The effect of ischemia and recirculation, hypoxia and recovery on anti-oxidant factors and beta-adrenoceptor density. Is the damage in the erythrocytes a reflection of brain damage caused by complete cerebral ischemia and by hypoxia?

Caffeic acid phenethyl ester protects rabbit brains against permanent focal ischemia by antioxidant action: a biochemical and planimetric study

The present study was conducted to investigate whether caffeic acid phenethyl ester (CAPE), an active component of propolis extract, has a protective effect on brain injury after focal permanent cerebral ischemia, and to determine the possible antioxidant mechanisms. Cerebral infarction in adult male New Zealand rabbits was induced by microsurgical procedures producing right focal permanent middle cerebral artery occlusion (pMCAO). CAPE was administered to the treatment group after pMCAO at a dose of 10 micromol kg(-1) once a day intraperitoneally for 7 days. Neurological deficits were evaluated, using a modified six-point scale. Spectrophotometric assay was used to determine the contents of malondialdehyde (MDA), glutathione (GSH), catalase (CAT), nitric oxide (NO) and xanthine oxidase (XO). In the ipsilateral hemisphere, the infarct volume of the brain was assessed in brain slices stained with heamatoxylen and eosin. The results showed that treatment with CAPE significantly reduced the percentage of infarction in the ipsilateral hemisphere compared with the ischemia group. CAPE treatment significantly attenuated the elevation of plasma MDA, CAT and XO content (p<0.05), whereas it significantly increased the levels of plasma GSH and NO (p<0.05). Therefore, subacute CAPE administration plays a protective role in focal pMCAO due to attenuation of lipid peroxidation and its antioxidant activity. All of these findings suggest that CAPE provides neuroprotection against cerebral ischemia injury through its antioxidant action.

Increased lipid peroxidation and neuron specific enolase in treatment refractory schizophrenics

It is well-known that increased lipid peroxidation and failure of antioxidant mechanisms leads to neuronal damage in schizophrenic patients. However, this neurodegenerative mechanism has not been studied in treatment refractory schizophrenics (TRS). Therefore, the main purpose of this study was to determine neuronal damage in TRS in comparison to non-refractory schizophrenics (NRS) by means of quantitative analysis of lipid peroxidation and neuron specific enolase (NSE) related to the psychopathology severity. Two groups of paranoid schizophrenics, TRS and NRS, and a group of healthy controls (CO) were assembled (n=13). Lipid peroxidation was analyzed through spectrophotometry for quantification of malonaldehyde (MDA) and 4-hydroxynonenal (4-HNE) serum concentrations. As well, serum NSE was quantified by radioimmunoassay (ELSA). Psychopathology was evaluated using the brief psychiatric rating scale (BPRS) and the positive and negative symptoms scale (PANSS). TRS showed significant higher concentrations of lipoperoxides by-products and NSE, than NRS and CO. Clinical scores also revealed a more severe pathology in TRS, than in NRS. Raised lipoperoxidation correlated with higher delusions and emotional withdrawal symptoms, and increased NSE correlated with a lower flow of the conversation and lack of spontaneity. All these results together suggest that TRS patients suffer a greater lipid peroxidation and neuronal damage than NRS, apparently related to worsening of some of the psychiatric symptoms.

The role of oxidative stress in postoperative delirium

AIM

This study aimed to determine a marker that predicts delirium using preoperative oxidative processes in patients undergoing cardiopulmonary bypass surgery.

METHOD

Twelve of the 50 patients included in the study showed signs of delirium during postoperative follow-up. The Delirium Rating Scale was used in patients with delirium according to DSM-IV-TR in the postoperative period. Venous blood samples were obtained from the patients the day before and the day after the surgery to determine plasma antioxidant enzyme levels.

RESULTS

While there were no differences in preoperative superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) levels in both groups, catalase (CAT) levels were significantly lower in the delirium group. Postoperative SOD and MDA levels were also higher in the delirium group, while the GSH-Px levels were found to be lower when compared with those during the preoperative period. In the nondelirium group, the postoperative MDA and GSH-Px levels were found to be lower than preoperative levels, and postoperative SOD levels were found to be higher than preoperative levels. CAT levels were lower in the delirium group when the pre- and postoperative levels were compared in both groups. The postoperative levels of SOD, GSH-Px and CAT in the nondelirium group and MDA in the delirium group were significantly higher than preoperative levels.

CONCLUSION

Patients with low preoperative CAT levels appeared to be more susceptible to delirium than patients with higher CAT levels.

The role of catecholamines in memory impairment in chicks following reduced gas exchange in ovo

We have shown previously that reducing gas exchange to chick embryos by half wrapping eggs with an impermeable membrane from either days 14-18 (W14-18) or days 10-18 (W10-18) of the 21 day incubation results in post-hatch memory deficits. In the W10-18 chicks, short-term memory following training is impaired, whereas in the W14-18 chicks, memory is intact for 30 min but does not consolidate into long-term storage. The reduction in gas exchange caused by half wrapping eggs resulted in alterations in hematocrit, O2 and CO2 tensions suggesting that the embryos are hypoxic and hypercapnic. Our aim was to test the hypothesis that increases in circulating levels of catecholamines in ovo, as a result of hypoxia, lead to a disturbance of the central noradrenergic pathways resulting in cognitive impairment. Noradrenaline is critical for memory consolidation and a disturbance during development could compromise cognitive ability. In the present study, plasma noradrenaline levels were significantly elevated compared with control levels 2 days after hatch in W14-18 chicks. There was also a decrease in tissue noradrenaline concentration in the anterior forebrain in both W14-18 and W10-18 chicks. The differential ability of centrally administered beta2- and beta3-adrenoceptor agonists to overcome the memory deficit post-training, suggests altered responsiveness of central beta2-adrenoceptors to noradrenaline in W14-18 chicks. By comparing the W10-18 and W14-18 chicks with those from eggs wrapped from W10-14 we show that it is the timing of the prenatal hypoxia, rather than its duration, that determines the nature of cognitive dysfunction. We conclude that prenatal hypoxia induced by restriction of gas exchange can disrupt or alter central noradrenergic transmission causing cognitive impairment.

Overproduction of neutrophil radical oxygen species correlates with negative symptoms in schizophrenic patients: parallel studies on neutrophil chemotaxis, superoxide production and bactericidal activity

Defective neutrophil function in schizophrenic patients has recently been reported. There are several lines of evidence to support the contribution of oxygen free radicals in schizophrenia, including increased lipid peroxidation, fatty acids and alterations in blood levels of anti-oxidant enzymes. Eighteen schizophrenic patients (DSM-IV) and 15 healthy controls were studied. Neutrophil chemotaxis, superoxide production and bactericidal activity were investigated. A statistically significant increase of superoxide anion release was found in schizophrenic patients compared with controls (mean+/-S.E.M., patients: 6.89+/-0.30 nmol O2-/10(6) cells/min, controls: 5.13+/-0.55 nmol O2-/10(6) cells/min). Moreover, a significant positive correlation between superoxide production and negative symptoms as assessed by the Positive and Negative Syndrome Scale was demonstrated. No differences were detected in chemotaxis and phagocytosis between schizophrenic patients and healthy controls. The present findings of a positive correlation between superoxide generation and negative symptoms in schizophrenic patients support the hypothesis that superoxide anion may participate in the pathogenesis of schizophrenia, as an excess of free radicals could contribute to the deterioration phase of the disease. Further studies are required to establish the role of oxidative stress in the ethiopathogenesis of schizophrenia.

Essential polyunsaturated fatty acid and lipid peroxide levels in never-medicated and medicated schizophrenia patients

BACKGROUND

Reduced levels of membrane essential polyunsaturated fatty acids (EPUFAs) and increased levels of lipid peroxidation products (thiobarbituric acid reactive substances; TBARS) have been observed in chronic medicated schizophrenics. The relationship of EPUFA and TBARS to psychopathology is unclear, since their levels may be altered differentially by duration of illness and antipsychotic treatment. To minimize these confounds, their levels were compared among never-medicated patients in early illness, medicated patients and control subjects with similar lifestyle and common ethnic background.

METHODS

RBC membrane EPUFAs, plasma TBARS, and various dimensions of psychopathology were measured using established procedures in never-medicated (n = 20) and medicated (n= 32) schizophrenia patients and in control subjects (n= 45).

RESULTS

Reduced levels of EPUFAs, particularly arachidonic acid (AA) and docosahexaenoic acid (DHA), were found in never-medicated compared with control subjects; however, the reductions in levels of both AA and DHA were much smaller in medicated versus never-medicated patients; AA levels were similar to levels in control subjects. Only DHA levels were significantly reduced in medicated patients. Lower membrane AA levels were associated with increased levels of plasma TBARS in never-medicated patients. Lower levels of membrane EPUFAs and higher levels of plasma TBARS were associated with the severe symptoms in never-medicated versus medicated patients.

CONCLUSIONS

Data indicate that reduced EPUFAs and increased TBARS exist in never-medicated patients, and these measures correlate with the severity of psychopathology indicating that the membrane EPUFA status may reflect the outcome of schizophrenia.

Effect of melatonin and nifedipine on some antioxidant enzymes and different energy fuels in the blood and brain of global ischemic rats

The brain normally derives most of its energy from the aerobic oxidation of glucose and therefore it must be nourished with a rich supply of both glucose and oxygen. Interference with the blood supply, such as in ischemia, could shift the brain to search for another source of energy and to spare its own glucose. Ischemia results not only in energy fuel disturbance, but also in free radical formation and Ca(2+) homeostasis disruption. Therefore, our investigations studied the influence of ischemia on energy fuels, on some natural free radical scavengers, and the relationship between the changes of these parameters in brain and blood. Each of these was also studied under the influence of melatonin, a well-known free radical scavenger, and nifedipine, a Ca(2+)-channel blocker and antioxidant, during ischemia followed by reperfusion (I/R). Adult male Wistar rats were subjected to global ischemia by occlusion of the two carotid arteries for 1 hr (group I), followed by reperfusion for another hour in group II. Drugs were injected after ischemia (group I), and before or after reperfusion onset in the second group. Two series of animals were used. In the first series the effect of the two drugs on the activity of superoxide dismutase (SOD), glutathione reductase (GR), and lactate dehydrogenase (LDH) was investigated in the cytosolic fraction of four brain areas, viz., cortex (CC), thalamus/hypothalamus (T/TH), midbrain (MB) and medulla, pons and cerebellum (MPC). Moreover, the level of both SOD and GR in the erythocytes of these rats was also estimated. In the second series, we studied the effect of each drug on the content of glucose and beta-hydroxybutyrate (beta-HB) in whole brain, in addition to the plasma levels of glucose, beta-HB and lactate. The results showed that (i), ischemia elevated the brain levels of LDH and beta-HB, as well as the plasma level of glucose, beta-HB, lactate and erythocytic GR. Conversely, it lowered glucose, SOD and GR levels in the brain; (ii), reperfusion reversed the ischemic effect on all the previously altered parameters except for plasma levels of lactate and glucose; (iii), melatonin (10 mg/kg, i.p) and nifedipine (1.5 mg/kg, i.p), restored the energy fuel levels in the brain of ischemic and I/R rats, as well as the ischemic effect on the erythocyte activities of SOD and GR. Furthermore, both drugs reversed I/R effect on the cytosolic activities of the antioxidant enzymes. We conclude that melatonin and nifedipine are both neuroprotective with improvement in the antioxidant system and energy fuels.

Elevated plasma lipid peroxides at the onset of nonaffective psychosis

BACKGROUND

Impaired antioxidant defense and increased lipid peroxidation has been reported in chronic schizophrenic patients. Recently, we have reported an impaired antioxidant defense in never medicated first-episode schizophrenic and schizophreniform patients. We report now a concomitant increase in plasma lipid peroxides.

METHODS

The plasma lipid peroxides [thiobarbituric acid reactive substances (TBARS)] were analyzed by chemical and high performance liquid chromatography procedures in 26 patients admitted for a first episode of schizophrenic (N = 17) or schizophreniform psychosis (N = 9) and 16 normal control subjects. The patients had a duration of 4.5 days (SD 2.8) of psychosis at the time of the study.

RESULTS

Plasma TBARS levels were significantly higher in the patients than in normal controls (P < .002). TBARS levels were above the normal range in 16 of the 26 patients. Higher TBARS levels were associated with a greater severity of negative symptoms and lower red blood cell activity of the glutathione peroxidase.

CONCLUSIONS

The findings indicate ongoing oxidative injury at the very onset of psychosis. If valid, this would indicate the need for adjunctive antioxidant treatment from the beginning of the course of nonaffective psychoses. This might prevent a deteriorating course and development of the deficit syndrome.

Hypoxic pretreatment protects against neuronal damage of the rat hippocampus induced by severe hypoxia

The present study investigates whether under conditions of successive hypoxic exposures pretreatment with mild (15% O(2)) or moderate (10% O(2)) hypoxia, protects hippocampal neurones against damage induced by severe (3% O(2)) hypoxia. The ultrastructural findings were also correlated with regional superoxide dismutase (SOD) activity changes. In unpretreated rats severe hypoxia induced ultrastructural changes consistent with the aspects of delayed neuronal death (DND). However, in preexposed animals hippocampal damage was attenuated in an inversely proportional way with the severity of the hypoxic pretreatment. The ultrastructural hypoxic tolerance findings were also closely related to increased regional SOD activity levels. Thus the activation of the endogenous antioxidant defense by hypoxic preconditioning, protects against hippocampal damage induced by severe hypoxia. The eventual contribution of increased endogenous adenosine and/or reduced excitotoxicity to induce hypoxic tolerance is discussed.

Free radical pathology and antioxidant defense in schizophrenia: a review

There is increasing evidence that free radical-mediated CNS neuronal dysfunction is involved in the pathophysiology of schizophrenia. Free radicals (oxyradicals, such as superoxide, hydroxyl ions, and nitric oxide) cause cell injury when they are generated in excess or the antioxidant defense is impaired. Both of these processes seem to be affected in schizophrenia. Evidence of excessive oxyradical generation is premised on the assumption that there is increased catecholamine turnover, though there is little direct evidence to support such a view, which is further accentuated by neuroleptic treatment. However, antioxidant enzymes (superoxide dismutase, SOD; glutathione peroxidase, GSHPx; and catalase, CAT) which are constitutively expressed in all tissues, are found to be altered in erythrocytes of schizophrenic patients. Also, possible oxyradical-mediated injury to CNS is suggested by increased lipid peroxidation products in cerebrospinal fluid and plasma, and reduced membrane polyunsaturated fatty acids (PUFAs) in the brain and RBC plasma membranes. The brain is more vulnerable to oxyradical-mediated injury,because its membranes are preferentially enriched in oxyradical sensitive PUFAs, and damaged adult neurons cannot be replaced. In addition to their pathological role, oxyradicals have critical physiological functions in neuronal development, differentiation, and signal transduction, all of which may be altered in some cases of schizophrenia. It may be possible to define cellular injury processes, investigate underlying dynamic regulatory molecular processes, and find ways to prevent these injury processes using peripheral cell models, e.g., red blood cells, lymphocytes and cultured skin fibroblasts. Information on the clinical implications of these processes are valuable for developing new and innovative therapeutic strategies for schizophrenia.

Impaired antioxidant defense at the onset of psychosis

Previous studies found peripheral activities of antioxidant enzymes to be abnormal in schizophrenic patients. It is not understood whether this is integral to the disease process or a result of long-term treatment with neuroleptics. Red blood cell activities of three antioxidant enzymes--superoxide dismutase, glutathione peroxidase, and catalase--were therefore examined in 14 drug-naive, first episode patients with a diagnosis of schizophrenia or schizophreniform disorder and 10 normal subjects. The patients had an average duration of psychosis of 4.46 days (SD 2.5). Superoxide dismutase activity was significantly lower in patients than in normal controls, with no difference between the groups in activities of the other two enzymes. Lower superoxide dismutase activity was associated with deterioration of school functioning from childhood to early adolescence and a history of poorer school functioning during early adolescence. These findings indicate a compromised antioxidant defense at the onset of psychosis, and suggest that oxidative injury might contribute to adverse developmental events in the pathogenic cascade of schizophrenia.

Effect of transient reduction of cerebral blood flow on membrane anisotropy and lipid peroxidation in different rat brain areas

Light-microscopical studies revealed that oligemic hypoxia for 24 and 60 min as produced by bilateral clamping of the carotid arteries (BCCA) in normotension does not produce neuronal cell necrosis in the vast majority of rat brain. Less than 5% of cases showed a pattern of mild selective neuronal necrosis as would be expected in ischemia. However, significant changes in both lipid peroxidation (as measured by MDA formation) and membrane anisotropy (measured by DPH or TMA-DPH, respectively, as a fluorescence probe) in cortical and striatal, but not in hippocampal, membrane fractions could be measured in ex vivo studies. Twenty-four and 60 min of BCCA without reperfusion decreased lipid peroxidation in the cerebral cortex but not in the striatum. BCCA, either for 24 or 60 min, and 60 min of reperfusion produced no changes in lipid peroxidation in either structure. However, 24 and 60 min of BCCA followed by 14 days of reperfusion led to a significant increase in MDA formation in the striatum, while lipid peroxidation in the cortex was only increased after 60 min of BCCA. Cortical as well as striatal membrane anisotropy increased significantly 14 days later in rats submitted to BCCA for 24 or 60 min. The study shows an increased lipid peroxidation 2 weeks after a transient reduction in cerebral blood flow although no neuronal necrosis could be observed in general.

Is brain superoxide dismutase activity increased following chronic treatment with 1-deprenyl?

L-deprenyl, a specific MAO-B inhibitor, has been proposed to possess a neuroprotective effect. The mechanism of such an effect is unclear. L-Deprenyl has been found to increase rat striatal superoxide dismutase (SOD) activity, which inactivates singlet oxygen. It would be very interesting to know how such activation occurs and whether or not other MAO inhibitors also have such an effect. We have analyzed rat striatal SOD activity using a very sensitive nitrite method and an immunological procedure. The effect of different doses and time of treatment with 1-deprenyl and M-2-PP (2-pentyl-N-methyl-propargylamine), a new highly potent, selective and non-amphetamine-like MAO-B inhibitor, on the rat brain has been investigated. We were unable to detect any increase of SOD activity in the rat striata and cerebral cortex nor any increase in the concentration of immunoreactive SOD antibody in the cortex following chronic treatment with 1-deprenyl and M-2-PP. It remains to be substantiated as to whether or not 1-deprenyl can enhance SOD levels.

Control of physical exercise of rats in a swimming basin

To study the mutual interaction between physical exercise and antioxidant systems in rats, we selected swimming as a model for exercise performance. Swimming belongs to the natural behavior of a rat, which under proper experimental conditions, primarily involves physical exercise with little emotional arousal. Therefore, we developed a swimming basin in which the intensity of exercise was manipulated by swimming speed and swimming duration. A laser beam interruption system enables recording of swimming patterns. For comparison we also used the basin to induce emotional arousal. Hereto the basin was transformed into a maze, in which unexpected blockade of a learned swimming route induced a panic-like emotional reaction. The antioxidant enzyme superoxide dismutase decreased in rat plasma after emotional arousal, not after physical exercise. Depletion of the antioxidant glutathione in the liver by diethyl maleate led to decrease of swimming performance. Noradrenaline but not adrenaline plasma levels increased in response to physical exercise. After emotional arousal the ratio noradrenaline/adrenaline did not change. In contrast, lactate only increased in response to emotional arousal. Plasma levels of glucose increased after both stress situations. Beta-adrenoceptor function, determined in the heart and in erythrocytes, only changed after physical exercise. The sensitivity to the beta-agonist (-)isoprenaline in the right atrium decreased and a downregulation of the beta-adrenoceptor density was observed in the erythrocyte.

Sequential changes in activities of superoxide dismutase and catalase in brain regions and liver during (-)deprenyl infusion in male rats

A continuous s.c. infusion of (-)deprenyl in young male rats at a dose of 2.0 mg/kg/day for 1 week significantly increased total superoxide dismutase (SOD) activities due to increases in both Cu Zn-SOD and Mn-SOD activities in certain brain regions such as the substantia nitra and striatum, but not in the hippocampus or cerebellum, or in the liver. With continuing infusion, enzyme activities of SOD were further increased in the following weeks, reaching a plateau at 3 weeks. In some cerebral cortices the increase became significant at 3 weeks. In contrast to SOD activities, an increase in catalase (CAT) activity became significant only after 2 weeks of infusion, and only in the brain regions where SOD activities were increased earlier. The delay in the increase in CAT activity following deprenyl infusion suggests that this increased CAT activity is an adaptive response to the earlier increase in deprenyl-induced SOD activities rather than a direct effect of deprenyl on CAT activity, although the latter possibility cannot be excluded.

Glutathione mobilization during cerebral ischemia and reperfusion in the rat

1. Cerebral ischemia applied for 15 min and followed by a 30 min reperfusion did not change the glutathione (GSH) levels and beta-adrenoceptor density (Bmax) in brain cortex. 2. A significant increase in erythrocyte-lysate GSH concentration (vs control) and a significant decrease of Bmax values in erythrocyte membranes (vs control) was found at the same time. 3. Pretreatment with the alpha-adrenoceptor antagonist phentolamine (5 mg/kg i.p.) prevented the erythrocyte GSH increase but not the decrease of Bmax value. Pretreatment with the beta-antagonist propranolol (2 mg/kg i.p.) did not influence the increase in erythrocyte GSH but circumvented the decrease of Bmax.

The ability of (-)deprenyl to increase superoxide dismutase activities in the rat is tissue and brain region selective

In a previous study we have shown that chronic administration of (-)deprenyl increases activities of superoxide dismutase (SOD) and catalase (CAT) in rat striatum (1). The present study attempted to clarify how specific the effect of deprenyl is to certain tissues and brain regions in the rat. Two mg/kg/day of deprenyl was continuously infused s.c. in young male Fischer-344 rats. On the 22nd day, rats were sacrificed and enzyme activities of SOD and CAT were determined in several different brain regions and the liver. Activities of both SOD and CAT were significantly increased in striatum and substantia nigra but not in hippocampus, cerebellum or liver. Both types of SOD (i.e. Cu Zn-SOD and Mn-SOD) were significantly increased in striatum, substantia nigra. Interestingly, in cerebral cortices of three different regions, activities also tended to increase (especially those of Mn-SOD), although the increase was not so striking as in substantia nigra and striatum. The results confirm the previous observation that (-)deprenyl can increase free radical scavenger enzyme activities in striatum and provide further evidence that this effect is selective to certain brain regions and tissue types.

Effect of phenazine methosulfate on electrophysiological activity of the semicircular canal: antioxidant properties of trimetazidine

Ischemia strokes appear to be the main source of cochleo-vestibular dysfunctions of peripheral origin. The present study aimed to investigate the action of oxygen free radicals on the bioelectric activity of the labyrinthine epithelium, using the frog semicircular canal as an in vitro preparation. We also examined the possible effect of the antianginal drug, trimetazidine (TMZ), under physiological conditions and during the administration of phenazine methosulfate (PMS). The model allows the ionic composition of endolymphatic and perilymphatic fluids bathing the semicircular canal to be dealt with separately. Spontaneous afferent vestibular nerve activity and the endolymphatic potential were recorded under resting conditions. Three additional parameters were investigated during mechanical displacement of the endolymphatic fluid: the ampullar direct current, the nerve direct current and the frequency of the evoked afferent spikes. Addition of TMZ (10(-6) and 10(-5) M, 50 min) into the perilymphatic compartment did not induce significant modifications of the different bioelectrical signals. Generation of oxygen free radicals, through administration of PMS (10(-5) M, 15 min) into the perilymphatic compartment, caused an impairment of all bioelectrical signals, except the ampullar direct current. The spontaneous activity, nerve direct current and frequency of afferent evoked spikes signals were significantly reduced 75 min after the start of PMS administration (-64, -17 and -32%, respectively). In contrast, there was a marked increase of the endolymphatic potential signal (+51%). Addition of TMZ (10(-6) or 10(-5) M) into the perilymph solution reversed the effect of PMS on all bioelectrical signals. These results indicate that TMZ acts as an antioxidant molecule which is capable of protecting the labyrinthine epithelium from the deleterious effect of oxygen radicals. Our data suggest that the protective effect of TMZ on ischemia-induced cochleo-vestibular dysfunctions may be accounted for by the antioxidant properties of this antianginal drug.