Efficacy of cosmetic products in cellulite reduction: systematic review and meta-analysis

BACKGROUND

The number of original articles investigating the efficacy of cosmetic products in cellulite reduction increased rapidly in the last decade; however, to our knowledge, no systematic review and meta-analysis has been performed so far.

OBJECTIVE

We conducted a systematic review of in vivo studies on humans adopting the PRISMA guidelines. Moreover, we used a meta-analytic approach to estimate the overall effect of cosmetic creams in cellulite treatment from controlled trials with more than 10 patients per arm, using thigh circumference reduction as the outcome measure.

METHODS

Medline and Embase were searched up to August 2012 to identify eligible studies.

RESULTS

Twenty-one original studies were included in the present systematic review. All studies were clinical trials, most of them recruited women only and 67% had an intra-patient study design. About half of the active cosmetic creams tested only contained one active ingredient among xanthenes, herbals or retinoids. The other studies tested cosmetic creams with more complex formulations and most of them included xanthenes. A total of seven controlled trials satisfied the inclusion criteria for the meta-analysis. The pooled mean difference of thigh circumference reduction between the treated and the controlled group was -0.46 cm (95% confidence intervals, CI: -0.85, -0.08), with significant heterogeneity between studies (P < 0.001).

CONCLUSION

This article provides a systematic evaluation of the scientific evidence of the efficacy of cosmetic products in cellulite reduction and supports a moderate efficacy in thigh circumference reduction.

Amifostine (WR-2721, Ethyol(TM)) can protect human endothelial but not tumor cells from cisplatin-induced cytotoxicity

Amifostine (WR-2721, Ethyol(TM)) is a chemo-and radioprotective agent which is increasingly used in clinical practice to minimize antitumor therapy-induced toxicities. The key of this property of amifostine is certainly its selective action in terms of differential protection of normal tissue and not of tumor cells. Using HUVEC cells and three different cancer cell lines (A549 non-small cell lung cancer, DND-1A melanoma and HeLa cervical carcinoma) we provide evidence that amifostine could protect normal, and not cancer cells, from cisplatin (CDDP)-induced cytotoxicity in vitro. Furthermore, low doses of amifostine, easily attainable in vivo, can protect 50% of normal cells in vitro from CDDP-induced cytotoxicity.

[Efficacy study in vitro: assessment of the properties of resveratrol and resveratrol + N-acetyl-cysteine on proliferation and inhibition of collagen activity]

During and after menopause the skin shows up clearly how the lack of estrogen affects tissues, and menopause can in fact be considered a "multisystemic" disorder of connective tissue. The low menopausal estrogen levels combined with age-related skin changes, accelerating skin aging. This affects both the epidermis and the dermis: fibroblasts not only become fewer, but they produce 30% less collagen, reflecting its metabolic decline. Estrogens act on collagen synthesis by directly stimulating fibroblasts. However, hormone replacement can prevent the postmenopausal loss of collagen--or eliminate it once it has started. The results of the Women's Health Initiative study drastically changed Italian gynecologists' prescribing habits. Natural products with estrogen-like activity are increasingly accepted, since they have good effects on collagen synthesis and/or inhibit collagenase activity, with a reassuring safety profile. This was confirmed by an in vitro study that assessed the tonic-trophic properties of two treatments on cultured skin fibroblasts. Cells were treated with resveratrol either alone or combined with NAC 10-100-1000 μM. There was a dose-related increase in the rate of cell proliferation and in inhibition of collagenase activity.

Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system

Since the 1980's there has been high interest in branched-chain amino acids (BCAA) by sports nutrition scientists. The metabolism of BCAA is involved in some specific biochemical muscle processes and many studies have been carried out to understand whether sports performance can be enhanced by a BCAA supplementation. However, many of these researches have failed to confirm this hypothesis. Thus, in recent years investigators have changed their research target and focused on the effects of BCAA on the muscle protein matrix and the immune system. Data show that BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis. Muscle damage develops delayed onset muscle soreness: a syndrome that occurs 24-48 h after intensive physical activity that can inhibit athletic performance. Other recent works indicate that BCAA supplementation recovers peripheral blood mononuclear cell proliferation in response to mitogens after a long distance intense exercise, as well as plasma glutamine concentration. The BCAA also modifies the pattern of exercise-related cytokine production, leading to a diversion of the lymphocyte immune response towards a Th1 type. According to these findings, it is possible to consider the BCAA as a useful supplement for muscle recovery and immune regulation for sports events.

[Experimental survey of a new topical anti-oxidant based on furfuryl palmitate in the treatment of child's and baby's dermatitis with eczema: results from a multicenter clinical investigation]

In this paper we present the preliminary results of a multi-center clinical investigation carried out on a new topical product (Triderm(R) Lenil+) containing Superoxidodismutase (SOD), 18-beta glycyrrethic acid, Vitamin E, alpha bisabolol and a new patented antioxidant molecule, Furfuryl palmitate. These active agents altogether protect skin from cell damages that promote the inflammatory syndrome; their action is furthermore sustained by agents such as phytosphingosine and phytosterols that act to repair the skin barrier. Furfuryl palmitate is an ester with a strong quenching ability towards the singlet oxygene (1O2) and with a high permeability potential through the biological membranes, thanks to its lipophylic formula. Further than being among the main responsible for skin ageing, the 1O2 is involved in the genesis of many topical pathologies such as allergic and irritant dermatitis, atopic dermatitis, inflammation, psoriasis and sunburns. The product has been extensively tested for its effectiveness and skin tolerability on a selected population of 60 children and babies with age ranging from 2 months to 14 years, suffering mainly with atopic dermatitis and irritant dermatitis. The topical use of the product caused a significant improvement of the inflammatory skin conditions, with evident and fast inflammation and eczema reduction in all the investigated pathologies, as shown in the present study. The product has been formulated in order to avoid any sensitisation risk and did not show any relevant side effect. It is particularly suitable in the treatment of pediatric dermatitis with symptoms like eczema, itching, desquamation and xerosis.

Prevention of neuronal cell damage induced by oxidative stress in-vitro: effect of different Ginkgo biloba extracts

The effect of two different Ginkgo biloba extracts (GB1 and GB4) was studied in-vitro on cultured neurons exposed to oxidative stress caused by H2O2(50 micromol L(-1)) and FeSO4(100 micromol L(-1)). Only about 50% of the neurons were still viable at the end of the experiment (8 h) in control conditions, while the two extracts dose dependently increased the number of viable cells, in the concentration range 10-200 microg mL(-1). The two Ginkgo biloba extracts differed in their effect on hydroxyl-radical-scavenging capacity: GB1 and GB4 had an IC50 (50% inhibiting concentration) value of 78 microg mL(-1) and 186 microg mL(-1), respectively. However, both extracts inhibited apoptosis in cortical neurons after oxidative stress in-vitro. These observations make one suppose that different preparations of Ginkgo biloba have quantitatively different actions and outline the importance of the contribution of apoptosis prevention toward their neuroprotective action.

Reduction of lipid peroxidation in different rat brain areas after cabergoline treatment

Oxidative stress and mitochondrial damage are involved in Parkinson's disease (PD). Several drugs used for PD treatment have demonstrated antioxidant properties. To evaluate the antioxidant efficacy of cabergoline, an ergot derivative with a long plasma half-life, male Wistar rats were treated with vehicle or with 2.5 mg kg(-1)and 10 mg kg(-1)of the drug three, six, or 10 times at 48-h intervals. Cabergoline decreased basal lipid peroxide levels (LPO) in the hippocampus of rats given 10 mg kg(-1)10 times, and in the striatum of rats given the same dose six or 10 times. Spontaneous LPO was inhibited in the hippocampus of rats given 10 mg kg(-1)10 times. Stimulated LPO was decreased in the striatum of rats given 10 mg kg(-1)six times and in rats given 2.5 and 10 mg kg(-1)10 times. The ability of cabergoline to reduce LPO suggests its anti-lipoperoxidative properties.

Age and sex differences in human skeletal muscle: role of reactive oxygen species

Previous studies, conducted on experimental animals, have indicated that reactive oxygen species (ROS) are involved in the aging process. The objective of this work was to study the relationship between oxidative damage and human skeletal muscle aging, measuring the activity of the main antioxidant enzymes superoxide dismutase (total and MnSOD), glutathione peroxidase (GPx) and catalase in the skeletal muscle of men and women in the age groups: young (17-40 years), adult (41-65 years) and aged (66-91 years). We also measured glutathione and glutathione disulfide (GSH and GSSG) levels and the redox index; lipid peroxidation and protein carbonyl content. Total SOD activity was lower in the 66-91 year-old vs. the 17-40 year-old men; MnSOD activity was significantly greater in 66-91 year-old vs. 17-40 year-old women. GPx activity remained unchanged. The activity of catalase was lower in adults than in young men but higher in the aged. We observed no changes in GSH levels and significantly higher GSSG levels only in aged men vs. adult men, and a significant decrease in aged women vs. aged men. The protein carbonyl content increased significantly in the 41-65 and 66-91 year-old vs. the 17-40 year-old men. Finally, young women have lower lipid peroxidation levels than young men. Significantly higher lipid peroxidation levels were observed in aged men vs. both young and adult men, and the same trend was noticed for women. We conclude that oxidative damage may play a crucial role in the decline of functional activity in human skeletal muscle with normal aging in both sexes; and that men appear to be more subject to oxidative stress than women.

In vitro antioxidant properties of amifostine (WR-2721, Ethyol)

PURPOSE

Amifostine (WR-2721), a phosphorylated aminothiol pro-drug which is an analogue of cysteamine, is a selective cytoprotective agent for normal tissues from the toxicities associated with chemotherapy and irradiation. Despite a growing number of reports strongly supporting amifostine's clinical efficacy, few authors have focused on the biochemical basis of amifostine's antioxidant activity.

METHODS

We report on amifostine's free-radical scavenging activity against superoxide (O(2;(-))), hydroxyl (OH(-)) and lipoperoxyl radicals in an in vitro model, using pure chemical systems. Amifostine was dephosphorylated to its active metabolite, WR-1065, by adding 10% non-heat-inactivated serum; different amifostine concentrations (1, 10, 50, 100 microM and 200 microM) and pH conditions (pH 5, 7.4 and 9) were tested.

RESULTS

Independent of the concentration, amifostine exhibited no major activity against O(2;(-)) ions, neither did any pH variations in the experimental model provide any scavenger effects of the drug against O(2;(-)) radicals. On the other hand, the protective effect of amifostine against OH(-) radicals was confirmed, yielding an EC(50) of 255 microM at pH 7.4 and 230 microM at pH 5. Finally, amifostine exhibited scavenging activity against spontaneous lipoperoxidation, but no apparent antioxidant effect on iron ascorbate-induced lipoperoxidation.

CONCLUSIONS

With this in vitro study, we are able to confirm the scavenging activity of the chemo- and radioprotector amifostine, whose activity seems to be particularly important from a biological point of view, since it is exerted mainly against highly reactive OH(-).

Age-dependent changes of antioxidant activities and markers of free radical damage in human skeletal muscle

This study was conducted in order to provide evidence for the role of reactive oxygen species (ROS) in human skeletal muscle aging. We used human muscle samples obtained from hospitalized patients in an open study with matched pairs of individuals of different ages. The subjects, ranging in age from 17 to 91 years, were grouped as follows: 17-25-, 26-35-, 36-45-, 46-55-, 56-65-, 66-75-, 76-85-, and 86-91-year-old groups. To investigate the relationship between muscle aging and oxidative damage we measured total and Mn-dependent superoxide dismutase (total SOD, MnSOD), glutathione peroxidase (GSHPx), and catalase (CAT) activities; total reduced and oxidized glutathione (GSHtot, GSH, and GSSG) levels; lipid peroxidation (LPO), and protein carbonyl content (PrC). Total SOD activity decreases significantly with age in the 66-75-year-old group, although MnSOD activity increases significantly in the 76-85-year-old group. The activity of the two H2O2 detoxifying enzymes (GSHPx and CAT) did not change with age, as do GSHtot and GSH levels. GSSG levels increased significantly (76-85- and 86-91-year-old groups) with age. We observed a significant increase in LPO levels (66-75- and 76-85-year-old groups), although the PrC content shows a trend of increase without gaining the statistical significance. These results support the idea that ROS play an important role in the human muscle aging process.

Oxidative stress in the human brain after subarachnoid hemorrhage

OBJECT

The aim of this study was to verify the patterns of antioxidant enzymatic activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the human brain after subarachnoid hemorrhage (SAH) to verify whether an "oxidative stress situation" characterizes the brain response to subarachnoid bleeding.

METHODS

Forty samples of gyrus rectus or temporal operculum that were obtained during a surgical approach to anterior circulation aneurysms were used for this study. The activity of total SOD, GSH-Px, and the SOD/GSH/Px ratio (which expresses the balance between the production of hydrogen peroxides by dismutation of superoxide radicals and the scavenging potential) were calculated in each case. Twelve samples were obtained from patients who underwent surgery for unruptured aneurysms (control group); 13 samples were obtained during surgical procedures performed within 72 hours of SAH; and 15 samples were obtained during delayed surgical procedures (> 10 days post-SAH). Ten patients presented with clinical deterioration caused by arterial vasospasm. In both SAH groups, the mean total SOD activity was significantly higher than in the control group (p=0.029). The mean activity of GSH-Px did not differ significantly between the SAH and control groups (p=0.731). There was a significant increase in the SOD/GSH-Px ratio in both SAH groups, as compared with controls (p < 0.05). There was a significant correlation between the enzymatic activity and the clinical severity of the hemorrhage, with findings of lower values of SOD and, mainly, of the SOD/GSH-Px ratio in the poor-grade patients. The SOD/GSH-Px ratio was 2.14+/-0.44 in patients who presented with clinical vasospasm and 1.24+/-0.2 in cases without vasospasm.

CONCLUSIONS

The results of this study show an imbalance of the antioxidant enzymatic activities in the human brain after SAH. which is linked to the severity of the initial bleeding and possibly modified by the development of arterial vasospasm.

Antioxidant status and alpha1-antiproteinase activity in subarachnoid hemorrhage patients

The antiproteasic activity of alpha1-antitrypsin (alpha1-AT) is reduced in cases of subarachnoid hemorrhage from ruptured intracranial aneurysm and particularly in patients currently smoking; alpha1-AT is very sensitive to oxidant agents. About 50% of physiological anti-oxidant systemic capacity is represented by Vitamin A, E and C. Plasmatic amounts of alpha1-AT, alpha1-AT Collagenase Inhibitory Capacity (CIC) and levels of vitamin A, vitamin E and vitamin C were analyzed in 39 patients, 26 women and 13 men, operated for intracranial aneurysm; 11 patients with unruptured intracranial aneurysm were considered as controls while 28 patients were included within 12 hours from subarachnoid hemorrhage (SAH). Plasmatic levels of vitamin A and vitamin E were significantly lower (p=0.038 and p=0.0158) in patients suffering SAH than in controls, while no statistically significant differences were found in mean plasmatic vitamin C levels. Level of alpha1-AT was not statistically different in controls and in patients with SAH; however, the activity of alpha1-AT, evaluated as CIC, is significantly reduced in patients with SAH (p=0.019). We have observed that systemic plasmatic levels of vitamins did not significantly differ in relation to smoking habit. Vitamin A and E represent an important defensive system against free radicals reactions. Particularly, vitamin E acts as an antioxidant by scavenging free-radicals. A reduced anti-oxidant status might be related to the higher sensibility of alpha1-AT to oxidative reactions and the activity of alpha1-AT is dependent on the antioxidant capacity of liposoluble vitamins. We can speculate that an acute systemic oxidative stress condition might influence the rupture of intracranial aneurysms.

Antioxidant enzymatic activities and lipid peroxidation in cultured human chondrocytes from vertebral plate cartilage

In vitro models based on primary cultured human chondrocytes could be useful to study the ROS-mediated inflammatory processes that seem to involve chondrocytes in vivo. In this work, we studied the enzymatic antioxidative capability of human chondrocytes removed from vertebral plates during micro-discectomy and cultured 18 days, measuring total superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSHPx) activities. We also evaluated in the same cells the amount of malondialdehyde (MDA) in order to verify the effect of the variation of the cellular enzymatic antioxidative capability on the degree of membrane lipid peroxidation. Total SOD activity increased, even if not significantly, between the 12th and the 18th day. A significant variation of GSHPx (P<0.01) and of catalase (P<0.001) activity was observed between the 3rd and the 6th day with no further variation until the 18th day. A significant increase (P<0.001) of lipid peroxidation from the 3rd to the 18th day was also observed. These results seem to indicate that only fresh human cultured chondrocytes are suitable to study, through in vitro models, the in vivo behavior of the antioxidative status of these cells.

Superoxide dismutase activity in cisternal cerebrospinal fluid after aneurysmal subarachnoid haemorrhage

It has been recognised that the level of superoxide dismutase (SOD) significantly increases in CSF as the result of cerebral ischaemic damage. The aim of this study was to correlate the CSF levels of SOD enzymatic activity to the patterns of subarachnoid haemorrhage with regards to ischaemic complications due to vasospasm. A series of 78 patients operated on for intracranial aneurysms was studied; all patients were monitored with serial TCD measurements every second day after SAH. CSF samples were obtained at surgery by cisternal puncture of the subarachnoid cistern nearest to the aneurysm. SOD activity was assayed spectrophotometrically. Mean cisternal CSF level of SOD in 12 control cases (12.99 +/- 2.33 U/ml) is significantly higher (p < 0.01) than in 26 patients operated on between day 1 and 3 from last SAH episode (4.44 +/- 0.7 U/ml) and in 40 patients treated by delayed surgery (7.64 +/- 0.92 U/ml). In 13 patients presenting neurological deterioration related to arterial vasospasm mean cisternal SOD level was 12.23 +/- 1.86 U/ml; in 27 cases without vasospasm mean level was 5.43 +/- 0.7 U/ml (p < 001). The present results suggest that (a) cisternal CSF levels of SOD significantly decreases after SAH, probably in relation to an impaired synthesis in the brain compartment and that (b) a substantial elevation of SOD levels is evident in patients suffering ischaemic complications vasospasm-related. Biochemical events in the brain compartment could influence the expression and release of anti-oxidant enzymes in CSF after SAH.

Blood free radical antioxidant enzymes and lipid peroxides following long-distance and lactacidemic performances in highly trained aerobic and sprint athletes

OBJECTIVE

We have determined the differences of the influence of prolonged exercise or higher intensity lactacidemic exercise, on plasma lipid peroxidation and on erythrocyte antioxidant enzymatic defence system.

EXPERIMENTAL DESIGN

We measured plasma indices of lipid peroxidation, conjugated dienes (CD) and malondialdehyde (MDA) and erythrocyte enzymes superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase (CAT). The biochemical evaluations were performed in six healthy control males (C) and twelve athletes: six marathon runners (MR) and six sprint-trained athletes (STA) at rest and after a half-marathon (MR) and a training session of 6 x 150 m (STA).

RESULTS

In resting conditions MDA was higher in STA and MR than in C (p < 0.01), while only the MR showed significantly elevated levels of CD (p < 0.05). In STA the enzymatic scavenging capacity showed a significantly higher SOD (p < 0.01) and GSHPx (p < 0.01), while CAT was lower than in controls (p < 0.05). In MR only SOD (p < 0.01) was significantly higher than in C. It increased significantly immediately after half-marathon, while CAT decreased 24 and 48 hours postexercise respectively. In these athletes the lipoperoxidative indices increased in the early postexercise phase, while at 24 and 48 hrs both CD and MDA levels decreased. In STA enzyme activities were not modified by anaerobic performance while CD showed a peak 6 hrs postexercise and the MDA showed a progressive increase until 48 hrs afterwards.

CONCLUSIONS

Both strenuous long duration exercise and exhaustive sprint training overwhelm our capacity to detoxify ROS, producing oxidative stress. Thus an adequate supply of antioxidants could be appropriate.

Synaptosomal iron-dependent lipid peroxidation inhibition after subarachnoid hemorrhage by lazaroid in vivo treatment

The production of oxygen-free radicals and their subsequent peroxidative action on membrane unsaturated fatty acids could be enhanced after subarachnoid hemorrhage (SAH). We have studied the effects of the in vivo pharmacological treatment with a lazaroid (U78517F) after experimental SAH, on lipid peroxidative patterns in cortical synaptosomal preparations. U78517F is a lipid-soluble antioxidant with a potent action to inhibit iron-dependent lipid peroxidation. Experimental SAH was induced in anesthetized rats by slow injection of 0.3 mL of autologous arterial blood into cisterna magna. The hemorrhagic animals were treated with 5 mg/kg iv of U78517F immediately after surgical operation. The animals were sacrificed 1 d after the hemorrhage and the thiobarbituric acid reactive material (TBAR) was assayed in basal conditions and after 1, 3, 5, 10, and 20 min of incubation at 37 degrees C with a pro-oxidant mixture on three different rat groups: sham-operated (0.3 mL of mock cerebrospinal fluid (CSF) into cisterna magna), hemorrhagic (0.3 mL of autologous arterial blood into cisterna magna), and hemorrhagic-treated. The hemorrhagic event did not influence the membrane lipoperoxidation levels in basal conditions, whereas peroxidative stimulation in vitro caused significant increases in hemorrhagic animals compared to the sham-operated, and in hemorrhagic-treated animals, the synaptosomal TBARs were similar to controls. The pharmacological treatment showed its effectiveness only following incubations with pro-oxidants; therefore, U78517F seems to be protective for membranes in case of severe lipid peroxidative stress.

Antioxidant enzymatic system and free radicals pathway in two different human cancer cell lines

Resistance to oxidative damage is an important feature of cancer cells. Cellular anti-radical enzymes, lipid peroxidation, glutathione pathway, capability to produce ROS, and cells' susceptibility to H2O2 and menadione toxicity, were analyzed in DND-1A and HeLa cancer cell lines. SOD and GSHPx activities were higher in DND-1A than in HeLa cells. Lipid peroxidation was the same in both cell lines, while menadione stimulation of ROS production was tenfold higher in HeLa cells. Total and reduced, but not oxidized, glutathione levels, were tenfold smaller in HeLa cells. H2O2 proved fatal to HeLa cells after 12 hours' incubation, while it was ineffective on DND-1A; DND-1A cells were more sensitive to menadione toxicity than HeLa cells. The two lines behaved differently in response to the above treatments. These observations might be important in designing more specific cancer treatments.

Alpha 1-antitrypsin activity in subarachnoid hemorrhage

An altered equilibrium of protease/protease-inhibitor factors may be involved in the pathogenesis of aneurysm rupture: alpha 1-antitrypsin (alpha 1-AT) represents the most relevant inhibitor of elastase, a proteolytic enzyme enhancing catabolic processes of collagen metabolism. In the present study we test the hypothesis whether the activity of alpha 1-AT is altered in SAH patients; 5 cases with unruptured intracranial aneurysm and 27 patients with diagnosis of aneurysm SAH were included in the study. Blood samples were obtained immediately at admission. As control samples we consider the 5 cases of unruptured aneurysm, 15 cases of unruptured aortic aneurysms and 10 patients with non-vascular CNS diseases. Measurement of alpha 1-AT level was determined by immunoturbidimetric method. Serum levels of alpha 1-AT are significantly lower in patients admitted within 72 hours after SAH, if compared to patients admitted in a delayed phase. The linear relationship between alpha 1-AT and collagenase inhibitory percentage capacity (CIC) was shown to be different in the 4 subgroups considered, and so were the mean % CIC values in the between-groups comparison, except for unruptured aneurysm vs controls. The alpha 1-AT CIC in patients with SAH is shown to be the lowest when compared to controls and unruptured aneurysms (p = 0.0001).

Oxidative stress after acute and chronic application of beta-amyloid fragment 25-35 in cortical cultures

The aim of this work was to investigate whether free radical reactions play a role in beta-amyloid neurotoxicity. Rat cortical neurons were exposed acutely (24 h) or chronically (3, 7 days) to beta-amyloid biologically active fragment beta 25-35 (50 microM). In these conditions, where only the longest exposure induced neuronal death, superoxide dismutase activity was increased after acute exposure but no change was detected after chronic treatments, whereas a different pattern was observed for glutathione peroxidase. In the basal condition, there was an eight-fold increase in dichlorofluoroscein, used as peroxide production marker, in neuronal cells after 7 days treatment with beta 25-35. Moreover, the intracellular peroxide production induced by Fe2+/ascorbate stimulation was amplified by beta 25-35, increasingly up to 7 days of exposure, by which time the dichlorofluoroscein-stimulated levels were 33 times higher than in controls. In conclusion, our results show that oxidative stress and free radical production are linked to beta 25-35 exposure and may contribute to neurodegenerative events associated with beta-amyloid deposits in Alzheimer's disease.

Oxidative events in neuronal and glial cell-enriched fractions of rat cerebral cortex

The aim of this work was to investigate how neurons and glial cells separated from rat brain cortex respond to "in vitro" oxidative stress induced by incubation of the cellular fractions in the presence of prooxidant mixtures; in addition, the endogenous enzymatic antioxidant capacity of the purified fractions was investigated. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex following passages of the tissue through meshes and centrifugations. The following parameters were evaluated: antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), and glucose-6-phosphate dehydrogenase (G6PDH); lipid peroxidation products (TBARS) prior to (basal) and after (iron-stimulated) incubation with a mixture of iron and ascorbic acid; intracellular production of reactive oxygen species (ROS) using a fluorescent probe, dichlorofluorescin-diacetate, in basal, iron-stimulated, and menadione stimulated conditions. SOD and GSHPx activities showed no significant changes between neurons and glia, whereas CAT and G6PDH activities were found to be significantly lower in glia than in neurons. TBARS levels were significantly lower in the glial fraction than in neurons, both in basal and iron-stimulated conditions. ROS production showed no differences between neurons and glia in both basal and menadione-stimulated conditions. Iron-stimulation produced a marked increase in ROS production, limited to the neuronal fraction, with the glial values being similar to the basal ones. Our conclusion is that glia and neurons isolated from rat cerebral cortex show a similar pattern of the most important antioxidant enzymes and of their basal ROS production, whereas glia is more resistant in "oxidative stress" conditions.

Changes in non-synaptosomal and synaptosomal mitochondrial membrane-linked enzymatic activities after transient cerebral ischemia

Non-synaptosomal and synaptosomal mitochondrial membrane-linked enzymatic activities, NADH-cytochrome c reductase rotenone insensitive (marker of the outer membrane) and cytochrome oxidase (marker of the inner membrane), were measured in rat brain hippocampus and striatum immediately after and 1, 4 and 7 days following the induction of complete transient ischemia (15 min) by the four vessel occlusion method. Furthermore citrate synthetase activity was measured with and without Triton X-100 in order to qualitatively evaluate the membrane permeability. Non-synaptosomal mitochondrial membranes showed reduction of both activities only in the late reperfusion phase: NADH-CCRRi decreased in striatal mitochondria after 4-7 days and only after 7 days in the hippocampus. COX activity decreased only in striatal mitochondria 7 days after ischemia. Non-synaptosomal mitochondrial membrane permeability did not show changes. Synaptosomal mitochondria showed a decrease of NADH-CCRRi only at 7 days of reperfusion both in hippocampus and striatum, while COX activity decreased only during ischemia and returned to normal levels in the following days in the two areas considered. In summary, free mitochondria showed insensitiveness to ischemia but they resulted damaged in the late reperfusion phase, while mitochondria from the synaptic terminal showed ischemic damage, partially restored during reperfusion. The striatal mitochondria showed a major susceptibility to ischemia/reperfusion damage, showing changes earlier than the hippocampal ones.

Experimental subarachnoid hemorrhage: events related to anti-oxidant enzymatic systems and eicosanoid peroxide enhancement

Experimental and clinical studies have emphasized the role of free radicals in the pathogenesis of vasospasm and neurological dysfunction after subarachnoid hemorrhage (SAH). Increases in both enzymatic (arachidonic acid cascade and eicosanoid peroxide production) and non-enzymatic (thiobarbituric acid reactive substances production) lipid peroxidation were found, pointing out the key role of arachidonic acid cascade in impairing membrane functionality in the post-hemorrhage brain. The aim of this work is to investigate whether a correlation exists between time-dependent modifications of eicosanoid peroxide production ("ex vivo" release of leukotriene C4 = LTC4) and antioxidant enzymatic systems in the brain after experimental subarachnoid hemorrhage in the rat. The release of the LTC4 is significantly enhanced at 1, 6 and 48 hours after SAH induction. Cu-Zn superoxide dismutase (SOD) activity is significantly reduced at 6 and 48 hours after SAH induction; Mn-SOD activity is significantly affected at 1, 6 and 48 hours after the hemorrhage. GSH-Px activity is significantly reduced only in the late phase (48 hours) after SAH. The linear regression of statistical analysis, performed to investigate any possible relationship among time-dependent modifications shows that the "ex vivo" release of LTC4 is significantly related to the decreasing trend of MnSOD activity (p < 0.001). The present results suggest that after SAH, a deficit in endogenous anti-oxidant defenses may play a role in making the brain more susceptible to lipid peroxidative events.

Experimental Parkinson's disease in monkeys. Effect of ergot alkaloid derivative on lipid peroxidation in different brain areas

The effects of the Parkinsonism induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were evaluated in four different monkey brain areas (frontal and occipital cortex, caudate putamen, substantia nigra). The basal and stimulated lipid peroxidation and the reduced glutathione (GSH) concentration were evaluated in three groups of male Macaca fascicularis monkeys (6 animals/group): (a) controls; (b) MPTP-treated animals; (c) animals treated with MPTP and alpha-dihydroergocryptine (DEK; ergot alkaloid characterized by a dopaminergic agonist action). In MPTP-treated animals the GSH concentration was unchanged or decreased in a non-significant way in the frontal and occipital cortex, and in substantia nigra. The basal thiobabituric acid reactive substance (TBARS) concentrations were significantly higher in the caudate putamen and substantia nigra of MPTP-treated animals. In the MPTP-treated monkeys the DEK administration induced a restoration of basal TBARS values to nearly normal ones. By incubating tissue from different brain areas with FeSO4 plus ascorbic acid, the stimulation of lipid peroxidation decreased the TBARS production in the substantia nigra of the MPTP-treated animals. These results, taken together, may indicate that an increased lipid peroxidation could possibly play a role in producing the Parkinson-like syndrome by MPTP and that a free radical excess could be responsible for the degeneration of the substantia nigra. The treatment with an ergot alkaloid (i.e., alpha-dihydroergocryptine) partially antagonizes the MPTP-induced increase in basal TBARS concentration in caudate putamen.

Cellular and molecular events of ischemic brain damage

Many events occurring during and after cerebral ischemia are well known, but they are not known enough to fully elucidate the mechanisms of brain damage. Energy failure alone cannot explain the functional damage occurring during the reperfusion phase, and, at present, four features of the ischemic and postischemic brain are the focus of interest: development of acidosis, calcium overload, free radical formation, and nitric oxide overproduction. It is likely that these events, perhaps with other less known ones, contribute altogether to the occurrence of irreversible damage. An understanding of them might lead to the development of a drug, or a drug cocktail, able to counteract ischemic lesions.

Antioxidant enzymatic activities after experimental subarachnoid hemorrhage in rats

Lipid peroxidation has been hypotesized as one of possible factors involved in the pathogenesis of neuronal damage and delayed vasospasm after subarachnoid hemorrhage. In the brain there are anti-oxidant enzymatic systems which act as scavengers of superoxides and free radicals. In the present study the pattern of enzymatic anti-oxidant activities (Cu-Zn and Mn superoxide dismutase, and glutathione peroxidase) was investigated in an experimental model of subarachnoid hemorrhage in the rat in order to verify whether the hemorrhagic insult may be responsible for an impairment of such anti-oxidant systems. Enzymatic activities were assayed in three different rat brain areas (cerebral cortex, hippocampus and brain stem) of sham-operated and at 30 min, 1, 6 and 48 h after subarachnoid hemorrhage induction. After the hemorrhage induction the Cu-Zn superoxide dismutase activity in cerebral cortex was significantly reduced at all the set times (p < .05), while Mn-superoxide dismutase activity was significantly decreased since 1 h (p < .05) until 48 h (p < .05). Glutathione peroxidase activity was significantly reduced only in the late phase (48 h) of subarachnoid hemorrhage (p < .01). In the hippocampus, all enzymatic activities were significantly reduced in the late phase. In the brain stem Cu-Zn superoxide dismutase was significantly impaired at 1 and 6 h (p < .05) after subarachnoid hemorrhage induction, while in the late phase (48 h) reached the control value. The mitochondrial Mn-superoxide dismutase was significantly reduced since 1 h (p < .05) until 48 h (p < .02) after subarachnoid hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen radicals and other toxic oxygen metabolites as key mediators of the central nervous system tissue injury

Free radicals are species containing one or more unpaired electrons, and for this reason they are highly reactive and can combine with a great variety of biomolecules, changing their physico-chemical characteristics. Oxygen free radicals are normally produced during cellular metabolism and aerobic cells are provided with antioxidant defense mechanisms able to counteract this physiological production. In conditions of increased production or decreased scavenging of free radicals, they can assume a fundamental importance in the pathogenesis of acute or chronic brain diseases.

Correlation between electroencephalogram isoelectric time and hippocampal norepinephrine levels, measured by microdialysis, during ischemia in rats

It is suggested that norepinephrine (NE) plays a role during transient forebrain ischemia. NE may have a protective action against neuronal cell death in the hippocampus, or it may be one of the causes of injurious ischemic effects. We used the microdialysis technique to study extracellular NE levels in the rat hippocampus before, during, and after 30 min of transient incomplete forebrain ischemia (induced by four-vessel occlusion) to describe the time course of NE in this condition. There was a maximal increase (fivefold) in extracellular NE after 10 min of reflow only when the electroencephalogram was isoelectric. NE levels returned to baseline 40 min after release of the carotid clamps and remained constant for the next 80 min. Thus there appears to be a transient NE overflow in the hippocampus during ischemia, closely related to the complete loss of brain electrical activity.

Ex vivo release of eicosanoids after aneurysmal subarachnoid hemorrhage: a preliminary experience in humans

Authors addressed the question whether the byosynthesis and the release of specific eicosanoids may occur in human brain cortex, and if the qualitative pattern of arachidonic acid metabolism is similar to that observed in experimental SAH. Human brain samples from 18 patients operated on for anterior communicating artery aneurysm (5 unruptured aneurysms considered as control cases, 7 patients operated on between Days 1 and 4 after SAH and 6 patients operated on between Days 10 and 14) were studied for the ex vivo release of 4 selected eicosanoids (Prostaglandin D2, E2, 6-keto-PGF1a and Leukotriene C4). Levels of arachidonate metabolites were determined by radioimmunoassay technique. PGD2 release is significantly lower in cases operated on delayed phase if compared to both control cases (p less than 0.05) and patients operated on in the acute phase, while there is no significant difference between the release of PGD2 in control cases and patients operated on in the acute phase. Release of 6-keto-PGF1a is significantly higher in patients operated on in a delayed phase (p less than 0.03 vs patients operated on in the acute phase and p less than 0.05 versus control cases). The release of LTC4 is significantly enhanced (p less than 0.05) in cases operated on in the acute phase if compared with unruptured aneurysms. The release of PGE2 is significantly enhanced in patients operated on in the acute phase (p less than 0.05) if compared to patients with unruptured aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of high-dose methylprednisolone on anti-oxidant enzymes after experimental SAH

Lipid peroxidation has been considered one of the most important factors involved in the pathogenesis of neuronal damage following subarachnoid hemorrhage. In the brain, the protective systems most involved against peroxidative and free radicals generated reactions are superoxide-dismutase (SOD) and glutathione-peroxidase (GSH-Px). Since these activities are subjected to a significant reduction following experimental SAH induction in rats, we investigated in the present study if the beneficial effect of high-dose methylprednisolone (MP) in inhibiting lipid peroxidative processes in SAH is possibly linked to an influence on anti-oxidant enzymatic activities. In brain cortex, after MP treatment, Cu-Zn SOD activity in the early phase and more dramatically in the late phase after SAH was restored (4.06 +/- 0.06 and 4.07 +/- 0.14 enzymatic units/mg of protein, respectively) if compared to hemorrhagic non-treated controls (3.69 +/- 0.16 and 2.96 +/- 0.06 enzymatic U/mg of protein) while Mn-SOD and GSH-Px activities were improved in treated animals only in the early and late phases after SAH, respectively. In the hippocampus, in treated rats Cu-Zn activity was partially restored only at 6 h, while Mn-SOD activity recovered at 48 h after SAH; no significant changes in GSH-Px activity were found in treated animals at any time. In the brain stem, in treated animals, Cu-Zn SOD activity was restored in the early phase (3.86 +/- 0.12 enzymatic U/mg of protein) up to control values of non-hemorrhagic rats (3.44 +/- 0.30 enzymatic U/mg of protein), while GSH-Px activity recovered in the late phase.(ABSTRACT TRUNCATED AT 250 WORDS)

The mitochondrial electron transfer alteration as a factor involved in the brain aging

The tissutal concentrations of reduced glutathione (GSH) and the contents of some key components in the electron transfer chain (namely ubiquinone, cytochromes b, c1, c, and aa3) of the intraterminal mitochondria are measured in the forebrains from 20-, 60-, or 100-week-old Wistar rats. Moreover, in 60-week-old rats, the biochemical analyses are performed also 18 h after the induction of a peroxidative stress by cyclohexene-1-one. The rats have been i.p. pretreated for 8 weeks (7 days/week) with agents acting on macrocirculation (papaverine), carbohydrate metabolism (hopanthenate), lipid metabolism (phosphatidylcholine), energy transduction (theniloxazine), and dopaminergic system (dihydroergocriptine). Brain aging is characterized by the decrease in both GSH and mitochondrial cytochrome aa3, without changes in ubiquinone and cytochrome b populations. In the same way, the peroxidative stress induced by cyclohexene-1-one causes both a GSH depletion and an imbalance among the concentrations of the mitochondrial electron transfer carriers. Only cytochrome aa3 retains all the partially-reduced oxygen intermediates tightly bound to its active sites. Therefore, it is possible to hypothesize that an electron leakage at the level of the auto-oxidizing chain components (i.e., cytochrome b and ubiquinone populations) increases the release of activated oxygen species (superoxide radical, hydroxyl radical). The treatment with the quoted pharmacological tools suggests that GSH and mitochondrial electron transfer carriers are functionally linked, but not interdependent one another.

Sequential damage in mitochondrial complexes by peroxidative stress

The biochemical characteristics of the electron transfer chain are evaluated in purified non-synaptic ("free") mitochondria from the forebrain of 60-week-old rats weekly subjected to peroxidative stress (once, twice, or three times) by the electrophilic prooxidant 2-cyclohexene-1-one. The following parameters are evaluated: (a) content of respiratory components, namely ubiquinone, cytochrome b, cytochrome c1, cytochrome c; (b) specific activity of enzymes, namely citrate synthase, succinate dehydrogenase, rotenone-sensitive NADH: cytochrome c reductase, cytochrome oxidase; (c) concentration of reduced glutathione (GSH). Before the first peroxidative stress induction, the rats are administered for 8 weeks by intraperitoneal injection of vehicle, papaverine, delta-yohimbine, almitrine or hopanthenate. The rats are treated also during the week(s) before the second or third peroxidative stress. The cerebral peroxidative stress induces: (a) initially, a decrease in brain GSH concentration concomitant with a decrease in the mitochondrial activity of cytochrome oxidase of aa3-type (complex IV), without changes in ubiquinone and cytochrome b populations; (b) subsequently, an alteration in the transfer molecule cytochrome c and, finally, in rotenone-sensitive NADH-cytochrome c reductase (complex I) and succinate dehydrogenase (complex II). The selective sensitivity of the chain components to peroxidative stress is supported by the effects of the concomitant subchronic treatment with agents acting at different biochemical steps. In fact, almitrine sets limits to its effects at cytochrome c content and aa3-type cytochrome oxidase activity, while delta-yohimbine sets limits to its effects at the level of tricarboxylic acid cycle (citrate synthase) and/or of intermediary between tricarboxylic acid cycle and complex II (succinate dehydrogenase).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nicardipine treatment on Na(+)-K+ ATPase and lipid peroxidation after experimental subarachnoid haemorrhage

The calcium theory of neuronal damage has been recently adapted to subarachnoid haemorrhage (SAH). It is proposed that haemorrhagic insult to the brain causes free radical-mediated destructive reactions of membrane phospholipids, and the consequent decrease of phospholipid-dependent enzymatic activities, such as Na(+)-K+ ATPase. In the present study we have studied the effects of Nicardipine treatment on lipid peroxidation and Na(+)-K+ ATPase activity after experimental induction of SAH. SAH was induced in anaesthesized rats by slow injection of 0.3 ml of autologous arterial blood into the cisterna magna. We assessed the extent of lipid peroxidation by measuring the level of thiobarbituric acid reactive substances (TBARS) and Na(+)-K+ ATPase activity in 3 different rat brain areas (cerebral cortex, hippocampus and brain stem) of sham-operated (0.3 ml of mock CSF into cisterna magna) and at 1 hour, 6 hours and 48 hours after SAH induction; simultaneously, we investigated the capacity of cerebral lipid peroxidation by measuring the accumulation of TBRAS in homogenates of brain areas incubated under aerobic conditions. Na(+)-K+ ATPase activity decreased in the cerebral cortex at 1 hour and 6 hours and in brain stem at 1 hour after SAH, while the same enzymatic activity did not change in the hippocampus. There was no significant difference in lipid peroxide content between sham-operated and haemorrhagic animals; Nicardipine treatment reduced the TBRAS content and induced the recovery of Na(+)-K+ ATPase activity, exerting a brain protective role against the detrimental effects of the haemorrhage.

Age-related acute depletion of cerebral glutathione by peroxidative stress

Cyclohexene-1-one and cycloheptene-1-one cause a severe age-related depletion of reduced glutathione (GSH) in the forebrain of 5- or 15- or 25-month-old rats. Chronic pretreatment with phosphatidylcholine partially inhibits the GSH depletion in old forebrains by the prooxidants tested, suggesting that in aged animals alterations in mitochondrial inner membrane phospholipid composition and/or cytochrome oxidase activity might play a role in oxygen free-radical production.

"Ex vivo" release of eicosanoid from human brain tissue: its relevance in the development of brain edema

The specific mechanism underlying the genesis of vasogenic brain edema is still debated: the role of arachidonic acid is considered extremely important, as it is a possible activator of self-maintaining reactions enhancing the release of vasoactive and cytotoxic compounds. The relationship between arachidonic acid metabolism and brain edema has been studied primarily in brain tissue samples or in the extracellular fluid, whereas the residual capacity of perilesional tissue to synthesize and release eicosanoids has not been investigated. In the present study, perilesional samples of brain tissue were available from 4 patients operated on for brain metastasis, from 8 patients who had malignant neuroepithelial tumors, from 4 with meningiomas, and from 5 with subarachnoid hemorrhage. A brain edema index was calculated from the preoperative computed tomographic scan. The "ex vivo" method allowed determination of the residual capacity of endogenous arachidonic acid metabolism. The edema index is significantly higher in patients with brain metastasis (6.5 +/- 0.8) and neuroepithelial tumors (3.6 +/- 0.2) than in those with meningiomas (1.5 +/- 0.06), subarachnoid hemorrhage (1.7 +/- 0.18), and in controls. In patients with metastatic and neuroepithelial tumors there is a significant correlation between peritumoral brain edema and the capacity to synthesize leukotriene C4 (P less than 0.05); the capacity to synthesize leukotriene C4 is also significantly elevated after subarachnoid hemorrhage (13.91 +/- 2.6 ng/ml of incubation medium) when compared with control cases (5.56 +/- 0.91). The capacity to synthesize prostacyclin is significantly higher in patients with brain metastasis than in those with neuroepithelial tumors and meningiomas (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of aging on the acute depletion of reduced glutathione induced by electrophilic agents

A severe age-dependent depletion of reduced glutathione (GSH) occurs in rat forebrain at 1-3 h from intraperitoneal injection of the electrophilic agents cyclohexene-1-one and cycloheptene-1-one. Chronic pretreatment with central dopamine agonists (i.e., ergot alkaloids; particularly, dihydroergocriptine) partially counteracts the GSH depletion induced in 15-month-old forebrains by the prooxidants tested. In contrast, chronic pretreatment with a vasodilator agent (i.e., papaverine) magnifies the GSH depletion.

Effect of high-dose methylprednisolone and U74006F on eicosanoid synthesis after subarachnoid hemorrhage in rats

Free radicals and lipid peroxidation of membrane fatty acids are thought to play a role in the pathogenesis of arterial vasospasm and the physiopathologic patterns of neuronal damage after subarachnoid hemorrhage. We have evaluated the effects of treatment with either high-dose methylprednisolone every 8 hours or a single dose of U74006F on the temporal profile of ex vivo synthesis of four selected eicosanoids in brain slices after experimental induction of subarachnoid hemorrhage in rats. Prostaglandins D2 and E2, prostacyclin and leukotriene C4 levels were determined by radioimmunoassay after 1-hour incubation of the brain slices. The synthesis of prostaglandin D2 and 6-ketoprostaglandin F1 alpha at 48 hours after subarachnoid hemorrhage was significantly higher when compared to sham-operated animals (p = 0.01); prostaglandin E2 release was significantly enhanced at 6 hours after subarachnoid hemorrhage (p = 0.01). The release of the lipoxygenase metabolite was significantly enhanced at 1, 6, and 48 hours after subarachnoid hemorrhage induction. Both treatment regimens significantly reduced the ex vivo synthesis of prostaglandin D2, prostaglandin E2, and leukotriene C4 at 1, 6, and 48 hours after subarachnoid hemorrhage, whereas the effects on 6-ketoprostaglandin F1 alpha synthesis differed in the two treatment groups. U74006F enhanced the synthesis of prostacyclin metabolite in the early phase after subarachnoid hemorrhage, and high-dose methylprednisolone reduced the increasing synthesis at 48 hours. A strict comparison between the two treatments was not possible because of the different modalities of administration. However, these data suggest that the antioxidant effect of single-dose treatment with U74006F influenced the early and delayed effects on enzymatic lipid peroxidation, whereas the effects of methylprednisolone administration every 8 hours were more significant in the delayed phase.

Experimental isobaric subarachnoid hemorrhage: regional mitochondrial function during the acute and late phase

Patients treated for aneurysmal subarachnoid hemorrhage show, in the long-term follow up, an elevated rate of cognitive disturbances that are mainly related to the impact of the initial bleeding: the neurotoxic effects of blood deposition in subarachnoidal spaces may result in a diffuse encephalopathy, but the intrinsic mechanism and the biochemical correlates are not known. In the present study we have evaluated mitochondrial function after experimental induction of subarachnoid hemorrhage. Mitochondrial function was evaluated in four different rat brain areas (frontal cortex, occipital cortex, hippocampus, and brain stem) after experimental isobaric subarachnoid hemorrhage in rats. Subarachnoid hemorrhage was induced by injecting 0.07 mL of arterial autologous blood into the cisterna magna. Intracranial pressure did not significantly increase. The nonsynaptic mitochondrial fraction was isolated from different rat brain areas, and the maximal rate of enzymatic reactions of some key enzymatic activities related to the Krebs cycle [nicotinamide adenine dinucleotide (oxidized form) (NAD+)-isocitrate dehydrogenase, citrate synthase, and succinate dehydrogenase] and of the electron transfer chain (cytochrome oxidase) were evaluated. The nonsynaptic mitochondrial fraction was utilized also to check parameters related to the mitochondrial respiration: state 3, state 4, uncoupled state, respiratory control ratio, and adenosine 5'-diphosphate/oxygen ratio. The biochemical parameters were measured at 1 and 72 hours after the subarachnoidal injection of blood. Subarachnoid hemorrhage did not affect the mitochondrial enzymatic activities both at 1 and 72 hours, while the mitochondrial enzymatic activities parameters were significantly affected: in particular, a significant decrease of respiratory control ratio in all tested brain areas was demonstrated. The increased mitochondrial vulnerability in the delayed phases could be one of the biochemical correlates of post-hemorrhagic encephalopathy.

Factors involved in the age-related alteration in the efficiency of the brain bioenergetics

The synaptic energy state may be defined by the redox state of the intramitochondrial NAD-couple (delta Gox-red) and the phosphorylation state of adenine nucleotide system (delta GATP). The biological energy 'lost' by the system during the coupled reactions is calculated as delta delta G = delta Gox-red-delta GATP. These evaluations are performed in synaptosomes isolated from the forebrain of rats of different ages (20, 60 and 100 weeks of age) and incubated in Krebs-Henseleit-Hepes (pH 7.4) buffer, for 10 min at 24 degrees C. The animals are submitted for 10 min to different degrees of in vivo hypoxia. To better elucidate the mechanism of action, the effects of the pretreatment with agents inducing vasodilation (papaverine), or acting on cerebral carbohydrate metabolism (hopanthenate), or on neurotransmission and cerebral metabolism (theniloxazine) are tested. In synaptosomes isolated from the forebrain of animals submitted to moderate degree of hypoxia (PaO2 = 32-29 mmHg) the efficiency of the system is quite similar to that observed in normoxia, with the exception of the older rats. In synaptosomes isolated from the forebrain of rats submitted to severe degree of hypoxia (PaO2 = 20-18 mmHg) the efficiency is altered as a function of both aging and severity of hypoxemia. Drug pretreatment may partially interfere with the delta delta G by hypoxemia, the action being related to the rat age and hypoxic degrees. The age-related decrease in the efficiency of the coupled states seems to be related to alteration in the phosphorylation state of adenine nucleotides.

Effects of high-dose methylprednisolone on Na(+)-K+ ATPase and lipid peroxidation after experimental subarachnoid hemorrhage

The production of oxygen-free radicals and their subsequent peroxidative action on membrane unsaturated fatty acids could be enhanced after subarachnoid hemorrhage. High-dose methylprednisolone (30 mg/Kg i.v.) treatment can antagonize acute SAH-induced brain hypoperfusion and protect the ultrastructural integrity of endothelial cell membranes. Experimental subarachnoid hemorrhage (SAH) was induced in anesthesized rats by slow injection of 0.3 ml of autologous arterial blood into cisterna magna. Tissue lipid peroxidation, quantified as thiobarbituric acid reactive material (TBAR) and Na(+)-K+ ATPase activity were assayed in three different rat brain areas (cerebral cortex, hippocampus and brain stem) of controls (without any surgical manipulation), sham-operated (0.3 ml. of mock CSF into cisterna magna) and after SAH induction, at 1 h, 6 h and 48 h. Na(+)-K+ ATPase activity decreased in the cerebral cortex at 1 h and 6 h and in brain stem at 1 h after SAH, while the same enzymatic activity was unchanged in the hippocampus. High-dose methyl-prednisolone treatment (started immediately after SAH induction) enhanced the Na(+)-K+ ATPase activity until control levels. There was no significant difference in lipid peroxide content between sham-operated and hemorrhagic animals; however, the injection itself induces a transient increase of TBAR (1 h after injection) and methylprednisolone treatment decreases the products of lipid peroxidation in all brain areas.

Influence of aging and drug treatment on the bioenergetics of hypoxic brain

Synaptosomes isolated from the forebrain of rats of different ages (20, 60 and 100 weeks of age) were incubated in Krebs-Henseleit-Hepes (pH 7.4) buffer, for 10 min at 24 degrees C. The energetic state was defined by the redox state of the intramitochondrial NAD-couple (delta Gox-red) and the phosphorylation state of adenine nucleotide system (delta GATP). The biological energy "lost" by the system during the coupled reactions was estimated by the delta delta G = delta Gox-red - delta GATP. The animals were submitted for 10 min to different degrees of in vivo hypoxia. To elucidate the mechanism of action, the effect of the pretreatment with drugs acting on oxygen availability (almitrine) or on microcirculation and metabolism (delta-yohimbine) was tested. In synaptosomes isolated from the forebrain of animals submitted to moderate degree of hypoxia (oxygen arterial partial pressure ranging between 32 and 29 mmHg) the efficiency of the system was quite similar to that observed in normoxia, with the exception of the older rats. In synaptosomes isolated from the forebrain of rats submitted to severe degree of hypoxia (oxygen arterial partial pressure ranging between 20 and 18 mmHg) the efficiency of the system was markedly altered as a function of both aging and severity of hypoxemia. The pretreatment with the agent increasing the oxygen availability partially modified the efficiency of the system, the alpha-blocking agent being less important. The drug action was markedly related to both the age and the degree of hypoxia.

High-dose methylprednisolone and 'ex vivo' release of eicosanoids after experimental subarachnoid haemorrhage

In the present study we have investigated the effects of high-dose methylprednisolone (MP) treatment on the 'ex vivo' release of four major eicosanoids in an experimental model of subarachnoid haemorrhage (SAH) with the aim of verifying: (a) the efficacy in reducing arachidonic acid metabolism enhancement; (b) whether high-dose methylprednisolone is effective on both the cyclooxygenase and lipoxygenase pathways; and (c) discussing the possible role of high-dose MP treatment in brain protection after SAH. Levels of prostaglandin D2 and E2, prostacyclin and also leukotriene C4 were determined by the radioimmunoassay technique after 1 h incubation of cerebral cortex samples of rats which had been subjected to experimental SAH procedure (injection of 0.3 ml of autologous arterial blood). The release of prostaglandin D2 at 48 h after SAH is significantly higher when compared to that of sham-operated animals (P less than 0.01); prostaglandin E2 release is significantly enhanced at 6 h after the SAH procedure (P less than 0.01); release of the lipoxygenase metabolite is significantly enhanced at 1, 6 and 48 h after SAH induction; MP significantly decreases the release of all eicosanoids, and values in treated animals do not differ from those of sham-operated animals. The results of the present study suggest that the global inhibitory effect of high-dose MP treatment on the 'ex vivo' release of eicosanoids after experimental SAH could be considered to be one of the neurochemical correlates for the reduced incidence and severity of arterial inflammatory response, which results in chronic vasospasm and supports the clinical evidence of MP efficacy in preventing or reducing the incidence of arterial vasospasm after aneurysmal rupture.

Influence of oxidative stress on the age-linked alterations of the cerebral glutathione system

The glutathione system (reduced and oxidized glutathione; redox index) was studied in the forebrain of male Wistar rats of 5, 15, and 25 months of age following the administration for 2 months in drinking water of chemicals that induce oxidative stress: paraquat and diethyldithiocarbamate (DDC) to increase superoxide radical formation, aminotriazole and hydrogen peroxide to increase hydroxyl radical generation, as well as diamide and ferrous chloride to decrease the glutathione cycle activity. Chronic oral administration of phosphatidylcholine for 2 months was evaluated in 25-month-old rats. Aging accentuated the changes produced by chemicals that induce oxidative stress; i.e., the changes in the glutathione redox index were most pronounced in the forebrains of the older paraquat-, DDC-, H2O2-, and diamide-treated rats. Markedly different adaptative changes occurred within the various drug groups. The reduced glutathione was increased (by paraquat, DDC and aminotrazole), decreased (by H2O2) or unchanged (by iron and diamide). Furthermore, in older rats, paraquat and DDC increased the glutathione redox index, whereas H2O2 and diamide decreased the glutathione redox index or were ineffective (i.e., aminotriazole, iron). The glutathione redox index altered by chronic drug administration was modified by the concomitant administration of phosphatidylcholine.