Comparative effects of vitamin D and methylprednisolone against ischemia/reperfusion injury of rabbit spinal cords

Impact of vitamin D on the prognosis after spinal cord injury: A systematic review

Vitamin D (VitD) insufficiency is a worldwide health problem and affects billions of people. Spinal cord injury (SCI) patients seem more susceptible to developing suboptimal levels of VitD. However, the literature regarding its impact on the prognosis of SCI is limited. Thus, in this review, we systematically investigated the published studies via a combination of keywords associated with SCI and VitD in four medical databases (Medline, Embase, Scopus, and Web of Science). All included studies were analyzed, and selected clinical data on the prevalence of VitD insufficiency (serum 25-hydroxyvitamin D < 30 ng/ml) and deficiency (serum 25-hydroxyvitamin D < 20 ng/ml) were collected for further meta-analysis via random effects. Through literature review, a total of 35 studies were eligible and included. The meta-analysis of VitD status (13 studies, 1,962 patients) indicated high prevalence of insufficiency (81.6% [75.7, 87.5]) and deficiency (52.5% [38.1, 66.9]) after SCI. Besides, low levels of VitD were reported to be associated with a higher risk of skeletal diseases, venous thromboembolism, psychoneurological syndromes, and chest illness after injury. Existing literature suggested that supplemental therapy might act as an adjuvant treatment to facilitate post-injury rehabilitation. Non-human experimental studies highlighted the neuroprotective effect of VitD, which was associated with enhancing axonal and neuronal survival, suppressing neuroinflammation, and modulating autophagy. Therefore, the current evidence suggests that the prevalence of VitD insufficiency is high in the SCI population, and low-level VitD may impair functional restoration after SCI. VitD supplemental treatment may have potential benefits to accelerate rehabilitation in mechanistically related processes after SCI. However, due to the limitation of the available evidence, more well-designed randomized controlled trials and mechanism experimental research are still needed to validate its therapeutic effect, elucidate its neuroprotective mechanism, and develop novel treatments.

Neuroprotective Effects of Dexpanthenol on Rabbit Spinal Cord Ischemia/Reperfusion Injury Model

OBJECTIVE

Dexpanthenol (DXP) reportedly protects tissues against oxidative damage in various inflammation models. This study aimed to evaluate its effects on oxidative stress, inflammation, apoptosis, and neurological recovery in an experimental rabbit spinal cord ischemia/reperfusion injury (SCIRI) model.

METHODS

Rabbits were randomized into 5 groups of 8 animals each: group 1 (control), group 2 (ischemia), group 3 (vehicle), group 4 (methylprednisolone, 30 mg/kg), and group 5 (DXP, 500 mg/kg). The control group underwent laparotomy only, whereas other groups were subjected to spinal cord ischemia by aortic occlusion (just caudal to the 2 renal arteries) for 20 min. After 24 h, a modified Tarlov scale was employed to record neurological examination results. Malondialdehyde and caspase-3 levels and catalase and myeloperoxidase activities were analyzed in tissue and serum samples. Xanthine oxidase activity was measured in the serum. Histopathological and ultrastructural evaluations were also performed in the spinal cord.

RESULTS

After SCIRI, serum and tissue malondialdehyde and caspase-3 levels and myeloperoxidase and serum xanthine oxidase activities were increased (P < 0.05-0.001). However, serum and tissue catalase activity decreased significantly (P < 0.001). DXP treatment was associated with lower malondialdehyde and caspase-3 levels and reduced myeloperoxidase and xanthine oxidase activities but increased catalase activity (P < 0.05-0.001). Furthermore, DXP was associated with better histopathological, ultrastructural, and neurological outcome scores.

CONCLUSIONS

This study was the first to evaluate antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects of DXP on SCIRI. Further experimental and clinical investigations are warranted to confirm that DXP can be administered to treat SCIRI.

Vitamin D Promotes Remyelination by Suppressing c-Myc and Inducing Oligodendrocyte Precursor Cell Differentiation after Traumatic Spinal Cord Injury

Demyelination due to oligodendrocytes loss occurs after traumatic spinal cord injury (TSCI). Several studies have suggested the therapeutic potential of vitamin D (VitD) in demyelinating diseases. However, experimental evidence in the context of TSCI is limited, particularly in the presence of prior VitD-deficiency. In the present study, a contusion and a transection TSCI rat model were used, representing mild and severe injury, respectively. Motor recovery was assessed in rats with normal VitD level or with VitD-deficiency after 8 weeks' treatment post-TSCI (Cholecalciferol, 500 IU/kg/day). The impact on myelin integrity was examined by transmission electron microscopy and studied in vitro using primary culture of oligodendrocytes. We found that VitD treatment post-TSCI effectively improved hindlimb movement in rats with normal VitD level irrespective of injury severity. However, cord-transected rats with prior deficiency did not seem to benefit from VitD supplementation. Our data further suggested that having sufficient VitD was essential for persevering myelin integrity after injury. VitD rescued oligodendrocytes from apoptotic cell death in vitro and enhanced their myelinating ability towards dorsal root axons. Enhanced myelination was mediated by increased oligodendrocyte precursor cells (OPCs) differentiation into oligodendrocytes in concert with c-Myc downregulation and suppressed OPCs proliferation. Our study provides novel insights into the functioning of VitD as a regulator of OPCs differentiation as well as strong preclinical evidence supporting future clinical testing of VitD for TSCI.

Biochemical, pathological and ultrastructural investigation of whether lamotrigine has neuroprotective efficacy against spinal cord ischemia reperfusion injury

INTRODUCTION

Lamotrigine, an anticonvulsant drug with inhibition properties of multi-ion channels, has been shown to be able to attenuates secondary neuronal damage by influencing different pathways. The aim of this study was to look into whether lamotrigine treatment could protect the spinal cord from experimental spinal cord ischemia-reperfusion injury.

MATERIALS AND METHODS

Thirty-two rats, eight rats per group, were randomly assigned to the sham group in which only laparotomy was performed, and to the ischemia, methylprednisolone and lamotrigine groups, where the infrarenal aorta was clamped for thirty minutes to induce spinal cord ischemia-reperfusion injury. Tissue samples belonging to spinal cords were harvested from sacrificed animals twenty-four hours after reperfusion. Tumor necrosis factor-alpha levels, interleukin-1 beta levels, nitric oxide levels, superoxide dismutase activity, catalase activity, glutathione peroxidase activity, malondialdehyde levels and caspase-3 activity were studied. Light and electron microscopic evaluations were also performed to reveal the pathological alterations. Basso, Beattie, and Bresnahan locomotor scale and the inclined-plane test was used to evaluate neurofunctional status at the beginning of the study and just before the animals were sacrificed.

RESULTS

Lamotrigine treatment provided significant improvement in the neurofunctional status by preventing the increase in cytokine expression, increased lipid peroxidation and oxidative stress, depletion of antioxidant enzymes activity and increased apoptosis, all of which contributing to spinal cord damage through different paths after ischemia reperfusion injury. Furthermore, lamotrigine treatment has shown improved results concerning the histopathological and ultrastructural scores and the functional tests.

CONCLUSION

These results proposed that lamotrigine may be a useful therapeutic agent to prevent the neuronal damage developing after spinal cord ischemia-reperfusion injury.

Zingerone protects liver and kidney tissues by preventing oxidative stress, inflammation, and apoptosis in methotrexate-treated rats

The clinical use of drugs used in the treatment of diseases is limited due to the toxic side effects, and many studies have been conducted to benefit from herbal adjuvant therapies recently to eliminate these effects. In this study, the protective effect of zingerone against liver and kidney damage generated in rats through methotrexate (MTX). Histopathological investigations were performed to determine tissue damage caused by MTX and the healing effect of zingone and liver function markers such as serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and renal function markers such as urea, creatine, and aquaporin-1 (AQP-1) were measured. The effects of MTX and protective properties of zingerone on oxidative stress were investigated through the measurement of malondialdehyde and reduced glutathione (GSH) levels, catalase (CAT), and glutathione peroxidase (GPx) enzyme activities. The anti-inflammatory effect of zingerone was determined by measuring the cytokine levels causing inflammation such as nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), and its effects on apoptosis were determined by immunohistochemical analysis of caspase-3 and B-cell lymphoma-2 (Bcl-2) expression levels. According to the results obtained within the scope of the study, it was determined that zingerone treatment prevented the increase in MTX-induced liver and kidney function markers, showed healing effects on antioxidant parameters degraded in both tissues, and decreased the inflammation parameters. It was determined that it also prevented apoptosis and possessed a protective effect on disrupted tissue architecture by decreasing the increased caspase-3 expression and increasing the decreased Bcl-2 level.

The Pathway of Let-7a-1/2-3p and HMGB1 Mediated Dexmedetomidine Inhibiting Microglia Activation in Spinal Cord Ischemia-Reperfusion Injury Mice

Microglial cell activation after spinal cord ischemia-reperfusion injury (SCIRI) commonly causes the secondary nerve motion function injury. This study aims to study the mechanism by which the drug dexmedetomidine (DEX) inhibits microglial cell activation and improves motion function of SCIRI mice. Mice SCIRI model was established, and microglia from spinal cord were isolated and cultured for subsequent molecule analysis of let-7a-1-3p, let-7a-2-3p, HMGB1, TNF-α, and IL-6. DEX was given by intraperitoneal injection. Mice motion function was evaluated by Basso mouse score. In vitro microglial cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) to imitate ischemia-reperfusion injury stimulation. DEX injection improves the mouse motion function in SCIRI model and upregulates let-7a-1/2-3p expression in the isolated activated microglia from SCIRI mice. In OGD/R-stimulated microglia, DEX treatment also caused the inactivation of cells, the upregulation of let-7a-1/2-3p expression, and the downregulation of HMGB1 expression. While the co-silencing of let-7a-1/2-3p in microglia in addition to DEX treatment restored the activation of microglia. HMGB1 is a targeted gene for let-7a-1/2-3p and negatively regulated by them. HMGB1 knockdown abrogates the pro-activation impact on microglial cell by let-7a-1/2-3p silencing. DEX inhibits the activation of microglial cell in the spinal cord of SCIRI mice, mediated by the let-7a-1/2-3p/HMGB1 pathway.