The effects of memantine on lipid peroxidation following closed-head trauma in rats

Neuroprotective Effects of Sildenafil on Traumatic Brain Injury in an Experimental Rat Model

Objective Not only primary injuries, secondary injuries such as posttraumatic biochemical cascades, ischemia, and hypoxia also affect the morbidity and mortality of traumatic brain injury (TBI). Sildenafil released the vasodilatation by relaxing the smooth muscle of the systemic artery and vein. Also, the effects of sildenafil are evidenced in multiple sclerosis, Alzheimer's disease, and memory loss as a part of experimental studies. Sildenafil decreases oxidative stress by increasing the cGMP level. We aimed to examine the protective effects of sildenafil on TBI with histopathological and biochemical parameters.

Method 21 Sprague–Dawley rats were separated into three groups (n = 7). “The weight drop injury model,” which was described by Marmou, was used for the head injury. Group 1: nontraumatic sham group, Group 2: nontreated TBI group, Group 3: sildenafil (100 mg/kg) treated TBI group. The whole brain and serum were collected for histopathological and biochemical study. The histopathological sections were examined under a light microscope.

Results On comparison of total antioxidant status (TAS), total oxidant status (TOS), nitric oxide (NO), and plasma nitrite/nitrate (PNOx) between groups, NO level was significantly high in group 3 (p = 0.013). Even though the TAS level was significantly high in group 3 (p = 0.02), there were no significant differences in TOS level in groups (p = 0.225). Disappearing Nissle granules occurred in a pyknotic situation in the cell nucleus, and acidophilic staining in neuron cells, which describe the neuron degeneration observed in the trauma group. The neuron degeneration markers were not seen in the sildenafil-treated trauma group.

Conclusion Our study has shown that sildenafil decreases the oxygen radicals and affects the recovery of experimental TBI in rats.

The effects of amantadine on lung tissue in lower limb ischemia/reperfusion injury model in rats

Background

This study aims to evaluate the effect of amantadine on lung tissue of after lower limb ischemia/reperfusion injury in rats.

Methods

A total of 24 Wistar rats were divided into four equal groups including six rats in each: sham group (Group S), amantadine group (Group A), ischemia/reperfusion group (Group I/R), and ischemia/reperfusion + amantadine group (Group I/R-A). All groups underwent a midline abdominal incision. In Groups I/R and I/R-A, the infrarenal abdominal aorta was clamped for 120 min and, then, reperfused for 120 min after removal of the clamp. Amantadine hydrochloride 45 mg/kg was administered intraperitoneally to the rats of Groups A and Group I/R-A 15 min before surgery. At the end of reperfusion period (240 min), all rats were sacrificed, and their lung tissues were obtained. Lung tissue catalase and superoxide dismutase activities and glutathione S-transferase and malondialdehyde levels were analyzed. Lung tissues were examined histopathologically.

Results

Catalase activity was lower in Groups A, I/R, and I/R-A compared to Group S. Superoxide dismutase activity was higher in Group I/R than Group S. Superoxide dismutase activity in Groups I/R-A and A decreased, compared to Groups S and I/R. Glutathione S-transferase levels decreased in Groups I/R and A, compared to Group S. Glutathione S-transferase levels in Group I/R-A were higher than Groups I/R and A. The highest level of malondialdehyde was found in Group I/R and the lowest level was found in Group I/R-A. According to histopathological examination, infiltration scores were significantly lower in Group S than Groups I/R and I/R-A (p=0.009 and p=0.011, respectively). The alveolar wall thickening scores in Group I/R were also significantly higher than Groups S and Group A (p=0.001 and p=0.001, respectively).

Conclusion

Lung tissue can be affected histopathologically by ischemia/ reperfusion injury and this injury can be reversed by amantadine administration.

Acute and chronic effects of single dose memantine after controlled cortical impact injury in adult rats

BACKGROUND

Altered glutamatergic neurotransmission after traumatic brain injury (TBI) contributes to excitotoxic cell damage and death. Prevention or suppression of such changes is a desirable goal for treatment of TBI. Memantine (3,5-dimethyl-1-adamantanamine), an uncompetitive NMDA receptor antagonist with voltage-dependent open channel blocking kinetics, was reported to be neuroprotective in preclinical models of excitotoxicity, brain ischemia, and in TBI when administered prophylactically, immediately, or within minutes after injury.

METHODS

The current study examined effects of memantine administered by single intraperitoneal injection to adult male rats at a more clinically relevant delay of one hour after moderate-severe controlled cortical impact (CCI) injury or sham surgery. Histopathology was assessed on days 1, 7, 21, and 90, vestibulomotor function (beam balance and beam walk) was assessed on days 1-5 and 71-75, and spatial memory (Morris water maze test, MWM) was assessed on days 14-21 and 83-90 after CCI injury or sham surgery.

RESULTS

When administered at 10 mg/kg, but not 2.5 or 5 mg/kg, memantine preserved cortical tissue and reduced neuronal degeneration 1 day after injury, and attenuated loss of synaptophysin immunoreactivity in the hippocampus 7 days after injury. No effects of 10 mg/kg memantine were observed on histopathology at 21 and 90 days after CCI injury or sham surgery, or on vestibulomotor function and spatial memory acquisition assessed during any of the testing periods. However, 10 mg/kg memantine resulted in trends for improved search strategy in the MWM memory retention probe trial.

CONCLUSIONS

Administration of memantine at a clinically-relevant delay after moderate-severe CCI injury has beneficial effects on acute outcomes, while more significant improvement on subacute and chronic outcomes may require repeated drug administration or its combination with another therapy.

Antioxidant Therapies in Traumatic Brain Injury

Due to a multiplicity of causes provoking traumatic brain injury (TBI), TBI is a highly heterogeneous pathology, characterized by high mortality and disability rates. TBI is an acute neurodegenerative event, potentially and unpredictably evolving into sub-chronic and chronic neurodegenerative events, with transient or permanent neurologic, cognitive, and motor deficits, for which no valid standardized therapies are available. A vast body of literature demonstrates that TBI-induced oxidative/nitrosative stress is involved in the development of both acute and chronic neurodegenerative disorders. Cellular defenses against this phenomenon are largely dependent on low molecular weight antioxidants, most of which are consumed with diet or as nutraceutical supplements. A large number of studies have evaluated the efficacy of antioxidant administration to decrease TBI-associated damage in various animal TBI models and in a limited number of clinical trials. Points of weakness of preclinical studies are represented by the large variability in the TBI model adopted, in the antioxidant tested, in the timing, dosages, and routes of administration used, and in the variety of molecular and/or neurocognitive parameters evaluated. The analysis of the very few clinical studies does not allow strong conclusions to be drawn on the real effectiveness of antioxidant administration to TBI patients. Standardizing TBI models and different experimental conditions, as well as testing the efficacy of administration of a cocktail of antioxidants rather than only one, should be mandatory. According to some promising clinical results, it appears that sports-related concussion is probably the best type of TBI to test the benefits of antioxidant administration.

Traumatic Brain Injury Patients Mortality and Serum Total Antioxidant Capacity

OBJECTIVE

Oxidation is involved in secondary brain injury after traumatic brain injury (TBI). Increased concentrations of total antioxidant capacity (TAC) in blood at the time of admission for TBI have been found in non-surviving patients. The main objective of this study was to determine the role of serum TAC levels at any time during the first week of TBI for the prediction of early mortality.

METHODS

Isolated (<10 points in non-cranial aspects of Injury Severity Score) and severe (<9 points in Glasgow Coma Scale) TBI patients were included. Serum TAC concentrations at days 1, 4, and 8 of TBI were determined. The end-point study was 30-day mortality.

RESULTS

Higher serum TAC levels at days 1 (p < 0.001), 4 (p < 0.001), and 8 (p = 0.002) of TBI were found in non-surviving (n = 34) than in surviving patients (n = 90). The area under curve (95% Confidence Interval) for prediction of 30-day mortality by serum TAC concentrations at days 1, 4, and 8 of TBI were 0.79 (0.71-0.86; p < 0.001), 0.87 (0.79-0.93; p < 0.001), and 0.76 (0.67-0.84; p = 0.006) respectively.

CONCLUSIONS

The novelty of our study was the ability to predict 30-day mortality by serum TAC concentrations at any time during the first week of TBI.

Maintained high sustained serum malondialdehyde levels after severe brain trauma injury in non-survivor patients

Objective

Higher blood malondialdehyde (biomarker of lipid peroxidation) levels in the first hours of traumatic brain injury (TBI) have been found in patients with a worst prognosis. The objective of this study was to determine whether serum malondialdehyde levels during the first week of severe TBI could be used as mortality biomarkers. This was a multicenter, prospective and observational study performed in six Spanish Intensive Care Units. We included patients with severe TBI (defined as Glasgow Coma Scale < 9), and with Injury Severity Score in non-cranial aspects < 9. We determined serum malondialdehyde concentrations at days 1, 4 and 8 of TBI. We stablished 30-day mortality as the end-point study.

Results

We found that serum malondialdehyde concentrations at days 1 (p < 0.001), 4 (p < 0.001), and 8 (p < 0.001) of TBI were higher in non-survivor (n = 34) than in survivor (n = 90) patients. We found an area under curve of serum malondialdehyde concentrations at days 1, 4, and 8 of TBI to predict 30-day mortality of 77% (p < 0.001), 87% (p < 0.001) and 84% (p < 0.001) respectively. Thus, the new and most relevant findings of our study were serum malondialdehyde levels during the first week of TBI could be used as mortality biomarkers.

Acute drivers of neuroinflammation in traumatic brain injury

Neuroinflammation is initiated as a result of traumatic brain injury and can exacerbate evolving tissue pathology. Immune cells respond to acute signals from damaged cells, initiate neuroinflammation, and drive the pathological consequences over time. Importantly, the mechanism(s) of injury, the location of the immune cells within the brain, and the animal species all contribute to immune cell behavior following traumatic brain injury. Understanding the signals that initiate neuroinflammation and the context in which they appear may be critical for understanding immune cell contributions to pathology and regeneration. Within this paper, we review a number of factors that could affect immune cell behavior acutely following traumatic brain injury.

Protective Effects of Epifriedelinol in a Rat Model of Traumatic Brain Injury Assessed with Histological and Hematological Markers

Background

This study evaluated the protective effects of epifriedelinol (EFD) in a rat model of traumatic brain injury (TBI).

Methodology

TBI was induced by dropping a weight from a specific height. The animals were separated into control, TBI, and EFD 100 and 200 mg/kg groups. The latter received 100 and 200 mg/kg EFD, respectively, for 2 days beginning 30 min after inducing TBI. The neurological examination score, permeability of the blood–brain barrier (BBB), water content of the brain, cytokine levels, and oxidative stress parameters were measured in the rats. The effects of EFD on glial fibrillary acidic protein (GFAP)-positive cells were evaluated using immunohistochemistry.

Result

The EFD treatment significantly decreased the neurological score, permeability of the BBB, and water content of brain compared with the TBI group. The levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and oxidative stress were significantly decreased in the EFD-treated groups. The number of GFAP-positive cells was also significantly reduced in the EFD-treated groups.

Conclusion

EFD attenuates the secondary injury in TBI rats by reducing the serum cytokine levels and oxidative stress.

Serum total antioxidant capacity prior to liver transplantation for hepatocellular carcinoma is associated with 1-year liver transplantation survival

Objective

To determine whether there was an association between serum total antioxidant capacity (TAC) levels prior to in liver transplantation (LT) for hepatocellular carcinoma (HCC) and 1-year LT mortality.

Methods

This observational retrospective single-centre study of patients with LT for HCC measured serum levels of TAC and malondialdehyde (as a biomarker of lipid peroxidation) before LT. The study endpoint was 1-year LT mortality.

Results

This study included 142 patients who underwent LT for HCC. Patients who survived the first year (n = 127) had significantly lower aged liver donors, significantly higher serum TAC levels, and significantly lower serum malondialdehyde levels compared with the non-survivors (n = 15). Logistic regression analysis found that serum TAC levels (odds ratio [OR] 0.275; 95% confidence interval [CI] 0.135, 0.562) and the age of the LT donor (OR 1.050; 95% CI 1.009, 1.094) were associated with 1-year LT mortality. There was an inverse association between serum levels of TAC and malondialdehyde levels (rho = –0.22).

Conclusions

There was an association between low serum TAC levels prior to LT for HCC and mortality during the first year after LT. There was an inverse association between serum TAC levels and lipid peroxidation as measured by malondialdehyde levels.

Biomarkers Associated with the Outcome of Traumatic Brain Injury Patients

This review focuses on biomarkers associated with the outcome of traumatic brain injury (TBI) patients, such as caspase-3; total antioxidant capacity; melatonin; S100B protein; glial fibrillary acidic protein (GFAP); glutamate; lactate; brain-derived neurotrophic factor (BDNF); substance P; neuron-specific enolase (NSE); ubiquitin carboxy-terminal hydrolase L-1 (UCH-L1); tau; decanoic acid; and octanoic acid.

The Protective Effect of Omeprazole Against Traumatic Brain Injury: An Experimental Study

BACKGROUND

The development of secondary brain injury via oxidative stress after traumatic brain injury (TBI) is a well-known entity. Consequently, the aim of the present study was to evaluate the role of omeprazole (OM) on rat model of TBI.

METHODS

A total of 24 male rats were used and divided into 4 groups as follows; control, trauma, OM, and methylprednisolone (MP). The trauma, OM, and MP groups were subjected to closed-head contusive weight-drop injuries. Rats received treatment with saline, OM, or MP, respectively. All the animals were sacrificed at 24 hours after trauma and brain tissues were extracted. The oxidant/antioxidant parameters (malondialdehyde, glutathione peroxidase, superoxide dismutase, nitric oxide) and caspase-3 in the cerebral tissue were analyzed, and histomorphologic evaluation of the cerebral tissue was performed.

RESULTS

Levels of MDA and activity of caspase-3 were significantly reduced in the OM and MP groups compared with the trauma group. Glutathione peroxidase and superoxide dismutase levels were increased both in the OM and MP groups compared with the trauma group. The pathology scores were statistically lower in the OM and MP groups than the trauma group.

CONCLUSIONS

The results of the present study showed that OM was as effective as MP in protecting brain from oxidative stress, and apoptosis in the early phase of TBI.

Mild traumatic brain injury-induced hippocampal gene expressions: The identification of target cellular processes for drug development

BACKGROUND

Neurological dysfunction after traumatic brain injury (TBI) poses short-term or long-lasting health issues for family members and health care providers. Presently there are no approved medicines to treat TBI. Epidemiological evidence suggests that TBI may cause neurodegenerative disease later in life. In an effort to illuminate target cellular processes for drug development, we examined the effects of a mild TBI on hippocampal gene expression in mouse.

METHODS

mTBI was induced in a closed head, weight drop-system in mice (ICR). Animals were anesthetized and subjected to mTBI (30g). Fourteen days after injury the ipsilateral hippocampus was utilized for cDNA gene array studies. mTBI animals were compared with sham-operated animals. Genes regulated by TBI were identified to define TBI-induced physiological/pathological processes. mTBI regulated genes were divided into functional groupings to provide gene ontologies. Genes were further divided to identify molecular/cellular pathways regulated by mTBI.

RESULTS

Numerous genes were regulated after a single mTBI event that mapped to many ontologies and molecular pathways related to inflammation and neurological physiology/pathology, including neurodegenerative disease.

CONCLUSIONS

These data illustrate diverse transcriptional changes in hippocampal tissues triggered by a single mild injury. The systematic analysis of individual genes that lead to the identification of functional categories, such as gene ontologies and then molecular pathways, illustrate target processes of relevance to TBI pathology. These processes may be further dissected to identify key factors that can be evaluated at the protein level to highlight possible treatments for TBI in human disease and potential biomarkers of neurodegenerative processes.

Association between Pre-Transplant Serum Malondialdehyde Levels and Survival One Year after Liver Transplantation for Hepatocellular Carcinoma

Previous studies have found higher levels of serum malondialdehyde (MDA) in hepatocellular carcinoma (HCC) patients compared to healthy controls and higher MDA concentrations in tumoral tissue of HCC patients than in non-tumoral tissue. However, the association between pre-transplant serum levels of MDA and survival in HCC patients after liver transplantation (LT) has not been described, and the aim of the present study was to determine whether such an association exists. In this observational study we measured serum MDA levels in 127 patients before LT. We found higher pre-LT serum MDA levels in 15 non-surviving than in 112 surviving patients one year after LT (p = 0.02). Exact binary logistic regression analysis revealed that pre-LT serum levels of MDA over 3.37 nmol/mL were associated with mortality after one year of LT (Odds ratio = 5.38; 95% confidence interval (CI) = from 1.580 to infinite; p = 0.007) adjusting for age of the deceased donor. The main finding of our study was that there is an association between serum MDA levels before LT for HCC and 1-year survival after LT.

New Prognostic Biomarkers in Patients With Traumatic Brain Injury

CONTEXT

Traumatic brain injury (TBI) is a leading cause of death, disability, and resource consumption per year. There are two kinds of brain injury in TBI, primary and secondary injuries. Primary injury refers to the initial physical forces applied to the brain at the moment of impact. Secondary injury occurs over a period of hours or days following the initial trauma and results from the activation of different pathways such as inflammation, coagulation, oxidation, and apoptosis.

EVIDENCE ACQUISITION

This review focuses on new prognostic biomarkers of mortality in TBI patients related to inflammation, coagulation, oxidation, and apoptosis.

RESULTS

Recently circulating levels of substance P (SP), soluble CD40 ligand (sCD40L), tissue inhibitor of matrix metalloproteinases (TIMP)-1, malondialdehyde (MDA), and cytokeratin (CK)-18 fragmented have been found to be associated with mortality in TBI patients. Substance P is a neuropeptide of the tachykinin family, mainly synthesized in the central and peripheral nervous system, with proinflammatory effects when binding to their neurokinin-1 receptor (NK1R). Soluble CD40 ligand, a member of the tumor necrosis factor (TNF) family that is released into circulation from activated platelets, exhibit proinflamatory, and procoagulant properties on binding to their cell surface receptor CD40. Matrix metalloproteinases (MMPs) are a family of zinc-containing endoproteinases involved neuroinflammation and TIMP-1 is the inhibitor of some of them. Malondialdehyde is an end-product formed during lipid peroxidation due to degradation of cellular membrane phospholipids, that is released into extracellular space and finally into the blood. Cytokeratin -18 is cleaved by the action of caspases during apoptosis, and CK-18 fragmented is released into the blood.

CONCLUSIONS

Circulating levels of some biomarkers, such as SP, sCD40L, TIMP-1, MDA, and CK-18 fragmented, related to inflammation, coagulation, oxidation, and apoptosis have been recently associated with mortality in patients with TBI. These biomarkers could help in the prognostic classification of the patients and open new research lines in the treatment of patients with TBI.

Association between serum malondialdehyde levels and mortality in patients with severe brain trauma injury

There is a hyperoxidative state in patients with trauma brain injury (TBI). Malondialdehyde (MDA) is an end-product formed during oxidative stress, concretely lipid peroxidation. In small studies (highest sample size 50 patients), higher levels of MDA have been found in nonsurviving than surviving patients with TBI. An association between serum MDA levels and mortality in patients with TBI, however, has not been reported. Thus, the objective of this prospective, observational, multicenter study, performed in six Spanish intensive care units, was to determine whether MDA serum levels are associated with early mortality in a large series of patients with severe TBI. Serum MDA levels were measured in 100 patients with severe TBI on day 1 and in 75 healthy controls. The end-point of the study was 30-day mortality. We found higher serum MDA levels in patients with severe TBI than in healthy controls (p < 0.001). Nonsurviving patients with TBI (n = 27) showed higher serum MDA levels (p < 0.001) than survivors (n = 73). Logistic regression analysis showed that serum MDA levels were associated with 30-day mortality (odds ratio [OR] = 4.662; 95% confidence interval [CI] = 1.466-14.824; p = 0.01), controlling for Glasgow Coma Score, age, and computed tomography findings. Survival analysis showed that patients with serum MDA levels higher than 1.96 nmol/mL presented increased 30-day mortality than patients with lower levels (hazard ratio = 3.5; 95% CI = 1.43-8.47; p < 0.001). Thus, the most relevant new finding of our study, the largest to date on serum MDA levels in patients with severe TBI, was an association between serum MDA levels and early mortality.

Total antioxidant capacity is associated with mortality of patients with severe traumatic brain injury

Background

Previously, circulating total antioxidant capacity (TAC) in traumatic brain injury (TBI) patients has been scarcely studied and only in studies of small sample size (lower than 55 TBI patients). In one study were found higher serum TAC in non-survivor than in survivor TBI patients; however, an association between circulating TAC and mortality in patients with TBI has not been previously reported. Thus, the objective of this study was to determine whether there is an association between circulating TAC, peroxidation state and mortality in patients with severe TBI.

Methods

This was a multicenter, observational and prospective study was carried out in six Spanish Intensive Care Units. We included patients with severe TBI defined as Glasgow Coma Scale (GCS) lower than 9. We excluded patients with Injury Severity Score (ISS) in non-cranial aspects higher than 9. We measured serum TAC on day 1 of TBI. The 30-day mortality was established as endpoint.

Results

Non-surviving TBI patients (N = 27) showed higher serum TAC (P < 0.001) than survivor ones (N = 73). Logistic regression analyses showed that serum TAC higher than 2.59 nmol/mL were associated with 30-day mortality controlling for APACHE-II and CT classification (OR = 4.40; 95 % CI = 1.14–16.98; P = 0.03), controlling for GCS and age (OR = 5.88; 95 % CI = 1.57–22.06; P = 0.009), and controlling for CT classification and admission abnormal pupils (OR = 3.89; 95 % CI = 1.30–11.61; P = 0.02). There was an association between serum TAC and malondialdehyde (a biomarker of lipid peroxidation) levels (rho = 0.25; p = 0.01), APACHE-II score (rho = 0.23; p = 0.03) and GCS (rho = −0.21; p = 0.04).

Conclusions

To our knowledge, our series is the largest reporting data on circulating TAC in patients with severe TBI. The most relevant and new findings of our study were that there is an association between circulating TAC and peroxidation state and mortality in patients with severe TBI.

Potential pharmacological strategies for the improved treatment of organophosphate-induced neurotoxicity

Organophosphates (OP) are highly toxic compounds that cause cholinergic neuronal excitotoxicity and dysfunction by irreversible inhibition of acetylcholinesterase, resulting in delayed brain damage. This delayed secondary neuronal destruction, which arises primarily in the cholinergic areas of the brain that contain dense accumulations of cholinergic neurons and the majority of cholinergic projection, could be largely responsible for persistent profound neuropsychiatric and neurological impairments such as memory, cognitive, mental, emotional, motor, and sensory deficits in the victims of OP poisoning. The therapeutic strategies for reducing neuronal brain damage must adopt a multifunctional approach to the various steps of brain deterioration: (i) standard treatment with atropine and related anticholinergic compounds; (ii) anti-excitotoxic therapies to prevent cerebral edema, blockage of calcium influx, inhibition of apoptosis, and allow for the control of seizure; (iii) neuroprotection by aid of antioxidants and N-methyl-d-aspartate (NMDA) antagonists (multifunctional drug therapy), to inhibit/limit the secondary neuronal damage; and (iv) therapies targeting chronic neuropsychiatric and neurological symptoms. These neuroprotective strategies may prevent secondary neuronal damage in both early and late stages of OP poisoning, and thus may be a beneficial approach to treating the neuropsychological and neuronal impairments resulting from OP toxicity.

Neuroprotective effects of caffeic acid phenethyl ester on experimental traumatic brain injury in rats

The aim of this study was to evaluate the therapeutic efficacy of caffeic acid phenethyl ester (CAPE) with an experimental traumatic brain injury (TBI) model in rats. Twenty-four adult male Sprague-Dawley rats were randomly divided into three groups of 8 rats each: control, TBI, and TBI + CAPE treatment. In TBI and TBI + CAPE treatment groups, 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 4 h after the onset of injury. Brain tissues were removed for biochemical and histopathological investigation. To date, no biochemical and histopathological changes of neurodegeneration in the frontal cortex after TBI in rats by CAPE treatment have been reported. The TBI significantly increased tissue malondialdehyde (MDA) levels, and significantly decreased tissue superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, but not tissue catalase (CAT) activity, when compared with controls. The administration of a single dose of CAPE (10 μmol/kg) 15 min after the trauma has shown protective effect via decreasing significantly the elevated MDA levels and also significantly increasing the reduced antioxidant enzyme (SOD and GPx) activities, except CAT activity. In the TBI group, severe degenerative changes, shrunken cytoplasma and extensively dark picnotic nuclei in neurons, as well as vacuolization indicating tissue edema formation. The morphology of neurons in the CAPE treatment group was well protected. The number of neurons in the trauma alone group was significantly less than that of both the control and TBI +CAPE treatment groups. The caspase 3 immunopositivity was increased in degenerating neurons of the traumatic brain tissue. Treatment of CAPE markedly reduced the immunoreactivity of degenerating neurons. TBI caused severe degenerative changes, shrunken cytoplasma, severely dilated cisternae of endoplasmic reticulum, markedly swollen mitochondria with degenerated cristae and nuclear membrane breakdown with chromatin disorganization in neurons of the frontal cortex. In conclusion, the CAPE treatment might be beneficial in preventing trauma-induced oxidative brain tissue damage, thus showing potential for clinical implications. We believe that further preclinical research into the utility of CAPE may indicate its usefulness as a potential treatment on neurodegeneration after TBI in rats.

Influence of a brief episode of anesthesia during the induction of experimental brain trauma on secondary brain damage and inflammation

It is unclear whether a single, brief, 15-minute episode of background anesthesia already modulates delayed secondary processes after experimental brain injury. Therefore, this study was designed to characterize three anesthesia protocols for their effect on molecular and histological study endpoints. Mice were randomly separated into groups that received sevoflurane (sevo), isoflurane (iso) or an intraperitoneal anesthetic combination (midazolam, fentanyl and medetomidine; comb) prior to traumatic brain injury (controlled cortical impact, CCI; 8 m/s, 1 mm impact depth, 3 mm diameter). Twenty-four hours after insult, histological brain damage, neurological function (via neurological severity score), cerebral inflammation (via real-time RT-PCR for IL6, COX-2, iNOS) and microglia (via immunohistochemical staining for Iba1) were determined. Fifteen minutes after CCI, the brain contusion volume did not differ between the anesthetic regimens (sevo = 17.9±5.5 mm³; iso = 20.5±3.7 mm³; comb = 19.5±4.6 mm³). Within 24 hours after injury, lesion size increased in all groups (sevo = 45.3±9.0 mm³; iso = 31.5±4.0 mm³; comb = 44.2±6.2 mm³). Sevo and comb anesthesia resulted in a significantly larger contusion compared to iso, which was in line with the significantly better neurological function with iso (sevo = 4.6±1.3 pts.; iso = 3.9±0.8 pts.; comb = 5.1±1.6 pts.). The expression of inflammatory marker genes was not significantly different at 15 minutes and 24 hours after CCI. In contrast, significantly more Iba1-positive cells were present in the pericontusional region after sevo compared to comb anesthesia (sevo = 181±48/mm³; iso = 150±36/mm³; comb = 113±40/mm³). A brief episode of anesthesia, which is sufficient for surgical preparations of mice for procedures such as delivering traumatic brain injury, already has a significant impact on the extent of secondary brain damage.

Pharmacological inhibition of lipid peroxidation attenuates calpain-mediated cytoskeletal degradation after traumatic brain injury

Free radical-induced lipid peroxidation (LP) is critical in the evolution of secondary injury following traumatic brain injury (TBI). Previous studies in our laboratory demonstrated that U-83836E, a potent LP inhibitor, can reduce post-TBI LP along with an improved maintenance of mouse cortical mitochondrial bioenergetics and calcium (Ca(2+)) buffering following severe (1.0 mm; 3.5 m/s) controlled cortical impact TBI (CCI-TBI). Based upon this preservation of a major Ca(2+) homeostatic mechanism, we have now performed dose-response and therapeutic window analyses of the ability of U-83836E to reduce post-traumatic calpain-mediated cytoskeletal (α-spectrin) proteolysis in ipsilateral cortical homogenates at its 24 h post-TBI peak. In the dose-response analysis, mice were treated with a single i.v. dose of vehicle or U-83836E (0.1, 0.3, 1.3, 3.0, 10.0 or 30.0 mg/kg) at 15 min after injury. U-83836E produced a dose-related attenuation of α-spectrin degradation with the maximal decrease being achieved at 3.0 mg/kg. Next, the therapeutic window was tested by delaying the single 3 mg/kg i.v. dose from 15 min post-injury out to 1, 3, 6 or 12 h. No reduction in α-spectrin degradation was observed when the treatment delay was 1 h or longer. However, in a third experiment, we re-examined the window with repeated U-83836E dosing (3.0 mg/kg i.v. followed by 10 mg/kg i.p. maintenance doses at 1 and 3 h after the initial i.v. dose) which significantly reduced 24 h α-α-spectrin degradation even when treatment initiation was withheld until 12 h post-TBI. These results demonstrate the relationship between post-TBI LP, disruptions in neuronal Ca(2+) homeostasis and calpain-mediated cytoskeletal damage.

Peaceful use of disastrous neurotoxicants

The increasing exposure to environmental neurotoxicants in the last decades caused serious health problems in the world population. Some of the neurotoxic agents are being used in agriculture and household such as insecticides and rodenticides and others are of natural origin like snake and scorpion venoms. Additional group of harmful substances is the chemical warfare agents including nerve and blistering agents that are known for their disastrous effects on neuronal tissues. The present paper presents a combination of epidemiological/clinical and molecular approaches for investigating the effect of certain groups of neurotoxicants on a variety of pathologies. The work of Finkelstein and coworkers describes epidemiological and clinical studies on acute and chronic organophosphate (OP)-induced neurotoxicity in certain populations in Israel. They mainly investigated the neurotoxic effects of low-level long-term exposure to OP in agricultural areas but also dealt with acute exposures as well. A molecular approach to OP mechanism of neuronal injury was described by Milatovic and coworkers. They demonstrated OP-induced oxidative injury in pyramidal neurons in the CA1 hippocampal area and its suppression by antioxidants. Lecht and coworkers described the novel snake venom angioneurins as important mediators of the physiological cross-talk between the cardiovascular and nervous systems. They also showed that under certain conditions these angioneurins may induce pathologies such as tumor development or disruption of the vascular barrier function during envenomation. Additional mechanistic/therapeutic approach was presented by Brodsky, Rosengarten, Proscura, Shapira and Wormser. They developed a novel anti-inflammatory peptide that reduced skin irritation induced by heat and sulfur mustard (SM) stimuli. Since SM causes neuropsychiatric symptoms and alterations in neurological functions this peptide may serve as a potential treatment of neuronal injuries caused by environmental neurotoxicants. These reviews highlight different aspects of neurotoxicity, addressing epidemiology and mechanisms of toxicity; and identifying novel potential therapies.

Pharmacodynamics of memantine: an update

Memantine received marketing authorization from the European Agency for the Evaluation of Medicinal Products (EMEA) for the treatment of moderately severe to severe Alzheimer s disease (AD) in Europe on 17(th) May 2002 and shortly thereafter was also approved by the FDA for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist with strong voltage-dependency and fast kinetics. Due to this mechanism of action (MOA), there is a wealth of other possible therapeutic indications for memantine and numerous preclinical data in animal models support this assumption. This review is intended to provide an update on preclinical studies on the pharmacodynamics of memantine, with an additional focus on animal models of diseases aside from the approved indication. For most studies prior to 1999, the reader is referred to a previous review [196].In general, since 1999, considerable additional preclinical evidence has accumulated supporting the use of memantine in AD (both symptomatic and neuroprotective). In addition, there has been further confirmation of the MOA of memantine as an uncompetitive NMDA receptor antagonist and essentially no data contradicting our understanding of the benign side effect profile of memantine.

Protection of DFP-induced oxidative damage and neurodegeneration by antioxidants and NMDA receptor antagonist

Prophylactic agents acutely administered in response to anticholinesterases intoxication can prevent toxic symptoms, including fasciculations, seizures, convulsions and death. However, anticholinesterases also have long-term unknown pathophysiological effects, making rational prophylaxis/treatment problematic. Increasing evidence suggests that in addition to excessive cholinergic stimulation, organophosphate compounds such as diisopropylphosphorofluoridate (DFP) induce activation of glutamatergic neurons, generation of reactive oxygen (ROS) and nitrogen species (RNS), leading to neurodegeneration. The present study investigated multiple affectors of DFP exposure critical to cerebral oxidative damage and whether antioxidants and NMDA receptor antagonist memantine provide neuroprotection by preventing DFP-induced biochemical and morphometric changes in rat brain. Rats treated acutely with DFP (1.25 mg/kg, s.c.) developed onset of toxicity signs within 7-15 min that progressed to maximal severity of seizures and fasciculations within 60 min. At this time point, DFP caused significant (p<0.01) increases in biomarkers of ROS (F2-isoprostanes, F2-IsoPs; and F4-neuroprostanes, F4-NeuroPs), RNS (citrulline), and declines in high-energy phosphates (HEP) in rat cerebrum. At the same time, quantitative morphometric analysis of pyramidal neurons of the hippocampal CA1 region revealed significant (p<0.01) reductions in dendritic lengths and spine density. When rats were pretreated with the antioxidants N-tert-butyl-alpha-phenylnitrone (PBN, 200 mg/kg, i.p.), or vitamin E (100 mg/kg, i.p./day for 3 days), or memantine (18 mg/kg, i.p.), significant attenuations in DFP-induced increases in F2-IsoPs, F4-NeuroPs, citrulline, and depletion of HEP were noted. Furthermore, attenuation in oxidative damage following antioxidants or memantine pretreatment was accompanied by rescue from dendritic degeneration of pyramidal neurons in the CA1 hippocampal area. These findings closely associated DFP-induced lipid peroxidation with dendritic degeneration of pyramidal neurons in the CA1 hippocampal area and point to possible interventions to limit oxidative injury and dendritic degeneration induced by anticholinesterase neurotoxicity.

Catalytic metalloporphyrin protects against paraquat neurotoxicity in vivo

OBJECTIVE

To examine the neuroprotective effects of a novel manganese porphyrin, manganese (III) meso-tetrakis (N,N'-diethylimidazolium-2-yl) porphyrin (MnTDM), in the mouse model of Parkinson's disease (PD) induced by paraquat (PQ).

METHODS

Male C57BL/6 mice were subcutaneously injected with either saline or PQ at 2-day intervals for a total of 10 doses, MnTDM was subcutaneously injected with the PQ 2 h before treatment. Performance on the pole and swim test were measured 7 days after the last injection and animals were sacrificed one day later. Levels of dopamine (DA) and its metabolites in the striatum were measured by high-performance liquid chromatography with an electrochemical detector (HPLC-ECD). Thiobarbituric acid (TBA) method was used to assay the lipid peroxidation product, malondialdehyde (MDA), and the number of tyrosine hydroxylase (TH) positive neurons was estimated using immunohistochemistry.

RESULTS

Pretreatment with MnTDM significantly attenuated PQ-impaired behavioral performance, depleted dopamine content in striata, increased MDA, and dopaminergic neuron loss in the substantia nigra.

CONCLUSIONS

Oxidative stress plays an important role in PQ-induced neurotoxicity which can be potentially prevented by manganese porphyrin. These findings also propose a possible therapeutical strategy for neurodegenerative disorders associated with oxidative stress such as PD.

Effects of halothane, isoflurane, and sevoflurane on lipid peroxidation following experimental closed head trauma in rats

BACKGROUND

In a rat closed head trauma model we examined both the time course of lipid peroxidation and the effects of halothane, isoflurane, and sevoflurane on it by analysis of malondialdehyde (MDA) formation.

METHODS

Animals were divided randomly into five groups: sham-operated (SO), n=18; control-closed head trauma to left frontal pole, n=18; closed head trauma model+halothane, n=18; closed head trauma model+isoflurane, n=18; and closed head trauma model+sevoflurane, n=18. Halothane, isoflurane, or sevoflurane were applied 15 min after trauma for 30 min. Rats were euthanized 1,3, and 5 h after the inhalation agents. Brain tissue samples were taken 5 mm from the left and right frontal poles. MDA was considered to reflect the degree of lipid peroxidation.

RESULTS

MDA concentrations were greater in the control, halothane, sevoflurane, and isoflurane groups than in SO animals (P<0.001). No statistical difference between the hemispheres was found between the halothane, isoflurane, or sevoflurane groups, but MDA levels were lower with isoflurane than in the halothane, sevoflurane, and control groups at 1, 3, and 5 h (P<0.001). MDA levels were higher as compared with the halothane and sevoflurane groups at 1 h but not at 3 or 5 h (P<0.001).

CONCLUSION

MDA levels with the isoflurane group were lower than in the other trauma groups, which suggest that isoflurane, given after closed head trauma, might be protective against lipid peroxidation of cerebral injury.

Oxidative stress and glaucoma: injury in the anterior segment of the eye

The perturbation of the pro-oxidant/antioxidant balance can lead to increased oxidative damage, especially when the first line of antioxidant defense weakens with age. Chronic changes in the composition of factors present in aqueous or vitreous humor may induce alterations both in trabecular cells and in cells of the optic nerve head. Free radicals and reactive oxygen species are able to affect the cellularity of the human trabecular meshwork (HTM). These findings suggest that intraocular pressure increase, which characterizes most glaucomas, is related to oxidative and degenerative processes affecting the HTM and, more specifically, its endothelial cells. This supports the theory that glaucomatous damage is the pathophysiological consequence of oxidative stress. Glaucomatous subjects might have a genetic predisposition, rendering them more susceptible to reactive oxygen species-induced damage. It is likely that specific genetic factors contribute to both the elevation of IOP and susceptibility of the optic nerve/retinal ganglion cells (RGCs) to degeneration. Thus, oxidative stress plays a fundamental role during the arising of glaucoma-associated lesions, first in the HTM and then, when the balance between nitric oxide and endothelins is broken, in neuronal cell. Vascular damage and hypoxia, often associated with glaucoma, lead to apoptosis of RGCs and may also contribute to the induction of oxidative damage to the HTM. On the whole, these findings support the hypothesis that oxidative damage is an important step in the pathogenesis of primary open-angle glaucoma and might be a relevant target for both prevention and therapy.

Potential role of N-methyl-D-aspartate receptors as executors of neurodegeneration resulting from diverse insults: focus on memantine

Glutamatergic neurotransmission is critical to normal learning and memory and when the activity of glutamate neurons becomes excessive, or the normal function of its primary receptors becomes dysfunctional, this may lead to pathological changes associated with age-related neurodegenerative diseases. Anomalous glutamatergic activity associated with Alzheimer's disease may be due to a postsynaptic receptor and downstream defects that produce inappropriately timed or sustained glutamate activation of N-methyl-D-aspartate receptors, leading to neuronal injury and death and cognitive deficits associated with dementia. The mechanisms leading to the condition of chronically depolarized membranes on vulnerable neurons in the Alzheimer's disease brain are likely due to a complex interaction between oxidative stress, mitochondrial failure, chronic brain inflammation and the presence of amyloid-beta and hyperphosphorylated-tau; each of these factors are highly interrelated with each other and are discussed with an emphasis upon potential therapeutic mechanisms underlying the neuroprotective actions of memantine.

Neurotoxicity of reactive aldehydes: The concept of “aldehyde load” as demonstrated by neuroprotection with hydroxylamines

The concept of "oxidative stress" has become a mainstay in the field of neurodegeneration but has failed to differentiate critical events from epiphenomena and sequalae. Furthermore, the translation of current concepts of neurodegenerative mechanisms into effective therapeutics for neurodegenerative diseases has been meager and disappointing. A corollary of current concepts of "oxidative stress" is that of "aldehyde load". This relates to the production of reactive aldehydes that covalently modify proteins, nucleic acids, lipids and carbohydrates and activate apoptotic pathways. However, reactive aldehydes can also be generated by mechanisms other than "oxidative stress". We therefore hypothesized that agents that can chemically neutralize reactive aldehydes should demonstrate superior neuroprotective actions to those of free radical scavengers. To this end, we evaluated hydroxylamines as aldehyde-trapping agents in an in vitro model of neurodegeneration induced by the reactive aldehyde, 3-aminopropanal (3-AP), a product of polyamine oxidase metabolism of spermine and spermidine. In this model, the hydroxylamines N-benzylhydroxylamine, cyclohexylhydroxylamine and t-butylhydroxylamine were shown to protect, in a concentration-dependent manner, against 3-AP neurotoxicity. Additionally, a therapeutic window of 3 h was demonstrated for delayed administration of the hydroxylamines. In contrast, the free radical scavengers TEMPO and TEMPONE and the anti-oxidant ascorbic acid were ineffective in this model. Extending these tissue culture findings in vivo, we examined the actions of N-benzylhydroxylamine in the trimethyltin (TMT) rat model of hippocampal CA3 neurodegeneration. This model involves augmented polyamine metabolism resulting in the generation of reactive aldehydes that compromise mitochondrial integrity. In the rat TMT model, NBHA (50 mg/kg, sc, daily) provided 100% protection against neurodegeneration, as reflected by measurements of KCl-evoked glutamate release from hippocampal brain slices and septal high affinity glutamate uptake. In contrast, ascorbic acid (100 mg/kg, sc, daily) failed to protect CA3 neurons from TMT toxicity. In summary, our data support further evaluation of the concept of "aldehyde load" in neurodegeneration and the potential clinical investigation of agents that are effective traps for reactive aldehydes.

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.