Low-Dose Edaravone Injection into the Clamped Aorta Prevents Ischemic Spinal Cord Injury

Histological Findings After Aortic Cross-Clamping in Preclinical Animal Models

Spinal cord ischemic injury and paralysis are devastating complications after open surgical repair of thoracoabdominal aortic aneurysms. Preclinical models have been developed to simulate the clinical paradigm to better understand the neuropathophysiology and develop therapeutic treatment. Neuropathological findings in the preclinical models have not been comprehensively examined before. This systematic review studies the past 40 years of the histological findings after open surgical repair in preclinical models. Our main finding is that damage is predominantly in the grey matter of the spinal cord, although white matter damage in the spinal cord is also reported. Future research needs to examine the neuropathological findings in preclinical models after endovascular repair, a newer type of surgical repair used to treat aortic aneurysms.

Effects of D‑Ala2, D‑Leu5‑Enkephalin pre‑ and post‑conditioning in a rabbit model of spinal cord ischemia and reperfusion injury

It has recently been revealed that during the aorta-clamped period, D-Ala², D-Leu⁵-Enkephalin (DADLE) infusion can protect the spinal cord against ischemia and reperfusion (I/R) injury. However, the protective effects of DADLE administration prior to ischemia or at the time of early reperfusion have not yet been investigated. Drug pre- or post-conditioning can serve as a more valuable clinical strategy. Therefore, the present study was designed to investigate the neuroprotective effect of DADLE infusion at different time intervals in order to determine the optimum time point for ischemic spinal cord protection. A total of 40 New Zealand white rabbits were randomly divided into 5 groups: Sham-operated (Sham), normal saline pre-conditioning (NS), DADLE per-conditioning (D_per), DADLE pre-conditioning (D_pre) and DADLE post-conditioning (D_post). All animals were subjected to spinal cord ischemia for 30 min followed by 48 h reperfusion. Hind limb motor functions were assessed according to the Tarlov criterion when the animals regained consciousness, 6, 24 and 48 h after reperfusion. Histological analysis and the number of viable α-motor neurons were also used to assess the extent of spinal cord injury. Compared with the NS group, the Tarlov scores and the number of normal neurons were significantly higher in the D_per group (P<0.05), which were consistent with the results of a previous study. In addition, the paraplegia rate and loss of normal motor neurons were lower in the DADLE per- and post-conditioning groups compared with the DADLE pre-conditioning; however, these were not statistically significant. DADLE 0.05 mg/kg administration at three time points all mitigated normal motor neuron injury in the anterior horn and decreased the paraplegia rates in rabbits. The therapeutic benefits appeared best in the post-conditioning group with DADLE, and worst in the pre-conditioning group.

Role of edaravone in managemant of septic peritonitis

BACKGROUND AND AIMS

Sepsis is a complex rapidly progressive infectious disease that remain a major cause of morbidity and mortality in surgical patients and trauma victims. Edaravone a novel free radical scavenger was approved in 2001 in Japan for treatment of acute cerebral and myocardial infarction. Hence, in this work we attempt to evaluate its role in cases of septic peritonitis (SP).

MATERIAL AND METHODS

This is a prospective randomized observer-blinded study carried out in surgical Intensive Care Unit (ICU) after approval by Hospital Ethical Committee. After admission to ICU patients were randomly divided into two groups of thirty patients each-Group (C): Control group managed according to the routine protocol of sepsis and Group (E): Edaravone treated SP managed according to the routine protocol of sepsis + edaravone at dose of 30 mg/12 h intravenous infusion for 2 weeks. All patients were monitored for invasive blood pressure, central venous pressure, heart rate, temperature, urine output, total fluid balance, and routine investigation. Blood sample was taken weekly for 2 weeks to measure the following parameters: Nuclear transcription factor kappa B activity (NFKB), mitogen-activated protein kinase (MAPK), heat shock protein 72 (HSP 72) and total antioxidant capacity (TAC).

RESULTS

There was significant decrease (P < 0.05) in serum level of NFKB, MAPK in Group E in comparison with Group C. While serum level of HSP 72 and TAC showed significant increase (P < 0.05) in Group E compared with Group C with better outcome.

CONCLUSION

SP treatment with edaravone could significantly improve the inflammatory and oxidative states with better patient outcomes.

Allicin protects spinal cord neurons from glutamate-induced oxidative stress through regulating the heat shock protein 70/inducible nitric oxide synthase pathway

Allicin, the main biologically active compound derived from garlic, exerts a broad spectrum of pharmacological activities and is considered to have therapeutic potential in many neurological disorders. Using an in vitro spinal cord injury model induced by glutamate treatment, we sought to investigate the neuroprotective effects of allicin in primary cultured spinal cord neurons. We found that allicin treatment significantly attenuated glutamate-induced lactate dehydrogenase (LDH) release, loss of cell viability and apoptotic neuronal death. This protection was associated with reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) generation, reduced lipid peroxidation and preservation of antioxidant enzyme activities. The results of western blot analysis showed that allicin decreased the expression of inducible nitric oxide synthase (iNOS), but had no effects on the expression of neuronal NOS (nNOS) following glutamate exposure. Moreover, allicin treatment significantly increased the expression of heat shock protein 70 (HSP70) at both mRNA and protein levels. Knockdown of HSP70 by specific targeted small interfere RNA (siRNA) not only mitigated allicin-induced protective activity, but also partially nullified its effects on the regulation of iNOS. Collectively, these data demonstrate that allicin treatment may be an effective therapeutic strategy for spinal cord injury, and that the potential underlying mechanism involves HSP70/iNOS pathway-mediated inhibition of oxidative stress.

Dose-effects of aorta-infused clenbuterol on spinal cord ischemia-reperfusion injury in rabbits

Background

The β₂ adrenergic receptor (β₂AR) plays an important role in ischemia-reperfusion (I/R) injury in various organs. Recently, a selective β₂AR agonist clenbuterol was suggested to protect against cerebral I/R injury. This study was designed to investigate changes of β₂ARs after spinal cord I/R injury and dose-effects of aorta-infused clenbuterol on spinal cord I/R injury in rabbits.

Methods

Spinal cord ischemia was induced in New Zealand white rabbits by infrarenal abdominal aortic occlusion with a balloon catheter for 30 minutes except the sham group. During occlusion, nothing (I/R group), normal saline (NS group) or clenbuterol at different doses of 0.005, 0.01, 0.05, 0.1, 0.5, or 1 mg/kg (C_0.005, C_0.01, C_0.05, C_0.1, C_0.5, and C₁ groups) was infused into the occluded aortic segments. The hemodynamic data, blood glucose and serum electrolytes were measured during experimental period. Neurological function was assessed according to the modified Tarlov scales until 48 hours after reperfusion. After that, the lumbar spinal cord was harvested for β₂AR immunohistochemistry and histopathologic evaluation in the anterior horns.

Results

The β₂AR expression in the anterior horns of the spinal cord was significantly higher in the I/R group than in the sham group. Tarlov scores and the number of viable α-motor neurons were higher in C_0.01-C_0.5 groups than in the NS group, C_0.005 and C₁ groups and were highest in the C_0.1 group. Hypotension and hyperglycemia were found in the C₁ group.

Conclusion

β₂ARs in the anterior horn were upregulated after spinal cord I/R injury. Aortic-infused clenbuterol (0.01–0.5 mg/kg) can attenuate spinal cord I/R injury dose-dependently during the ischemic period. The Optimal dosage was 0.1 mg/kg. Activation of β₂AR could be a new therapeutic strategy for the treatment of spinal cord I/R injury.

Trehalose protects against spinal cord ischemia in rabbits

OBJECTIVE

This study tested to see if trehalose, a cytoprotective disaccharide, protects against spinal cord ischemia in a rabbit model.

METHODS

The infrarenal aorta was mobilized in four groups of 10 rabbits. In groups I, II, and III, it was clamped proximally and distally for 20 minutes. In group I, the clamped aorta was infused at 2.5 L/min for 2 hours with lactated Ringer's (LR) solution. In group II, the clamped aorta was infused with 5% trehalose in LR. LR was administered intravenously (2.0 mL/min) in groups I and II starting 30 minutes before clamping. In group III, 5% trehalose in LR was infused intravenously only. Group IV was a sham-operated control group without aortic clamping. At 8, 24, and 48 hours after reperfusion, hind limb function was scored using the Tarlov score (paralysis = 0, perceptible joint movement = 1, good joint movement but unable to stand = 2, able to walk = 3, normal = 4). Histologic analysis and electron microscopy were performed on anterior horn cells.

RESULTS

The Tarlov scores in groups I, II, and III were, respectively, 1.1 ± 1.4, 3.5 ± 0.5, and 2.9 ± 0.9 at 8 hours; 0.8 ± 1.2, 3.9 ± 0.3, and 2.9 ± 0.9 at 24 hours; and 0.6 ± 0.7, 3.9 ± 0.3, and 2.7 ± 0.9 at 48 hours after reperfusion. Group IV scores were normal (4 ± 0) at all assessments. These scores were higher in groups II and III than in group I (P < .01) at all assessments. Scores at 24 and 48 hours were higher in group II than in group III (P < .05). In group III, delayed paraparesis developed in one rabbit at 24 hours and in two more at 48 hours. Histopathologic analysis showed the number of normal neurons was higher in groups II (P < .0001), III (P = .006), and IV (P < .0001) vs group I. Electron microscopy confirmed preserved neuronal cell ultrastructure in rabbits with normal limb function.

CONCLUSIONS

Transaortic trehalose infusion was protective against paraplegia, whereas intravenous trehalose reduced spinal cord ischemia. This study was preliminary and further studies are needed.

Reversal of acute monoparesis following thoracoabdominal aortic aneurysm repair

A 67-year-old man underwent surgical repair for a Crawford extent V thoracoabdominal aortic aneurysm under cerebrospinal fluid drainage and motor evoked potential monitor on distal aortic perfusion. Postoperatively, weakness of right-sided leg graded 2/5 and bladder disorder were recognized. Magnetic resonance imaging revealed hyperintensity between Th11 and L1 on T2-weighted image. Intravenous glycerin and edaravone for spinal cord ischemia had been administered. The strength of right leg resolved completely with disappearance of hyperintensity on magnetic resonance image. Finally, he could walk on foot with bladder disorder.

New method for absolute spinal cord ischemia protection in rabbits

OBJECTIVE

This study aims to establish a superior procedure to prevent spinal cord damage after severe spinal cord ischemia during aortic surgery. We examined the synergistic effect of topical hypothermia of the spinal cord combined with radical scavenger infusion into the clamped segment of the aorta to prevent spinal cord damage in an animal model.

METHODS

Spinal cord ischemia was induced in rabbits by clamping the aorta between the renal artery and aortic bifurcation for 30 minutes. Rabbits were divided into four groups of 16 each: group I, sham-operated; group II, edaravone (6 mL, 4°C, 1 mg/kg); group III, saline (6 mL, 4°C) with transvertebral cooling pads; group IV, edaravone (6 mL, 4°C, 1 mg/kg) and transvertebral cooling pads. Solutions were injected into the clamped segment of the aorta. Postoperative assessments included the Tarlov score, spinal cord histopathology, and measurement of malondialdehyde levels in the spinal cord tissue.

RESULTS

At 48 hours after reperfusion, the mean Tarlov scores in groups I, II, III, and IV were 4.0, 1.5, 1.9, and 4.0, respectively. The mean number of normal motor neurons was significantly higher in groups I (54.1) and IV (53.7) than in groups II (32.8) and III (36.3; P < .001). The mean malondialdehyde level in groups I (19.8 nmol/mL) and IV (22.6 nmol/mL) was significantly lower than in groups II (64.8 nmol/mL) and III (60.9 nmol/mL; P < .001). At 168 hours after reperfusion, the mean Tarlov scores in groups I, II, III, and IV were 4.0, 1.1, 1.3, and 4.0, respectively. The mean number of normal motor neurons was significantly higher in groups I (52.9) and IV (50.8) than in groups II (22.4) and III (25.9; P < .001). The mean malondialdehyde level in groups I (20.7 nmol/mL) and IV (23.4 nmol/mL) was significantly lower than in groups II (68.9 nmol/mL) and III (61.6 nmol/mL; P < .001).

CONCLUSION

In a rabbit model with aortic clamping up to 30 minutes, which consistently produces complete paraplegia in rabbits, spinal cord damage was partially reduced by topical cooling with transvertebral cooling pads or the injection of edaravone into the clamped segment of aorta, but was more effectively protected by a combined use of these two strategies.

Protective effects of edaravone on experimental spinal cord injury in rats

BACKGROUND

Spinal cord injury (SCI) is a leading cause of morbidity and mortality among youth and adults. Secondary injury mechanisms within the spinal cord (SC) are well known to cause deterioration after an acute impact. Free radical scavengers are among the most studied agents in animal models of SCI. Edaravone is a scavenger of hydroxyl radicals.

METHODS

We aimed to measure and compare the effects of both methylprednisolone and edaravone on tissue and on serum concentrations of nitric oxide (NO), malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, and tissue total antioxidant capacity (TAC) in rats with SCI. SCI was induced in four groups of Wistar albino rats by a weight-drop method. The neurological function of the rats was periodically tested. At the end of the experiment, blood samples were collected, and SC tissue samples were harvested for biochemical evaluation.

RESULTS

The tissue level of NO was decreased in the edaravone-treated group compared with the no-treatment group (p < 0.05). The tissue levels of SOD and GSH-Px were higher in the edaravone-treated group than in the no-treatment group (p < 0.05). The serum levels of NO were lower in the edaravone-treated and methylprednisolone-treated groups than in the no-treatment group (p < 0.05). The serum levels of SOD in the edaravone-treated group did not differ from those of any other group. The serum levels of MDA in the edaravone-treated and no-treatment groups were higher than in the two other groups (p < 0.05). Tissue levels of MDA in the edaravone-treated group were lower than in the no-treatment group (p < 0.05). Tissue levels of TAC in the edaravone-treated group were higher than in the no-treatment and methylprednisolone-treated groups (p < 0.05). The neurological outcome scores of the animals in treatment groups did not depict any statistically significant improvement in motor functions. However, edaravone seemed to prevent further worsening of the immediate post-SCI neurological status.

CONCLUSION

Our biochemical analyses indicate that edaravone is capable of blunting the increased oxidative stress that follows SCI. We show, for the first time, that edaravone enhances the TAC in SC tissue. This beneficial effect of edaravone on antioxidant status may act to minimize the secondary neurological damage that occurs during the acute phase after SCI.

Pharmacokinetic interaction between puerarin and edaravone, and effect of borneol on the brain distribution kinetics of puerarin in rats

Objectives

The aim was to investigate the pharmacokinetic interaction between puerarin and edaravone, and the effect of borneol on the brain distribution kinetics of puerarin in rats.

Methods

A reversed-phase high performance liquid chromatography method was developed and validated for the simultaneous determination of puerarin and edaravone in rat plasma. The detection method was successfully applied to compare the pharmacokinetic interaction and brain distribution kinetics of puerarin and edaravone using in-situ microdialysis sampling in rats after intravenous administration and co-administration with a single dose.

Key findings

The method gave good linearity and no endogenous material interfered with the two target compounds and internal standard peaks. The limit of detection of puerarin and edaravone was 0.03 and 0.05 μg/ml, respectively. The average recovery of the two compounds from rat plasma was &gt;94%. The precision of the test was determined to be within 10%. The combination of puerarin and edaravone reduced drug elimination rates, gave a wider distribution, and the disposition of both drugs in rats was optimized. The distribution of puerarin in brain tissues was significantly increased and its elimination was noticeably slower with borneol pretreatment.

Conclusions

The results provide important information for the improved combined use of puerarin and edaravone with borneol pretreatment in clinical practice.