BACKGROUND

The current study was carried out to examine the gastroprotective effects of Parkia speciosa against ethanol-induced gastric mucosa injury in rats.

RESULTS

Sprague Dawley rats were separated into 7 groups. Groups 1-2 were orally challenged with carboxymethylcellulose (CMC); group <em>3</em> received 20 mg/kg omeprazole and groups 4-7 received 50, 100, 200 and 400 mg/kg of ethanolic leaf extract, respectively. After 1 h, CMC or absolute ethanol was given orally to groups 2-7. The rats were sacrificed after 1 h. Then, the injuries to the gastric mucosa were estimated through assessment of the gastric wall mucus, the gross appearance of ulcer areas, histology, immunohistochemistry and enzymatic assays. Group 2 exhibited significant mucosal injuries, with reduced gastric wall mucus and severe damage to the gastric mucosa, whereas reductions in mucosal injury were observed for groups 4-7. Groups <em>3</em>-7 demonstrated a reversal in the decrease in Periodic acid-Schiff (PAS) staining induced by ethanol. No symptoms of toxicity or death were observed during the acute toxicity tests.

CONCLUSIONS

Treatment with the extract led to the upregulation of heat-shock protein 70 (HSP70) and the downregulation of the pro-apoptotic protein BAX. Significant increases in the levels of the antioxidant defense enzymes glutathione (GSH) and superoxide dismutase (SOD) in the gastric mucosal homogenate were observed, whereas that of a lipid peroxidation marker (MDA) was significantly decreased. Significance was defined as p<0.05 compared to the ulcer control group (Group 2).

We report the direct synthesis of cerium oxide nanoparticles (CNPs) in polyethylene glycol (PEG) based solutions with efficient radical scavenging properties. Synthesis of CNPs in PEG demonstrated a concentration dependent (of PEG) redox activity characterized by UV-visible spectroscopy. PEGylated CNPs acted as efficient radical scavengers, and superoxide dismutase (<em>SOD</em>) activity of CNPs synthesized in various concentration of PEG did not reduce compared to bare nanoceria. In addition to superoxide, PEGylated nanoceria demonstrated quenching of peroxide radicals as well. It was observed that the reaction with hydrogen peroxide leads to the formation of a charge transfer complex governed by the concentration of PEG. The stability of the charge transfer complex provides the tunable oxidation state of CNPs. The stability of this complex influences the regenerative capacity of the active <em>3</em>+ oxidation state of CNPs. The cell viability as well as <em>SOD</em> activity of PEGylated CNPs is compared to those of bare CNPs, and the differences are outlined.

Using models of serum deprivation and 1-methyl-4-phenylpyridinium (MPP(+)), we investigated the mechanism by which thioredoxin (Trx) exerts its antiapoptotic protection in human neuroblastoma cells (SH-SY5Y) and preconditioning-induced neuroprotection. We showed that SH-SY5Y cells are highly sensitive to oxidative stress and responsive to both extracellularly administered and preconditioning-induced Trx. Serum deprivation and MPP(+) produced an elevation in the hydroxyl radicals, malondialdehyde and 4-hydroxy-2,<em>3</em>-nonenal (HNE), causing the cells to undergo mitochondria-mediated apoptosis. Trx in the submicromolar range blocked the observed apoptosis via a multiphasic protection mechanism that includes the suppression of cytochrome c release (most likely via the induction of Bcl-2), the inhibition of procaspase-9 and procaspase-<em>3</em> activation, and the elevated level of Mn-<em>SOD</em>. The reduced form of Trx suppresses the serum-free-induced hydroxyl radicals, lipid peroxidation, and apoptosis, indicating that H(2)O(2) is removed by Trx peroxidase. The participation of Trx in preconditioning-induced neuroprotection is supported by the observation that inhibition of Trx synthesis with antisense oligonucleotides or of Trx reductase drastically reduced the hormesis effect. This effect of Trx-mediated hormesis against oxidative stress-induced apoptosis is striking. It induced a <em>3</em>0-fold shift in LD(50) in the MPP(+)-induced neurotoxicity.

Ultraviolet A (UVA) light exposed cells can induce the production of reactive oxygen species (ROS) which can damage the cellular elements. Antioxidants can interfere with the production of ROS. In this study, malondialdehyde (MDA), reduced glutathione (GSH), glutathione reductase (GSSGR), glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (<em>SOD</em>) levels were measured in the liver of rats exposed to UVA light in various doses. The effects of quercetin were determined as antioxidant on those parameters. Rats were divided into three groups as control, ultraviolet (UV), and ultraviolet+quercetin (UV+Q). UV and UV+Q group rats were irradiated 4 h per day with UVA light (1.25 mW/cm(2)) during periods of 0,<em>3</em>,6,9 days. Thus, on days 0,<em>3</em>,6 and 9, the rats have received 0,54,108,162 W/cm(2) light, respectively. Quercetin (50 mg/kg body wt.) was administered intraperitoneally before each irradiation period in the UV+Q group rats. MDA level in the UV group increased significantly on day-9 when compared to the control group (P<0.05). The MDA levels in the UV+Q group decreased significantly on day-6 and 9 in comparison with the UV group (P<0.05, P<0.001, respectively). GSH levels in all groups were not significantly different. GSSGR and GPx activities in the UV group were significantly lower on day-6 and 9 than in the control group (P<0.001). On all days these enzyme activities in the UV+Q group were significantly higher than in the UV group and higher than in the control group (P<0.001). <em>SOD</em> and CAT activities in the UV group decreased significantly on day-<em>3</em>, 6, and 9 in comparison with the control group (P<0.001). These enzyme activities also increased significantly in the UV+Q group on all days when compared to the UV group (P<0.001). This study demonstrated that the exposure of rats to UVA led to oxidative stress as reflected by increased MDA levels and reduced enzymic antioxidant levels, quercetin may be useful by reducing or preventing photobiologic damage.

Toxicity to nontumor-derived tissue has proven to be a significant obstacle in achieving therapeutic levels of gamma irradiation in the treatment of cancer. The formation of reactive oxygen species (ROS) such as superoxide radicals (O2-) following irradiation is thought to be a major determinant of cellular damage. To this end, we describe the generation of two recombinant adenoviral vectors expressing the radical-scavenging enzymes Mn<em>SOD</em> and CuZn<em>SOD</em> to test therapeutic strategies of radioprotection. Using a human lung epithelial cell line (IB-<em>3</em>), we have demonstrated that infections with both Ad.CMVMn<em>SOD</em> or Ad.CMVCuZn<em>SOD</em> significantly increase both the levels of <em>SOD</em> protein and enzymatic activity as compared to control cells. This increase in <em>SOD</em> expression reduced the level of apoptosis at 72 hr post-irradiation by 50% as compared to mock- or Ad.CMVLacZ-infected cells. Such studies provide the foundation for radioprotective gene therapies in the treatment of cancer.

The purpose of the present study was to examine myocardial antioxidant and oxidative stress changes in male and female rats in the presence of physiological sex hormone concentrations and after castration. Twenty-four 9-week-old Wistar rats were divided into four groups of 6 animals each: 1) sham-operated females, 2) castrated females, <em>3</em>) sham-operated males, and 4) castrated males. When testosterone and estrogen levels were measured by radioimmunoassay, significant differences were observed between the castrated and control groups (both males and females), demonstrating the success of castration. Progesterone and catalase levels did not change in any group. Control male rats had higher levels of glutathione peroxidase (50%) and lower levels of superoxide dismutase (<em>SOD</em>, 14%) than females. Control females presented increased levels of <em>SOD</em> as compared to the other groups. After castration, <em>SOD</em> activity decreased by 29% in the female group and by 14% in the male group as compared to their respective controls. Lipid peroxidation (LPO) was assessed to evaluate oxidative damage to cardiac membranes by two different methods, i.e., TBARS and chemiluminescence. LPO was higher in male controls compared to female controls when evaluated by both methods, TBARS (<em>3</em>60%) and chemiluminescence (46%). Castration induced a 200% increase in myocardial damage in females as determined by TBARS and a 20% increase as determined by chemiluminescence. In males, castration did not change LPO levels. These data suggest that estrogen may have an antioxidant role in heart muscle, while testosterone does not.

The present study was undertaken to investigate whether chronic endurance exercise affects tau phosphorylation levels in the brain with Alzheimer's disease (AD)-like pathology. To address this, the transgenic (Tg) mouse model of tauopathies, Tg-NSE/htau2<em>3</em>, which expresses human tau2<em>3</em> in the brain, was chosen. Animals were subjected to chronic exercise for <em>3</em> months from 16 months of age. The exercised Tg mouse groups were treadmill run at speeds of 12 m/min (intermediate exercise group) or 19 m/min (high exercise group) for 1 hr/day, 5 days/week, during the <em>3</em>-month period. Chronic endurance exercise in Tg mice increased the expression of Cu/Zn-superoxide dismutase (<em>SOD</em>) and catalase, and also their enzymatic activities in the brain. In parallel, chronic exercise in Tg mice up-regulated the expression of phospho-PKCalpha, phospho-AKT, and phospho-PI<em>3</em>K, and down-regulated the expressions of phospho-PKA, phosphor-p<em>3</em>8, phospho-JNK, and phospho-ERK. Moreover, chronic exercise up-regulated both cytosolic and nuclear levels of beta-catenin, and the expression of T-cell factor-4 (Tcf-4) and cyclin D1 in the brain. As a consequence of such changes, the levels of phospho-tau in the brain of Tg mice were markedly decreased after exercise. Immunohistochemical analysis showed an exercised-induced decrease of the phospho-tau levels in the CA<em>3</em> subregion of the hippocampus. These results suggest that chronic endurance exercise may provide a therapeutic potential to alleviate the tau pathology.

OBJECTIVE

To investigate the effect of sulforaphane (SFN) on regulation of NF-E2-related factor-2 (Nrf2)-antioxidant response element (ARE) pathway in liver injury induced by intestinal ischemia/reperfusion (I/R).

METHODS

Rats were divided randomly into four experimental groups: control, SFN control, intestinal I/R and SFN pretreatment groups (n = 8 in each group). The intestinal I/R model was established by clamping the superior mesenteric artery for 1 h and 2 h reperfusion. In the SFN pretreatment group, surgery was performed as in the intestinal I/R group, with intraperitoneal administration of <em>3</em> mg/kg SFN 1 h before the operation. Intestine and liver histology was investigated. Serum levels of aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were measured. Liver tissue superoxide dismutase (<em>SOD</em>), myeloperoxidase (MPO), glutathione (GSH) and glutathione peroxidase (GSH-Px) activity were assayed. The liver transcription factor Nrf2 and heme oxygenase-1 (HO-1) were determined by immunohistochemical analysis and Western blotting analysis.

RESULTS

Intestinal I/R induced intestinal and liver injury, characterized by histological changes as well as a significant increase in serum AST and ALT levels (AST: 260.1<em>3</em> +/- 40.17 U/L vs 186.00 +/- 24.21 U/L, P < 0.01; ALT: 1<em>3</em>9.6<em>3</em> +/- 11.<em>3</em>5 U/L vs 48.<em>3</em>8 +/- 10.7<em>3</em> U/L, P < 0.01), all of which were reduced by pretreatment with SFN, respectively (AST: 260.1<em>3</em> +/- 40.17 U/L vs 216.6<em>3</em> +/- 22.65 U/L, P < 0.05; ALT: 1<em>3</em>9.6<em>3</em> +/- 11.<em>3</em>5 U/L vs 97.6<em>3</em> +/- 15.56 U/L, P < 0.01). The activity of <em>SOD</em> in the liver tissue decreased after intestinal I/R (P < 0.01), which was enhanced by SFN pretreatment (P < 0.05). In addition, compared with the control group, SFN markedly reduced liver tissue MPO activity (P < 0.05) and elevated liver tissue GSH and GSH-Px activity (P < 0.05, P < 0.05), which was in parallel with the increased level of liver Nrf2 and HO-1 expression.

CONCLUSIONS

SFN pretreatment attenuates liver injury induced by intestinal I/R in rats, attributable to the antioxidant effect through Nrf2-ARE pathway.

The purpose of the present study was to evaluate the protective effects of astragaloside IV (AS IV) against paraquat (PQ)-induced pulmonary injury in vivo. Fifty BALB/C mice were randomized into five groups: (1) control, (2) PQ, (<em>3</em>) PQ + dexamethasone (Dex, 5 mg/kg), (4) PQ + AS IV (50 mg/kg), and (5) PQ + AS IV (100 mg/kg). A single dose of PQ (50 mg/kg, i.p.) was intraperitoneally given to induced acute lung injury. Then, mice were treated with AS IV (50 and 100 mg/kg/day, orally) for 5 days. At the end of the experiment, animals were euthanized; then, the bronchoalveolar lavage fluid (BALF) and lung tissues were collected for histological observation, biochemical assay, and Western blot analysis. Malondialdehyde (MDA), myeloperoxidase (MPO), catalase (CAT), superoxide dismutase (<em>SOD</em>), glutathione peroxidase (GSH-Px) in lung tissues, and interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α) levels in BALF were determined. Histological examination indicated that AS IV attenuated lung damage caused by PQ. Biochemical results showed that AS IV treatment significantly reduced the levels of MDA, MPO, and inflammatory cytokines while increased the levels of <em>SOD</em>, CAT, and GSH-Px compared with those in PQ group. Western blot results revealed that AS IV attenuated the Txnip/Trx expressions and inhibited Rho/ROCK/nuclear factor kappaB (NF-κB) signaling pathway in PQ-challenged mice. These findings suggested the protective effect of AS IV as a natural product on PQ-induced pulmonary injury.

Copper, zinc superoxide dismutase is a dimeric enzyme, and it has been shown that no cooperativity between the two subunits of the dimer is operative. The substitution of two hydrophobic residues, Phe 50 and Gly 51, with two Glu's at the interface region has disrupted the quaternary structure of the protein, thus producing a soluble monomeric form. However, this monomeric form was found to have an activity lower than that of the native dimeric species (10%). To answer the fundamental question of the role of the quaternary structure in the catalytic process of superoxide dismutase, we have determined the solution structure of the reduced monomeric mutant through NMR spectroscopy. Another fundamental issue with respect to the enzymatic mechanism is the coordination of reduced copper, which is the active center. The three-dimensional solution structure of this 15<em>3</em>-residue monomeric form of <em>SOD</em> (16 kDa) has been determined using distance and dihedral angle constraints obtained from 1<em>3</em>C, 15N triple-resonance NMR experiments. The solution structure is represented by a family of <em>3</em>6 structures, with a backbone rmsd of 0.81 +/- 0.1<em>3</em> A over residues <em>3</em>-150 and of 0.56 +/- 0.08 A over residues <em>3</em>-49 and 70-150. This structure has been compared with the available X-ray structures of reduced <em>SODs</em> as well as with the oxidized form of human and bovine isoenzymes. The structure contains the classical eight-stranded Greek key beta-barrel. In general, the backbone and the metal sites are not affected much by the monomerization, except in the region involved in the subunit-subunit interface in the dimeric protein, where a large disorder is present. Significative changes are observed in the conformation of the electrostatic loop, which forms one side of the active site channel and which is fundamental in determining the optimal electrostatic potential for driving the superoxide anions to the copper site which is the rate-limiting step of the enymatic reaction under nonsaturating conditions. In the present monomer, its conformation is less favorable for the diffusion of the substrate to the reaction site. The structure of the copper center is well-defined; copper(I) is coordinated to three histidines, at variance with copper(II) which is bound to four histidines. The hydrogen atom which binds the histidine nitrogen detached from copper(I) is structurally identified.

Rotenone a widely used pesticide that inhibits mitochondrial complex I has been used to investigate the pathobiology of PD both in vitro and in vivo. Studies have shown that the neurotoxicity of rotenone may be related to its ability to generate reactive oxygen species (ROS), leading to neuronal apoptosis. The current study was carried out to investigate the neuroprotective effects of hesperidin, a citrus fruit flavanol, against rotenone-induced apoptosis in human neuroblastoma SK-N-SH cells. We assessed cell death, mitochondrial membrane potential, ROS generation, ATP levels, thiobarbituric acid reactive substances, reduced glutathione (GSH) levels, and the activity of catalase, superoxide dismutase (<em>SOD</em>) and glutathione peroxidase (GPx) using well established assays. Apoptosis was determined in normal, rotenone, and hesperidin treated cells, by measuring the protein expression of cytochrome c (cyt c), caspases <em>3</em> and 9, Bax, and Bcl-2 using the standard western blotting technique. The apoptosis in rotenone-induced SK-N-SH cells was accompanied by the loss of mitochondrial membrane potential, increased ROS generation, the depletion of GSH, enhanced activities of enzymatic antioxidants, upregulation of Bax, cyt c, and caspases <em>3</em> and 9, and downregulation of Bcl-2, which were attenuated in the presence of hesperidin. Our data suggests that hesperidin exerts its neuroprotective effect against rotenone due to its antioxidant, maintenance of mitochondrial function, and antiapoptotic properties in a neuroblastoma cell line.

Recent evidence indicates that elevated plasma levels of homocysteine are a risk factor for ischemic cerebrovascular diseases. However, little is known about cerebrovascular effects of homocysteine. Homocysteine could impair cerebrovascular function by metal-catalyzed production of activated oxygen species. We studied whether homocysteine, in the presence of Cu2+, alters reactivity of cerebral circulation and, if so, whether this effect depends on O-2 generation. In halothane-anesthetized rats the parietal cortex was exposed and superfused with Ringer solution. Cerebrocortical blood flow (CBF) was monitored by a laser-Doppler probe. With Ringer solution superfusion, CBF increased with hypercapnia (+1<em>3</em>4 +/- 7%; PCO2 = 50-60 mmHg) and topical application of 10 microM ACh (+<em>3</em>5 +/- <em>3</em>%), the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 500 microM; +66 +/- 6%), or 1 mM papaverine (+100 +/- 6%; n = 5). Superfusion with 40 microM Cu2+ alone did not perturb resting CBF or responses to hypercapnia, ACh, SNAP, or papaverine (P>> 0.05, n = 5). However, superfusion of homocysteine-Cu2+ reduced resting CBF (-28 +/- 4%) and attenuated (P < 0.05) responses to hypercapnia (-<em>3</em>1 +/- 9%), ACh (-7<em>3</em> +/- 6%), or SNAP (-48 +/- 4%), but not papaverine. The effect was observed only at 1 mM homocysteine. Cerebrovascular effects of homocysteine-Cu2+ were prevented by coadministration of superoxide dismutase (<em>SOD</em>; 1,000 U/ml; n = 5). <em>SOD</em> alone did not affect resting CBF or CBF reactivity (n = 5). The observation that homocysteine-Cu2+ attenuates the response to hypercapnia, ACh, and SNAP, but not the NO-independent vasodilator papaverine, suggests that homocysteine-Cu2+ selectively impairs NO-related cerebrovascular responses. The fact that <em>SOD</em> prevents such impairment indicates that the effect of homocysteine is O-2 dependent. The data support the conclusion that O-2, generated by the reaction of homocysteine with Cu2+, inhibits NO-related cerebrovascular responses by scavenging NO, perhaps through peroxynitrite formation. O-2-mediated scavenging of NO might be one of the mechanisms by which hyperhomocysteinemia predisposes to cerebrovascular diseases.

There is a large body of evidence indicating an age-related increase in the rate of mitochondrial O2- and H2O2 generation and huge amounts of oxidative damage leading to several neurodegenerative disorders, perhaps due to an imbalance between free radical generation and anti-oxidant defense system. The aim of the present study was to elucidate the effect of aging on free radical scavenger system profile in rat brain and lymphocytes. The enzyme activities of gamma-GCS, GR, GPx, gamma-GTP, GST, catalase, and <em>SOD</em> as well as GSH content were assayed from discrete brain areas viz., CH, CB, BS and DC along with lymphocytes from four different age group rats, namely, 1-month-old young rats, <em>3</em>-4-month-old young adults, 12-month-old adults and 24-month-old aged rats. Significant decline was observed in all the enzyme activities in 12- and 24-month-old rats as compared to <em>3</em>-4-month-old young adult rats and also, 1-month-old rats showed lower levels of enzyme activities as compared to <em>3</em>-4-month-old rats. The maximum scavenger system activity was found in the young adult rats (<em>3</em>-4 months) as compared to the remaining age groups. Lymphocytes and brain showed a parallel pattern of age-related alterations in the free radical scavenger system components. The analysis of such alterations is important in ultimately determining the basis of neuronal dysfunction associated with aging and also defining the nature of these changes may help to develop therapeutic means to cure not only elderly but also individuals suffering from certain organic or psychiatric disorders.

In type 2 diabetes (T2D), postprandial and fasting hyperglycemia are important predictors of cardiovascular diseases; however, few drugs are currently available to simultaneously suppress these conditions. Here, we report an enduring antidiabetic effect of the heme oxygenase (HO) inducer hemin on Goto-Kakizaki rats (GK), a nonobese insulin-resistant T2D model. HO breaks down the heme-moiety-generating antioxidants (biliverdin/bilirubin and ferritin) and carbon monoxide, which stimulate insulin secretion. Hemin induces HO-1 to potentiate HO activity and the HO-derived products. Chronically applied hemin (<em>3</em>0 mg/kg ip) for a month reduced and maintained fasting glucose at physiological levels for <em>3</em> mo. Before therapy, glucose levels were 9.<em>3</em> +/- 0.<em>3</em> mmol/l (n = 14). At 1, 2, and <em>3</em> mo posttherapy, we recorded 6.7 +/- 0.1<em>3</em>, 5.9 +/- 0.2, and 7.2 +/- 0.2 mmol/l, respectively. Hemin was also effective against postprandial hyperglycemia (14.6 +/- 1.1 vs. 7.5 +/- 0.4 mmol/l; n = 14; P < 0.01), and the effect remained sustained for <em>3</em> mo after therapy. The reduction of hyperglycemia was accompanied by enhanced HO-1, HO activity, and cGMP of the soleus muscle, alongside increased plasma bilirubin, ferritin, <em>SOD</em>, total antioxidant capacity, and insulin levels, whereas markers/mediators of oxidative stress like urinary-8-isoprostane and soleus muscle nitrotyrosine, NF-kappaB, and activator protein-1 and -2 were abated. Furthermore, inhibitors of insulin signaling including soleus muscle glycogen synthase kinase-<em>3</em> and JNK were reduced, while the insulin-sensitizing adipokine, adiponectin, alongside AMPK were increased. Correspondingly, hemin improved glucose tolerance, suppressed insulin intolerance, reduced insulin resistance, and overturned the inability of insulin to enhance glucose transporter 4, a protein required for glucose uptake. Hemin also upregulated HO-1/HO activity and cGMP and lowered glucose in euglycemic Sprague-Dawley control rats albeit less intensely, suggesting greater selectivity of the HO system in diabetic conditions. In conclusion, reduced oxidative stress alongside the concomitant and paradoxical enhancement of insulin secretion and insulin-sensitizing pathways may account for the <em>3</em>-mo-enduring antidiabetic effect. The synergistic interaction among HO, adiponectin, and GLUT4 may be explored against insulin-resistant diabetes.

This study was designed to investigate whether Resveratrol (Res) could be a prophylactic factor in the prevention of I/R injury and to shed light on its underlying mechanism. Primary culture of neonatal rat cardiomyocytes were randomly distributed into three groups: the normal group (cultured cardiomyocytes were in normal conditions), the I/R group (cultured cardiomyocytes were subjected to 2 h simulated ischemia followed by 4 h reperfusion), and the Res+I/R group (100 µmol/L Res was administered before cardiomyocytes were subjected to 2 h simulated ischemia followed by 4 h reperfusion). To test the extent of cardiomyocyte injury, several indices were detected including cell viability, LDH activity, Na(+)-K(+)-ATPase and Ca(2+)-ATPase activity. To test apoptotic cell death, caspase-<em>3</em> activity and the expression of Bcl-2/Bax were detected. To explore the underlying mechanism, several inhibitors, intracellular calcium, <em>SOD</em> activity and MDA content were used to identify some key molecules involved. Res increased cell viability, Na(+)-K(+)-ATPase and Ca(2+)-ATPase activity, Bcl-2 expression, and <em>SOD</em> level. While LDH activity, capase-<em>3</em> activity, Bax expression, intracellular calcium and MDA content were decreased by Res. And the effect of Res was blocked completely by either L-NAME (an eNOS inhibitor) or MB (a cGMP inhibitor), and partly by either DS (a PKC inhibitor) or Glybenclamide (a K(ATP) inhibitor). Our results suggest that Res attenuates I/R injury in cardiomyocytes by preventing cell apoptosis, decreasing LDH release and increasing ATPase activity. NO, cGMP, PKC and K(ATP) may play an important role in the protective role of Res. Moreover, Res enhances the capacity of anti-oxygen free radical and alleviates intracellular calcium overload in cardiomyocytes.

OBJECTIVE

Recent studies have shown the antiapoptotic neuroprotective effects of lecithinized superoxide dismutase (PC-SOD) in different forms of brain injury. We tested the effects of PC-SOD in focal cerebral ischemia in the rat middle cerebral artery occlusion model (MCAO).

METHODS

Adult male Sprague-Dawley rats were treated with PC-SOD (0.3, 1.0, and 3.0 mg/kg) administered intravenously after 90 minutes of occlusion (beginning of reperfusion). Physiological parameters, neurological score, and infarct volume were assessed at 24 and 72 hours in 3 groups of animals: sham-operated (n=18), MCAO treated with vehicle (n=26), and MCAO treated with PC-SOD (n=37). Oxidative stress was evaluated by malondialdehyde assay, and the apoptotic mechanisms were studied by Western blotting.

RESULTS

PC-SOD treatment significantly reduced infarct volume and improved neurological scores at different time points compared with the vehicle-treated group. PC-SOD treatment decreased malondialdehyde levels, cytochrome c, and cleaved caspase 3 expression and increased mitochondrial Bcl-2 expression.

CONCLUSIONS

Inhibition of oxidative stress with PC-SOD treatment improves outcomes after focal cerebral ischemia. This neuroprotective effect is likely exerted by antiapoptotic mechanisms.

OBJECTIVE

The role of copper, zinc-superoxide dismutase (CuZn-SOD) in hippocampal injury after transient global ischemia was studied using transgenic (Tg) mice and wild-type littermates.

METHODS

Global ischemia was induced by bilateral common carotid artery occlusion. The hemisphere with the hypoplastic posterior communicating artery was determined and then the hippocampus in this hemisphere was evaluated qualitatively using a score of 0 to 4 and quantitatively using an image analyzer.

RESULTS

Hippocampal injury was reduced in Tg mice after both 5 and 10 minutes of ischemia. In the 5-minute ischemia group, the mean score of the injury was significantly lower in Tg than nontransgenic (nTg) mice at 3 days. In the 10-minute group, the hippocampal injury was reduced more in Tg than nTg mice at 1 day. Quantitative evaluation by an image analyzer confirmed the qualitative data. Neurons with fragmented DNA were also studied in the hippocampal injury. In the 5-minute group, despite the reduction of the injury in Tg mice, their neurons with fragmented DNA were relatively increased at 1 day. In the 10-minute group, this ratio was almost the same in both nTg and Tg mice.

CONCLUSIONS

CuZn-SOD plays a protective role in the pathogenesis of selective hippocampal injury after brief ischemia, whether the insult is relatively mild or intense. Furthermore, CuZn-SOD may reduce both necrotic and DNA fragmented neuronal death after global ischemia.

Ethanol by its property of generating free radicals during the course of its metabolism causes damage to cell structure and function. The study investigates the protective effects of the antioxidant aminoacid taurine on ethanol-induced lipid peroxidation and antioxidant status. Male Wistar rats of body weight 170-190 g were divided into 4 groups and maintained for 28 days as follows: a control group and taurine-supplemented control group, taurine supplemented and unsupplemented ethanol-fed group. Ethanol was administered to rats at a dosage of <em>3</em> g/kg body weight twice daily and taurine was provided in the diet (10 g/kg diet). Lipid peroxidation products and antioxidant potential were quantitated in plasma and in following tissues liver, brain, kidney and heart. Increased levels of thiobarbituric acid substances (TBARS) and lipid hydroperoxides (LHP) in plasma and tissues, decreased activities of superoxide dismutase (<em>SOD</em>), catalase (CAT) and glutathione peroxidase (GPx) were observed in hemolysate and tissues of ethanol-fed rats. The contents of reduced glutathione (GSH), alpha-tocopherol and ascorbic acid in plasma and tissues were significantly reduced in these animals as compared to control animals. Simultaneous administration of taurine along with ethanol attenuated the lipid peroxidation process and restored the levels of enzymatic and non-enzymatic antioxidants. We propose that taurine may have a bioprotective effect on ethanol-induced oxidative stress.

Sprague-Dawley rats were fed either a high-salt (HS) diet (4.0% NaCl) or a low-salt (LS) diet (0.4% NaCl) for <em>3</em> days. Nitric oxide (NO) and superoxide production were assessed in the thoracic aorta by evaluating the fluorescence signal intensity from 4,5-diaminofluorescein (DAF-2DA) and dihydroethidine, respectively. Methacholine caused increased NO release in the aortas from rats on a LS but not HS diet. The <em>SOD</em> mimetic tempol restored methacholine-induced NO release in aortas from rats on a HS diet. Methacholine also caused superoxide production in the aortas of rats on a HS diet but not in the aortas of rats on a LS diet. Tempol and N(G)-monomethyl-l-arginine eliminated methacholine-induced superoxide production in the aortas of rats on a HS diet. Aortic rings from rats on the HS diet showed impaired methacholine-induced relaxation, which was improved by tempol. Tempol alone caused a NO-dependent relaxation of norepinephrine-precontracted aortas that was significantly greater in the aortas of rats on the HS diet than in vessels from rats on the LS diet. These data suggest that a HS diet impairs endothelium-dependent relaxation via reduced NO levels and increased superoxide production.

Membrane abnormalities in essential hypertensives (EH) are well known. The respiratory burst enzyme, NADPH oxidase is located in the cell membrane of the neutrophil (PMNLs) and its activity is important in generation of oxygen derived free radical (OFR). Recently OFR have been implicated in vascular changes in variety of conditions. An attempt was made to delineate the status of OFR and antioxidants in EH. Ten, age and sex-matched, healthy controls (GpI) and 26 untreated EH (Gp IIA mild-8, Gp IIB Moderate-8, Gp IIC Severe-10) were studied. After clinical examination and basic laboratory evaluation of subjects, neutrophils isolated from their blood were studied. Chemiluminescence (CL) emitted by PMNLs after stimulation was measured (counts/min) in a luminometer and was taken as measure of OFR production and thereby of NADPH oxidase activity. The levels of antioxidants, superoxide dismutase (<em>SOD</em>) and reduced glutathione (GSH), were also estimated. Chemiluminescence was increased significantly (p less than 0.01) in Gp IIC (24<em>3</em>.04 +/- 24.9 x 10(<em>3</em>) counts per minute) as compared to Gp IIA (2.80 +/- 1.87), Gp IIB (<em>3</em>4.54 +/- <em>3</em>0.24) and Gp I (0.52 +/- 0.15) and <em>SOD</em> was reduced significantly (p less than 0.05) in all EH (Gp IIA <em>3</em>.9 +/- 0.<em>3</em> units per mg protein, Gp IIB <em>3</em>.5 +/- 0.<em>3</em> and Gp IIC <em>3</em>.12 +/- 0.<em>3</em>) as compared to controls (4.1 +/- 0.2). Similarly GSH was reduced (p less than 0.05) in EH (Gp IIA 11.2 +/- 1.7 mg per gm protein, Gp IIB 8.5 +/- 1.1 and Gp IIC 6.6 +/- 0.<em>3</em>) as compared to Gp I (1<em>3</em>.5 +/- 2.5).(ABSTRACT TRUNCATED AT 250 WORDS)

1. Acetylcholine (ACh, 0.0<em>3</em>-<em>3</em>.0 microM) induced a dose-dependent vasodilatation in the isolated Langendorff-perfused heart of the rabbit. The vasodilatation was mimicked by exogenous nitric oxide (NO, 0.045-4.5 nmol). 2. There was no detectable vascular relaxing activity in the cardiac effluent when these concentrations of ACh or NO were injected through the heart, even in the presence of an infusion of superoxide dismutase (<em>SOD</em>). <em>3</em>. Acetylcholine (0.0<em>3</em>-<em>3</em>.0 microM), however, induced the release into the cardiac effluent of a material which produced a chemiluminescent signal when reacted with ozone, a response which could be mimicked with exogenous NO (0.045-4.5 nmol) injected through the heart. 4. The effects of ACh, but not those of NO, were antagonized by atropine (2 microM). Prostacyclin (1 microM) injected through the heart induced vasodilatation without the release of a biologically active or chemiluminescent material. 5. During passage through the heart, greater than 99% of the biological activity of exogenous NO disappeared, whereas there was approximately 50% reduction of its chemiluminescent response. This indicates complete transformation into a mixture containing approximately 50% NO2- and 50% of other non-chemiluminescent material(s), presumably NO<em>3</em>-. 6. This study suggests that ACh induces endothelium-dependent vasodilatation in the coronary circulation through the release of the endogenous nitrovasodilator, NO, which is rapidly converted to NO2- and NO<em>3</em>-.

The Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (Mn(III)TE-2-PyP(5+)) is a potent superoxide dismutase (<em>SOD</em>) mimic in vitro and was beneficial in rodent models of oxidative stress pathologies. Its high activity has been ascribed to both the favorable redox potential of its metal center and to the electrostatic facilitation assured by the four positive charges encircling the metal center. Its comparison with the non-alkylated, singly charged analogue Mn(III) beta-octabromo meso-tetrakis(2-pyridyl)porphyrin (Mn(III)Br(8)T-2-PyP(+)) enabled us to evaluate the electrostatic contribution to the catalysis of O(2)() dismutation. Both compounds exhibit nearly identical metal-centered redox potential for Mn(III)/Mn(II) redox couple: +228 mV for Mn(III)TE-2-PyP(5+) and +219 mV versus NHE for Mn(III)Br(8)T-2-PyP(+). The eight electron-withdrawing beta pyrrolic bromines contribute equally to the redox properties of the parent Mn(III)T-2-PyP(+) as do four quaternized cationic meso ortho pyridyl nitrogens. However, the <em>SOD</em>-like activity of the highly charged Mn(III)TE-2-PyP(5+) is >100-fold higher (log k(cat) = 7.76) than that of the singly charged Mn(III)Br(8)T-2-PyP(+) (log k(cat) = 5.6<em>3</em>). The kinetic salt effect showed that the catalytic rate constants of the Mn(III)TE-2-PyP(5+) and of its methyl analogue, Mn(III)TM-2-PyP(5+), are exactly 5-fold more sensitive to ionic strength than is the k(cat) of Mn(III)Br(8)T-2-PyP(+), which parallels the charge ratio of these compounds. Interestingly, only a small effect of ionic strength on the rate constant was found in the case of penta-charged para (Mn(III)TM-4-PyP(5+)) and meta isomers (Mn(III)TM-<em>3</em>-PyP(5+)), indicating that the placement of the positive charges in the close proximity of the metal center (ortho position) is essential for the electrostatic facilitation of O(2)() dismutation.

We describe the isolation of a cDNA clone for the nuclear-encoded manganese superoxide dismutase (<em>SOD</em>-<em>3</em>) of maize mitochondria. The cDNA, pSod<em>3</em>.1c, selects by hybridization an RNA which produces the <em>SOD</em>-<em>3</em> precursor upon in vitro translation. The DNA sequence of pSod<em>3</em>.1c was determined from fragments subcloned in M1<em>3</em>. The amino-acid sequence deduced from the nucleotide sequence displays significant homology with the amino-acid sequences of prokaryotic and eukaryotic Mn-<em>SODs</em>, but displays greater homology with mammalian Mn-<em>SOD</em> than it does with yeast or bacterial Mn-<em>SOD</em>. A <em>3</em>1 amino-acid transit peptide also is encoded by the pSod<em>3</em>.1c clone. Analysis of poly(A)+ RNA indicates that Sod<em>3</em> mRNA is approx. 1250 nucleotides in length. The amount of Sod<em>3</em> transcript in seedling leaves is increased by light.

Methylglyoxal (MG) is a metabolite of glucose. Our previous study demonstrated an elevated MG level with an increased oxidative stress in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats. Whether MG causes the generation of nitric oxide (NO) and superoxide anion (O2*-), leading to peroxynitrite (ONOO-) formation in VSMCs, was investigated in the present study. Cultured rat thoracic aortic SMCs (A-10) were treated with MG or other different agents. Oxidized DCF, reflecting H2O2 and ONOO- production, was significantly increased in a concentration- and time-dependent manner after the treatment of SMCs with MG (<em>3</em>-<em>3</em>00 microM) for 45 min-18 h (n = 12). MG-increased oxidized DCF was effectively blocked by reduced glutathione or N-acetyl-l-cysteine, as well as L-NAME (p < 0.05, n = 12). Both O2*- scavenger <em>SOD</em> and NAD(P)H oxidase inhibitor DPI significantly decreased MG-induced oxidized DCF formation. MG significantly and concentration-dependently increased NO and O2*- generation in A-10 cells, which was significantly inhibited by L-NAME and <em>SOD</em> or DPI, respectively. In conclusion, MG induces significant generation of NO and O2*- in rat VSMCs, which in turn causes ONOO- formation. An elevated MG level and the consequential ROS/RNS generation would alter cellular signaling pathways, contributing to the development of different insulin resistance states such as diabetes or hypertension.