Induction and its spread of apoptosis in rat spinal cord after mechanical trauma

Erythropoietin to Treat Spinal Cord Injury: Evaluation of Different Doses and Magnitudes of Trauma in Rats

STUDY DESIGN

Experimental spinal cord lesion study.

OBJECTIVES

To evaluate the effects of erythropoietin at different doses on neural regeneration in rats undergoing spinal cord injury.

METHODS

Anesthetized Wistar rats were submitted to standardized spinal cord injury and randomized into eight groups, receiving different magnitudes of trauma and single or repeated doses of intraperitoneal erythropoietin (500 or 5000 IU/kg of body weight). We evaluated motor function using BBB scores and sensorimotor behavior by observing the rats walking on a horizontal ladder (at 2, 4, and 6 weeks) and performed histological analysis of the spinal cord after euthanasia. We compared the scores between groups using analysis of variance (ANOVA) and Bonferroni multiple comparisons.

RESULTS

The experiments were conducted with 10 animals per group (n = 80), none of which died or were excluded. BBB scores increased over time (meaning recovery) in all groups (P < 0.001 for all). From the fourth week, animals receiving lower trauma and higher erythropoietin doses had higher BBB scores than those receiving lower doses. The total number of steps and correct steps taken on the horizontal ladder increased, and slips decreased over time with treatment in all groups. Although the number of errors was different between moments (P < 0.001), it was not different between groups (P = 0.707). Rats receiving higher impact lesions had more spinal cord necrosis and worse recovery of neuronal fibers than the rest.

CONCLUSIONS

Animals receiving a higher dose of erythropoietin and suffering minor trauma showed better and faster neurological recovery. Repeating erythropoietin after a week showed no benefit.

Catalpol as a Component of Rehmannia glutinosa Protects Spinal Cord Injury by Inhibiting Endoplasmic Reticulum Stress-Mediated Neuronal Apoptosis

Disturbance of the internal environment in the spinal cord after spinal cord injury (SCI) is an important cause of the massive death of neurons in the injury area and one of the major problems that lead to the difficult recovery of motor function in patients. Rehmannia glutinosa, a famous traditional Chinese medicine, is commonly used in neurodegenerative diseases, whereas an iridoid glycoside extract of catalpol (CAT), with antioxidant, antiapoptotic, and neuroprotective pharmacological effects. However, the neuroprotective and anti-apoptosis mechanism of CAT in SCI remains unclear. In our study, we found that CAT has a restorative effect on the lower limb motor function of rats with SCI by establishing a rat model of SCI and treating CAT gavage for 30 days. Our study further found that CAT has the effect of inhibiting apoptosis and protecting neurons, and the action pathway may reduce endoplasmic reticulum (ER) stress by inhibiting CHOP and GRP78 expression and then reduce apoptosis and protect neurons through the Caspase3/Bax/Bcl-2 pathway. In conclusion, we demonstrated that CAT can treat SCI by inhibiting ER stress-mediated neuronal apoptosis and has the potential to be a clinical drug for the treatment of SCI.

Photobiomodulation reduces hippocampal apoptotic cell death and produces a Raman spectroscopic “signature”

Apoptotic cell death within the brain represents a significant contributing factor to impaired post-traumatic tissue function and poor clinical outcome after traumatic brain injury. After irradiation with light in the wavelength range of 600–1200 nm (photobiomodulation), previous investigations have reported a reduction in apoptosis in various tissues. This study investigates the effect of 660 nm photobiomodulation on organotypic slice cultured hippocampal tissue of rats, examining the effect on apoptotic cell loss. Tissue optical Raman spectroscopic changes were evaluated. A significantly higher proportion of apoptotic cells 62.8±12.2% vs 48.6±13.7% (P<0.0001) per region were observed in the control group compared with the photobiomodulation group. After photobiomodulation, Raman spectroscopic observations demonstrated 1440/1660 cm-1 spectral shift. Photobiomodulation has the potential for therapeutic utility, reducing cell loss to apoptosis in injured neurological tissue, as demonstrated in this in vitro model. A clear Raman spectroscopic signal was observed after apparent optimal irradiation, potentially integrable into therapeutic light delivery apparatus for real-time dose metering.

Nerve growth factor loaded macrophage-derived nanovesicles for inhibiting neuronal apoptosis after spinal cord injury

Spinal cord injury (SCI) is an extremely destructive central nervous system lesion. Studies have shown that NGF can promote nerve regeneration after SCI. However, it cannot produce the desired effect due to its stability in the body and is difficulty in passing through the blood-brain barrier. In this study, we prepared nanovesicles derived from macrophage membrane encapsulating NGF (NGF-NVs) as a drug carrier for the treatment of SCI. Cell experiments showed that NGF-NVs were effectively taken up by PC12 cells and inhibited neuronal apoptosis. In vivo imaging experiments, a large quantity of NGF was delivered to the injured site with the aid of the good targeting of NVs. In animal experiments, NGF-NVs improved the survival of neurons by significantly activating the PI3K/AKT signaling pathway and had good behavioral and histological recovery effects after SCI. Therefore, NVs are a potential drug delivery vector for SCI therapy.

Critical Role of p38 in Spinal Cord Injury by Regulating Inflammation and Apoptosis in a Rat Model

STUDY DESIGN

To evaluate the effect of p38 pathway on spinal cord injury (SCI), a rat model of SCI was performed.

OBJECTIVE

We determined the effect of p38 on SCI and SCI related inflammation, apoptosis, and autophagy.

SUMMARY OF BACKGROUND DATA

SCI is a severe clinical problem worldwide. It is difficult to prevent cell necroptosis and promote the survival of residual neurons after SCI. p38, a class of mitogen-activated protein kinases, its effect on SCI and SCI related inflammation, apoptosis, and autophagy have not been studied very well.

METHODS

The rats were randomly divided into the following four groups: the sham-operated (sham) group, the SCI group, the SCI + vehicle group, and the SCI + SB203580 (10 mg/kg) group. The p38 inhibitor SB203580 was administered by oral (10 mg/kg/d) gavage once per day for 14 days. Neurological recovery was assessed using the Basso, Beattie, and Bresnahan locomotion rating scale. Apoptosis, autophagy, and inflammation related proteins were measured by enzyme-linked immunosorbent assay kits or western blotting.

RESULTS

Our results showed that p38 was upregulated after SCI from day 3, which was paralleled with the levels of its proteins ATF-2, suggesting an increase in p38 activity. Our results showed administration of SB203580 attenuated histopathology and promoted locomotion recovery in rats after SCI. SB203580 administration significantly inhibited inflammatory cytokines levels as well as the inflammation signaling pathway. SB203580 administration also modulated the apoptosis and autophagy signaling pathway.

CONCLUSION

Our findings suggest that p38 inhibitor SB203580 treatment alleviates secondary SCI by inhibiting inflammation and apoptosis, thereby promoting neurological and locomoter functional recovery, thus suggest the important role of p38 in neuronal protection after SCI.

LEVEL OF EVIDENCE

N/A.

MGMT-Mediated neuron Apoptosis in Injured Rat Spinal Cord

Spinal cord injury (SCI) induces a series of endogenous biochemical changes that lead to secondary degeneration, including apoptosis. The aim of this study was to investigate the potential effect and mechanism of action of MGMT in strengthing neuronal apoptosis following SCI. To determine MGMT-mediated apoptosis in spinal cord injury, we performed western blot and analyzed the expression change of MGMT with different timepoints. Western blot analysis showed the upregulation of MGMT has a peak at 21 days in injured spinal cord tissues. Expression and location was observed in the neurons after SCI. Upregulation of p53, Bax, cleaved caspase3 and cleaved caspase9 and downregulation of Bcl2 were detected after SCI. Co-localization of cleaved caspase3 with MGMT indicated MGMT involved in apoptosis taking place after SCI. In addition, we carried out H₂O₂ stimulation to further confirm MGMT played a role in neuron apoptosis process and activated p53 signaling pathway in vitro. Finally, based above data, we packaged lenti-associated virus inhibit MGMT expression and injected into rat spinal cords after SCI model was built. LV-MGMT not only reduces the neuron apoptosis, but also increases GAP43 expression and promotes hindlimbs locomotor function recovery. Taken together, the in vivo data and the in vitro observations prove MGMT-mediated apoptosis in the injured spinal cord.

GSK-3 Inhibitor Promotes Neuronal Cell Regeneration and Functional Recovery in a Rat Model of Spinal Cord Injury

The reparative process following spinal cord injury (SCI) is extremely complicated. Cells in the microenvironment express multiple inhibitory factors that affect axonal regeneration over a prolonged period of time. The axon growth inhibitory factor glycogen synthase kinase-3 (GSK-3) is an important factor during these processes. TDZD-8 (4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione) is the most effective and specific non-ATP-competitive inhibitor of GSK-3. Here, we show that administering TDZD-8 after SCI was associated with significantly inhibited neuronal apoptosis, upregulated GAP-43 expression, increased density of cortical spinal tract fibers around areas of injury, and increased Basso, Beattie, and Bresnahan (BBB) scores in the lower limbs. These findings support the notion that GSK-3 inhibitors promote neuronal cell regeneration and lower limb functional recovery.

Polymer scaffolds facilitate spinal cord injury repair

During the past decades, improving patient neurological recovery following spinal cord injury (SCI) has remained a challenge. An effective treatment for SCI would not only reduce fractured elements and isolate developing local glial scars to promote axonal regeneration but also ameliorate secondary effects, including inflammation, apoptosis, and necrosis. Three-dimensional (3D) scaffolds provide a platform in which these mechanisms can be addressed in a controlled manner. Polymer scaffolds with favorable biocompatibility and appropriate mechanical properties have been engineered to minimize cicatrization, customize drug release, and ensure an unobstructed space to promote cell growth and differentiation. These properties make polymer scaffolds an important potential therapeutic platform. This review highlights the recent developments in polymer scaffolds for SCI engineering. STATEMENT OF SIGNIFICANCE: How to improve the efficacy of neurological recovery after spinal cord injury (SCI) is always a challenge. Tissue engineering provides a promising strategy for SCI repair, and scaffolds are one of the most important elements in addition to cells and inducing factors. The review highlights recent development and future prospects in polymer scaffolds for SCI therapy. The review will guide future studies by outlining the requirements and characteristics of polymer scaffold technologies employed against SCI. Additionally, the peculiar properties of polymer materials used in the therapeutic process of SCI also have guiding significance to other tissue engineering approaches.

Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

There is growing recognition of the kyphotic clivo-axial angle (CXA) as an index of risk of brainstem deformity and craniocervical instability. This review of literature and prospective pilot study is the first to address the potential correlation between correction of the pathological CXA and postoperative clinical outcome. The CXA is a useful sentinel to alert the radiologist and surgeon to the possibility of brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographically manifest as a kyphotic CXA, underwent correction of deformity (normalization of the CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessed preoperatively and at one, three, six, and twelve months after surgery, using established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, and Karnofsky Index. Parametric and non-parametric statistical tests were performed to correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screws adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinical metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinical improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Upregulation of PTP1B After Rat Spinal Cord Injury

Protein tyrosine phosphatase 1B (PTP1B), a member of the protein tyrosine phosphatase family, attaches to the endoplasmic reticulum (ER) via its C-terminal tail. Previous studies have reported that PTP1B participates in various signal transduction pathways in many human diseases, including diabetes, cancers, osteoporosis, and obesity. It also plays an important role in the ER stress. ER stress induced by spinal cord injury (SCI) was reported to result in cell apoptosis. Till now, the role of PTP1B in the injury of the central nervous system remains unknown. In the present study, we built an adult rat SCI model to investigate the potential role of PTP1B in SCI. Western blot analysis detected a notable alteration of PTP1B expression after SCI. Immunohistochemistry indicated that PTP1B expressed at a low level in the normal spinal cord and greatly increased after SCI. Double immunofluorescence staining revealed that PTP1B immunoreactivity was predominantly increased in neurons following SCI. In addition, SCI resulted in a significant alteration in the level of active caspase-3, caspase-12, and 153/C/EBP homologous transcription factor protein, which were correlated with the upregulation of PTP1B. Co-localization of PTP1B/active caspase-3 was also detected in neurons. Taken together, our findings elucidated the PTP1B expression in the SCI for the first time. These results suggested that PTP1B might be deeply involved in the injury response and probably played an important role in the neuro-pathological process of SCI.

EphB3 receptors function as dependence receptors to mediate oligodendrocyte cell death following contusive spinal cord injury

We demonstrate that EphB3 receptors mediate oligodendrocyte (OL) cell death in the injured spinal cord through dependence receptor mechanism. OLs in the adult spinal cord express EphB3 as well as other members of the Eph receptor family. Spinal cord injury (SCI) is associated with tissue damage, cellular loss and disturbances in EphB3-ephrinB3 protein balance acutely (days) after the initial impact creating an environment for a dependence receptor-mediated cell death to occur. Genetic ablation of EphB3 promotes OL survival associated with increased expression of myelin basic protein and improved locomotor function in mice after SCI. Moreover, administration of its ephrinB3 ligand to the spinal cord after injury also promotes OL survival. Our in vivo findings are supported by in vitro studies showing that ephrinB3 administration promotes the survival of both oligodendroglial progenitor cells and mature OLs cultured under pro-apoptotic conditions. In conclusion, the present study demonstrates a novel dependence receptor role of EphB3 in OL cell death after SCI, and supports further development of ephrinB3-based therapies to promote recovery.

Gelatin Nanostructured Lipid Carriers Incorporating Nerve Growth Factor Inhibit Endoplasmic Reticulum Stress-Induced Apoptosis and Improve Recovery in Spinal Cord Injury

Clinical translation of growth factor therapies faces multiple challenges; the most significant one is the short half-life of the naked protein. Gelatin nanostructured lipid carriers (GNLs) had previously been used to encapsulate the basic fibroblast growth factor to enhance the functional recovery in hemiparkinsonian rats. In this research, we comparatively study the enhanced therapy between nerve growth factor (NGF) loaded GNLs (NGF-GNLs) and NGF only in spinal cord injury (SCI). The effects of NGF-GNLs and NGF only were tested by the Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test, and footprint analysis. Western blot analysis and immunofluorescent staining were further performed to identify the expression of ER stress-related proteins, neuron-specific marker neuronal nuclei (NeuN), and growth-associated protein 43 (GAP43). Correlated downstream signals Akt/GSK-3β and ERK1/2 were also analyzed with or without inhibitors. Results showed that NGF-GNLs, compared to NGF only, enhanced the neuroprotection effect in SCI rats. The ER stress-induced apoptosis response proteins CHOP, GRP78 and caspase-12 inhibited by NGF-GNL treatment were more obvious. Meanwhile, NGF-GNLs in the recovery of SCI are related to the inhibition of ER stress-induced cell death via the activation of downstream signals PI3K/Akt/GSK-3β and ERK1/2.

The Effects of Difumarate Salt S-15176 after Spinal Cord Injury in Rats

Objective

In the present study we analyzed neuroprotective and antiapoptotic effect of the difumarate salt S-15176, as an anti-ischemic, an antioxidant and a stabilizer of mitochondrial membrane in secondary damage following spinal cord injury (SCI) in a rat model.

Methods

Three groups were performed with 30 Wistar rats; control (1), trauma (2), and a trauma+S-15176 (10 mg/kg i.p., dimethyl sulfoxide) treatment (3). SCI was performed at the thoracic level using the weight-drop technique. Spinal cord tissues were collected following intracardiac perfusion in 3rd and 7th days of posttrauma. Hematoxylin and eosin staining for histopatology, terminal deoxynucleotidyl transferase dUTP nick end labeling assay for apoptotic cells and immunohistochemistry for proapoptotic cytochrome-c, Bax and caspase 9 were performed to all groups. Functional recovery test were applied to each group in 3rd and 7th days following SCI.

Results

In trauma group, edematous regions, diffuse hemorrhage, necrosis, leukocyte infiltration and severe degeneration in motor neurons were observed prominently in gray matter. The number of apoptotic cells was significantly higher (p<0.05) than control group. In the S-15176-treated groups, apoptotic cell number in 3rd and 7th days (p<0.001), also cytochrome-c (p<0.001), Bax (p<0.001) and caspase 9 immunoreactive cells (p<0.001) were significantly decreased in number compared to trauma groups. Hemorrhage and edema in the focal areas were also noticed in gray matter of treatment groups. Results of the locomotor test were significantly increased in treatment group (p<0.05) when compared to trauma groups.

Conclusion

We suggest that difumarate salt S-15176 prevents mitochondrial pathways of apoptosis and protects spinal cord from secondary injury and helps to preserve motor function following SCI in rats.

Acute administration of ucf-101 ameliorates the locomotor impairments induced by a traumatic spinal cord injury

Secondary death of neural cells plays a key role in the physiopathology and the functional consequences of traumatic spinal cord injury (SCI). Pharmacological manipulation of cell death pathways leading to the preservation of neural cells is acknowledged as a main therapeutic goal in SCI. In the present work, we hypothesize that administration of the neuroprotective cell-permeable compound ucf-101 will reduce neural cell death during the secondary damage of SCI, increasing tissue preservation and reducing the functional deficits. To test this hypothesis, we treated mice with ucf-101 during the first week after a moderate contusive SCI. Our results reveal that ucf-101 administration protects neural cells from the deleterious secondary mechanisms triggered by the trauma, reducing the extension of tissue damage and improving motor function recovery. Our studies also suggest that the effects of ucf-101 may be mediated through the inhibition of HtrA2/OMI and the concomitant increase of inhibitor of apoptosis protein XIAP, as well as the induction of ERK1/2 activation and/or expression. In vitro assays confirm the effects of ucf-101 on both pathways as well as on the reduction of caspase cascade activation and apoptotic cell death in a neuroblastoma cell line. These results suggest that ucf-101 can be a promising therapeutic tool for SCI that deserves more detailed analyses.

Nerve growth factor improves functional recovery by inhibiting endoplasmic reticulum stress-induced neuronal apoptosis in rats with spinal cord injury

Background

Endoplasmic reticulum (ER) stress-induced apoptosis plays a major role in various diseases, including spinal cord injury (SCI). Nerve growth factor (NGF) show neuroprotective effect and improve the recovery of SCI, but the relations of ER stress-induced apoptosis and the NGF therapeutic effect in SCI still unclear.

Methods

Young adult female Sprague-Dawley rats’s vertebral column was exposed and a laminectomy was done at T9 vertebrae and moderate contusion injuries were performed using a vascular clip. NGF stock solution was diluted with 0.9% NaCl and administered intravenously at a dose of 20 μg/kg/day after SCI and then once per day until they were executed. Subsequently, the rats were executed at 1d, 3 d, 7d and 14d. The locomotor activities of SCI model rats were tested by the 21-point Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test and footprint analysis. In addition, Western blot analysis was performed to identify the expression of ER-stress related proteins including CHOP, GRP78 and caspase-12 both in vivo and in vitro. The level of cell apoptosis was determined by TUNEL in vivo and Flow cytometry in vitro. Relative downstream signals Akt/GSK-3β and ERK1/2were also analyzed with or without inhibitors in vitro.

Results

Our results demonstrated that ER stress-induced apoptosis was involved in the injury of SCI model rats. NGF administration improved the motor function recovery and increased the neurons survival in the spinal cord lesions of the model rats. NGF decreases neuron apoptosis which measured by TUNEL and inhibits the activation of caspase-3 cascade. The ER stress-induced apoptosis response proteins CHOP, GRP78 and caspase-12 are inhibited by NGF treatment. Meanwhile, NGF administration also increased expression of growth-associated protein 43 (GAP43). The administration of NGF activated downstream signals Akt/GSK-3β and ERK1/2 in ER stress cell model in vitro.

Conclusion

The neuroprotective role of NGF in the recovery of SCI is related to the inhibition of ER stress-induced cell death via the activation of downstream signals, also suggested a new trend of NGF translational drug development in the central neural system injuries which involved in the regulation of chronic ER stress.

Modulatory effects of l-carnitine on tamoxifen toxicity and oncolytic activity

The aim of this study was to investigate the protective effect of l-carnitine (l-CAR) in tamoxifen (TAM)-induced toxicity and antitumor activity. Adult female rats were randomly divided into four groups. Group I was served as control, groups II and III were treated with TAM (10 mg/kg, periorally) and l-CAR (300 mg/kg, intraperitoneally), respectively, while group IV was treated with both compounds. The treatment continued daily for 28 days. Administration of TAM resulted in significant increase in serum lipid profiles, liver enzymes, and bilirubin level. TAM produced a significant increase in lipid peroxides (LPO) level and nonsignificant change in nitrogen oxide (NO( x)) level accompanied with significant decrease in superoxide dismutase (SOD) activity of hepatic and uterus tissues and significant decrease in glutathione (GSH) content of uterus tissue. Administration of l-CAR for 1 h prior to TAM treatment decreased serum lipids and liver enzymes significantly and significantly increased SOD activity in liver and uterus tissues compared with TAM-treated group. Furthermore, it restored LPO and GSH levels and increased NO( x) level in uterus tissue. DNA fragmentation and the apoptotic marker, caspase-3, were not detected in the liver of all treated groups. Histopathologically, alterations in the liver and uterus structures after TAM treatment, which was attenuated after l-CAR administration. The antitumor effect and survival of the combined treatment of Ehrlich ascites carcinoma (EAC)-bearing mice was less than each one alone. l-CAR interestingly increased survival rate of EAC-bearing mice more than TAM-treated group. In conclusion, l-CAR has beneficial effects regarding TAM toxicity; however, it interferes with its antitumor effect.

Neuroprotective effects of perflurocarbon (oxycyte) after contusive spinal cord injury

Spinal cord injury (SCI) often results in irreversible and permanent neurological deficits and long-term disability. Vasospasm, hemorrhage, and loss of microvessels create an ischemic environment at the site of contusive or compressive SCI and initiate the secondary injury cascades leading to progressive tissue damage and severely decreased functional outcome. Although the initial mechanical destructive events cannot be reversed, secondary injury damage occurs over several hours to weeks, a time frame during which therapeutic intervention could be achieved. One essential component of secondary injury cascade is the reduction in spinal cord blood flow with resultant decrease in oxygen delivery. Our group has recently shown that administration of fluorocarbon (Oxycyte) significantly increased parenchymal tissue oxygen levels during the usual postinjury hypoxic phase, and fluorocarbon has been shown to be effective in stroke and head injury. In the current study, we assessed the beneficial effects of Oxycyte after a moderate-to-severe contusion SCI was simulated in adult Long-Evans hooded rats. Histopathology and immunohistochemical analysis showed that the administration of 5 mL/kg of Oxycyte perfluorocarbon (60% emulsion) after SCI dramatically reduced destruction of spinal cord anatomy and resulted in a marked decrease of lesion area, less cell death, and greater white matter sparing at 7 and 42 days postinjury. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining showed a significant reduced number of apoptotic cells in Oxycyte-treated animals, compared to the saline group. Collectively, these results demonstrate the potential neuroprotective effect of Oxycyte treatment after SCI, and its beneficial effects may be, in part, a result of reducing apoptotic cell death and tissue sparing. Further studies to determine the most efficacious Oxycyte dose and its mechanisms of protection are warranted.

The retrograde delivery of adenovirus vector carrying the gene for brain-derived neurotrophic factor protects neurons and oligodendrocytes from apoptosis in the chronically compressed spinal cord of twy/twy mice

STUDY DESIGN

The twy/twy mouse undergoes spontaneous chronic mechanical compression of the spinal cord; this in vivo model system was used to examine the effects of retrograde adenovirus (adenoviral vector [AdV])-mediated brain-derived neurotrophic factor (BDNF) gene delivery to spinal neural cells.

OBJECTIVE

To investigate the targeting and potential neuroprotective effect of retrograde AdV-mediated BDNF gene transfection in the chronically compressed spinal cord in terms of prevention of apoptosis of neurons and oligodendrocytes.

SUMMARY OF BACKGROUND DATA

Several studies have investigated the neuroprotective effects of neurotrophins, including BDNF, in spinal cord injury. However, no report has described the effects of retrograde neurotrophic factor gene delivery in compressed spinal cords, including gene targeting and the potential to prevent neural cell apoptosis.

METHODS

AdV-BDNF or AdV-LacZ (as a control gene) was injected into the bilateral sternomastoid muscles of 18-week old twy/twy mice for retrograde gene delivery via the spinal accessory motor neurons. Heterozygous Institute of Cancer Research mice (+/twy), which do not undergo spontaneous spinal compression, were used as a control for the effects of such compression on gene delivery. The localization and cell specificity of β-galactosidase expression (produced by LacZ gene transfection) and BDNF expression in the spinal cord were examined by coimmunofluorescence staining for neural cell markers (NeuN, neurons; reactive immunology protein, oligodendrocytes; glial fibrillary acidic protein, astrocytes; OX-42, microglia) 4 weeks after gene injection. The possible neuroprotection afforded by retrograde AdV-BDNF gene delivery versus AdV-LacZ-transfected control mice was assessed by scoring the prevalence of apoptotic cells (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells) and immunoreactivity to active caspases -3, -8, and -9, p75, neurofilament 200 kD (NF), and for the oligodendroglial progenitor marker, NG2. RESULTS.: Four weeks after injection, the retrograde delivery of the LacZ marker gene was identified in cervical spinal neurons and some glial cells, including oligodendrocytes in the white matter of the spinal cord, in both the twy/twy mouse and the heterozygous Institute of Cancer Research mouse (+/twy). In the compressed spinal cord of twy/twy mouse, AdV-BDNF gene transfection resulted in a significant decrease in the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells present in the spinal cord and a downregulation in the caspase apoptotic pathway compared with AdV-LacZ (control) gene transfection. There was a marked and significant increase in the areas of the spinal cord of AdV-BDNF-injected mice that were NF- and NG2-immunopositive compared with AdV-LacZ-injected mice, indicating the increased presence of neurons and oligodendrocytes in response to BDNF transfection.

CONCLUSION

Our results demonstrate that targeted retrograde BDNF gene delivery suppresses apoptosis in neurons and oligodendrocytes in the chronically compressed spinal cord of twy/twy mouse. Further work is required to establish whether this method of gene delivery may provide neuroprotective effects in other situations of compressive spinal cord injury.

Protective effect of Withania somnifera against radiation-induced hepatotoxicity in rats

The aim of this study was to investigate the protective effect of root extract of Withania somnifera (WS) against gamma-irradiation-induced oxidative stress and DNA damage in hepatic tissue after whole body gamma-irradiation. Fourty male albino rats were divided into four groups. In the control group, rats were administered vehicle by tube for 7 consecutive days. The second group were administered WS (100mg/kg, by gavage) for 7 consecutive days. Animals in the third group were administered vehicle by tube for 7 consecutive days, then exposed to single dose gamma-irradiation (6 Gy). The fourth group received WS for 7 consecutive days, one hour later rats were exposed to gamma-irradiation. Irradiation hepatotoxicity was manifested biochemically by an increase in hepatic serum enzymes, significant elevation in levels of malondialdehyde (MDA) and total nitrate/nitrite NO(x), significant increase in heme oxygenase activity (HO-1), as well as a significant decrease in reduced glutathione (GSH) content and the activities of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) in hepatic tissues. Marked DNA damage was observed. WS pretreatment showed significant decrease in serum hepatic enzymes, hepatic NO(x) and MDA levels and DNA damage, significant HO-1 induction and significant increase in SOD, GSHPx activities and GSH content compared to irradiated group. These observations suggest that WS could be developed as a potential preventive drug for ionizing irradiation induced hepatotoxicity disorders via enhancing the antioxidant activity and induction of HO-1.

The delayed post-injury administration of soluble fas receptor attenuates post-traumatic neural degeneration and enhances functional recovery after traumatic cervical spinal cord injury

Spinal cord injury (SCI) is a devastating condition that currently lacks clinically-relevant and effective neuroprotective therapeutic options. Optimal therapeutic agents for clinical translation should show efficacy in a cervical compression/contusion model using a clinically-relevant post-injury therapeutic time window. To date, few compounds have met that rigorous standard. The objective of this work was to evaluate the efficacy of delayed post-injury administration of soluble Fas receptor (sFasR) via intrathecal catheter following acute cervical SCI in a clinically-relevant contusion/compression model. Female Wistar rats were given a C7-T1 moderately severe clip compression injury, followed by either 8-h or 24-h delayed treatment initiation. Long-term neurobehavioral analysis of motor recovery and neuropathic pain development was undertaken. The extent of oligodendrocyte and neuron survival was assessed in peri-lesional cord sections 8 weeks post-SCI. This was complemented by an evaluation of the level of tissue preservation at and adjacent to the site of injury. In animals treated with sFasR delayed 8 h post-injury, significant behavioral effects were observed, coinciding with enhanced cell survival, peri-lesional tissue sparing, and enhanced integrity of descending fiber tracts compared to control treatments. Animals treated with sFasR delayed by 24 h showed more modest improvements in behavioral recovery, and had consistent improvements in cell survival and tissue preservation. This work has shown for the first time that the Fas-mediated apoptotic pathway can be therapeutically targeted in a clinically-relevant time window post-SCI.

Apoptosis of neurons and oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy): possible pathomechanism of human cervical compressive myelopathy

Introduction

Cervical compressive myelopathy is the most serious complication of cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) and the most frequent cause of spinal cord dysfunction. There is little information on the exact pathophysiological mechanism responsible for the progressive loss of neural tissue in the spinal cord of such patients. In this study, we used the spinal hyperostotic mouse (twy/twy) as a suitable model of human spondylosis, and OPLL to investigate the cellular and molecular changes in the spinal cord. Mutant twy/twy mouse developed ossification of the ligamentum flavum at C2–C3 and exhibited progressive paralysis.

Materials and methods

The mutant twy/twy mice, aged 16 and 24 weeks, were used in the present study. The cervical spinal cord was analyzed histologically and immunohistochemically.

Results

We observed that a significant correlation between the proportion of apoptotic oligodendrocytes in the compressed area of the spinal cord and the magnitude of cord compression. Immunohistochemical analysis indicated overexpression of TNFR1, CD95, and p75^NTR in the twy/twy mice, which was localized by the immunofluorescence in the neurons and oligodendrocytes.

Conclusion

The expression of such factors seems to play at least some role in the apoptotic process, which probably contributes to axonal degeneration and demyelination in the twy/twy mice spinal cords with severe compression.

Electronic supplementary material

The online version of this article (doi:10.1007/s00586-011-2025-x) contains supplementary material, which is available to authorized users.

Mechanostasis in apoptosis and medicine

Mechanostasis describes a complex and dynamic process where cells maintain equilibrium in response to mechanical forces. Normal physiological loading modes and magnitudes contribute to cell proliferation, tissue growth, differentiation and development. However, cell responses to abnormal forces include compensatory apoptotic mechanisms that may contribute to the development of tissue disease and pathological conditions. Mechanotransduction mechanisms tightly regulate the cell response through discrete signaling pathways. Here, we provide an overview of links between pro- and anti-apoptotic signaling and mechanotransduction signaling pathways, and identify potential clinical applications for treatments of disease by exploiting mechanically-linked apoptotic pathways.

Tumor necrosis factor-α antagonist reduces apoptosis of neurons and oligodendroglia in rat spinal cord injury

STUDY DESIGN

To examine the effects of a tumor necrosis factor (TNF)-α antagonist (etanercept) on rat spinal cord injury and identify a possible mechanism for its action.

OBJECTIVE

To elucidate the contribution of etanercept to the pathologic cascade in spinal cord injury and its possible suppression of neuronal and oligodendroglial apoptosis.

SUMMARY OF BACKGROUND DATA

Etanercept has been recently used successfully for treatment of inflammatory disorders. However, only a few studies have examined its role in suppressing neuronal and oligodendroglial apoptosis in spinal cord injury.

METHODS

Etanercept or saline (control) was administered by intraperitoneal injection 1 hour after thoracic spinal cord injury in rats. The expressions and localizations of TNF-α, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2) were examined by immunoblot and immunohistochemical analyses. Spinal cord tissue damage between saline- and etanercept-treated groups was also compared after hematoxylin-eosin and luxol fast blue (LFB) staining. The Basso-Beattie-Bresnahan (BBB) scale was used to evaluate rat locomotor function after etanercept administration. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were counted and the immunoreactivity to active caspase-3 and caspase-8 was examined after etanercept administration.

RESULTS

Immunoblot and double immunofluorescence staining revealed suppression of TNF-α, TNFR1, and TNFR2 expression after administration of etanercept in the acute phase of spinal cord injury. LFB staining demonstrated potential myelination in the etanercept-treated group from 2 week after spinal cord injury, together with an increased BBB locomotor score. Double immunofluorescence staining showed a significant decrease in TUNEL-positive neurons and oligodendroglia from 12 hour to 1 week in the gray and white matters after etanercept administration. Immunoblot analysis demonstrated overexpression of activated caspase-3 and caspase-8 after spinal cord injury, which was markedly inhibited by etanercept.

CONCLUSION

Our results indicated that etanercept reduces the associated tissue damage of spinal cord injury, improves hindlimb locomotor function, and facilitates myelin regeneration. This positive effect of etanercept on spinal cord injury is probably attributable to the suppression of TNF-α, TNFR1, TNFR2, and activated caspase-3 and caspase-8 overexpressions, and the inhibition of neuronal and oligodendroglial apoptosis.

Overexpression of glucose-regulated protein 94 after spinal cord injury in rats

Glucose-regulated protein (GRP) 94 is a member of the stress protein family, which is localized in the endoplasmic reticulum (ER). Spinal cord injury (SCI) induced ER stress that results in apoptosis. However, the role of GRP94 in injury of the central nervous system remains unknown. In this study, we performed SCI in adult rats and investigated acutely the protein expression and cellular localization of GRP94 in the spinal cord. Western blot analysis revealed that GRP94 was low in normal spinal cord. It rose at 6h after SCI, peaked at 1 day, remained for another 3 days, then declined to basal levels at 5 days after injury. Immunohistochemistry further confirmed that GRP94 immunoactivity was expressed at low levels in gray matter and white matter in normal condition and increased after SCI. Double immunofluorescence staining showed that GRP94 was co-expressed with NeuN (neuronal marker), and GFAP (astroglial marker). In addition, caspase-12, caspase-3 and phospho-c-Jun NH2-kinase (p-JNK) levels increased at 6h, peaked at 1day, and then gradually reduced to normal levels for 2 weeks after SCI by western blot analysis. Co-localization of GRP94/caspase-12 and GRP94/p-JNK was detected in neurons and glial cells. Taken together, these data suggest GRP94 involvement in the injury response of the adult spinal cord of the rats.

Molecular Mechanisms Underlying Cell Death in Spinal Networks in Relation to Locomotor Activity After Acute Injury in vitro

Understanding the pathophysiological changes triggered by an acute spinal cord injury is a primary goal to prevent and treat chronic disability with a mechanism-based approach. After the primary phase of rapid cell death at the injury site, secondary damage occurs via autodestruction of unscathed tissue through complex cell-death mechanisms that comprise caspase-dependent and caspase-independent pathways. To devise novel neuroprotective strategies to restore locomotion, it is, therefore, necessary to focus on the death mechanisms of neurons and glia within spinal locomotor networks. To this end, the availability of in vitro preparations of the rodent spinal cord capable of expressing locomotor-like oscillatory patterns recorded electrophysiologically from motoneuron pools offers the novel opportunity to correlate locomotor network function with molecular and histological changes long after an acute experimental lesion. Distinct forms of damage to the in vitro spinal cord, namely excitotoxic stimulation or severe metabolic perturbation (with oxidative stress, hypoxia/aglycemia), can be applied with differential outcome in terms of cell types and functional loss. In either case, cell death is a delayed phenomenon developing over several hours. Neurons are more vulnerable to excitotoxicity and more resistant to metabolic perturbation, while the opposite holds true for glia. Neurons mainly die because of hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) with subsequent DNA damage and mitochondrial energy collapse. Conversely, glial cells die predominantly by apoptosis. It is likely that early neuroprotection against acute spinal injury may require tailor-made drugs targeted to specific cell-death processes of certain cell types within the locomotor circuitry. Furthermore, comparison of network size and function before and after graded injury provides an estimate of the minimal network membership to express the locomotor program.

Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis

Background:

Chiari malformation, functional cranial settling and subtle forms of basilar invagination result in biomechanical neuraxial stress, manifested by bulbar symptoms, myelopathy and headache or neck pain. Finite element analysis is a means of predicting stress due to load, deformity and strain. The authors postulate linkage between finite element analysis (FEA)-predicted biomechanical neuraxial stress and metrics of neurological function.

Methods:

A prospective, Internal Review Board (IRB)-approved study examined a cohort of 5 children with Chiari I malformation or basilar invagination. Standardized outcome metrics were used. Patients underwent suboccipital decompression where indicated, open reduction of the abnormal clivo-axial angle or basilar invagination to correct ventral brainstem deformity, and stabilization/ fusion. FEA predictions of neuraxial preoperative and postoperative stress were correlated with clinical metrics.

Results:

Mean follow-up was 32 months (range, 7-64). There were no operative complications. Paired t tests/ Wilcoxon signed-rank tests comparing preoperative and postoperative status were statistically significant for pain, bulbar symptoms, quality of life, function but not sensorimotor status. Clinical improvement paralleled reduction in predicted biomechanical neuraxial stress within the corticospinal tract, dorsal columns and nucleus solitarius.

Conclusion:

The results are concurrent with others, that normalization of the clivo-axial angle, fusion-stabilization is associated with clinical improvement. FEA computations are consistent with the notion that reduction of deformative stress results in clinical improvement. This pilot study supports further investigation in the relationship between biomechanical stress and central nervous system (CNS) function.

Synergistic effect of melatonin on exercise-induced neuronal reconstruction and functional recovery in a spinal cord injury animal model

Nitric oxide (NO) may aggravate neuronal damage after spinal cord injury (SCI). We hypothesized that NO produced by inducible nitric oxide synthase (iNOS) accelerates secondary damage to spinal tissue, which may be reversed by the neuroprotectant, melatonin. This study investigated the effects of combination therapy with melatonin (10 mg/kg) and exercise (10 m/min) on recovery from SCI caused by contusion. We examined locomotor recovery, iNOS gene expression, autophagic and apoptotic signaling, including Beclin-1, LC3, p53 and IKKalpha protein expression and histological alterations in the ventral horn of the spinal cord. Melatonin in combination with exercise resulted in significantly increased hindlimb movement (P < 0.05), a reduced level of iNOS mRNA (P < 0.05) and more motor neurons in the ventral horn, versus control SCI and SCI plus exercise alone, with no effect on the other signaling molecules examined. This study shows that combined therapy with melatonin and exercise reduces the degree of secondary damage associated with SCI in rats and supports the possible use of melatonin in combination with exercise to reduce the side effects related to exercise-induced fatigue and impairment.

Targeted retrograde gene delivery of brain-derived neurotrophic factor suppresses apoptosis of neurons and oligodendroglia after spinal cord injury in rats

STUDY DESIGN

Histologic and immunohistochemical studies after targeted retrograde adenovirus (AdV)-mediated brain-derived neurotrophic factor (BDNF) gene delivery via intramuscular injection in rats with injured spinal cord.

OBJECTIVE

To investigate the neuroprotective effect of targeted retrograde AdV-BDNF gene transfection in the traumatically injured spinal cord in terms of prevention of apoptosis of neurons and oligodendrocytes.

SUMMARY OF BACKGROUND DATA

Several studies investigated the neuroprotective effects of neurotrophins including BDNF on spinal cord injury, with respect to prevention of neural cell apoptosis in injured spinal cord. However, no report has described the potential effect of targeted retrograde neurotrophic factor gene delivery in injured spinal cord on prevention of neural cell apoptosis.

METHODS

AdV-BDNF or AdV-LacZ was used for retrograde delivery via bilateral sternomastoid muscles to the spinal accessory motoneurons immediately after spinal cord injury in rats. Localization of beta-galactosidase expression produced by LacZ gene or AdV-BDNF gene transfection was examined by immunofluorescence staining and double staining of cell markers (NeuN, RIP, GFAP, OX-42, and NG2) in the injured spinal cord. TUNEL-positive cells were counted and immunoreactivity to active caspase-3 and NG2 was examined after gene injection.

RESULTS

Retrograde delivery of LacZ marker gene was identified in cervical spinal neurons and glial cells including oligodendrocytes in the white matter.AdV-BDNF transfection resulted in a significant decrease in the number of TUNEL-positive apoptotic cells by downregulating the caspase apoptotic pathway, with significant promotion of NG2 expression in injured spinal cord, compared with AdV-LacZ injection.

CONCLUSION

Our results suggest that targeted retrograde BDNF gene delivery suppresses apoptosis of neurons and oligodendrocytes in the injured rat spinal cord.

Tumor necrosis factor-alpha and its receptors contribute to apoptosis of oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy) sustaining chronic mechanical compression

STUDY DESIGN.: To examine the distribution of apoptotic cells and expression of tumor necrosis factor (TNF)-alpha and its receptors in the spinal hyperostotic mouse (twy/twy) with chronic cord compression using immunohistochemical methods. OBJECTIVE.: To study the mechanisms of apoptosis, particularly in oligodendrocytes, which could contribute to degenerative change and demyelination in chronic mechanical cord compression. SUMMARY OF BACKGROUND DATA.: TNF-alpha acts as an external signal initiating apoptosis in neurons and oligodendrocytes after spinal cord injury. Chronic spinal cord compression caused neuronal loss, myelin destruction, and axonal degeneration. However, the biologic mechanisms of apoptosis in chronically compressed spinal cord remain unclear. METHODS.: The cervical spinal cord of 34 twy mice aged 20 to 24 weeks and 11 control animals were examined. The apoptotic cells were detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) staining. The expression and the localization of TNF-alpha, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2) were examined using immunoblot and immnohistochemical analysis. RESULTS.: The number of TUNEL-positive cells in the white matter increased with the severity of compression, which was further increased bilaterally in the white matter of twy/twy mice. Double immunofluorescence staining showed that the number of cells positive for TUNEL and RIP, a marker of oligodendrocytes, increased in the white matter with increased severity of cord compression. Immunoblot analysis demonstrated overexpression of TNF-alpha, TNFR1, and TNFR2 in severe compression. The expression of TNF-alpha appeared in local cells including microglia while that of TNFR1 and TNFR2 was noted in apoptotic oligodendrocytes. CONCLUSION.: Our results suggested that the proportion of apoptotic oligodendrocytes, causing spongy axonal degeneration and demyelination, correlated with the magnitude of cord compression and that overexpression of TNF-alpha, TNFR1, and TNFR2 seems to participate in apoptosis of such cells in the chronically compressed spinal cord.

Spinal cord decompression reduces rat neural cell apoptosis secondary to spinal cord injury

OBJECTIVE

To determine whether spinal cord decompression plays a role in neural cell apoptosis after spinal cord injury.

STUDY DESIGN

We used an animal model of compressive spinal cord injury with incomplete paraparesis to evaluate neural cell apoptosis after decompression. Apoptosis and cellular damage were assessed by staining with terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) and immunostaining for caspase-3, Bcl-2 and Bax.

METHODS

Experiments were conducted in male Sprague-Dawley rats (n=78) weighing 300-400 g. The spinal cord was compressed posteriorly at T10 level using a custom-made screw for 6 h, 24 h or continuously, followed by decompression by removal of the screw. The rats were sacrificed on Day 1 or 3 or in Week 1 or 4 post-decompression. The spinal cord was removed en bloc and examined at lesion site, rostral site and caudal site (7.5 mm away from the lesion).

RESULTS

The numbers of TUNEL-positive cells were significantly lower at the site of decompression on Day 1, and also at the rostral and caudal sites between Day 3 and Week 4 post-decompression, compared with the persistently compressed group. The numbers of cells between Day 1 and Week 4 were immunoreactive to caspase-3 and B-cell lymphoma-2 (Bcl-2)-associated X-protein (Bax), but not to Bcl-2, correlated with those of TUNEL-positive cells.

CONCLUSION

Our results suggest that decompression reduces neural cell apoptosis following spinal cord injury.

Therapeutic efficacy of Ac-DMQD-CHO, a caspase 3 inhibitor, for rat spinal cord injury

We investigated the therapeutic efficacy of Ac-DMQD-CHO, a caspase-3 inhibitor, and functional recovery in spinal cord injury in a rat model. Thirty rats were randomized into three groups of 10 each. In groups 2 and 3, spinal cord trauma was produced in the thoracic region. Group 3 rats were treated with Ac-DMQD-CHO. Treatment responses were evaluated based on histopathological and TUNEL staining findings at 24 h and 5 days post-injury. Neurologic performance was assessed during and following treatment. Twenty-four hours after injury, light microscopy examination revealed diffuse hemorrhagic necrosis, edema, vascular thrombi, and polymorphonuclear leukocyte infiltration in group 2 and 3 rats, but cavitation and demyelinization were less prominent in group 3. At this time point, treatment of the rats with Ac-DMQD-CHO significantly reduced the number of apoptotic cells. Traumatic injury to the spinal cord causes apoptosis and administration of Ac-DMQD-CHO decreases apoptosis and improves functional outcome.

Neuroprotective effects of Ac.YVAD.cmk on experimental spinal cord injury in rats

BACKGROUND

Apoptosis as a cell death mechanism is important in numerous diseases, including traumatic SCI. We evaluated the neuroprotective effects of Ac.YVAD.cmk and functional outcomes in a rat SCI model.

METHODS

Thirty rats were randomized into 3 groups of 10: sham-operated, trauma only, and trauma plus Ac.YVAD.cmk treatment. Trauma was produced in the thoracic region by a weight-drop technique. Group 3 rats received Ac.YVAD.cmk (1 mg/kg, ip) 1 minute after trauma. The rats were killed at 24 hours and 5 days after injury. Efficacy was evaluated with light microscopy and TUNEL staining. Functional outcomes were assessed with the inclined plane technique and a modified version of the Tarlov grading system.

RESULTS

At 24 hours postinjury, the respective mean number of apoptotic cells in groups 1, 2, and 3 were 0, 5.26 +/- 0.19, and 0.97 +/- 0.15. Microscopic examination of group 2 tissues showed widespread hemorrhage, edema, necrosis, and polymorphic nuclear leukocyte infiltration and vascular thrombi. Group 3 tissues revealed similar features, but cavitation and demyelination were less prominent than those in group 2 samples at this period. At 5 days postinjury, the respective mean inclined plane angles in groups 1, 2, and 3 were 65.5 +/- 2.09, 42.00 +/- 2.74, and 52.5 +/- 1.77. Motor grading of animals revealed a similar trend. These differences were statistically significant (P < .05).

CONCLUSIONS

Ac.YVAD.cmk inhibited posttraumatic apoptosis in a rat SCI model. This may provide the basis for development of new therapeutic strategies for the treatment of SCI.

Temporal and spatial profiles of cell loss after spinal cord injury: Reduction by a metalloporphyrin

This study presents quantitative temporal and spatial profiles of neuronal loss and apoptosis following a contusion spinal cord injury (50 g . cm). The profiles were evaluated by counting the cresol violet-stained surviving cells and the total number of TUNEL-positive cells and of TUNEL-positive neurons in sections 0- 4 mm from the epicenter and 1, 6, 12, 24, 48, and 72 hr and 1 week postinjury. We demonstrated that neurons continue to disappear over 1 week postinjury and that neuronal loss shifts to areas longer distances from the epicenter over time. TUNEL-positive cells in both gray and white matter appeared after 6 hr, gradually increased to a peak level after 48 hr, and declined by 72 hr postinjury. TUNEL-positive neurons peaked earlier and were present for 1 week, although the total number of neurons was reduced significantly by the end of the week. The neuronal loss and apoptosis were partially prevented by a metalloporphyrin [Mn(III) tetrakis (4-benzoic acid) porphyrin (MnTBAP)]. We demonstrated that MnTBAP (10 and 50 mg/kg, given intraperitoneally) significantly reduced neuronal death in the sections 1-2.5 mm rostral and 1 mm caudal from the epicenter compared with that in the vehicle-treated group, suggesting MnTBAP is more effective in the sections rostral than in those caudal to the epicenter. MnTBAP (10 mg/kg) significantly reduced the number of TUNEL-positive neurons in the sections 1 mm caudal from the epicenter. Our profiles provide a database for pharmacological intervention, and our results on MnTBAP treatment support an important role for antioxidant therapy in spinal cord injury.

Protective effect of N-acetylcysteine against radiation induced DNA damage and hepatic toxicity in rats

The present study was designed to evaluate the radioprotective effect of N- acetylcysteine (NAC) on gamma-radiation induced toxicity in hepatic tissue in rat. The cellular changes were estimated using malondialdehyde (MDA, an index of lipid peroxidation), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), reduced glutathione (GSH), and total nitrate/nitrite (NO(x)) as markers of hepatic oxidative stress in rats following gamma-irradiation. The DNA damage was determined by agarose gel electrophoresis. To achieve the ultimate goal of this study, 40 adult rats were randomly divided into 4 groups of 10 animals each. Group I was injected intraperitoneally with saline solution for 7 consecutive days and served as control group. Group II was irradiated with a single dose of 6Gy gamma-radiation. Group III was daily injected with NAC (1g/kg, i.p.) for 7 consecutive days. Group IV received a daily i.p. injection of NAC (1g/kg, i.p.) for 7 consecutive days and 1h after the last dose, rats were irradiated with a single dose (6Gy) gamma-radiation. The animals were sacrificed after 24h. DNA damage was observed in tissue after total body irradiation with a single dose of 6Gy. Malondialdehyde and total nitrate/nitrite were increased significantly whereas the levels of GSH and antioxidant enzymes were significantly decreased in gamma-irradiated group. Pretreatment with NAC showed a significant decrease in the levels of MDA, NO(x) and DNA damage. The antioxidant enzymes increased significantly along with the levels of GSH. Moreover, histopathological examination of liver tissues confirmed the biochemical data. Thus, our results show that pretreatment with N-acetylcysteine offers protection against gamma-radiation induced cellular damage.

Umbilical cord blood stem cell mediated downregulation of fas improves functional recovery of rats after spinal cord injury

Human umbilical cord blood stem cells (hUCB), due to their primitive nature and ability to develop into nonhematopoietic cells of various tissue lineages, represent a potentially useful source for cell-based therapies after spinal cord injury (SCI). To evaluate their therapeutic potential, hUCB were stereotactically transplanted into the injury epicenter, one week after SCI in rats. Our results show the presence of a substantial number of surviving hUCB in the injured spinal cord up to five weeks after transplantation. Three weeks after SCI, apoptotic cells were found especially in the dorsal white matter and gray matter, which are positive for both neuron and oligodendrocyte markers. Expression of Fas on both neurons and oligodendrocytes was efficiently downregulated by hUCB. This ultimately resulted in downregulation of caspase-3 extrinsic pathway proteins involving increased expression of FLIP, XIAP and inhibition of PARP cleavage. In hUCB-treated rats, the PI3K/Akt pathway was also involved in antiapoptotic actions. Further, structural integrity of the cytoskeletal proteins alpha-tubulin, MAP2A&2B and NF-200 has been preserved in hUCB treatments. The behavioral scores of hind limbs of hUCB-treated rats improved significantly than those of the injured group, showing functional recovery. Taken together, our results indicate that hUCB-mediated downregulation of Fas and caspases leads to functional recovery of hind limbs of rats after SCI.

Spinal cord injury induces endoplasmic reticulum stress with different cell-type dependent response

The mechanisms of injury-induced apoptosis of neurons within the spinal cord are poorly understood. In this study, we show that spinal cord injury (SCI) induces endoplasmic reticulum stress revealed by the activation of an unbalanced unfolded protein response (UPR). Using a weight-drop contusion model of SCI, the UPR activation was characterized by a quick transient phosphorylation of alpha subunit of eukaryotic initiation factor 2 soon restored by the up-regulation of its regulator Gadd34; an effective cleavage/activation of the ATF6alpha transcription factor leading to up-regulation of the canonical UPR target genes Chop, Xbp1 and Grp78; the presence of the processing of Xbp1 mRNA indicative of inositol requiring kinase 1 activation, and a gradual accumulation of C/EBP homologous transcription factor protein (CHOP) with concomitant caspase-12 activation. Interestingly, the subcellular distribution of CHOP was found in the nucleus of neurons and oligodendrocytes but in the cytoplasm of astrocytes. Considering the pro-apoptotic action attributed to this transcription factor, this phenomenon might account for the different susceptibility of cell types to dye after SCI.

Mesenchymal stem cells from rat bone marrow downregulate caspase-3-mediated apoptotic pathway after spinal cord injury in rats

Mesenchymal stem cells have been intensively studied for their potential use in reparative strategies for neurodegenerative diseases and traumatic injuries. We used mesenchymal stem cells (rMSC) from rat bone marrow to evaluate the therapeutic potential after spinal cord injury (SCI). Immunohistochemistry confirmed a large number of apoptotic neurons and oligodendrocytes in caudal segments 2 mm away from the lesion site. Expression of caspase-3 on both neurons and oligodendrocytes after SCI was significantly downregulated by rMSC. Caspase-3 downregulation by rMSC involves increased expression of FLIP and XIAP in the cytosol and inhibition of PARP cleavage in the nucleus. Animals treated with rMSC had higher Basso, Beattie, Bresnahan (BBB) locomotor scoring and better recovery of hind limb sensitivity. Treatment with rMSC had a positive effect on behavioral outcome and histopathological assessment after SCI. The ability of rMSC to incorporate into the spinal cord, differentiate and to improve locomotor recovery hold promise for a potential cure after SCI.

Changes in nitric oxide synthase expression in young and adult rats after spinal cord injury

OBJECTIVE

To examine the clinical meaning of the changes in nitric oxide synthase (NOS) expression and activity after spinal cord injury (SCI) according to the age of the experiment animal.

MATERIAL AND METHOD

Ten 5- and 16-week-old Sprague-Dawley rats were laminectomized at T10 and SCI induced at this level using a New York impactor. Outcome measures to assess SCI utilized the Basso-Beatti-Bresnahan scale to quantitate hind limb motor dysfunction as a functional outcome measure. NOS isoforms (nNOS, neuronal NOS; iNOS, inducible NOS; and eNOS, endothelial NOS) were also immunolocalized in sections of control and spinal cord injury in the two sample groups using specific monoclonal antibodies. Student's t-test evaluated the difference between the young and adult rats, and P<0.05 was considered as significant value.

RESULT

As the expression of nNOS on the spinal gray matter of the adult rat decreased, eNOS activity increased. Different from the adult rat, expression of the nNOS in the young rat was maintained until 1 day after SCI, and compared with the adult rat; eNOS activity was increased in the vessels from the damaged gray matter area after 7 days of SCI. iNOS expression was maintained until the 7th day of SCI on the adult rat, but iNOS expression after 7 days of SCI on young rat decreased. The young rat showed relatively less motor disability on the hind limb when compared with the adult rat, and had a rapid recovery.

CONCLUSION

Neural protective eNOS activity increased after SCI in the young rat, and neural destructive iNOS expression was more remarkable in the adult rat.

Preventive effect of erythropoietin on spinal cord cell apoptosis following acute traumatic injury in rats

STUDY DESIGN

Using a rat spinal cord injury (SCI) model, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), anti-active caspase-3 antibody staining, histological examination, and histochemical studies were used to examine the antiapoptotic effect of erythropoietin.

OBJECTIVE

To evaluate in detail the antiapoptotic effect of erythropoietin following SCI.

SUMMARY OF BACKGROUND DATA

Although some investigators have reported antiapoptotic effects of erythropoietin using the TUNEL method, it has not been determined whether erythropoietin can prevent both acute neuronal death and secondary injury. Therefore, we examined the temporal and spatial effects of erythropoietin using TUNEL and active caspase-3 following SCI.

METHODS

An in vitro study used a cerebrocortical culture in which the antiapoptotic effect of erythropoietin was examined after N-methyl-D-aspartate treatment. Using an in vivo study, rats with SCI received erythropoietin intraperitoneally, and were examined histologically and immunohistochemically with TUNEL, active caspase-3, and cell markers between 6 hours and 7 days after injury.

RESULTS

Cerebrocortical culture confirmed an antiapoptotic effect of erythropoietin. Erythropoietin treatment significantly decreased TUNEL-positive apoptotic neurons and oligodendrocytes as early as 6 hours after SCI in rats. This antiapoptotic effect was observed until 7 days after injury. In addition, erythropoietin treatment significantly decreased the number of active caspase-3 immunoreactive cells within the SCI. In the in vitro study, cerebrocortical culture confirmed an antiapoptotic effect of erythropoietin.

CONCLUSIONS

These findings suggest that exogenous erythropoietin decreases the number of apoptotic cells observed between the very early and subchronic stages following traumatic SCI.

Apoptotic cell death following traumatic injury to the central nervous system

Apoptotic cell death is a fundamental and highly regulated biological process in which a cell is instructed to actively participate in its own demise. This process of cellular suicide is activated by developmental and environmental cues and normally plays an essential role in eliminating superfluous, damaged, and senescent cells of many tissue types. In recent years, a number of experimental studies have provided evidence of widespread neuronal and glial apoptosis following injury to the central nervous system (CNS). These studies indicate that injury-induced apoptosis can be detected from hours to days following injury and may contribute to neurological dysfunction. Given these findings, understanding the biochemical signaling events controlling apoptosis is a first step towards developing therapeutic agents that target this cell death process. This review will focus on molecular cell death pathways that are responsible for generating the apoptotic phenotype. It will also summarize what is currently known about the apoptotic signals that are activated in the injured CNS, and what potential strategies might be pursued to reduce this cell death process as a means to promote functional recovery.

FAS deficiency reduces apoptosis, spares axons and improves function after spinal cord injury

After spinal cord injury (SCI), apoptosis of neurons and oligodendrocytes is associated with axonal degeneration and loss of neurological function. Recent data have suggested a potential role for FAS death receptor-mediated apoptosis in the pathophysiology of SCI. In this study, we examined the effect of FAS deficiency on SCI in vitro and in vivo. FAS(Lpr/lpr) mutant mice and wildtype background-matched mice were subjected to a T5-6 clip compression SCI, and complementary studies were done in an organotypic slice culture model of SCI. Post-traumatic apoptosis in the spinal cord, which was seen in neurons and oligodendrocytes, was decreased in the FAS-deficient mice both in vivo and in vitro particularly in oligodendrocytes. FAS deficiency was also associated with improved locomotor recovery, axonal sparing and preservation of oligodendrocytes and myelin. However, FAS deficiency did not result in a significant increase in surviving neurons in the spinal cord at 6 weeks after injury, likely reflecting the importance of other cell death mechanisms for neurons. We conclude that inhibition of the FAS pathway may be a clinically attractive neuroprotective strategy directed towards oligodendroglial and axonal preservation in the treatment of SCI and neurotrauma.

The neuroprotective effects of z-DEVD.fmk, a caspase-3 inhibitor, on traumatic spinal cord injury in rats

BACKGROUND

Apoptosis is one of the most important forms of cell death seen in a variety of physiological and pathological conditions, including traumatic injuries. This type of cell death occurs via mediators known as caspases. Previous studies have investigated the roles that apoptosis and different caspases play in the pathogenesis of secondary damage after spinal cord injury (SCI). The aim of this research was to assess the neuroprotective effect of z-DEVD.fmk, a caspase-3 inhibitor, in a rat model of SCI.

METHODS

Forty-five Wistar albino rats were studied in 3 groups of 15 animals: sham-operated control animals (group 1); trauma-only control animals (group 2); and rats subjected to trauma + z-DEVD.fmk treatment (group 3). Spinal cord injury was produced at the thoracic level using the weight-drop technique. Responses to injury and the efficacy of z-DEVD.fmk were assessed by light microscopy and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining in cord tissues collected at 4 and 24 hours posttrauma. Five rats from each group were used to assess functional recovery at 7 days after SCI. The functional evaluations were done using the inclined-plane technique and a modified Tarlov motor grading scale.

RESULTS

At 4 hours postinjury, the mean apoptotic index in groups 1, 2, and 3 was 0, 33.01+/-6.62, and 16.40+/-4.91, respectively. The group 3 count was significantly lower than the group 2 count (P<.01). At 24 hours postinjury, light microscopic examination of group 2 tissues showed widespread hemorrhage, necrosis, polymorphonuclear leukocyte infiltration, and vascular thrombi. The group 3 tissues showed similar features. The prominent findings in group 2 were hemorrhage and necrosis, whereas the prominent findings in group 3 were focal hemorrhage and leukocyte infiltration. The mean inclined-plane angles in groups 1, 2, and 3 were 64.5 degrees+/-1.0 degrees, 41.5 degrees+/-1.3 degrees, and 47 degrees+/-2.0 degrees, respectively. Motor scale results in all groups showed a similar trend.

CONCLUSION

Local application of z-DEVD.fmk after SCI in rats reduces secondary tissue injury and helps preserve motor function. These effects can be explained by inhibition of apoptotic death in all cell types in the spinal cord.

Molecular targets in spinal cord injury

The spinal cord can be compared to a highway connecting the brain with the different body levels lying underneath, with the axons being the ultimate carriers of the electrical impulse. After spinal cord injury (SCI), many cells are lost because of the injury. To reconstitute function, damaged axons from surviving neurons have to grow through the lesion site to their initial targets. However, the territory they have to traverse has changed: the highway is full of inhibitory signals (myelin and scar components); the pavement itself has become bumpy (demyelination); and specialized cells are recruited to clear the way (inflammatory cells). Thus, actual strategies to treat spinal injuries aim at providing a permissive environment for regenerating axons and boosting the endogenous potential of axons to regenerate while limiting progression of secondary damage. Here we review some of the strategies currently under consideration to treat spinal injuries.

Neuroprotection and functional recovery after application of the caspase-9 inhibitor z-LEHD-fmk in a rat model of traumatic spinal cord injury

OBJECT

Apoptosis is considered one of the most significant mechanisms in the pathogenesis of neuronal damage after spinal cord injury (SCI). This form of cell death occurs via mediators known as caspases. The aim of this study was to evaluate the neuroprotective effect of the caspase-9 inhibitor, z-LEHD-fmk, in a rat model of spinal cord trauma.

METHODS

Fifty-four Wistar albino rats were studied in the following three groups of 18 animals each: sham-operated controls (Group 1); trauma-only controls (Group 2); and trauma combined with z-LEHD-fmk-treated animals (0.8 microM/kg; Group 3). Spinal cord injury was produced at the thoracic level by using the weight-drop technique. Responses to SCI and the efficacy of z-LEHD-fmk treatment were determined on the basis of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining and light and electron microscopy findings in cord tissue at 24 hours and 7 days posttrauma. Six rats from each group were also assessed for functional recovery at 3 and 7 days after SCI. This was conducted using the inclined-plane technique and a modified version of the Tarlov motor grading scale. At 24 hours postinjury, light microscopic examination of Group 2 tissue samples showed hemorrhage, edema, necrosis, polymorphonuclear leukocyte infiltration, and vascular thrombi. Those obtained in Group 3 rats at this stage showed similar features. At 24 hours postinjury, the mean apoptotic cell count in Group 2 was significantly higher than that in Group 3 (90.25 +/- 2.6 and 50.5 +/- 1.9, respectively; p < 0.05). At 7 days postinjury, the corresponding mean apoptotic cell counts were 49 +/- 2.1 and 17.7 +/- 2.6, also a significant difference (p < 0.05). Electron microscopy findings confirmed the occurrence of programmed cell death in different cell types in the spinal cord and showed that z-LEHD-fmk treatment protected neurons, glia, myelin, axons, and intracellular organelles.

CONCLUSIONS

Examination of the findings in this rat model of SCI revealed that apoptosis occurs not only in neurons and astrocytes but also in oligodendrocytes and microglia. Furthermore, immediate treatment with the caspase-9 inhibitor z-LEHD-fmk blocked apoptosis effectively and was associated with better functional outcome. More in-depth research of the role of programmed cell death in spinal cord trauma and further study of the ways in which caspases are involved in this process may lead to new strategies for treating SCI.