Effect of nimodipine and N-acetylcysteine on lipid peroxidation after experimental spinal cord injury

Protective Effect of N-Acetylcysteine Amide on Blast-Induced Increase in Intracranial Pressure in Rats

Blast-induced traumatic brain injury is associated with acute and possibly chronic elevation of intracranial pressure (ICP). The outcome after TBI is dependent on the progression of complex processes which are mediated by oxidative stress. So far, no effective pharmacological protection against TBI exists. In this study, rats were exposed to a single or repetitive blast overpressure (BOP) at moderate intensities of 72 or 110 kPa in a compressed air-driven shock tube. The degree and duration of the increase in ICP were proportional to the intensity and frequency of the blast exposure(s). In most cases, a single dose of antioxidant N-acetylcysteine amide (NACA) (500 mg/kg) administered intravenously 2 h after exposure to BOP significantly attenuated blast-induced increase in ICP. A single dose of NACA was not effective in improving the outcome in the group of animals that were subjected to repetitive blast exposures at 110 kPa on the same day. In this group, two treatments with NACA at 2 and 4 h post-BOP exposure resulted in significant attenuation of elevated ICP. Treatment with NACA prior to BOP exposure completely prevented the elevation of ICP. The findings indicate that oxidative stress plays an important role in blast-induced elevated ICP as treatment with NACA-ameliorated ICP increase, which is frequently related to poor functional recovery after TBI.

Decreased GFAP expression and improved functional recovery in contused spinal cord of rats following valproic acid therapy

Many studies have illustrated that much of the post-traumatic degeneration of the spinal cord cells is caused by the secondary mechanism. The aim of this study is to evaluate the effect of the anti-inflammatory property of valproic acid (VPA) on injured spinal cords (SC). The rats with the contused SC received intraperitoneal single injection of VPA (150, 200, 300, 400 or 500 mg/kg) at 2, 6, 12 and 24 h post-injury. Basso-Beattie-Bresnahan (BBB) test and H-reflex evaluated the functional outcome for 12 weeks. The SC were investigated 3 months post-injury using morphometry and glial fibrillary acid protein (GFAP) expression. Reduction in cavitation, H/M ratio, BBB scores and GFAP expression in the treatment groups were significantly more than that of the untreated one (P < 0.05). The optimal improvement in the condition of the contused rats was in the ones treated at the acute phase of injury with 300 mg/kg of VPA at 12 h post-injury, they had the highest increase in BBB score and decrease in astrogliosis and axonal loss. We conclude that treating the contused rats with 300 mg/kg of VPA at 12 h post-injury improves the functional outcome and reduces the traumatized SC gliosis.

Efficacy of N-acetylcysteine on neuroclinical, biochemical, and histopathological parameters in experimental spinal cord trauma: comparison with methylprednisolone

BACKGROUND

N-acetylcysteine (NAC) is an antioxidant agent that has been shown to have beneficial effects when treating various diseases. The aim of this study was to investigate the effects of NAC on spinal cord injury in an experimental rat model.

METHODS

A total of 48 adult male wistar albino rats were divided into six groups. Group C included the control rats, group L included the rats that underwent laminectomy, and group T included the rats in which spinal cord trauma was induced by the weight-drop method after laminectomy. Groups M (the methylprednisolone group), N (the NAC group), and MN (the methylprednisolone + NAC group) were the treatment groups. In the fourth group (group M), 30 mg/kg methylprednisolone (MP) was administered as a bolus intraperitoneally (IP), and a standard MP treatmentat a dose of 5.4 mg/kg was applied for 24 h. In the fifth group (group N), only 300 mg/kg NAC was administered as a bolus IP. In the sixth group (group MN), the standard MP treatment and a single 300 mg/kg dose of NAC were administered as a bolus IP. The motor functions of the rats were evaluated on the 1st, 7th, and 14th days using the inclined plane test defined by Rivlin and Tator and the motor scale defined by Gale et al. Spinal cord samples were obtained on the 14th day. The samples were evaluated using pathological and biochemical analysis.

RESULTS

In the neuroclinical assessment, no differences were observed between groups T and M in terms of motor improvement. However, statistically significant differences were observed between group T and groups N and MN (p < 0.001, p = 0.01, respectively). Statistically significant differences were also seen between group M and groups N and MN on the 1st and 7th days (p < 0.017, p < 0.01, respectively). Additionally, when groups N and MN were compared with groups T and M,the pathological and biochemical analyses were found to be statistically different (p < 0.05, p < 0.001, respectively).

CONCLUSION

It was concluded that NAC treatment and the combined NAC + MP treatment may be more useful for healing in rats with experimental spinal cord injury in terms of neuroclinical, pathological, and biochemical results than MP-only therapy.

Translational potential of preclinical trials of neuroprotection through pharmacotherapy for spinal cord injury

There is a need to enhance the pipeline of discovery and evaluation of neuroprotective pharmacological agents for patients with spinal cord injury (SCI). Although much effort and money has been expended on discovering effective agents for acute and subacute SCI, no agents that produce major benefit have been proven to date. The deficiencies of all aspects of the pipeline, including the basic science input and the clinical testing output, require examination to determine remedial strategies. Where has the neuroprotective/pharmacotherapy preclinical process failed and what needs to be done to achieve success? These are the questions raised in the present review, which has 2 objectives: 1) identification of articles that address issues related to the translational readiness of preclinical SCI pharmacological therapies; and 2) examination of the preclinical studies of 5 selected agents evaluated in animal models of SCI (including blunt force trauma, penetrating trauma, or ischemia). The 5 agents were riluzole, glyburide, magnesium sulfate, nimodipine, and minocycline, and these were selected because of their promise of translational readiness as determined by the North American Clinical Trials Network Consortium.

The authors found that there are major deficiencies in the effort that has been extended to coordinate and conduct preclinical neuroprotection/pharmacotherapy trials in the SCI field. Apart from a few notable exceptions such as the NIH effort to replicate promising strategies, this field has been poorly coordinated. Only a small number of articles have even attempted an overall evaluation of the neuroprotective/pharmacotherapy agents used in preclinical SCI trials. There is no consensus about how to select the agents for translation to humans on the basis of their preclinical performance and according to agreed-upon preclinical performance criteria.

In the absence of such a system and to select the next agent for translation, the Consortium has developed a Treatment Strategy Selection Committee, and this committee selected the most promising 5 agents for potential translation. The results show that the preclinical work on these 5 agents has left numerous gaps in knowledge about their preclinical performance and confirm the need for significant changes in preclinical neuroprotection/pharmacotherapy trials in SCI. A recommendation is made for the development and validation of a preclinical scoring system involving worldwide experts in preclinical and clinical SCI.

Neuroprotective effects of N-acetyl-cysteine and acetyl-L-carnitine after spinal cord injury in adult rats

Following the initial acute stage of spinal cord injury, a cascade of cellular and inflammatory responses will lead to progressive secondary damage of the nerve tissue surrounding the primary injury site. The degeneration is manifested by loss of neurons and glial cells, demyelination and cyst formation. Injury to the mammalian spinal cord results in nearly complete failure of the severed axons to regenerate. We have previously demonstrated that the antioxidants N-acetyl-cysteine (NAC) and acetyl-L-carnitine (ALC) can attenuate retrograde neuronal degeneration after peripheral nerve and ventral root injury. The present study evaluates the effects of NAC and ALC on neuronal survival, axonal sprouting and glial cell reactions after spinal cord injury in adult rats. Tibial motoneurons in the spinal cord were pre-labeled with fluorescent tracer Fast Blue one week before lumbar L5 hemisection. Continuous intrathecal infusion of NAC (2.4 mg/day) or ALC (0.9 mg/day) was initiated immediately after spinal injury using Alzet 2002 osmotic minipumps. Neuroprotective effects of treatment were assessed by counting surviving motoneurons and by using quantitative immunohistochemistry and Western blotting for neuronal and glial cell markers 4 weeks after hemisection. Spinal cord injury induced significant loss of tibial motoneurons in L4–L6 segments. Neuronal degeneration was associated with decreased immunostaining for microtubular-associated protein-2 (MAP2) in dendritic branches, synaptophysin in presynaptic boutons and neurofilaments in nerve fibers. Immunostaining for the astroglial marker GFAP and microglial marker OX42 was increased. Treatment with NAC and ALC rescued approximately half of the motoneurons destined to die. In addition, antioxidants restored MAP2 and synaptophysin immunoreactivity. However, the perineuronal synaptophysin labeling was not recovered. Although both treatments promoted axonal sprouting, there was no effect on reactive astrocytes. In contrast, the microglial reaction was significantly attenuated. The results indicate a therapeutic potential for NAC and ALC in the early treatment of traumatic spinal cord injury.

Chemical priming for spinal cord injury: a review of the literature part II-potential therapeutics

INTRODUCTION

Spinal cord injury is a complex cascade of reactions secondary to the initial mechanical trauma that puts into action the innate properties of the injured cells, the circulatory, inflammatory, and chemical status around them, into a non-permissive and destructive environment for neuronal function and regeneration. Priming means putting a cell, in a state of "arousal" towards better function. Priming can be mechanical as trauma is known to enhance activity in cells.

MATERIALS AND METHODS

A comprehensive review of the literature was performed to better understand the possible chemical primers used for spinal cord injuries.

CONCLUSIONS

Taken together, many studies have shown various promising results using the substances outlined herein for treating SCI.

Antioxidant therapies for acute spinal cord injury

One of the most investigated molecular mechanisms involved in the secondary pathophysiology of acute spinal cord injury (SCI) is free radical-induced, iron-catalyzed lipid peroxidation (LP) and protein oxidative/nitrative damage to spinal neurons, glia, and microvascular cells. The reactive nitrogen species peroxynitrite and its highly reactive free radicals are key initiators of LP and protein nitration in the injured spinal cord, the biochemistry, and pathophysiology of which are first of all reviewed in this article. This is followed by a presentation of the antioxidant mechanistic approaches and pharmacological compounds that have been shown to have neuroprotective properties in preclinical SCI models. Two of these, which act by inhibition of LP, are high-dose treatment with the glucocorticoid steroid methylprednisolone (MP) and the nonglucocorticoid 21-aminosteroid tirilazad, have been demonstrated in the multicenter NASCIS clinical trials to produce at least a modest improvement in neurological recovery when administered within the first 8 hours after SCI. Although these results have provided considerable validation of oxidative damage as a clinically practical neuroprotective target, there is a need for the discovery of safer and more effective antioxidant compounds for acute SCI.

The effect of n-acetylcysteine and deferoxamine on exercise-induced oxidative damage in striatum and hippocampus of mice

The aim of this study was to analyze the effects of intense exercise on brain redox status, associated with antioxidant supplementation of N-acetylcysteine (NAC), deferoxamine (DFX) or a combination of both. Seventy-two C57BL-6 adult male mice were randomly assigned to 8 groups: control, NAC, DFX, NAC plus DFX, exercise, exercise with NAC, exercise with DFX, and exercise with NAC plus DFX. They were given antioxidant supplementation, exercise training on a treadmill for 12 weeks, and sacrificed 48 h after the last exercise session. Training significantly increased (P < 0.05) soleus citrate synthase (CS) activity when compared to control. Blood lactate levels classified the exercise as intense. Exercise significantly increased (P < 0.05) oxidation of biomolecules and superoxide dismutase activity in striatum and hippocampus. Training significantly increased (P < 0.05) catalase activity in striatum. NAC and DFX supplementation significantly protected (P < 0.05) against oxidative damage. These results indicate intense exercise as oxidant and NAC and DFX as antioxidant to the hippocampus and the striatum.

Neuroprotective Effects of N-acetylcysteine on Experimental Closed Head Trauma in Rats

N-acetylcysteine (NAC) is a precursor of glutathione, a potent antioxidant, and a free radical scavenger. The beneficial effect of NAC on nervous system ischemia and ischemia/reperfusion models has been well documented. However, the effect of NAC on nervous system trauma remains less understood. Therefore, we aimed to investigate the therapeutic efficacy of NAC with an experimental closed head trauma model in rats. Thirty-six adult male Sprague-Dawley rats were randomly divided into three groups of 12 rats each: Group I (control), Group II (trauma-alone), and Group III (trauma+NAC treatment). In Groups II and III, a cranial impact was delivered to the skull from a height of 7 cm at a point just in front of the coronal suture and over the right hemisphere. Rats were sacrificed at 2 h (Subgroups I-A, II-A, and III-A) and 12 h (Subgroups I-B, II-B, and III-B) after the onset of injury. Brain tissues were removed for biochemical and histopathological investigation. The closed head trauma significantly increased tissue malondialdehyde (MDA) levels (P < 0.05), and significantly decreased tissue superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities (P < 0.05), but not tissue catalase (CAT) activity, when compared with controls. The administration of a single dose of NAC (150 mg/kg) 15 min after the trauma has shown protective effect via decreasing significantly the elevated MDA levels (P < 0.05) and also significantly (P < 0.05) increasing the reduced antioxidant enzyme (SOD and GPx) activities, except CAT activity. In the trauma-alone group, the neurons became extensively dark and degenerated into picnotic nuclei. The morphology of neurons in the NAC treatment group was well protected. The number of neurons in the trauma-alone group was significantly less than that of both the control and trauma+NAC treatment groups. In conclusion, the NAC treatment might be beneficial in preventing trauma-induced oxidative brain tissue damage, thus showing potential for clinical implications.

Effects of nimodipine on tissue lactate and malondialdehyde levels in experimental head trauma

We studied the effects of nimodipine on brain tissue lactate and malondialdehyde (MDA) levels one hour after experimental head trauma in 25 New Zealand rabbits. Group 1 (n=5) was the sham operated group. Group 2 (n=10) received head trauma without treatment and in group 3 (n=10) nimodipine was administered for 30 minutes intravenously (2 microg/kg/min) immediately after head trauma. In groups 2 and 3, tissue samples from the non-traumatized side was named as "a" and traumatized side as "b". The lactate and malondialdehyde contents were significantly higher in groups 2a, 2b, 3a and 3b when compared with to group 1 (P<0.05). The differences between non-treated groups (2a, 2b) and nimodipine treated groups (3a, 3b) were not significant (P>0.05). The differences between the traumatized sides (2b, 3b) and non-traumatized sides (2a, 3a) were significant (P<0.05). These results demonstrated that nimodipine is ineffective in suppressing the increase of tissue lactate and malondialdehyde levels in the early period of experimental head trauma.