anti-tumor and immune regulatory effects. However, the neuroprotective effects of rutin in spinal cord injury are unknown. The p38 mitogen activated protein kinase (p38 MAPK) pathway is the most important member of the MAPK family that controls inflammation. We assumed that the mechanism of rutin in the repair of spinal cord injury is associated with the inhibition of p38 MAPK pathway. Allen's method was used to establish a rat model of spinal cord injury. The rat model was intraperitoneally injected with rutin (30 mg/kg) for 3 days. After treatment with rutin, Basso, Beattie and Bresnahan locomotor function scores increased. Water content, tumor necrosis factor alpha, interleukin 1 beta, and interleukin 6 levels, p38 MAPK protein expression and caspase-3 and -9 activities in T_8–9 spinal cord decreased. Oxidative stress related markers superoxide dismutase and glutathione peroxidase levels increased in peripheral blood. Rutin exerts neuroprotective effect through anti-oxidation, anti-inflammation, anti-apoptosis and inhibition of p38 MAPK pathway.

Resveratrol, an antioxidant, protects spinal cord injury in rats by suppressing MAPK pathway

Resveratrol, a polyphenol found in various plants, including grapes, plums and peanuts has shown various medIRInal properties, including antioxidant, protection of cardiovascular disease and cancer risk. However, the effects of resveratrol on spinal cord reperfusion injury have not been investigated. Hence, the present study was designed to evaluate the effect of resveratrol on nitric oxide synthase (iNOS)/p38MAPK signaling pathway and to elucidate its regulating effect on the protection of spinal cord injury. Spinal cord ischemia–reperfusion injury (IRI) was performed by the infrarenal abdominal aorta with mini aneurysm clip model. The expressions of iNOS and p38MAPK and the levels of biochemical parameters, including nitrite/nitrate, malondialdehyde (MDA), advanced oxidation products (AOPP), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were measured in control and experimental groups. IRI-induced rats treated with 10 mg/kg resveratrol protected spinal cord from ischemia injury as supported by improved biological parameters measured in spinal cord tissue homogenates. The resveratrol treatment significantly decreased the levels of plasma nitrite/nitrate, iNOS mRNA and protein expressions and phosphorylation of p38MAPK in IRI-induced rats. Further, IRI-produced free radicals were reduced by resveratrol treatment by increasing enzymatic and non-enzymatic antioxidant levels such as GSH, SOD and CAT. Taken together, administration of resveratrol protects the damage caused by spinal cord ischemia with potential mechanism of suppressing the activation of iNOS/p38MAPK pathway and subsequent reduction of oxidative stress due to IRI.

The Neuroprotective Effect of Syringic Acid on Spinal Cord Ischemia/Reperfusion Injury in Rats

Acute arterial occlusions via different vascular pathologies are the main causes of spinal cord ischemia. We investigated neuroprotective effects of syringic acid on spinal cord ischemia injury in rats. Rats were divided into four groups: (I) sham-operated control rats, (II) spinal cord ischemia group, (III) spinal cord ischemia group performed syringic acid, and (IV) spinal cord ischemia group performed methylprednisolone intraperitoneally. Spinal cord ischemia was performed by the infrarenal aorta cross-clamping model. The spinal cord was removed after the procedure. The biochemical and histopathological changes were observed within the samples. Functional assessment was performed for neurological deficit scores. A significant decrease was seen in malondialdehyde levels in group III as compared to group II (P < 0.05). Besides these, nuclear respiratory factor-1 and superoxide dismutase activity of group III were significantly higher than group II (P < 0.05). In histopathological samples, when group III was compared with group II, there was a significant decrease in numbers of apoptotic neurons (P < 0.05). In immunohistochemical staining, BECN1 and caspase-3-immunopositive neurons were significantly decreased in group III compared with group II (P < 0.05). The neurological deficit scores of group III were significantly higher than group II at twenty-fourth hour of ischemia (P < 0.05). Our study revealed that syringic acid pretreatment in spinal cord ischemia/reperfusion reduced oxidative stress and neuronal degeneration as a neuroprotective agent. Ultrastructural studies are required for syringic acid to be developed as a promising therapeutic agent to be utilized for human spinal cord ischemia in the future.

Ischemia-reperfusion model in rat spinal cord: cell viability and apoptosis signaling study

This work aimed at determining the ideal ischemia time in an in vitro ischemia-reperfusion model of spinal cord injury. Rat spinal cord slices were prepared and then exposed or not to oxygen deprivation and low glucose (ODLG) for 30, 45, 60, 75 and 90 minutes. Cell viability was assessed by triphenyltetrazolium (TTC), lactate dehydrogenase (LDH) release, and fluorochrome dyes specific for cell dead (ethidium homodimer) using the apotome system. Glutamate release was enzymatically measured by a fluorescent method. Gene expression of apoptotic factors was assessed by real time RT-PCR. Whereas spinal cord slices exposed to ODLG exhibited mild increase in fluorescence for 30 minutes after the insult, the 45, 60, 75 and 90 minutes caused a 2-fold increase. ODLG exposure for 45, 60, 75 or 90 minutes, glutamate and LDH release were significantly elevated. nNOS mRNA expression was overexpressed for 45 minutes and moderately increased for 60 minutes in ODLG groups. Bax/bcl-xl ratio, caspase 9 and caspase 3 mRNA expressions were significantly increased for 45 minutes of ODLG, but not for 30, 60, 75 and 90 minutes. Results showed that cell viability reduction in the spinal cord was dependent on ischemic time, resulting in glutamate and LDH release. ODLG for 45 minutes was adequate for gene expression evaluation of proteins and proteases involved in apoptosis pathways.

Dantrolene enhances the protective effect of hypothermia on cerebral cortex neurons

Therapeutic hypothermia is the most promising non-pharmacological neuroprotective strategy against ischemic injury. However, shivering is the most common adverse reaction. Many studies have shown that dantrolene is neuroprotective in in vitro and in vivo ischemic injury models. In addition to its neuroprotective effect, dantrolene neutralizes the adverse reaction of hypothermia. Dantrolene may be an effective adjunctive therapy to enhance the neuroprotection of hypothermia in treating ischemic stroke. Cortical neurons isolated from rat fetuses were exposed to 90 minutes of oxygen-glucose deprivation followed by reoxygenation. Neurons were treated with 40 μM dantrolene, hypothermia (at 33°C), or the combination of both for 12 hours. Results revealed that the combination of dantrolene and hypothermia increased neuronal survival and the mitochondrial membrane potential, and reduced intracellular active oxygen cytoplasmic histone-associated DNA fragmentation, and apoptosis. Furthermore, improvements in cell morphology were observed. The combined treatment enhanced these responses compared with either treatment alone. These findings indicate that dantrolene may be used as an effective adjunctive therapy to enhance the neuroprotective effects of hypothermia in ischemic stroke.

Behavioral and Histopathological Study of Changes in Spinal Cord Injured Rats Supplemented with Spirulina platensis

Spinal cord injury (SCI) is a devastating disease that leads to permanent disability and causes great suffering. The resulting neurological dysfunction and paralysis is proportional to the severity of the trauma itself. Spirulina is widely used as a nutritional supplement due to its high protein and antioxidant content. In the present study, the protective effect of the Spirulina treatment on locomotor function and morphological damage after SCI was investigated. Seventy Sprague-Dawley (SD) rats were divided into three groups: Sham (laminectomy alone), Control (laminectomy with SCI), and Experimental (laminectomy with SCI +180 mg/kg per day Spirulina platensis). A laminectomy was performed at T12 and an Inox No.2 modified forceps was used to perform a partial crush injury on the spinal cord. The rats were then perfused at 3, 7, 14, 21, and 28 days after injury for morphological investigations. The injured rat spinal cord indicated a presence of hemorrhage, cavity, and necrosis. Pretreatment with Spirulina significantly improved the locomotor function and showed a significant reduction on the histological changes. The experimental results observed in this study suggest that treatment with Spirulina platensis possesses potential benefits in improving hind limb locomotor function and reducing morphological damage to the spinal cord.

Effects of methylprednisolone, dantrolene, and their combination on experimental spinal cord injury

This study aimed to evaluate the effect of methylprednisolone sodium succinate, dantrolene sodium, and their combination on experimental spinal cord injury. We used 25 rats (Rattus norvegicus) that were divided into five groups. The negative control group (NC) consisted of animals without spinal cord trauma. In the groups with spinal cord trauma, the positive control group (PC) was given no treatment, the MS group was treated with methylprednisolone, the MS/DS group was treated with methylprednisolone and dantrolene, and the DS group was treated with dantrolene alone. The animals' motor function was evaluated daily, as measured with the open field test. Eight days after surgery, the animals were euthanized for spinal cord collection. Descriptive morphological evaluation, anti-NeuN immunohistochemistry, TUNEL, and anti-Bax immunofluorescence were performed. There was no significant difference between the PC, MS, MS/DS and DS groups with respect to BBB scores, neuronal and glial staining, or Bax expression (P < 0.05). Therefore, we conclude that methylprednisolone sodium succinate, dantrolene sodium, or the combination of these drugs did not reduce neuronal and glial loss, intrinsic pathway apoptosis, or promote functional recovery.

Omega-conotoxin MVIIC attenuates neuronal apoptosis in vitro and improves significant recovery after spinal cord injury in vivo in rats

Excessive accumulation of intracellular calcium is the most critical step after spinal cord injury (SCI). Reducing the calcium influx should result in a better recovery from SCI. Calcium channel blockers have been shown a great potential in reducing brain and spinal cord injury. In this study, we first tested the neuroprotective effect of MVIIC on slices of spinal cord subjected to ischemia evaluating cell death and caspase-3 activation. Thereafter, we evaluated the efficacy of MVIIC in ameliorating damage following SCI in rats, for the first time in vivo. The spinal cord slices subjected a pretreatment with MVIIC showed a cell protection with a reduction of dead cells in 24.34% and of caspase-3-specific protease activation. In the in vivo experiment, Wistar rats were subjected to extradural compression of the spinal cord at the T12 vertebral level using a weigh of 70 g/cm, following intralesional treatment with either placebo or MVIIC in different doses (15, 30 and 60 pmol) five minutes after injury. Behavioral testing of hindlimb function was done using the Basso Beattie Bresnahan locomotor rating scale, and revealed significant recovery with 15 pmol (G15) compared to other trauma groups. Also, histological bladder structural revealed significant outcome in G15, with no morphological alterations, and anti-NeuN and TUNEL staining showed that G15 provided neuron preservation and indicated that this group had fewer neuron cell death, similar to sham. These results showed the neuroprotective effects of MVIIC in in vitro and in vivo model of SCI with neuronal integrity, bladder and behavioral improvements.

Substance P as a mediator of neurogenic inflammation after balloon compression induced spinal cord injury

Although clinical spinal cord injury (SCI) occurs within a closed environment, most experimental models of SCI create an open injury. Such an open environment precludes the measurement of intrathecal pressure (ITP), whose increase after SCI has been linked to the development of greater tissue damage and functional deficits. Raised ITP may be potentiated by edema, which we have recently shown to be associated with substance P (SP) induced neurogenic inflammation in both traumatic brain injury and stroke. The present study investigates whether SP plays a similar role as a mediator of neurogenic inflammation after SCI. A closed balloon compression injury was induced at T10 in New Zealand white rabbits. Animals were thereafter assessed for blood spinal cord barrier (BSCB) permeability, edema, ITP, histological outcome, and functional outcome from 5 h to 2 weeks post-SCI. The balloon compression model produced significant increases in BSCB permeability, edema, and ITP along with significant functional deficits that persisted for 2 weeks. Histological assessment demonstrated decreased SP immunoreactivity in the injured spinal cord while NK1 receptor immunoreactivity initially increased before returning to sham levels. In addition, aquaporin 4 immunoreactivity increased early post-SCI, implicating this water channel in the development of edema after SCI. The changes described in the present study support a role for SP as a mediator of neurogenic inflammation after SCI.

Effect of neuroglobin genetically modified bone marrow mesenchymal stem cells transplantation on spinal cord injury in rabbits

Objective

This study aims to investigate the potentially protective effect of neuroglobin (Ngb) gene-modified bone marrow mesenchymal stem cells (BMSCs) on traumatic spinal cord injury (SCI) in rabbits.

Methods

A lentiviral vector containing an Ngb gene was constructed and used to deliver Ngb to BMSCs. Ngb gene-modified BMSCs were then injected at the SCI sites 24 hours after SCI. The motor functions of the rabbits were evaluated by the Basso–Beattie–Bresnahan rating scale. Fluorescence microscopy, quantitative real-time PCRs, Western blots, malondialdehyde (MDA) tests, and terminal deoxynucleotidyltransferase-mediated UTP end labeling assays were also performed.

Results

Ngb expression in the Ngb-BMSC group increased significantly. A more significant functional improvement was observed in the Ngb-BMSC group compared with those in the other groups. Traumatic SCI seemingly led to an increase in MDA level and number of apoptotic cells, which can be prevented by Ngb-BMSC treatment.

Conclusion

This study demonstrates that Ngb gene-modified BMSCs can strengthen the therapeutic benefits of BMSCs in reducing secondary damage and improving the neurological outcome after traumatic SCI. Therefore, the combined strategy of BMSC transplantation and Ngb gene therapy can be used to treat traumatic SCI.

Dantrolene is neuroprotective in vitro, but does not affect survival in SOD1(G⁹³A) mice

Amyotrophic Lateral Sclerosis (ALS) is a devastating progressive neurodegenerative disease. One of the proposed disease mechanisms is excitotoxicity, in which excessive cytosolic calcium causes neuronal death. Although most calcium may originate from the extracellular space through activation of calcium-permeable AMPA receptors, we investigated in this study the contribution of endoplasmic reticulum calcium release by blocking the ryanodine receptor (RyR) using dantrolene. In vitro, dantrolene provides a significant protection to motor neurons exposed to a brief excitotoxic insult. However, daily administration of dantrolene to mice overexpressing superoxide dismutase 1 glycine to alanine at position 93 (SOD1(G93A)) does affect neither survival nor the number of motor neurons and ubiquitin aggregates indicating that calcium release through RyRs does not contribute to the selective motor neuron death in this animal model for ALS.

Royal jelly can diminish secondary neuronal damage after experimental spinal cord injury in rabbits

The aim of this experimental study was to investigate the neuroprotective effect of Royal jelly (RJ) on traumatic spinal cord injury (SCI). Twenty-one New Zealand male rabbits, weighing between 2.5 and 3.0 kg were divided into three groups: Sham (no drug or operation, n = 7), Control (laminectomy+single dose of 1 ml/kg saline orally, after trauma; n = 7) and RJ (laminectomy+100mg/kg RJ, orally, after trauma, n = 7). Laminectomy was perfor med at T10 and balloon catheter was applied extradurally for traumatic SCI. Four and 24h after surgery, rabbits were evaluated according to the Tarlov scoring system. Blood, cerebrospinal fluid and tissue sample from spinal cord were taken for measurements of antioxidant status or detection of apoptosis. Four hours after SCI, all animals in control or RJ treated groups became paraparesic. Significant improvement was observed in RJ treated group, 24h after SCI, with respect to control. Traumatic SCI led to increase in the lipid peroxidation and decrease enzymic or non-enzymic endogenous antioxidative defense systems, and increase in apoptotic cell numbers. RJ treatment mostly prevented lipid peroxidation and also augmented endogenous enzymic or non-enzymic antioxidative defense systems. Again, RJ treatment significantly decreased the apoptotic cell number induced by SCI.

Inflammation & apoptosis in spinal cord injury

Spinal cord injury (SCI) consists of a two-steps process involving a primary mechanical injury followed by an inflammatory process and apoptosis. Secondary insult is characterized by further destruction of neuronal and glial cells, and leads to expansion of the damage, so that the paralysis can extend to higher segments. With the identification of mechanisms that either promote or prevent neuronal inflammation and apoptosis come new approaches for preventing and treating neurodegenerative disorders. From a clinical perspective, this article discusses novel targets for the development of therapeutic agents that have the potential to protect the spinal cord from irreversible damage and promote functional recovery.

Spinal cord injury sequelae alter drug pharmacokinetics: an overview

STUDY DESIGN

Literature review.

OBJECTIVES

Critical review of the literature published on the physiological alterations caused by spinal cord injury (SCI) and their effect on the pharmacokinetic parameters of commonly employed drugs. The review introduces the most recent treatment protocols of a variety of drugs, enabling the modern clinician to apply efficacious and cost-effective solutions to the pharmacological treatment of SCI patients.

METHODS

Studies published in international indexed journals up to January 2011 were selected from the PubMed database.

RESULTS

The review evaluated the sequelae of SCI and their effect on pharmacological processes. The results demonstrated that these alterations affected the pharmacokinetics of drugs commonly administered to SCI patients, such as antibiotics, muscle relaxants, immunosuppressants and analgesics.

CONCLUSION

There are multiple etiologies to SCI and patients present with varying degrees of impairment. Factors such as level of injury and completeness of the injury create a very heterogeneous population within the SCI community. The heterogeneity of this population creates a problem when trying to standardize pharmacokinetic (PK) parameters. It is because of this that specific physiological alterations must be linked to changes in PK and be identified within the clinical setting. This relationship between physiology and PK enables the clinician to be alert for possible pharmacological complications in individual patients based on their clinical manifestations. Future research should aim to develop rigorous therapeutic guidelines tailored to the diverse manifestations of SCI so as to provide effective, affordable and safe pharmacotherapy.

Effects of dantrolene on apoptosis and immunohistochemical expression of NeuN in the spinal cord after traumatic injury in rats

Dantrolene has been shown to be neuroprotective by reducing neuronal apoptosis after brain injury in several animal models of neurological disorders. In this study, we investigated the effects of dantrolene on experimental spinal cord injury (SCI). Forty-six male Wistar rats were laminectomized at T13 and divided in six groups: GI (n = 7) underwent SCI with placebo and was euthanized after 32 h; GII (n = 7) underwent laminectomy alone with placebo and was euthanized after 32 h; GIII (n = 8) underwent SCI with dantrolene and was euthanized after 32 h; GIV (n = 8) underwent SCI with placebo and was euthanized after 8 days; GV (n = 8) underwent laminectomy alone with placebo and was euthanized after 8 days; and GVI (n = 8) underwent SCI with dantrolene and was euthanized after 8 days. A compressive trauma was performed to induce SCI. After euthanasia, the spinal cord was evaluated using light microscopy, TUNEL staining and immunochemistry with anti-Caspase-3 and anti-NeuN. Animals treated with dantrolene showed a smaller number of TUNEL-positive and caspase-3-positive cells and a larger number of NeuN-positive neurons, both at 32 h and 8 days (P ≤ 0.05). These results showed that dantrolene protects spinal cord tissue after traumatic SCI by decreasing apoptotic cell death.