Effect of a free radical scavenger, edaravone, on free radical reactions: related signal transduction and cerebral vasospasm in the rabbit subarachnoid hemorrhage model

Edaravone Dexborneol Treatment Attenuates Neuronal Apoptosis and Improves Neurological Function by Suppressing 4-HNE-Associated Oxidative Stress After Subarachnoid Hemorrhage

Edaravone dexborneol is a novel neuroprotective drug that comprises edaravone and (+)-borneol in a 4:1 ratio. Phase II and III studies have demonstrated that Chinese patients treated with edaravone dexborneol within 48 h of AIS onset have better functional outcomes than those treated with edaravone alone. However, the effect of edaravone dexborneol on subarachnoid hemorrhage (SAH) has not yet been elucidated. This study aimed to investigate the therapeutic effects of edaravone dexborneol on SAH-induced brain injury and long-term behavioral deficits and to explore the possible mechanisms. The experimental rat SAH model was induced by an intraluminal puncture of the left middle cerebral artery (MCA). Edaravone dexborneol or edaravone at a clinical dose was infused into the tail vein for 3 days post-SAH surgery. Behavioral outcomes were assessed by a modified Garcia scoring system and rotarod, foot-fault, and corner tests. Immunofluorescence, Western blot, and ELISA methods were used to evaluate neuronal damage and oxidative stress. Our results showed that a post-SAH therapeutic regimen with edaravone dexborneol helped improve neurological function up to 21 days after SAH surgery and demonstrated a greater beneficial effect than edaravone alone, accompanied by an obvious inhibition of neuronal apoptosis in the CA1 hippocampus and basal cortex regions. Mechanistically, edaravone dexborneol not only suppressed the lipid peroxidation product malondialdehyde (MDA) but also improved the total antioxidant capability (TAC) 3 days after SAH. Notably, edaravone dexborneol treatment significantly inhibited the expression of another lipid peroxidation product, 4-hydroxynonenal (4-HNE), in the CA1 hippocampus and basal cortex, which are vital participants in the process of neuronal oxidative damage and death after SAH because of their acute cytotoxicity. Together, our results demonstrate that edaravone dexborneol confers neuroprotection and stabilizes long-term behavioral ability after SAH injury, possibly by suppressing 4-HNE-associated oxidative stress. These results may help develop new clinical strategies for SAH treatment.

Protective Effects of Betanin against Oxidative Stress in a Peripheral Artery Vasospasm Model in Rat

Objective: The aim of this study is to determine protective/modulatory effects of betanin in a femoral artery vasospasm model in rats. Materials and Methods: Sprague-Dawley rats were divided into three groups. Group 1: sham (n = 7), group 2: vasospasm model only (n = 7), group 3: postoperative betanin treatment in the vasospasm model (n = 7). 100 mg/kg betanin was administered orally to group 3 for 7 days, postoperatively. Peripheral blood malondialdehyde (MDA) and nitric oxide (NO) levels were measured for the quantification of oxidative stress, lumen diameter and wall thickness of femoral artery segments were determined to assess vasodilator effects of betanin. Results: Femoral artery vasospasm formation significantly increased both MDA (13.54 ± 3.09 mmol/mL) and NO levels (0.61 ± 0.06 µmol/mL) relative to the sham (9.07 ± 1.09 and 0.48 ± 0.1, respectively). Upon betanin administration, both MDA and NO approached baseline levels (9.95 ± 0.92 and 0.5 ± 0.06, respectively). Pathological examination of lumen diameter and wall thickness of the femoral arteries also revealed that betanin administration resulted in significant increase in lumen diameter when compared to vasospasm group (614.15 ± 245.77 versus 117.40 ± 46.19 µm) and decrease in wall thickness (64.68 ± 14.13 versus 96.73 ± 9.20 µm). Conclusion: Betanin was shown to have protective effect against oxidative stress in a peripheral artery vasospasm model in rats. It may also have a role in mitigating maladaptive changes in arterial structure, as shown in pathological examination.

Hydrogen therapy: from mechanism to cerebral diseases

The medicinal value of hydrogen (H₂) was ignored prior to research illustrating that inhalation of 2% H₂ can significantly decrease the damage of cerebral ischemia/reperfusion caused by oxidative stress via selective elimination of hydroxyl freebase (OH) and peroxynitrite anion (ONOOˉ). Subsequently, there have been numerous experiments on H₂. Most research and trials involving the mechanisms underlying H₂ therapy show the effects of antioxygenation, anti-inflammation, and anti-apoptosis. Among quantities of diseases related with H₂ therapy, the brain disease is a hotspot as brain tissue and cell damage are easier to be induced by oxidative stress and other stimulations. In this review, emphasis is on stroke, traumatic brain injuries, and degenerative diseases, such as Alzheimer's disease and Parkinson's disease. Taking into account the blood-brain barrier, penetrability, possible side effects, and the molecular properties of H₂ within a single comprehensive review should contribute to advancing both clinical and non-clinical research and therapies. A systematic introduction of H₂ therapy with regards to mechanisms and cerebral diseases both in animal and human subjects can make it easier to comprehend H₂ therapy and therefore provide the basis for further clinical strategy.

Effects of simvastatin and taurine on delayed cerebral vasospasm following subarachnoid hemorrhage in rabbits

The aim of the current study was to observe the effects of simvastatin and taurine on delayed cerebral vasospasm (DCVS) following experimental subarachnoid hemorrhage (SAH) in rabbits. A total of 48 New Zealand white rabbits were allocated at random into four groups (control, SAH, SAH + simvastatin and SAH + taurine groups; n=12 each). The rabbit model of DCVS was established using a double hemorrhage method, which involved injecting autologous arterial blood into the cisterna magna in the SAH groups. The SAH + simvastatin group was administered oral simvastatin (5 mg/kg) daily between days 0-6. The SAH + taurine group was administered oral taurine (50 mg/kg) daily between days 0-6. Starch (50 mg/kg) was administered orally to the animals in the other two groups (control and SAH groups). The control group were not subjected to any other injections or treatment. The internal diameter and internal diameter/wall thickness of the basilar artery (BA) were measured. The expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were determined using immunohistochemical and quantitative polymerase chain reaction methods following the sacrifice of all animals on day 7. The activity of nuclear factor (NF)-κB in the BA was also measured using an electrophoretic mobility shift assay. The BA walls in the SAH + simvastatin and SAH + taurine groups exhibited reduced narrowing and corrugation of the tunica elastica interna compared with the SAH group. At the protein and cDNA levels, it was found that cerebral vasospasm of the BA in the SAH + simvastatin and SAH + taurine groups was alleviated, as indicated by the reduced expression of TNF-α, IL-1β, IL-6 and NF-κB compared with the SAH group (P<0.05). In conclusion, simvastatin and taurine reduced DCVS following SAH in rabbits, which suggests that these compounds may exert anti-inflammatory effects.

Hyperbaric oxygen for cerebral vasospasm and brain injury following subarachnoid hemorrhage

The impact of acute brain injury and delayed neurological deficits due to cerebral vasospasm (CVS) are major determinants of outcomes after subarachnoid hemorrhage (SAH). Although hyperbaric oxygen (HBO) had been used to treat patients with SAH, the supporting evidence and underlying mechanisms have not been systematically reviewed. In the present paper, the overview of studies of HBO for cerebral vasospasm is followed by a discussion of HBO molecular mechanisms involved in the protection against SAH-induced brain injury and even, as hypothesized, in attenuating vascular spasm alone. Faced with the paucity of information as to what degree HBO is capable of antagonizing vasospasm after SAH, the authors postulate that the major beneficial effects of HBO in SAH include a reduction of acute brain injury and combating brain damage caused by CVS. Consequently, authors reviewed the effects of HBO on SAH-induced hypoxic signaling and other mechanisms of neurovascular injury. Moreover, authors hypothesize that HBO administered after SAH may "precondition" the brain against the detrimental sequelae of vasospasm. In conclusion, the existing evidence speaks in favor of administering HBO in both acute and delayed phase after SAH; however, further studies are needed to understand the underlying mechanisms and to establish the optimal regimen of treatment.