Effects of antiperoxidants on FeCl2-induced lipid peroxidation and focal edema in rat brain

Epileptogenesis following experimentally induced traumatic brain injury - a systematic review

Traumatic brain injury (TBI) is a complex neurotrauma in civilian life and the battlefield with a broad spectrum of symptoms, long-term neuropsychological disability, as well as mortality worldwide. Posttraumatic epilepsy (PTE) is a common outcome of TBI with unknown mechanisms, followed by posttraumatic epileptogenesis. There are numerous rodent models of TBI available with varying pathomechanisms of head injury similar to human TBI, but there is no evidence for an adequate TBI model that can properly mimic all aspects of clinical TBI and the first successive spontaneous focal seizures follow a single episode of neurotrauma with respect to epileptogenesis. This review aims to provide current information regarding the various experimental animal models of TBI relevant to clinical TBI. Mossy fiber sprouting, loss of dentate hilar neurons along with recurrent seizures, and epileptic discharge similar to human PTE have been studied in fluid percussion injury, weight-drop injury, and cortical impact models, but further refinement of animal models and functional test is warranted to better understand the underlying pathophysiology of posttraumatic epileptogenesis. A multifaceted research approach in TBI model may lead to exploration of the potential treatment measures, which are a major challenge to the research community and drug developers. With respect to clinical setting, proper patient data collection, improved clinical trials with advancement in drug delivery strategies, blood-brain barrier permeability, and proper monitoring of level and effects of target drug are also important.

The Anticonvulsant Effects of Vitamin E: A Further Evaluation

Vitamin E (d-α-tocopherol) has proven to be a useful adjunct to anticonvulsant drugs in clinical studies. Improvement has occurred even in patients with complex partial seizures, which are often resistant to drug therapy. In animals, vitamin E is effective against ferrous chloride seizures, hyperbaric oxygen seizures and penicillin-induced seizures. It has failed, however, to show anticonvulsant effects in the standard animal models used for drug screening – the maximal electroshock and threshold pentylenetetrazol tests. The present experiments were designed to further explore the anti-epileptic actions of vitamin E in animals. Three models related to complex partial epilepsy were used: 1) the development of amygdala-kindled seizures; 2) the development of electrically-induced status in kindled animals; and 3) the development of kainic-acid seizures. Vitamin E failed to produce significant effects in any of the models.

Antioxidants as a preventive treatment for epileptic process: a review of the current status

Epilepsy is known as one of the most frequent neurological diseases, characterized by an enduring predisposition to generate epileptic seizures. Oxidative stress is believed to directly participate in pathways leading to neurodegeneration, which serves as the most important propagating factor, leading to the epileptic condition and cognitive decline. Moreover, there is also a growing body of evidence showing the disturbance of antioxidant system balance and consequently increased production of reactive species in patients with epilepsy. A meta-analysis, conducted in the present review confirms an association between epilepsy and increased lipid peroxidation. Furthermore, it was also shown that some of the antiepileptic drugs could potentially be responsible for additionally increased lipid peroxidation. Therefore, it is reasonable to propose that during the epileptic process neuroprotective treatment with antioxidants could lead to less sever structural damages, reduced epileptogenesis and milder cognitive deterioration. To evaluate this hypothesis studies investigating the neuroprotective therapeutic potential of various antioxidants in cells, animal seizure models and patients with epilepsy have been reviewed. Numerous beneficial effects of antioxidants on oxidative stress markers and in some cases also neuroprotective effects were observed in animal seizure models. However, despite these encouraging results, till now only a few antioxidants have been further applied to patients with epilepsy as an add-on therapy. Based on the several positive findings in animal models, a strong need for more carefully planned, randomized, double-blind, cross-over, placebo-controlled clinical trials for the evaluation of antioxidants efficacy in patients with epilepsy is warranted.

Treadmill exercise protects against pentylenetetrazol-induced seizures and oxidative stress after traumatic brain injury

Traumatic brain injury (TBI) is a major cause of acquired epilepsy, and significant resources are required to develop a better understanding of the pathologic mechanism as targets for potential therapies. Thus, we decided to investigate whether physical exercise after fluid percussion injury (FPI) protects from oxidative and neurochemical alterations as well as from behavioral electroencephalographic (EEG) seizures induced by subeffective convulsive doses of pentylenetetrazol (PTZ; 35 mg/kg). Behavioral and EEG recordings revealed that treadmill physical training increased latency to first clonic and tonic-clonic seizures, attenuated the duration of generalized seizures, and protected against the increase of PTZ-induced Racine scale 5 weeks after neuronal injury. EEG recordings also revealed that physical exercise prevented PTZ-induced amplitude increase in TBI animals. Neurochemical analysis showed that exercise training increased glutathione/oxidized glutathione ratio and glutathione levels per se. Exercise training was also effective against alterations in the redox status, herein characterized by lipid peroxidation (thiobarbituric acid reactive substances), protein carbonyl increase, as well as the inhibition of superoxide dismutase and Na⁺,K⁺-ATPase activities after FPI. On the other hand, histologic analysis with hematoxylin and eosin revealed that FPI induced moderate neuronal damage in cerebral cortex 4 weeks after injury and that physical exercise did not protect against neuronal injury. These data suggest that the ability of physical exercise to reduce FPI-induced seizures is not related to its protection against neuronal damage; however, the effective protection of selected targets, such as Na⁺/K⁺-ATPase elicited by physical exercise, may represent a new line of treatment for post-traumatic seizure susceptibility.

Posttraumatic Epilepsy: What's Contusion Got to Do With It?

Text of Abstract Liability to develop posttraumatic epilepsy (PTE) correlates in a general way with trauma dose. While contusion of the brain produces an admixture of extravasated blood, edema fluid and necrotic tissue at the site of skull trauma and in regions remote from the direct force, an unpredictable cascade of shearing injury, torsion and rotation and a myriad of physiological changes occur in structures subject to the mechanical pressure wave. Animal models mimic components of injury, some more thoroughly than others. Designing a treatment that is a prophylaxis for the development of PTE awaits understanding the mechanisms of epileptogenesis initiated by trauma.

Posttraumatic epilepsy: hemorrhage, free radicals and the molecular regulation of glutamate

Traumatic brain injury causes development of posttraumatic epilepsy. Bleeding within neuropil is followed by hemolysis and deposition of hemoglobin in neocortex. Iron from hemoglobin and transferring is deposited in brains of patients with posttraumatic epilepsy. Iron compounds form reactive free radical oxidants. Microinjection of ferric ions into rodent brain results in chronic recurrent seizures and liberation of glutamate into the neuropil, as is observed in humans with epilepsy. Termination of synaptic effects of glutamate is by removal via transporter proteins. EAAC-1 is within neurons while GLT-1 and GLAST are confined to glia. Persistent down regulation of GLAST production is present in hippocampal regions in chronic seizure models. Down regulation of GLAST may be fundamental to a sequence of free radical reactions initiated by brain injury with hemorrhage. Administration of antioxidants to animals causes interruption of the sequence of brain injury responses induced by hemorrhage, suggesting that such a strategy needs to be evaluated in patients with traumatic brain injury.

Inhibitory role of Acorus calamus in ferric chloride-induced epileptogenesis in rat

The roots and rhizomes of Acorus calamus (Family: Araceae) have been used in the ancient systems of medicine for the treatment of various neurological disorders. Of the various methods used for inducing experimental epileptic models, the intracortical administration of ferric chloride (FeCl(3)) into sensorimotor cortex induces recurrent seizures and epileptic discharge similar to human post-traumatic epilepsy through the generation of free radicals. The present study focuses on the effect of Acorus calamus on the behavioral, electroencephalographic, and antioxidant changes in FeCl(3)-induced rat epileptogenesis. Topical administration of FeCl(3) (5 microL; 100 mM) into the sensorimotor cortex of rats showed an increase in the wet dog shake behavior, spike wave discharges together with an significant increase in antioxidant enzyme activity, such as superoxide dismutase and catalase, resulting in an increase in the level of lipid peroxidation in cerebral cortex. Pretreatment with Acorus calamus (200 mg/kg b.w., p.o. for 14 days) and also diazepam (DZ, 20 mg/kg b.w., i.p.) decreased the WDS behavior, spike wave discharges with single isolated positive waves, and a significant decrease in activity of superoxide dismutase and level of lipid peroxidation was observed in cerebral cortex with respect to those observed in FeCl(3)-induced epileptic group. Data presented in this study clearly show that Acorus calamus possesses the ability for preventing the development of FeCl(3)-induced epileptogenesis by modulating antioxidant enzymes, which in turn exhibit the potentiality of Acorus calamus to be developed as an effective anti-epileptic drug.

Factors associated with epilepsy in children with periventricular leukomalacia

Children with cerebral palsy associated with periventricular leukomalacia frequently develop unprovoked epileptic seizures. This article reports an analysis of risk factors for epilepsy in children with radiologically confirmed periventricular leukomalacia. This cohort was screened for epilepsy and for an array of clinical and demographic factors. Of 154 subjects with radiologically confirmed periventricular leukomalacia, 40 (26.0%) had epilepsy. In the epileptic group, radiologic pathology other than periventricular leukomalacia was uncommon. Significant associations were found between epilepsy and cerebral palsy patterns other than spastic diparesis, mental handicap, cortical visual impairment, neonatal seizures, and severe periventricular leukomalacia. Only the presence of neonatal seizures was significantly associated with epilepsy once other risk factors were controlled in the regression model. Some previous studies have shown an association between neonatal seizures and later epilepsy for cerebral palsy in general. This is the first report of such an association for a single predominant type of cerebral pathology.

Does edaravone (MCI- 186) act as an antioxidant and a neuroprotector in experimental traumatic brain injury?

Edaravone (MCI-186) is a novel synthetic free radical scavenger intended to have neuroprotective effect against ischemic insult. It is currently used on patients with cerebral infarction. Here, we note beneficial pharmaceutical effects of edaravone in rat experimental traumatic brain injury. Under specific experimental conditions, edaravone minimized traumatic brain injury by functioning as a synthetic antioxidant. Clinical trials testing the efficacy of edaravone are warranted.

Neuroprotection and epilepsy

During the last years it has become obvious that the current way of treating epilepsy with antiepeileptic drugs is insufficient concerning the modification of the underlying disesease and provides merely a symptomatic treatment, without clear influence on the course of the disease. There is a pressing need to find alternative strategies and to find possibilities to intervene either into the basic processes determining the development of epilepsies or to promote compensatory processes in repairing these dysfunctions. The increasing knowledge about the basic neuronal changes underlying epilepsies allows now to analyse the potential role of neuroprotective agents in in epileptogenesis. In epilepsy the most frequent constellation is the presence of damage and overexcitation together. Increase in excitability may develop after a primary damage as in posttraumatic epilepsy, or outburst of epileptic excitability may cause neuronal damage as in cell loss after status epilepticus or in any case of the so called cytotoxic damage from extensive glutamatergic involvement. Epilepsy in certain forms is a progressive disease. The factors determining the progressive course and the possibe prevention of it is obviously an overlaping field with neuroprotection. Therefore although neuroprotection works only against certain aspects of a complex cascade of pathological events, might be a promising option in several stadiums during the development and course of epilepsy. We provide evidences that some of the new antiepileptic drugs have neuroprotective effect on different animal models of chronic partial epilepsies, and how this effect is fitting to the antiepileptogenic, and seizure supressing effect of the same drugs.

Preclinical development of antiepileptic drugs: past, present, and future directions

Since 1993, nine new antiepileptic drugs (AEDs) have been introduced into the U.S. market for the symptomatic treatment of partial epilepsy. Their antiepileptic activity was, for the most part, defined by acute seizure models such as the maximal electroshock (MES) and subcutaneous pentylenetetrazol (scPTZ) seizure tests and the kindled rat. Unfortunately, the clinical evidence to date would suggest that none of these models, albeit useful, are likely to identify those therapeutics that will effectively manage the patient with refractory seizures. In recent years, a number of in vivo and in vitro models have been developed that display varying degrees of pharmacoresistance. As such, they may provide a unique opportunity for identifying the truly novel AED. Through a greater understanding of the pathophysiology of acquired epilepsy at the molecular and genetic level, it may be possible to identify a new therapeutic approach that reaches beyond the symptomatic treatment of epilepsy to modify the progression, or, dare we suggest, prevent the development of epilepsy in the susceptible patient. The realization of such a possibility will necessitate a change in our current AED discovery approach. The present review describes the current approach used in the search for new AEDs and offers some insight into future directions incorporating new and emerging models of therapy resistance and epileptogenesis.

Post-traumatic epilepsy following fluid percussion injury in the rat

The lack of an adequate model of post-traumatic epilepsy (PTE), in which, similarly to the human condition, chronic spontaneous focal seizures follow a single episode of traumatic brain injury, has hampered the identification of clinically relevant epileptogenic mechanisms and the development of effective therapies. We studied the electrophysiological, behavioural and structural consequences of a clinically relevant model of closed head injury, the lateral fluid percussion injury (FPI), in the rat. We found that a single episode of severe FPI is sufficient to cause PTE. Chronic electrocorticography (ECoG) demonstrated spontaneous chronic seizures that were partial, originated from the neocortex at the site of injury, and progressively worsened and spread over time. The cases of epilepsy in the post-traumatic population increased over time following injury. Post-FPI epileptic rats exhibited pauses in their behaviour, facial automatisms and myoclonus at the time of epileptiform ECoG events. In vitro local field potential recordings demonstrated persistent hyperexcitability of the neocortex at and around the site of injury that was associated with intense glial reactivity. These results for the first time demonstrate persistent hyperexcitability of the injured neocortex and define a useful model for pathophysiological studies of basic mechanisms of spontaneous epileptogenesis and for preclinical screening of effective antiepileptogenic drugs.

Effects of mexiletine, ginkgo biloba extract (EGb 761), and their combination on experimental head injury

Lipid peroxidation (LP) and brain edema are important factors that produce tissue damage in head injury. The purpose of this study was to investigate the effect of mexiletine, gingko biloba extract (EGb 761), and their combination on LP and edema after moderate head trauma. Forty rats were randomly and blindly divided into four groups of ten animals each: control group (bolus injection of physiological saline), mexiletine group (50 mg/kg per injection), EGb 761 group (30 mg/kg per injection), and mexiletine plus EGb 761 group (50 mg/kg and 30 mg/kg per injection, respectively). The injections were given intraperitoneally at 1 h, 9 h, and 17 h after trauma. Twenty-four hours after injury, the rats were killed, and malondialdehyde (MDA) levels and brain water content were determined. Rats treated with mexiletine, EGb 761, and mexiletine plus EGb 761 had significantly lower MDA levels than the control group (P<0.01). The lowest MDA levels were measured in the mexiletine plus EGb 761 group. However, there was no significant difference in brain water content between treated groups and the control group (P>0.05). These findings show the usefulness of mexiletine and its combination with EGb 761 as a cerebroprotective agent in this model of experimental head injury.

alpha-Tocopheryl-L-ascorbate-2-O-phosphate diester, a hydroxyl radical scavenger, prevents the occurrence of epileptic foci in a rat model of post-traumatic epilepsy

Intracortical injection of iron ions has been used to model post-traumatic epilepsy. The results obtained using these models suggest that oxidation of neural membranes by active oxygen free radicals may be involved in the etiology of post-traumatic epilepsy. This is a study of the effects of alpha-tocopheryl-L-ascorbate-2-O-phosphate diester potassium salt (EPC-K1), known as a hydroxyl radical scavenger, on the peroxidation of neural membranes by FeCl(3) in vitro and on the occurrence of epileptic discharges in the FeCl(3) injected post-traumatic epilepsy model rats. EPC-K1 dose-dependently inhibited the production of thiobarbituric acid reactive substances (TBARS) and protein carbonyl (P-Carb), both indices of biogenic macromolecular peroxidation. In vivo studies, sporadic spike discharges and/or epileptiform activities were observed in electrocorticograms (ECoG) of male Sprague-Dawley rat 15-90 min after 500 nmol of FeCl(3) was injected into the motor cortex. On the other hand, when 200 mg/kg of EPC-K1 was injected intraperitoneally 60 min prior to the injection of FeCl(3), the occurrence of epileptic discharges was prevented or delayed. When EPC-K1 (2.5-5 nmol) was injected along with the ferric ions, the occurrence of epileptiform activities was also prevented or delayed. EPC-K1 prevented the induction of early convulsion, the major risk factor of post-traumatic epilepsy. Rats in the Fe+EPC group were injected with 500 nmol of FeCl(3) into the left motor cortex and were given an EPC-K1-diet (CE-2 chow contained 0.2% of EPC-K1, and daily EPC-K1 intake was about 80 mg/kg/day). In the Fe+EPC group rats, the percent induction of epileptic discharges in ECoGs was significantly lower than that in the Fe+CE group rats, which were fed CE-2 after FeCl(3) injection. In the homotropic contra lateral cortex, TBARS and P-Carb content did not show any changes. However, the relative TBARS content in the focal area significantly increased in the Fe+CE and Fe+EPC group rats 3 h after the injection. It became normal 3 days after in the Fe+EPC group. The relative P-Carb content in the focal area significantly increased in the Fe+CE and Fe+EPC group rats 3 h after the injection. However, it became normal after 3 days. In the present study, EPC-K1, which consists of vitamins E and C connected by a phosphate, protected the oxidation of neural membranes and prevented the occurrence of ferric ion-induced epileptic discharges by its radical scavenger activity. These data suggest that EPC-K1 may be clinically useful in not only preventing the focus formation of post-traumatic epilepsy, but also in treating and attenuating the progression of free radical-induced degenerative disorders.

Plasma vitamin C levels are decreased and correlated with brain damage in patients with intracranial hemorrhage or head trauma

BACKGROUND AND PURPOSE

Free radical hyperproduction may play an important role in brain hemorrhage and ischemia/reperfusion injury. The aims of this study were to assess whether antioxidant depletion occurs after intracranial hemorrhage (ICH) and head trauma (HT) and to evaluate the relation between the diameter of the brain lesion, the degree of the neurological impairment, and any observed antioxidant changes.

METHODS

We measured plasma levels of vitamin C (ascorbic acid, AA), uric acid (UA), vitamin E (alpha-tocopherol), and ubiquinol-10 in 13 patients with ICH and 15 patients with HT on the day of the brain injury and subsequently every other day up to 1 week. Patients were compared with 40 healthy control subjects.

RESULTS

ICH and HT patients had significantly lower plasma levels of AA compared with healthy subjects, in contrast to plasma levels of UA, alpha-tocopherol, and ubiquinol-10. AA levels were significantly inversely correlated with the severity of the neurological impairment as assessed by the Glasgow Coma Scale and the National Institutes of Health Stroke Scale. AA levels were also significantly inversely correlated with the major diameter of the lesion. In addition, mean plasma AA levels were lower in jugular compared with peripheral blood samples obtained from 5 patients.

CONCLUSIONS

These findings suggest that a condition of oxidative stress occurs in patients with head trauma and hemorrhagic stroke of recent onset. The consequences of early vitamin C depletion on brain injury as well as the effects of vitamin C supplementation in ICH and HT patients remain to be addressed in further studies.

Lipid peroxidation and oedema in experimental brain injury: comparison of treatment with methylprednisolone, tirilazad mesylate and vitamin E

Trauma-induced lipid peroxidation (LP) is one of the most important factors that produces tissue damage in head trauma. In the present study, the protective effects of free radical suppression with methylprednisolone (MP), tirilazad mesylate (TM) and vitamin E on the development of cerebral LP and oedema resulting from head trauma have been investigated. Rats were divided randomly into four groups. Bolus injections of physiological saline, MP (initial 30 mg/kg for 1 h, continuing administration of 5.4 mg/kg per hour until 24 h), TM (10 mg/kg), or vitamin E (30 mg/kg) were given 1 h after the head trauma. The animals were killed 24 h after the weight-drop injury for removal of the brain, and the malondialdehyde (MDA) level and water content of the brain were determined. Rats treated with TM had MDA levels which decreased significantly in comparison with the control group (P<0.03), and none of the drugs had an effect on LP and water content of the brain (P>0.05) that was statistically different. These findings demonstrated the beneficial effect of TM in this model of experimental brain injury.

Effect of nitric oxide on hemoprotein-catalyzed oxidative reactions

Hemoglobin or myoglobin-catalyzed oxidation reactions have been suggested to initiate and/or exacerbate tissue injury associated with a variety of pathological conditions including post-ischemic tissue injury, hemorrhagic disorders, and chronic inflammation. In the present study, we investigated what effect different fluxes of nitric oxide (NO) have on hemoprotein-catalyzed oxidation reactions in vitro. The hypoxanthine/xanthine oxidase system was used to generate both O2- and H2O2, whereas the spontaneous decomposition of the spermine/NO adduct was used to generate NO at a known and constant rate. We assessed the ability of myoglobin (Mb) or hemoglobin (Hb) to oxidize dihydrorhodamine (DHR) to rhodamine (RH) in the presence of O2-/H2O2 and/or NO. In the presence of a constant flux of O2- and H2O2 (1 nmol/min each), 500 nM MetMb (Fe3+) stimulated DHR oxidation from normally undetectable levels to approximately 35 microM. This oxidation reaction was inhibited by catalase but not SOD, suggesting the formation of the ferryl-hemoprotein adduct (Fe4+). Equimolar fluxes of O2-, H2O2, and NO increased further DHR oxidation to approximately 50 microM. The 15 microM increase in DHR oxidation was independent of heme concentration and was inhibited by SOD. This suggested that equal fluxes of O2- and NO interact to yield a potent oxidant such as peroxinitrite (OONO-) which together with Mb-Fe4+ oxidizes DHR. Further increases in NO fluxes significantly inhibited DHR oxidation (80%) via the NO-dependent inhibition of Mb-Fe4+ formation. Additional studies using methemoglobin (Hb-Fe3+)-catalyzed oxidative reactions yielded virtually identical results. We conclude that in the presence of a hemoprotein such as myoglobin or hemoglobin, NO may promote or inhibit oxidation reactions depending upon the relative fluxes of O2-, H2O2, and NO.

Superoxide radical generation and histopathological changes in hippocampal CA1 after ischaemia/reperfusion in gerbils

PURPOSE

We investigated the relationship between the generation of superoxide radicals and histopathological changes on delayed neuronal death in the hippocampal CA1 subfield.

METHODS

Seventy gerbils were randomly assigned to two groups, a sham group and an ischaemia/reperfusion (I/R) group. In the I/R group, transient forebrain ischaemia was induced by occluding the bilateral common carotid arteries for four minutes. The cerebrum was removed after reperfusion at intervals of one minute, six, twelve and twenty-four hr and at three, five and seven days. Each forebrain was cut into two portions including the hippocampus. The quantity of superoxide radicals was measured by using chemiluminescence, and histopathological changes in the hippocampal CA1 subfield were examined.

RESULTS

In the I/R group, superoxide radicals increased on the 3rd and 5th days compared with the sham group (16.1 +/- 3.4 vs 3.2 +/- 1.0 on the third day (P < 0.0001); 10.9 +/- 1.9 vs 3.3 +/- 0.8 on the fifth day (P < 0.0001)). In the I/R group, the pyramidal cells were atrophic and pycnotic; vacuolation, and structural disruption of the radial striated zone were observed from the third through the seventh day. In the sham group, these changes were not observed. There were differences of degenerative ratios in the pyramidal cells between the two groups from the third to seventh days (5.6 +/- 2.0 vs 80.9 +/- 3.3 on the third day (P < 0.05); 6.9 +/- 0.4 vs 93.6 +/- 2.4 on the fifth day (P < 0.05); 6.2 +/- 1.5 vs 95.0 +/- 1.3 on the seventh day (P < 0.05)).

CONCLUSION

There is a correlation between the generation of superoxide radicals and histopathological changes of the pyramidal cells in the hippocampal CA1 subfield.

5-aminocoumarans: dual inhibitors of lipid peroxidation and dopamine release with protective effects against central nervous system trauma and ischemia

A series of 2,3-dihydro-5-benzofuranamines (5-aminocoumarans) were developed for the treatment of traumatic and ischemic central nervous system (CNS) injury. Compounds within this class were extremely effective inhibitors of lipid peroxidation in vitro and antagonized excitatory behavior coupled with peroxidative injury induced by spinal intrathecal injection of FeCl2 (mouse-FeCl2-it assay) in vivo. Selected compounds were tested for antagonistic activity on methamphetamine (MAP)-induced hypermotility resulting from dopamine release in the mouse brain. Among the compounds synthesized, compound 26n (2,3-dihydro-2,4,6,7-tetramethyl-2-[(4-phenyl-1-piperidinyl) methyl]-5-benzofuranamine) exhibited potent effects in these assays (inhibition of lipid peroxidation, IC50 = 0.07 microM; mouse-FeCl2-it assay, ID50 = 10.4 mg/ kg, po; MAP-induced hypermotility, 98% inhibition, 10 mg/kg, ip). The S-(+)-form of compound 26n dihydrochloride (TAK-218), which has 30 times more potent antagonistic activity on MAP-induced hypermotility than the R-(-)-form, improved more significantly the survival rate in the cerebral ischemia model (rat, 1-3 mg/kg, ip) during the period of 1-14 days after ischemia and decreased functional disorders in the traumatic brain injury model (rat, 0.1-1 mg/kg, ip) 3-14 days after injury. These results imply a role for dopamine in deterioration of CNS function after ischemic and traumatic injury. TAK-218 is a promising compound for the treatment of stroke and CNS trauma and is now under clinical investigation.

Quantitative photometrical assessment of iron deposits in synovial membranes in different joint diseases

We investigated 86 synovial membranes from patients suffering either from rheumatoid arthritis (RA) or osteoarthritis (OA). Iron deposits in the synovial membrane were stained by the Prussian blue reaction, and the amount of stained iron was quantitatively assessed by microscope photometry. We found a statistically significant increase in iron deposits in the synovial membrane of RA patients when compared to OA patients. The amount of iron deposits correlated with the histological subtype of synovitis, those presenting with more exudative and proliferative features showing greater amounts of iron deposits. We also observed an inverse correlation between the haemoglobin concentration and erythrocytes in the serum and the amount of iron in the synovial membrane. From our data we concluded that iron deposits in the synovial membrane can contribute by several mechanisms, including activation of oxygen radicals, to the chronic inflammatory reaction in RA synovitis.

Adenosines scavenged hydroxyl radicals and prevented posttraumatic epilepsy

Intracortical injection of iron ions has been used as a model of posttraumatic epilepsy. Oxidation of lipids in neural membranes by reactive oxygen species, especially hydroxyl radicals (OH), is involved in the mechanisms responsible for iron-induced seizures. We examined the scavenging effects of adenosine (Ado) and 2-chloroadenosine (Cl-Ado) on OH radicals and superoxide (O2.-) using an electron spin resonance (ESR) spectrometer, and the occurrence of epileptic discharges in electrocorticogram (ECoG) induced by FeCl3 injection into the sensorimotor cortex of rats. Though DMPO-O2.- spin adducts generated by the hypoxanthine-xanthine oxidase system were not quenched by Ado or Cl-Ado, 5 mM of each showed a quenching effect on DMPO-OH spin adducts (5.3 x 10(16) spins/ml) generated by the Fenton reagent. In ECoG of rats, spike discharges appeared 15-45 min after FeCl3 injection (500 nmol) into the sensorimotor cortex, and polyspikes and/or ictal patterns were observed 70-90 min after the injection. Cl-Ado (1 mg/kg) or Ado (5 mg/kg) injected intraperitoneally 30 min prior to the FeCl3 injection suppressed or delayed the occurrence of epileptic discharges induced by FeCl3. Cl-Ado and Ado may suppress the occurrence of epileptic discharges by scavenging OH and by their anticonvulsant effect.

Effect of [dl]-alpha-tocopherol on FeCl2-induced lipid peroxidation in rat amygdala

Peroxidative injury of neural membrane lipids can be initiated by iron-containing blood products, chelated ferrous or ferric ions, and low valence iron in aqueous solution. Lipid peroxidation was measured following focal injection of 3 microliters of 100 mM FeCl2 into rat amygdala. Acute parenteral administration of [dl]-alpha-tocopherol as the alcohol limited the quantity of peroxidation products generated. These data suggest a potential role for alpha-tocopherol administration in limiting brain injury responses.

Randomized, double-blind, placebo-controlled, clinical trial of D-alpha-tocopherol (vitamin E) as add-on therapy in uncontrolled epilepsy

In a double-blind, cross-over trial, vitamin E, and placebo were compared as add-on therapy in 43 patients with uncontrolled epilepsy. The study consisted of a 3-month baseline period followed by two treatment phases of vitamin E or placebo with cross-over to the second phase after 3 months. No significant side effects were noted during the study. Mean seizure frequency in the baseline period was 15.9 +/- 10.5 as compared with 11.8 +/- 10.9 during the placebo phase and 13.7 +/- 11.1 during the vitamin E phase. No significant change in seizure frequency was observed with vitamin E as compared with placebo (p > 0.1). Similar observation was noted in subgroups with generalized seizures (n = 25), partial with secondarily generalized seizures (n = 11), or complex partial seizures (CPS) (n = 7). This study did not corroborate the earlier claims of therapeutic efficacy of vitamin E as add-on therapy in refractory epilepsy in adults.

Proposed toxic oxidant inhibitors fail to reduce brain edema

Toxic oxidants (oxygen free radicals) have been implicated in the formation of brain edema from ischemia-reperfusion injury or tumor growth. We investigated the ability of an iron chelator, a calcium channel blocker, and a xanthine oxidase inhibitor to reduce formation of brain edema following a cold lesion in cats. The agents were given independently of each other in an attempt to inhibit the Haber-Weiss reaction, prevent Ca++ modulated uncoupling of oxidative phosphorylation, and inhibit the generation of toxic oxidants via xanthine oxidase, respectively. Pentastarch-deferoxamine conjugate at a dose of 50 mg/kg was given 15 minutes before and 60 minutes after the cold lesion. Nimodipine was given at a dose of 1 mg/kg 1 hour before and 2 hours after the cold lesion. Allopurinol was given at a dose of 50 mg/kg 24 hours before, at the time of the lesion and, 24 and 48 hours after the lesion. Gravimetric measurements of multiple brain areas were performed at 24 hours post-lesion in the pentastarch-deferoxamine and nimodipine groups and at 72 hours post-lesion in the allopurinol group. None of these agents led to significant reduction in brain edema formation as measured with a gravimetric column of kerosene and bromobenzene. Pentastarch-deferoxamine conjugate was utilized to avoid the confounding effects of arterial hypotension which is seen with intravenous deferoxamine. There was even a suggestion of increased edema in the periventricular white matter in animals treated with nimodipine. Taken together, independent inhibition of the Haber-Weiss reaction, of calcium channels, or of xanthine oxidase does not reduce formation of brain edema in the cold lesion model.

Effect of pretreatment with vitamin E or diazepam on brain metabolism of stressed rats

The effect of vitamin E (VE) or diazepam (DZ) pretreatment on some carbohydrate metabolic aspects in the brains of stressed rats was studied. DZ and VE were given i.p. at doses of 5 mg/kg body wt for 6 days prior to subjecting the animals to single swimming stress (SSS). Pretreatment of the rats with DZ or VE diminished the stress-induced increases in plasma corticosterone and glucose levels and reversed the decrease due to stress on brain ATP, glucose, glycogen and pyruvate contents. The increase in brain ADP and lactate was brought back to levels which approached the pre-stressed values. Moreover, DZ and VE pretreatments helped in attenuating the stress-induced alteration in brain mitochondrial and cytosolic hexokinase as well as sodium, potassium adenosine triphosphatase (Na+,K(+)-ATPase) activities. The change in these metabolic parameters produced by VE pre-treatment was less than that exhibited by DZ. The effects of VE were explained in light of its antioxidant property in preventing the free radical production and lipid peroxide formation which are important factors in the pathogenesis of stress.

Antioxidant and pro-oxidant activities of p-hydroxybenzyl alcohol and vanillin: effects on free radicals, brain peroxidation and degradation of benzoate, deoxyribose, amino acids and DNA

We examined the antioxidant and pro-oxidant activities of p-hydroxybenzyl alcohol (p-HBA), the major component of Gastrodia elata Bl. (GE), and compared them with those of vanillin, which is also a component of GE and a known antioxidant. Both p-HBA and vanillin are powerful scavengers of 1,1-diphenyl-2-picryl hydrozyl, superoxide and hydroxyl radicals. Like vanillin, p-HBA also inhibits iron-dependent lipid peroxidation in rat brain homogenate, microsomes and mitochondria. In addition, p-HBA and vanillin in a dose-dependent fashion inhibit Fe(II)-H2O2-induced damage to benzoate, deoxyribose, glutamic acid, 2-aminobutyric acid and methionine, as well as benzoate hydroxylation. Vanillin has a pro-oxidant effect on Fe(III)-superoxide-induced damage to benzoate, deoxyribose, amino acids and benzoate hydroxylation, whereas p-HBA shows no pro-oxidant activity in the system. Vanillin and p-HBA stimulate bleomycin-iron-dependent damage to DNA only at very high concentrations. These findings suggest that the antioxidant effect of GE extract in the rat brain may result from the antioxidant actions of p-HBA and other phenolic compounds such as vanillin at the cellular and molecular level in brain.

Lipid peroxidation induced "in vivo" by iron-carbohydrate complex in the rat brain cortex

In view of the emerging role of metals and particularly iron in the pathogenesis of several ischemic or degenerative CNS diseases, via a lipid peroxidative process, a model of slow iron-induced peroxidative damage in the rat brain cortex has been carried out. Iron-carbohydrate complexes were injected in the right brain cortex, and biochemical assays were performed on ipsilateral and contralateral samples two hours or seven days after injection. Iron-saccharate caused a significant increase in the ipsilateral cortex in TBARS, conjugated dienes and fluorescent substances seven days after injection, whereas no biochemical alteration was observed two hours after treatment. In order to prevent or to limit lipid peroxidation, some drugs known for chelating and/or scavenging activity were administered to iron-injected rats. DL-alpha-tocopherol, methylprednisolone, D-penicillamine significantly decreased the value of fluorescent products formed by iron-saccharate, whereas desferrioxamine was not effective.

Glutathione levels in specific brain regions of genetically epileptic (tg/tg) mice

The tottering (tg/tg) mouse is a genetic model of human generalized epilepsy; these mice exhibit spontaneous absence seizures accompanied by bilaterally synchronous spike-wave discharges (6). The mechanism(s) for seizure activity are unknown in these mice. Several recent studies have suggested that membrane lipid peroxidation may be causally involved in some forms of experimentally induced epilepsies (18). Since reduced glutathione (GSH) is the most important free radical scavenging compound in vivo that can prevent membrane lipid peroxidation, the objective of this study was to investigate GSH concentrations in specific central nervous system regions of genetically epileptic, tg/tg, mice as compared to age-matched controls. Three brain regions, cerebellum, hippocampus, and occipital cortex, were dissected, weighed and the concentrations of reduced and oxidized glutathione (GSH and GSSG, respectively) were measured in each of these tissues. GSH content was significantly lower in the occipital cortex of tg/tg mice compared to controls; no differences were observed in the other two brain regions examined. Total GSH content (GSH plus 2 x GSSG) paralleled GSH concentration differences. GSSG content from tg/tg mice was lower in the hippocampus and occipital cortex, compared to controls. This is the first report of an association between decreased central nervous system glutathione concentrations and seizure activity in animals exhibiting generalized seizures.

Post-traumatic epilepsy: cellular mechanisms and implications for treatment

Epilepsy complicates severe head trauma. Development of persistent seizures appears to correlate with the extent of trauma. Although early reports suggested that prophylactic administration of antiepileptic drugs would prevent epileptogenesis, controlled studies have failed to corroborate this assumption. Head trauma initiates a sequence of responses that includes altered blood flow and vasoregulation, disruption of the blood-brain barrier, increases in intracranial pressure, focal or diffuse ischemia, hemorrhage, inflammation, necrosis, and disruption of fiber tracts. The presence of an intracranial hematoma has a robust association with the development of post-traumatic epilepsy. Extravasation of blood is followed by hemolysis and deposition of heme-containing compounds into the neuropil, initiating a sequence of univalent redox reactions and generating various free radical species, including superoxides, hydroxyl radicals, peroxides, and perferryl ions. Free radicals initiate peroxidation reactions by hydrogen abstraction from methylene groups adjacent to double bonds of fatty acids and lipids within cellular membranes. Intrinsic enzymatic mechanisms for control of free radical reactions include activation of catalase, peroxidase, and superoxide dismutase. Steroids, proteins, and tocopherol also terminate peroxidative reactions. Tocopherol and selenium are effective in preventing tissue injury initiated by ferrous chloride and heme compounds. Treatment strategies for prevention or prophylaxis of post-traumatic epilepsy must await absolute knowledge of mechanisms. Antioxidants and chelators may be useful, given the speculation that peroxidative reactions may be an important component of brain injury responses. However, potential treatment strategies involving gamma-aminobutyric acid (GABA) agonists, NMDA receptor antagonists, and barbiturates need further scientific assessment.

Prevention of chemically induced changes in synaptosomal membrane order by ganglioside GM1 and alpha-tocopherol

Synaptosomal membrane order has been studied by analysis of light depolarization by fluorescent dyes intercalated within membranes following exposure to various environmental toxicants. Two probes were explored: 1,6-diphenyl-1,3,5-hexatriene (DPH), signaling predominantly from the lipid-rich membrane core, and 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH), reporting from the more hydrophilic membrane surface. Chlordecone, a neurotoxic insecticide, decreased the anisotropy of either dye and this change could be prevented by prior treatment of synaptosomes with ganglioside GM1 but not alpha-tocopherol. Exposure to an iron-ascorbic acid oxidizing mixture enhanced synaptosomal membrane order and this effect was blocked by preincubation with alpha-tocopherol but not ganglioside GM1. While these interactions may have partially reflected additive anisotropy changes, the protective agents were also effective at concentrations where they did not in themselves modulate membrane order. Methyl mercuric chloride at concentrations up to 100 microM had no discernable effect upon membrane order. It is suggested that these changes in membrane order may underlie some of the previously reported variations in the content of ionic calcium and in the leakiness of synaptosomes.

An evaluation of the anticonvulsant effects of vitamin E

The anticonvulsant effects of D-alpha-tocopherol (vitamin E) were studied in 4 animal seizure models: the Metrazol threshold model (MET), the maximal electroshock model (MES), the kindling model (well-established seizures), and the ferrous chloride model. Vitamin E failed to antagonize seizures in the MES, MET, or the kindling models. It was, however, able to significantly delay the onset of electrographic seizures in the intracerebral ferrous chloride model. Thus, vitamin E shows activity in the ferrous chloride model, but not in the animal models commonly used to screen for anticonvulsant drug actions.

Biochemical pathogenesis of post-traumatic epilepsy

Head trauma is often followed by epilepsy and may be related to the breakdown of red blood cells and hemoglobin within the CNS. Injection of hemoglobin or iron salts into the rat cortex is known to induce a chronic epileptic focus. We observed the formation of superoxide anion (O2) and hydroxyl radical (.OH) after ferric chloride injection into the rat cerebral cortex and suggest that these radicals, especially .OH, may be responsible for the initiation of lipid peroxidation in neuronal membranes and for the accelerated production of guanidine compounds in the brain, which may in turn lead to epileptogenicity. Then, we found that treatment with epigallocatechin (EGC) or a phosphate diester of vitamins E and C (EPC), which are potent .OH scavengers, significantly inhibited the formation of malondialdehyde and epileptic discharges in the iron-induced epileptic focus.

Lipid peroxidation and glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and glucose-6-phosphate dehydrogenase activities in FeCl3-induced epileptogenic foci in the rat brain

This study investigated the relationship between lipid peroxidation, subsequent activation of antioxidative enzymes, and development of iron-induced epilepsy in the rat. Epileptic foci were produced in rat cerebral cortex by intracortical injection of ferric chloride (FeCl3). The epileptic foci were identified by electrocorticography (ECoG). Epileptiform ECoG activity was shown to occur in the contralateral homotopic cerebral cortex as well. We measured levels of lipid peroxides and changes in the activities of the enzymes: superoxide dismutase (SOD), glutathione peroxidase (GP), glutathione reductase (GR), catalase (CA), and glucose-6-phosphate dehydrogenase (G6P) in the epileptogenic focus (both ipsilateral and contralateral) at days 3, 8, 15, and 23 after FeCl3 injection. Biochemical estimations were made in subcellular fractions, and changes in the ipsilateral site were compared with those in the contralateral site. The results of this study showed that large increases in lipid peroxidation were associated with development and buildup of the ECoG epileptiform discharges. Lipid peroxides increased in the ipsilateral focus by approximately 100% as compared with control. In the contralateral site, however, the increase in lipid peroxides was marginal only. The increase in lipid peroxidation was concomitant with development of the high level of epileptiform activity. The time course of changes in lipid peroxidation paralleled the time course of development and persistence of the epileptiform activity. Regarding changes in the enzyme activities accompanying development of iron epilepsy, the data showed that although SOD and G6P increased by approximately 60% and GR increased by approximately 40%, the increases in the enzyme GP and CA were much lower, less than 20%. Thus, comparatively less increase in CA and GP activities produces a deficiency of these two enzymes in the iron (ipsilateral) focus. Among the various biochemical disturbances that have been identified as involved in epileptogenesis, peroxidative injury resulting from lipid peroxidation in neural plasma membrane may be causally related to development of paroxysmal epileptiform activity in the iron focus. Since GP is an enzyme of major importance in detoxification of lipid peroxides in the brain, based on the results presented in this article, it appears reasonable to suggest that GP deficiency causes lipid peroxidation to increase tremendously during iron epileptogenesis.

Reduction of glutamine synthetase specific activity in cultured astroglia by ferrous chloride

Immature and mature rat astroglia in culture were assayed for glutamine synthetase (GS) activity after a single exposure to the epileptogen FeCl2. Cells were cultured with both standard and elevated extracellular potassium or glutamate (Glu) concentrations. FeCl2 reduced GS activity below control levels, whereas high Glu increased GS activity. However, stimulation by high Glu was significantly attenuated in cultures given both FeCl2 and high Glu, indicating that cells treated with FeCl2 were not able to respond as effectively to increased extracellular glutamate by increasing their GS activity. The significance of these findings is that glial regulation of the neuronal environment may be impaired, based on the proposed importance of GS in ammonia detoxification in the brain.

Perturbations in cerebral oxygen radical formation and membrane order following vitamin E deficiency

The effects of dietary vitamin E deficiency on mouse cerebral membrane order and oxygen reactive species were studied. Quantitation of vitamin E levels in several brain regions showed greatest deficiencies in striatum and cerebellum, followed by substantia nigra, and cortex. Vitamin E deficiency increased central-core membrane order in cerebral P2 fraction, but was without effect in the superficial hydrophilic membrane domain. Oxygen radical formation was studied using the probe 2',7'-dichlorofluorescein diacetate. Basal generation rates of oxygen reactive species were 2.5-fold higher when compared to control animals. While hepatic levels of vitamin E are much more reduced than brain levels, in deficient mice, the rate of oxygen radical formation in the liver was unaltered. This implies an special susceptibility of the brain to deficiency of this lipophilic antioxidant vitamin. Data demonstrate that endogenous levels of free radical scavengers, such as vitamin E, may play an important role in maintaining basal oxygen radical levels and membrane integrity. The dietary vitamin E depletion paradigm suggests that a relation exists between elevated levels of oxygen radicals and more rigid hydrophobic central-cores in cerebral membranes, effects that may play a role in mechanisms underlying the neuropathologic lesions observed following vitamin E deficiency.

Protective effect of the iron chelator deferoxamine on cold-induced brain edema

Oxygen free radicals such as superoxide radical and iron-catalyzed hydroxyl radical generated by the superoxide system have been implicated in the genesis of brain edema. Therefore, deferoxamine (DFO), an iron chelator, could potentially be used to treat brain edema. To examine this hypothesis, vasogenic brain edema was produced in 48 cats by a cortical freezing lesion. The animals were separated into three groups: Group 1 comprised 14 cats that received no DFO and were sacrificed at 6 or 24 hours; Group 2 consisted of 12 cats that were treated with DFO (50 mg/kg/ml, intravenously) at 15 minutes before the lesion was made and 60 minutes later and were sacrificed at 6 or 24 hours; and Group 3 included 12 cats that were treated with DFO (50 mg/kg/ml, intravenously) at 15 minutes after the lesion was produced and 60 minutes later and were sacrificed at 6 or 24 hours. The effect of DFO on arterial blood pressure was also studied in the remaining 10 cats. Brain water content in eight sampling areas was measured by the specific gravity method. Blood-brain barrier disruption was assessed by spread of Evans blue dye with planimetry. Specific gravity values at 6 and 24 hours were significantly higher in Group 2 than in Group 1 animals. Areas of Evans blue dye extravasation at 6 and 24 hours were significantly reduced in Group 2 relative to Group 1. Group 3 cats showed improvement in specific gravity values and Evans blue extravasation at 6 hours, but not at 24 hours. The iron chelator DFO prevented early development of brain edema; thus, this oxygen free radical scavenger may provide a foundation for a new therapy for brain edema.

Vitamin E attenuates the toxic effects of intrastriatal injection of 6-hydroxydopamine (6-OHDA) in rats: behavioral and biochemical evidence

Unilateral 6-hydroxydopamine (6-OHDA) injections into the striatum lead to the development of apomorphine-induced rotation in rats. The circling behavior was associated with significant decreases in dopamine, dihydroxyphenylacetic acid and homovanillic acid in the ipsilateral striatum. Pretreatments with either D-alpha-tocopherol or all-racemic-alpha-tocopherol caused significant attenuation of both the behavioral and biochemical abnormalities. These results are discussed in terms of their support for the free radical hypothesis of Parkinson's disease and for the role of antioxidants in the treatment of this neurodegenerative disorder.

The effects of chronic two-fold dietary vitamin E supplementation on subarachnoid hemorrhage-induced brain hypoperfusion

The effects of chronic dietary supplementation with D-alpha-tocopherol (vitamin E, 70 I.U./lb dry food for 16 weeks) were examined on the acute pathophysiology of experimental subarachnoid hemorrhage (SAH). The SAH was induced in alpha-chloralose-anesthetized cats by intracisternal injection of 0.5 ml/kg of unheparinized arterial blood after prior withdrawal of an equivalent cerebrospinal fluid (CSF) volume. Caudate nuclear blood flow (CBF) was measured via H2 clearance together with intracranial pressure (ICP), mean arterial blood pressure (MABP), cerebral perfusion pressure (CPP), and caudate vascular resistance (CVR). In 6 non-supplemented cats (30 I.U. vitamin E/lb dry food), the SAH resulted in an initial 21.3 +/- 2.4% decrease in CBF by 5 min, followed by a slower secondary decline of 30.1% over the subsequent 3 h after SAH. Together with the fall in CBF, the ICP rose progressively by 18.5 mm Hg (P less than 0.004) and CPP decreased by 36.6 mm Hg (P less than 0.01) at 3 h post-SAH. Furthermore, the CVR increased by 42.9% over the course of the experiment. In comparison, in 6 vitamin E-pretreated cats, there was a complete inhibition of the acute decline in CBF and increase in CVR. In addition, the magnitude of the SAH-induced increase in ICP was significantly less than in the non-supplemented animals. However, the decrease in CPP was unaffected. The ability of intensive anti-oxidant treatment to antagonize post-hemorrhagic hypoperfusion suggests that cerebral microvascular lipid peroxidation may play a key role in its development.

Failure of inhibition of lipid peroxidation by vitamin E to protect against gentamicin nephrotoxicity in the rat

We tested the hypothesis that accelerated lipid peroxidation, possibly at the level of the lysosome, is linked causally to the pathogenesis of aminoglycoside nephrotoxicity by investigating whether administration of vitamin E would inhibit lipid peroxidation and prevent or ameliorate gentamicin-induced proximal tubular cell injury. Five groups of rats were injected with either saline, vitamin E (600 mg/kg per day) for 6 days, gentamicin (100 mg/kg per day) for 6 days, vitamin E for 6 days plus gentamicin for 6 days or vitamin E for 12 days and gentamicin for the last 6 days. Gentamicin alone induced a 16% increase in renal cortical phospholipids; vitamin E had no significant effect on this change. Gentamicin alone caused accelerated lipid peroxidation evident by a doubling of renal cortical malondialdehyde to 1.23 nmol/mg protein, and a sharp decline of esterified polyunsaturated fatty acids, especially arachidonic acid which fell 43%. These changes were accompanied by depressions of superoxide dismutase, catalase, and total glutathione and a shift from reduced to oxidized glutathione. Concurrent treatment of rats with vitamin E plus gentamicin for 6 days had no significant effect on the gentamicin-induced alterations of malondialdehyde, superoxide dismutase, catalase or the glutathione cascade; however, the shift from polyunsaturated to saturated fatty acids was largely reversed. In rats pretreated with vitamin E for 6 days, gentamicin failed to raise renal cortical malondialdehyde above that of saline-treated rats. The changes in esterified fatty acids were prevented almost entirely, and there were no significant alterations from control of the glutathione cascade. The depressions of superoxide dismutase and of catalase, however, were not reversed. Vitamin E did not affect the amount of gentamicin accumulated in renal cortex nor did it prevent the gentamicin-induced rise of serum creatinine. Examination of renal cortex by light and electron microscopy revealed that vitamin E did not prevent or even reduce the severity of gentamicin-induced proximal tubular cell lesions and necrosis. These results confirm those we obtained in a previous study with the antioxidant diphenyl-phenylenediamine. The observation that inhibition of lipid peroxidation by two distinct antioxidants failed to prevent proximal tubular cell injury and renal dysfunction associated with gentamicin administration leads us to conclude that lipid peroxidation is a consequence and not a cause of gentamicin-induced nephrotoxicity.

The role of iron-induced hippocampal peroxidation in acute epileptogenesis

Intracortical injection of iron salts causes lipid peroxidation, focal edema, necrosis, gliosis, and the development of behavioral and electrographic seizures. Tocopherol pretreatment prevents the histopathologic perturbations associated with iron injection, and appears to accelerate the resolution of focal accumulation of peroxidation products. In this experiment, rats were pretreated with 500 mg/kg DL-alpha-tocopherol acetate prior to the injection of 3 microliter of 100 mM FeCl2 into the dorsal hippocampus, or induction of convulsive seizures by s.c. injection of 0.8 mg/100 g bicucullin. Tocopherol pretreatment prevented the occurrence of convulsive seizures in a significant number of iron-salts injected animals. Lipid peroxidation measured in the dissected hippocampus was significantly increased in untreated rats developing iron-induced seizures and in rats treated with tocopherol, but developing convulsive seizures. Tocopherol failed to prevent bicucullin-induced seizures. Further, convulsive seizures induced by bicucullin failed to alter hippocampal fluorescence levels. Hence, we concluded that the epileptogenic effects of hippocampal injection of iron salts appear to be related to the induction of peroxidation of neural lipids within the injection site.