Endogenous bacteria-triggered inducible nitric oxide synthase activation protects the ovariectomized rat stomach

Under experimental circumstances, ovariectomy attenuates gastric mucosal injury where nitric oxide (NO)-mediated pathways are involved. In this study, we have examined the changes in constitutive (cNOS) and inducible NO synthase (iNOS) enzyme activities (assessed by the citrulline assay), and the role of endogenous bacteria in ovariectomy-provoked mucosal defence. Gastric lesions were induced by indomethacin (50 mg/kg, s.c.) over a 4 h period in sham-operated and ovariectomized female Wistar rats. Groups of animals received the wide-spectrum antibiotic ampicillin (800 mg/kg/day, p.o., for 3 days), and others were injected with bacterial endotoxin (E. coli, 3 mg/kg, i.v., 5 h before autopsy). We found that ovariectomy increased iNOS and decreased cNOS activity (resulting an elevated total gastric NOS level), and protected the stomach, effects reversed by ampicillin treatment. In ovary-intact rats, administration of bacterial endotoxin enhanced gastric iNOS activity and reduced lesion-formation. These results suggest that ovariectomy improves gastric mucosal defence perhaps by endogenous bacteria-triggered induction of iNOS.     

Oxidative damage following cerebral ischemia depends on reperfusion - a biochemical study in rat

The extent of brain injury during reperfusion appears to depend on the experimental pattern of ischemia/reperfusion. The goals of this study were: first, to identify the rate of free radicals generation and the antioxidant activity during ischemia and reperfusion by means of biochemical measurement of lipid peroxidation (LPO) and both enzymatic (superoxid dismutase - SOD, catalase - CAT, glutathion peroxidase - GPx) and non-enzymatic antioxidants activity (glutathione - GSH); and second, to try to find out how the pattern of reperfusion may influence the balance between free radical production and clearance. Wistar male rats were subject of four-vessel occlusion model (Pulsinelly & Brierley) cerebral blood flow being controlled by means of two atraumatic arterial microclamps placed on carotid arteries. The level of free radicals and the antioxidant activity were measured in ischemic rat brain tissue homogenate using spectrophotometrical techniques. All groups subjected to ischemia shown an increase of LPO and a reduction of the activity of enzymatic antioxidative systems (CAT, GPx, SOD) and non-enzymatic systems (GSH). For both groups subjected to ischemia and reperfusion, results shown an important increase of LPO but less significant than the levels found in the group with ischemia only. Statistically relevant differences (p<0.01) between continuous reperfusion and fragmented reperfusion were observed concerning the LPO, CAT, SOD and GSH levels, oxidative aggresion during fragmented reperfusion being more important.     

Antioxidant response and oxidative stress levels in Macrobrachium borellii (Crustacea: Palaemonidae) exposed to the water-soluble fraction of petroleum

The aim of the present work was to evaluate the effect of the water soluble fraction of hydrocarbons (WSF) on the antioxidant status of the freshwater prawn Macrobrachium borellii. First, seasonal variations were studied in a non-polluted area. Hepatopancreas and gills showed season-related fluctuations in catalase (CAT), glutathione-S-transferase (GST) activities and in lipid peroxidation levels (LPO), but not in superoxide dismutase (SOD). Then, adults were exposed semi-statically to sublethal doses for 7days. CAT, SOD, GST, and glutathione peroxidase (GPx) activities and LPO, reduced glutathione (GSH) and protein oxidation (PO) levels were determined. Exposed individuals showed significant increases in CAT, SOD, and GST activities in hepatopancreas and CAT activity in gills. GPx activity did not vary in either tissues. While LPO levels increased, GSH levels decreased significantly in hepatopancreas of exposed animals, but PO levels showed no variation. Induction of SOD was also assessed by Real-time PCR mRNA expression in hepatopancreas. The non-enzymatic antioxidant activity was also tested; ABTS 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) was higher in hemolymph of treated-prawns compared to controls, but ferric reducing activity of plasma assay (FRAP) values did not change. Taken together, the present results indicated that the antioxidant defenses of M. borellii, mainly in hepatopancreas, were significantly affected by aquatic hydrocarbon contamination, regardless of the season.     

The effects of selenium on oxidative stress biomarkers in the freshwater characid fish matrinxã, Brycon cephalus (Günther, 1869) exposed to organophosphate insecticide Folisuper 600 BR (methyl parathion)

Methyl parathion (MP), an organophosphate widely applied in agriculture and aquaculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The antioxidant roles of selenium (Se) were evaluated in Brycon cephalus exposed to 2 mg L(-1) of Folisuper 600 BR (MP commercial formulation - MPc, 600 g L(-1)) for 96 h. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the gills, white muscle and liver were evaluated in fish fed on diets containing 0 or 1.5 mg Se kg(-1) for 8 weeks. In fish treated with a Se-free diet, the MPc exposure increased SOD and CAT activities in all tissues. However, the GPx activity decreased in white muscle and gills whereas no alterations were observed in the liver. MPc also increased GST activity in all tissues with a concurrent decrease in GSH levels. LPO values increased in white muscle and gills and did not change in liver after MPc exposure. A Se-supplemented diet reversed these findings, preventing increases in LPO levels and concurrent decreases in GPx activity in gills and white muscle. Similarly, GSH levels were maintained in all tissue after MPc exposure. These results suggest that dietary Se supplementation protects cells against MPc-induced oxidative stress.     

Fenugreek seeds modulate 1,2-dimethylhydrazine-induced hepatic oxidative stress during colon carcinogenesis

1,2-dimethylhydrazine (DMH) is a colon carcinogen which undergoes oxidative metabolism in the liver. We have investigated the modulatory effect of fenugreek seeds (a spice) on colon tumor incidence as well as hepatic lipid peroxidation (LPO) and antioxidant status during DMH-induced colon carcinogenesis in male Wistar rats. In DMH treated rats, 100% colon tumor incidence was accompanied by enhanced LPO and a decrease in reduced glutathione (GSH) content as well as a fall in glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities. Inclusion of fenugreek seed powder in the diet of DMH treated rats reduced the colon tumor incidence to 16.6%, decreased the LPO and increased the activities of GPx, GST, SOD and CAT in the liver. We report that fenugreek modulates DMH-induced hepatic oxidative stressduring colon cancer     

Oxidative stress biomarkers in the freshwater characid fish, Brycon cephalus, exposed to organophosphorus insecticide Folisuper 600 (methyl parathion)

Methyl parathion (MP) is an organophosphorus insecticide used worldwide in agriculture and aquaculture due to its high activity against a broad spectrum of insect pests. The effect of a single exposure to 2 mg L(- 1) of a commercial formulation of MP (MPc: Folisuper 600(R), MP 600 g L(- 1)) on catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) of the liver, white muscle and gills of Brycon cephalus was evaluated after 96 h of treatment. MPc exposure resulted in a significant induction of SOD, CAT and GST activity in all tissues. However, the GPx activity decreased significantly in white muscle and gills, whereas no alterations were observed in hepatic GPx activity. MPc also induced a significant increase in LPO values in the white muscle and gills, while hepatic LPO levels did not show any significant alteration. The current data suggest that MPc has oxidative-stress-inducing potential in fish, and that gills and white muscle are the most sensitive organs of B. cephalus, with poor antioxidant potentials. The various parameters studied in this investigation can also be used as biomarkers of exposure to MPc.     

Gastroprotection by pentoxyfilline against stress-induced gastric damage. Role of lipid peroxidation, antioxidizing enzymes and proinflammatory cytokines.

Impairment of blood perfusion in gastric mucosa results in the formation of erosions and ulcers. Nitric oxide (NO), produced via activity of NO-synthase (NOS), appears to be a one of major factors, involved in the regulation of the gastric blood flow (GBF). Inhibition of this enzyme by N-nitro-L-arginine (L-NNA) results in local decrease of NO production, reduces GBF and impairs gastric mucosal integrity, the effects that can be reversed by the pretreatment with L-arginine, the NOS substrate. However, little information is available regarding the contribution of reactive oxygen species (ROS)-induced lipid peroxidation and NO to the mechanism of gastric mucosal integrity. Therefore, the aim of our present study was to determine the action of pentoxyfilline (PTX), an inhibitor of tumor necrosis factor alpha (TNFalpha) with or without NOS inhibition by L-NNA administration in rats with water immersion and restraint stress (WRS)-induced gastric lesions. Experiments were carried out on 100 male Wistar rats. The gastric blood flow (GBF) was measured using laser Doppler flowmeter. The area of gastric lesions was determined by planimetry and the levels of proinflammatory cytokines (IL-1beta and TNFalpha) were measured by ELISA. Colorimetric assays were employed to determine gastric mucosal levels of lipid peroxidation products, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) and antioxidant enzymes including superoxide dismutase (SOD) activity, as well as tissue concentration of reduced glutathione (GSH). Administration of PTX significantly attenuated the gastric lesions, induced by 3.5 h of WRS and this was accompanied by the rise in the GBF and a significant decrease in plasma proinflammatory cytokines (IL-1beta and TNFalpha) levels, as well as the reduction of lipid peroxidation. Exposure of rats to WRS suppressed the SOD and GSH activities and these effects were reversed by PTX. The protective and hyperemic effects of PTX, as well as an increase in mucosal SOD activity and GSH concentration were counteracted by pretreatment with L-NNA, but restored by the pretreatment with L-arginine, a NOS substrate. We conclude that PTX exerts beneficial, gastroprotective effect against WRS-induced gastric lesions due to enhancement in gastric microcirculation, possibly mediated by the enhanced NOS activity as well as local action of NO and by the attenuation of oxidative metabolism and generation proinflammatory cytokines.     

Role of endogenous nitric oxide in mucosal defense of inflamed rat stomach following iodoacetamide treatment

Nitric oxide (NO) plays a role in regulating the mucosal integrity of the stomach. However, its part in the mucosal defense of the inflamed stomach remains unclear. In the present study, we examined the effects of various NO synthase (NOS) inhibitors on gastric ulcerogenic and acid secretory responses following daily exposure of the stomach to iodoacetamide and investigated the role of each NOS isozyme in gastric protection from subchronic mucosal irritation. Gastric mucosal irritation was induced in rats by addition of 0.1% iodoacetamide to drinking water, and the gastric mucosa was examined on the 6th day. L-NAME (a nonselective NOS inhibitor: 20 mg/kg) or aminoguanidine (a selective iNOS inhibitor: 20 mg/kg) was given s.c. twice 24 h and 3 h before the termination of iodoacetamide treatment. Giving iodoacetamide in drinking water for 5 days produced minimal damage in the stomach with an increase in myeloperoxidase (MPO) activity and lipid peroxidation. Iodoacetamide treatment up-regulated the expression of iNOS mRNA and NO production in the stomach, without affecting nNOS expression. Both L-NAME and aminoguanidine markedly aggravated gastric lesions induced by iodoacetamide treatment, with a further enhancement in MPO activity and lipid peroxidation. Basal acid secretion as determined in pylorous-ligated stomachs was decreased following iodoacetamide treatment, but the response was significantly restored by both L-NAME and aminoguanidine. These results suggest that endogenous NO derived from both cNOS and iNOS is involved in mucosal defense of the inflamed stomach, partly by decreasing acid secretion, and contributes to maintaining mucosal integrity under such conditions.     

Maternal cadmium intoxication: effects on fetal brain antioxidant defense parameters

Summary

The antioxidant potential of the brain in developing fetuses was assessed at gestational days (GD) 16, 18 and 20 and postnatal day (PND)1. Higher activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were noticed during fetal development which were reduced to about half and one-quarter, respectively, at PND 1. Glutathione reductase (GR) activity remained stationary throughout the experiment and the values were very high compared to those reported for weanling rats. In contrast, catalase (CAT) activity increased with development. Glutathione (GSH) and total sulfhydryls (TSH) were maximum in 16-day fetal brains and declined subsequently. Brain lipid peroxidation (LPO) was found to increase with age. A group of animals was exposed to 20 ppm cadmium (Cd) in drinking water from the day of conception up to PND 1. Cd was found to increase the activities of brain SOD, CAT, and GR significantly at all the time intervals. The metal exposure decreased fetal brain GPx at GD 18 and 20, whereas GPx activity declined precipitously in both groups on PND 1. Cd caused both increments and decrements in the GSH and TSH levels (depending on gestational day) and increased the LPO in brain. It may be concluded that the Cd-intoxicated fetal brain undergoes significant changes in antioxidant defense parameters which, overall, may be sufficient to permit near-normal development and prevent substantial oxidant damage.     

Accumulation and oxidative stress biomarkers in Japanese flounder larvae and juveniles under chronic cadmium exposure

This study investigated how Cd exposure affected oxidative biomarkers in Japanese flounder, Paralichthys olivaceus, at early life stages (ELS). Fish were exposed to waterborne Cd (0–48 µg L^− 1) from embryonic to juvenile stages for 80 days. Growth, Cd accumulation, activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione S-transferase (GST, EC 2.5.1.18), and levels of glutathione (GSH) and lipid peroxidation (LPO) were investigated at three developmental stages. Flounder growth decreased and Cd accumulation increased with increasing Cd concentration. In metamorphosing larvae, CAT and SOD activities were inhibited and GSH level was elevated, while LPO was enhanced by increasing Cd concentrations. CAT and GST activities of settling larvae were inhibited but GSH level was elevated at high Cd concentrations. In juveniles, SOD activity and LPO level were increased but GST activity was inhibited as Cd concentration increased. Antioxidants in flounder at ELS were able to develop ductile responses to defend against oxidative stress, but LPO fatally occurred due to Cd exposure. These biochemical parameters could be used as effective oxidative biomarkers for evaluating Cd contamination and toxicity in marine environments: CAT, SOD, GSH, and LPO for metamorphosing stage; CAT, GSH, and GST for settling stage; and SOD, GST, and LPO for juvenile stage.     

Thyroid hormone-induced haemoglobin changes and antioxidant enzymes response in erythrocytes

Thyroid hormones modulate haemoglobin and reactive oxygen species (ROS) production, leading to antioxidant changes. This study evaluated the antioxidant response to ROS in erythrocytes in hypothyroid and hyperthyroid rats. Wistar rats were divided into four groups: control; hyperthyroid (T4-12 mg 1(-1) in drinking water); sham operated (simulation of thyroidectomy); and hypothyroid (thyroidectomized). Four weeks after, blood was collected and haemoglobin and T(4) levels, lipid peroxidation (LPO), protein oxidation, superoxide dismutase (SOD), catalase (CAT) , glutathione S-transferase (GST) and glutathione peroxidase (GPx) activities, and total radical antioxidant potential (TRAP) were measured. SOD, CAT and GST immunocontent was evaluated. Haemoglobin levels were increased in hyperthyroid erythrocytes. LPO and carbonyls were augmented (65% and 55%, respectively) in hyperthyroid and reduced (31% and 56%, respectively) in hypothyroid group. SOD and CAT activities have not changed, as well as CAT immunocontent. TRAP was diminished in both hyperthyroid and hypothyroid groups (36% and 37%, respectively). GST activity and immunocontent, as well as GPx activity, were increased in hyper and hypothyroid rats. The data suggest that thyroid hormone changes determine ROS concentration changes and decrease of some antioxidant defences that would lead to a compensatory answer of the GST and GPx enzymes, which could be consider as credible biomarkers.     

Hepatoprotective effect of Origanum vulgare in Wistar rats against carbon tetrachloride-induced hepatotoxicity

The effect of an aqueous extract of Origanum vulgare (OV) leaves extract on CCl₄-induced hepatotoxicity was investigated in normal and hepatotoxic rats. To evaluate the hepatoprotective activity of OV, rats were divided into six groups: control group, O. vulgare group, carbon tetrachloride (CCl₄; 2 ml/kg body weight) group, and three treatment groups that received CCl₄ and OV at doses of 50, 100, 150 mg/kg body weight orally for 15 days. Alanine amino transferase (ALT), alkaline phosphatase (ALP), and aspartate amino transferase (AST) in serum, lipid peroxide (LPO), GST, CAT, SOD, GPx, GR, and GSH in liver tissue were estimated to assess liver function. CCl₄ administration led to pathological and biochemical evidence of liver injury as compared to controls. OV administration led to significant protection against CCl₄-induced hepatotoxicity in dose-dependent manner, maximum activity was found in CCl₄?+?OV3 (150 mg/kg body weight) groups and changes in the hepatocytes were confirmed through histopathological analysis of liver tissues. It was also associated with significantly lower serum ALT, ALP, and AST levels, higher GST, CAT, SOD, GPx, GR, and GSH level in liver tissue. The level of LPO also decreases significantly after the administration of OV leaves extract. The biochemical observations were supplemented with histopathological examination of rat liver sections. Thus, the study suggests O. vulgare showed protective activity against CCl₄-induced hepatotoxicity in Wistar rats and might be beneficial for the liver toxicity.     

Ouabain attenuates oxidative stress and modulates lipid composition in hippocampus of rats in lipopolysaccharide-induced hypocampal neuroinflammation in rats

Our study aimed to analyze the effect of ouabain (OUA) administration on lipopolysaccharide (LPS)-induced changes in hippocampus of rats. Oxidative parameters were analyzed in Wistar rats after intraperitoneal injection of OUA (1.8 µg/kg), LPS (200 µg/kg), or OUA plus LPS or saline. To reach our goal, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), in addition to levels of reduced glutathione (GSH), protein carbonyl (PCO) and lipid peroxidation (LPO) were evaluated. We also analyzed the membrane lipid profile and some important lipids for the nervous system, such as phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic acid and sphingomyelin. The group that received only LPS showed increased oxidative stress, as evidenced by an increase in LPO (about twice), PCO (about three times) levels, and CAT activity (80%). Conversely, administration of LPS decreased GSH levels (55%), and GPx activity (30%), besides a reduction in the amount of PI (60%) and PC (45%). By other side, OUA alone increased the amount of PI (45%), PE (85%), and PC (70%). All harmful effects recorded were attenuated by OUA, suggesting a protective effect against LPS-induced oxidative stress. The relevance of our results extends beyond changes in oxidative parameters induced by LPS, because nanomolar doses of OUA may be useful in neurodegenerative models. Other studies on other cardenolides and substances related issues, as well as the development of new molecules derived from OUA, could also be useful in general oxidative and/or cellular stress, a condition favoring the appearance of neuronal pathologies.     

Diallyl sulfide attenuates bleomycin-induced pulmonary fibrosis: critical role of iNOS, NF-kappaB, TNF-alpha and IL-1beta

Diallylsulfide (DAS), an antioxidant and anti-inflammatory agent was evaluated for its ability to repress lung fibrosis induced by bleomycin in Wistar rats. A single intra tracheal administration of bleomycin (6.5 U/kg BW) was administered to pulmonary fibrosis group, while DAS (120 mg/kg BW) was administered intraperitoneally throughout the experimental period. Fibrotic changes in the lungs were estimated by measuring lung hydroxyproline content. Bleomycin administration significantly (P<0.05) reduced the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the lung tissues. Bleomycin caused a significant decrease in the level of reduced glutathione (GSH), which was accompanied with significant increase in lipid peroxidation (LPO) level, and myeloperoxidase (MPO) activity, in the lung tissues. An increase in the level of cell counts in bronchoalveolar lavage fluid (BALF) was observed in bleomycin induced group. DAS administration altered the levels of enzymic antioxidants, TBARS, MPO and GSH towards normal values. Histopathological analysis and picrosirius red staining showed an increased collagen deposition in rats receiving bleomycin alone that was decreased upon DAS treatment. Immunohistochemical studies revealed that DAS reduced the bleomycin-induced activation of inducible nitric oxide synthase (iNOS) and nuclear factor kappa-B (NF-kappaB) and decreased the augmented levels of the early inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), in the lung tissues. The present study provides evidence that DAS might serve as a novel target for the therapeutic treatment of lung fibrosis.     

Effect of plantain banana on gastric ulceration in NIDDM rats: role of gastric mucosal glycoproteins, cell proliferation, antioxidants and free radicals

Methanolic extract of Musa sapientum var. Paradisiaca (MSE, 100 mg/kg) was studied for its antiulcer and mucosal defensive factors in normal and non-insulin dependent diabetes mellitus (NIDDM) rats. NIDDM was induced by administering streptozotocin (STZ, 70 mg/kg, ip) to 5 days old rat pups. The animals showing blood glucose level >140mg/dL after 12 weeks of STZ administration were considered as NIDDM positive. Effects of MSE were compared with known ulcer protective drug, sucralfate (SFT, 500 mg/kg) and anti-diabetic drug glibenclamide (GLC, 0.6 mg/kg) when administered orally, once daily for 6 days against gastric ulcers (GU) induced by cold-restraint stress (CRS) and ethanol and subsequent changes in gastric mucosal glycoproteins, cell proliferation, free radicals (lipid peroxidation and nitric oxide) and anti-oxidants enzymes (super oxide dismutase and catalase) and glutathione (GSH) levels. MSE showed better ulcer protective effect in NIDDM rats compared with SFT and GLC in CRS-induced GU. NIDDM caused a significant decrease in gastric mucosal glycoprotein level without having any effect on cell proliferation. However, all the test drugs reversed the decrease in glycoprotein level in NIDDM rats, but cell proliferation was enhanced in case of MSE alone. Both CRS or NIDDM as such enhanced gastric mucosal LPO, NO and SOD, but decreased CAT levels while CRS plus NIDDM rats caused further increase in LPO and NO level without causing any further changes in SOD and CAT level. MSE pretreatment showed reversal in the levels of all the above parameters better than GLC. Ethanol caused a decrease in glutathione level which was further reduced in NIDDM-ethanol rats. MSE reversed the above changes significantly in both normal as well as in NIDDM rats, while GLC reversed it only in NIDDM rats. However, SFT was ineffective in reversing the changes induced by CRS or ethanol or when given in NIDDM-CRS or NIDDM-ethanol rats. The results indicated that the ulcer protective effect of MSE could be due to its predominant effect on mucosal glycoprotein, cell proliferation, free radicals and antioxidant systems.     

Effect of alpha-ketoglutarate on neurobehavioral, neurochemical and oxidative changes caused by sub-chronic cyanide poisoning in rats

Recent studies revealed that alpha-ketoglutarate (A-KG) alone or with sodium thiosulfate (STS) provide significant protection against acute and sub-acute cyanide poisoning in rodents. This study addresses the protective effect of A-KG and/or STS in sub-chronic (90 days) cyanide poisoning. Wistar rats were divided into seven groups (n = 10): Control animals, potassium cyanide (KCN) A-KG, STS, KCN + A-KG, KCN + STS and KCN + A-KG + STS. Spontaneous motor activity and motor coordination were recorded every 15th day. Lipid peroxidation (LPO), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) in blood, brain, liver and kidney, and glutamate, aspartate and dopamine in discrete regions of brain were measured following 90 days exposure. Cyanide significantly decreased motor coordination, accompanied by increase in LPO (blood, brain and liver) and dopamine (corpus striatum and cerebral cortex) levels, and depletion in GSH (blood, brain and liver), GPx (brain and liver), SOD (brain and liver), and CAT (blood and brain) levels. Although treatment of A-KG and STS alone significantly blunted the toxicity of KCN, concomitant use of both afforded the maximum protection. This study shows a promising role of A-KG and STS as treatment regime for long term cyanide exposure.     

Role of nitric oxide in a progressive neurodegeneration model of Parkinson's disease in the rat

Abstract

This study was undertaken to investigate the nitric oxide synthase (NOS) activity in the striatum following 6-hydroxydopamine (6-OHDA) induced neurodegeneration in rats. Constitutive NOS (cNOS) activity remained unaltered at 3, 7 and 14 days after lesion, while a 43% and 45% decrease was observed at 30 and 50 days, respectively. Inducible NOS (iNOS) activity was detected only on the 3rd day after lesion and not in subsequent days or the control striatum. N^G-nitro-L-arginine methyl ester (L-NAME) pretreatment blocked the amphetamine-induced rotations and inhibited the iNOS activity at the 3rd day after the 6-OHDA injection. L-NAME pretreatment also significantly restored the striatal dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels in 6-OHDA treated rats. Thus a possible role of nitric oxide in 6-OHDA induced neurodegeneration is suggested.     

The free radical mechanisms in beta-carotene induced gastric cytoprotection in HCl model

The aims of our experiments were to clear up the possible correlations between the free radical mechanisms and the gastric cytoprotection of beta-carotene on HCl-induced gastric mucosal lesions. The beta-carotene was intragastrically given in doses of 1 and 10 mg/kg and 30 min. later 1 ml 0.6 N HCl was given to provoke the mucosal damage. After 1, 5, 15, 30 and 60 min. the animals were sacrificed. The number and severity of gastric mucosal lesions were calculated. The superoxide dismutase (SOD), glutathion peroxidase (GPX), catalase (CAT) activity and the malondialdehyde (MDA) and reduced glutathion (GSH) contents were determined from the gastric mucosa of rats. It was found that 1. beta-carotene was able to reduce the number and severity of ulcers only after 30 min.; 2. the CAT activity was decreased at 60 min. by carotene; 3. the GPX activity became dissimilar in the different groups after 15 min; 4. the changes of GSH were found to be similar ones; 5. the SOD activity was lower during the cyto-protection; 6. the MDA level remained practically unchanged. It has been concluded that 1. the free radicals are the consequences of the development of gastric ulcer and cytoprotection; 2. the scavenger character of beta-carotene is involved in its cytoprotective effect.     

Lead-induced lipid peroxidation and antioxidant defense components of developing chick embryos.

Administration of lead (1.25 and 2.5 mumol/kg egg weight) to 14-day-old chick embryos enhanced the level of lipid peroxides (LPO) in tissues of liver, brain, and heart. Accumulation of LPO was maximum at 9 h after treatment with lead and returned to normal level by 72 h. Further, we have studied the levels of glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase. At 9 h posttreatment, the hepatic GR was reduced significantly with the induction of GST and considerable depletion of GSH. However, in brain and heart, both GR and GST activities were unaltered with significant reduction of GSH. Further, an increase of non-Se-dependent GPx and SOD activities were observed in liver, brain, and heart. Similarly, at 72 h, although the GPx activity was found decreased in liver and brain, the GST, catalase, and SOD activities were significantly increased in all the three tissues alike, suggesting tissue-specific changes of antioxidant defense components in response to lead treatment. Our results suggests that the elevated levels of GST, SOD, and catalase at 72 h were successful in bringing LPO levels back to normal.