OBJECTIVES: Spinal cord ischemia-reperfusion injury (SCIRI) remains a major challenge in the field of organ protection due to the lack of effective prevention and therapeutic strategies. Hyperglycemia, a common perioperative condition, contributes to neurological injury via multiple mechanisms. However, its role and underlying mechanism in SCIRI are still unclear. This study aims to investigate the involvement of the precursor of brain-derived neurotrophic factor (proBDNF) in hyperglycemia-induced SCIRI in mice. METHODS: Eight-week-old male C57BL/6 mice were randomly assigned to a control group (Vehicle) or a diabetes mellitus (DM) group. The DM group was established using intraperitoneal injection of streptozotocin (STZ) combined with 10% sucrose water. The Vehicle group received an equal volume of 50 mmol/L sodium citrate buffer (pH 4.5). Fasting blood-glucose levels ≥11.1 mmol/L were considered successful DM modeling. Both Vehicle and DM groups underwent SCIRI modeling via descending aortic clamping, while the Sham group underwent a sham procedure without aortic occlusion. Lower limb motor function was assessed using the Basso Mouse Scale (BMS) and its subscale (sub-BMS). Locomotor activity was evaluated using an open field test. Immunohistochemistry was performed to detect changes in neuronal nuclear protein (NeuN) and proBDNF expression in spinal cord tissues. Real-time reverse transcription polymerase chain reaction (RT-PCR) was used to measure mRNA expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). To explore the effect of proBDNF inhibition, diabetic mice were divided into groups: A DM+SCIRI+monoclonal anti-proBDNF antibody (McAb-proB) group received an intraperitoneal injection of 100 μg of McAb-proB 30 minutes before SCIRI modeling, and a DM+SCIRI+Vehicle group received an equal amount of isotype immunoglobulin G. BMS and sub-BMS scores were recorded, and the gene expression of inflammatory cytokines mentioned above were evaluated. RESULTS: Compared with the Vehicle+SCIRI group, the DM+SCIRI group showed significantly reduced BMS and sub-BMS scores, decreased NeuN expression, shorter total movement distance, slower locomotion, increased proBDNF expression, and elevated IL-1β, IL-6, and TNF-α mRNA levels (all P<0.05 or P<0.01). Compared with the DM+SCIRI+Vehicle group, the DM+SCIRI+McAb-proB group exhibited significantly improved BMS and sub-BMS scores and decreased mRNA expression of IL-1β, IL-6, and TNF-α (all P<0.05 or P<0.01). CONCLUSIONS Hyperglycemia exacerbates neural injury and inflammatory response in SCIRI through upregulation of proBDNF expression, delaying motor functional recovery. Antagonizing proBDNF expression can alleviate neurological damage and promote functional recovery in diabetic mice after SCIRI.
Animals ; Male ; Hyperglycemia/metabolism* ; Brain-Derived Neurotrophic Factor/genetics* ; Mice, Inbred C57BL ; Reperfusion Injury/metabolism* ; Mice ; Diabetes Mellitus, Experimental/metabolism* ; Inflammation/metabolism* ; Disease Models, Animal ; Spinal Cord/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Protein Precursors/genetics* ; Spinal Cord Ischemia/metabolism* ; Interleukin-6/metabolism* ; Interleukin-1beta/metabolism*

OBJECTIVE: The purpose of this study was to determine whether xenon post-conditioning affects mTOR signaling as well as endoplasmic reticulum stress (ERS)-apoptosis pathway in rats with spinal cord ischemia/reperfusion injury. METHODS: Fifty male rats were randomized equally into sham-operated group (Sham group), I/R model group (I/R group), I/R model+ xenon post-conditioning group (Xe group), I/R model+rapamycin (a mTOR signaling pathway inhibitor) treatment group (I/R+ Rapa group), and I/R model + xenon post- conditioning with rapamycin treatment group (Xe + Rapa group).. In the latter 4 groups, SCIRI was induced by clamping the abdominal aorta for 85 min followed by reperfusion for 4 h. Rapamycin (or vehicle) was administered by daily intraperitoneal injection (4 mg/kg) for 3 days before SCIRI, and xenon post-conditioning by inhalation of 1∶1 mixture of xenon and oxygen for 1 h at 1 h after initiation of reperfusion; the rats without xenon post-conditioning were given inhalation of nitrogen and oxygen (1∶ 1). After the reperfusion, motor function and histopathologic changes in the rats were examined. Western blotting and real-time PCR were used to detect the protein and mRNA expressions of GRP78, ATF6, IRE1α, PERK, mTOR, p-mTOR, Bax, Bcl-2 and caspase-3 in the spinal cord. RESULTS: The rats showed significantly lowered hind limb motor function following SCIRI (P < 0.01) with a decreased count of normal neurons, increased mRNA and protein expressions of GRP78, ATF6, IRE1α, PERK, and caspase-3, and elevated p-mTOR/mTOR ratio and Bax/Bcl-2 ratio (P < 0.01). Xenon post-conditioning significantly decreased the mRNA and protein levels of GRP78, ATF6, IRE1α, PERK and caspase-3 (P < 0.05 or 0.01) and reduced p-mTOR/mTOR and Bax/Bcl-2 ratios (P < 0.01) in rats with SCIRI; the mRNA contents and protein levels of GRP78 and ATF6 were significantly decreased in I/R+Rapa group (P < 0.01). Compared with those in Xe group, the rats in I/R+Rapa group and Xe+Rapa had significantly lowered BBB and Tarlov scores of the hind legs (P < 0.01), and caspase-3 protein level and Bax/Bcl-2 ratio were significantly lowered in Xe+Rapa group (P < 0.05 or 0.01). CONCLUSION By inhibiting ERS and neuronal apoptosis, xenon post- conditioning may have protective effects against SCIRI in rats. The mTOR signaling pathway is partially involved in this process.
Animals ; Apoptosis ; Caspase 3/metabolism* ; Endoplasmic Reticulum Stress ; Endoribonucleases/pharmacology* ; Injections, Intraperitoneal ; Male ; Neurons/pathology* ; Nitrogen/metabolism* ; Oxygen/metabolism* ; Protein Serine-Threonine Kinases ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; RNA, Messenger/metabolism* ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury/metabolism* ; Sirolimus/pharmacology* ; Spinal Cord Ischemia/pathology* ; TOR Serine-Threonine Kinases/metabolism* ; Xenon/therapeutic use* ; bcl-2-Associated X Protein/metabolism*

OBJECTIVETo study the effect of adenosine preconditioning on cell apoptosis and expressions of glucose-regulated protein (GRP-78) and cysteinyl aspartate-specific protease 12 (caspase-12) in rats with spinal cord ischemia-reperfusion injury.

METHODSTwenty-seven rats were randomized into 3 equal groups and subjected to sham operation (group A), spinal cord ischemia-reperfusion injury (group B), or ischemia-reperfusion injury with adenosine treatment. Spinal cord ischemia-reperfusion injury was induced by cross-clamping of the abdominal aorta inferior to the left renal artery. The spinal cord function was assessed using the Modified Tarlov Scale at 6, 12, and 24 h after reperfusion. At 24 h after reperfusion, histological analysis was carried out with HE staining; cell apoptosis and viability were determined with TUNEL staining, and the expressions of GRP-78 and caspase-12 proteins were determined with Western blotting.

RESULTSHE staining of the spinal cord showed extensive spinal cord injury such as cell edema in group B as compared with group C. Compared with group A, group B showed a significantly increased number of apoptotic cells; the number of apoptotic cells in group B was greater than that in group C. Compared with group B, group C showed significantly increased GRP-78 expression (P<0.01) and decreased caspase-12 expression (P<0.01).

CONCLUSIONAdenosine can up-regulate GRP-78 expression and down-regulate caspase-12 expression, and protects the spinal cord against ischemia-reperfusion injury by inhibiting cell apoptosis.

Adenosine ; pharmacology ; Animals ; Apoptosis ; drug effects ; Caspase 12 ; metabolism ; Heat-Shock Proteins ; metabolism ; Ischemic Preconditioning ; methods ; Male ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; metabolism ; Spinal Cord Ischemia ; metabolism

The effects of tacrolimus postconditioning on protein-serine-threonine kinases (Akt) phosphorylation and apoptotic cell death in rats after spinal cord ischemia-reperfusion injury were investigated. Ninety male SD rats were randomly divided into sham operation group, ischemia-reperfusion group and tacrolimus postconditioning group. The model of spinal cord ischemia was established by means of catheterization through femoral artery and balloon dilatation. The spinal cord was reperfused 20 min after ischemia via removing saline out of balloon. The corresponding spinal cord segments were excised and determined for Akt activity in spinal cord tissue by using Western blotting at 5, 15, and 60 min after reperfusion respectively. Spinal cord tissue sections were stained immunohistochemically for detection of the phosphorylated Akt expression at 15 min after reperfusion. Flow cytometry was applied to assess apoptosis of neural cells, and dry-wet weights method was employed to measure water content in spinal cord tissue at 24 h after reperfusion. The results showed that the activities of Akt in tarcolimus postconditioning group were significantly higher than those in ischemia-reperfusion group at 5, 15, and 60 min after reperfusion (P<0.05, P<0.01). The Akt activities reached the peak at 15 min after reperfusion in ischemia-reperfusion group and tacrolimus postconditioning group. The percentage of apoptotic cells and water content in spinal cord tissue were significantly reduced (P<0.01) in tacrolimus postconditioning group as compared with those in ischemia-reperfusion group at 24 h after reperfusion. It is concluded that tacrolimus post-conditioning can increase Akt activity in spinal cord tissue of rats, inhibit apoptosis of neural cells as well as tissue edema, and thereby alleviate spinal cord ischemia-reperfusion injury.
Animals ; Apoptosis ; drug effects ; Immunosuppressive Agents ; pharmacology ; therapeutic use ; Male ; Phosphorylation ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; drug therapy ; metabolism ; Spinal Cord ; drug effects ; metabolism ; pathology ; Spinal Cord Ischemia ; drug therapy ; metabolism ; Tacrolimus ; pharmacology ; therapeutic use ; Up-Regulation

BACKGROUNDLittle is known about neuronal death mechanisms following spinal cord ischemia. The present study aimed to investigate the protective effect of pentoxifylline (PTX) against spinal cord ischemia/reperfusion (I/R) injury.

METHODSRabbits sustained spinal cord ischemia following 45 minutes cross-clamping of the infrarenal aorta. Experimental groups were as follows: the first group of animals (sham, n = 8) underwent laparotomy alone and served as the sham group; the second group (I/R, n = 20) received carrier (3 ml saline solution) and served as the control group; the third group (PTX-A, n = 20) received PTX intravenously 10 minutes prior to ischemia; and the fourth group (PTX-B, n = 20) received PTX intravenously at the onset of reperfusion. Rabbits were evaluated for hind-limb motor function with the Tarlov scoring system at 48 hours. Serum was assayed with enzyme-linked immunosorbent assay for tumor necrosis factor alpha (TNF-alpha) and spinal cords were harvested for myeloperoxidase (MPO) activity, histopathological analysis, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling staining, platelet/endothelial cell adhesion molecule-1 (PECAM-1) and caspase-3 immunohistochemistry, and the number of necrotic and apoptotic neuron were counted and data analyzed at 12, 24, 48 and 72 hours of reperfusion. Spinal cords were studied by electron microscopy.

RESULTSImproved Tarlov scores were seen in PTX-treated rabbits as compared with ischemic control rabbits at 48 hours. A significant reduction was found in TNF-alpha in serum, activity of MPO and immunoreactivity of the PECAM-1 and caspase-3 in PTX-treated rabbits. There were fewer apoptotic neurons than necrotic neurons (P < 0.05). A significant decrease in both necrotic and apoptotic neurons was observed in the PTX-treated groups (PTX-A and PTX-B) compared with the I/R group (P < 0.05). Both necrotic and apoptotic neurons were found with the electron microscope.

CONCLUSIONSPTX may induce protection against ischemia injury in the spinal cord, thereby preventing both necrosis and apoptosis. A major mode of cell death in spinal cord ischemia/reperfusion injury is necrosis while apoptosis is not dominant.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Immunohistochemistry ; In Situ Nick-End Labeling ; Microscopy, Electron, Transmission ; Necrosis ; Pentoxifylline ; pharmacology ; therapeutic use ; Rabbits ; Reperfusion Injury ; prevention & control ; Spinal Cord ; blood supply ; pathology ; ultrastructure ; Spinal Cord Ischemia ; prevention & control ; Vasodilator Agents ; pharmacology ; therapeutic use

OBJECTIVETo study the effects of Ginkgo biloba extract (GBE) on lipid peroxidation and apoptosis after spinal cord ischemia/reperfusion (I/R) in rabbits.

METHODSSpinal cord I/R injury model was established according to the description of Erten et al. A total of 27 New Zealand white rabbits were divided into three groups randomly: a sham group (9 rabbits treated with sham operation but without aortic occlusion), a model group (9 rabbits treated with aortic occlusion and volume-matched saline), and a GBE group (9 rabbits treated with aortic occlusion and Ginaton (100 mg/kg) injected 30 minutes before aortic clamping and at the onset of reperfusion). The neurological outcomes were evaluated at 24 and 48 hours after reperfusion, respectively. The spinal cord malondialdehyde (MDA) level, superoxide dismutase (SOD) were then detected. Neural cell apoptosis was determined by terminal deoxynucleotidyl t-ransferase (TdT)-mediated dUTP-fluorescence nick end labeling (TUNEL) method and the expression of bcl-2 and bax were examined histologically in the spinal cord with immunohistochemistry.

RESULTSI/R produced a significant decrease in neurological scoring. The motor scores of the GBE group were significantly higher than those of the model group at 24 and 48 hours after reperfusion (P<0.05). Compared with the model group, GBE ameliorated the down-regulation of SOD and produced a significant reduction of the MDA level (P<0.01). The positive cells for TUNEL in the model group were much more than those of the GBE group (P<0.01). The bcl-2 was up-regulated after I/R, especially in the GBE group (P<0.01). The up-regulation of bax was greatly diminished by GBE (P<0.01).

CONCLUSIONSGBE has protective effects against spinal cord I/R injury, and the mechanism may be that it can scavenge oxygen free radicals and inhibit the apoptosis of neural cells.

Animals ; Apoptosis ; drug effects ; Ginkgo biloba ; Lipid Peroxidation ; drug effects ; Malondialdehyde ; analysis ; Neuroprotective Agents ; therapeutic use ; Phytotherapy ; Plant Extracts ; therapeutic use ; Rabbits ; Reperfusion ; Spinal Cord ; drug effects ; pathology ; Spinal Cord Ischemia ; metabolism ; pathology ; Superoxide Dismutase ; analysis

OBJECTIVETo evaluate effect of ischemic pretreatment on expression of heat shock protein 70 (HSP70) and injury of spinal cord in canine.

METHODSFourty-one canine were divided into three groups: the sham-operative group, the pretreatment group and the control group. In the pretreatment group aorta was obstructed for 6 min, and then was opened for 6 min, this procedure was repeated twice, finally aorta was obstructed for 35 min. In the control group aorta was obstructed for 35 min. Nervous function were assessed and HSP70 expression were detected in tissue of spinal cord.

RESULTSIn the pretreatment group, HSP70 expressed in cytoplasm and nucleus at 6, 24 hour after reperfusion, and intensity of HSP70 expression was stronger than that in the control group; The score of nervous function in the pretreatment group was higher than that in the control group. On 7 day after reperfusion the score of nervous function in pretreatment group had no obvious variation, and HSP70 expression was still observed.

CONCLUSIONSIschemic pretreatment can improve ischemic tolerance of spinal cord; HSP70 expression in cytoplasm and nucleus may play a role in ischemic tolerance.

Animals ; Disease Models, Animal ; Dogs ; Female ; HSP70 Heat-Shock Proteins ; metabolism ; physiology ; Ischemic Preconditioning ; Male ; Reperfusion Injury ; prevention & control ; Spinal Cord ; metabolism ; Spinal Cord Injuries ; prevention & control ; Spinal Cord Ischemia ; physiopathology ; prevention & control

OBJECTIVETo study the sequential changes of HIF-1alpha (hypoxia-inducible factor 1 alpha) in experimental spinal cord injury in rats and to analyze its potential effects in SCI.

METHODSA static compression model of SCI was employed in this study. Expressions of HIF-1alpha were measured with immunohistochemical staining, while flow cytometry was used to determine the apoptotic ratio and bcl-2 expressions.

RESULTSHIF-1alpha began to increase 1 day after injury, and reached the peak at 3-7 days. Two weeks later, it declined significantly. The sequential changes of HIF-1alpha coincided well with the alterations of apoptotic ratio and contents of bcl-2.

CONCLUSIONSHIF-1alpha possibly participates in the secondary ischemic and hypoxic procedures after spinal cord injury, and may mediate the traumatic apoptosis. Further understanding of HIF-1alpha may provide new therapeutic regimens for SCI.

Animals ; Apoptosis ; Biomarkers ; analysis ; DNA-Binding Proteins ; analysis ; metabolism ; Disease Models, Animal ; Female ; Flow Cytometry ; Hypoxia-Inducible Factor 1 ; Hypoxia-Inducible Factor 1, alpha Subunit ; Injury Severity Score ; Ischemia ; pathology ; Nuclear Proteins ; analysis ; metabolism ; Probability ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; metabolism ; pathology ; Transcription Factors