Psychological Stress-Induced Lower Serum Zinc and Zinc Redistribution in Rats

In humans, long-term exposure to uncontrollable and unpredictable life stressors is a major precipitant in the development of depressive disorders. There are strong evidences that depression is accompanied by lower serum zinc. The aim of present study is to assess the effects of repeated psychological stress (PS) on the zinc metabolism in rat. The rats were divided into control group and PS group which were subdivided into three subgroups: 7-day group, 14-day group, and recovery group (ten rats in each subgroup). PS model was created by a communication box which contains room A and room B. Rats in room A were only exposed to the responses of rats which were randomly given electrical shock for 30 min in room B. PS was given to rats for 30 min every morning for 14 days. The serum corticosterone (CORT), zinc in serum and tissues, and zinc apparent absorption after PS exposure were investigated. The results showed that the serum CORT increased and serum zinc decreased after 7 and 14 days of PS treatment. The zinc concentration in the liver was increased by 14 days PS exposure, whereas its concentration in the hippocampus was decreased by 7 and 14 days of PS exposure. There were no significant changes in zinc concentration in the heart, spleen, kidney, duodenum, cortex, and cerebellum. A decrease in the zinc apparent absorption was observed in the 7- and 14-day PS groups. The increased serum CORT and liver zinc concentrations and decreased serum zinc and apparent absorption of zinc recovered to normal concentrations 7 days away from PS exposure. The results suggest that PS could induce lower serum zinc, which might be correlated with decreased zinc absorption in the small intestine and increased liver zinc accumulation after PS exposure. The consequent effects of decreased hippocampal and serum zinc and increased CORT concentration after PS exposure on stress-related diseases await further research.     

Different susceptibility of prefrontal cortex and hippocampus to oxidative stress following chronic social isolation stress

Chronic oxidative stress plays an important role in depression. The aim of present study was to examine the stress-induced changes in serum corticosterone (CORT) levels, cytosolic protein carbonyl groups, malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO) and total superoxide dismutase (SOD) activity in the prefrontal cortex versus hippocampus of male Wistar rats exposed to acute (2 h of immobilization or cold), chronic (21d of social isolation) stress, and their combination (chronic + acute stress). The subcellular distribution of nuclear factor-κB (NF-κB) and cytosolic cyclooxygenase 2 (COX-2) protein expressions were also examined. Depressive- and anxiety-like behaviors were assessed via the forced swim, sucrose preference, and marble burying tests in chronically isolated rats. Although both acute stressors resulted in elevated CORT, increased MDA in the prefrontal cortex and NF-κB activation accompanied by increased NO in the hippocampus were detected only following acute cold stress. Chronic isolation resulted in no change in CORT levels, but disabled appropriate response to novel acute stress and led to depressive- and anxiety-like behaviors. Increased oxidative/nitrosative stress markers, likely by NF-κB nuclear translocation and concomitant COX-2 upregulation, associated with decreased SOD activity and GSH levels, suggested the existence of oxidative stress in the prefrontal cortex. In contrast, hippocampus was less susceptible to oxidative damage showing only increase in protein carbonyl groups and depleted GSH. Taken together, the prefrontal cortex seems to be more sensitive to oxidative stress than the hippocampus following chronic isolation stress, which may be relevant for further research related to stress-induced depressive-like behavior.     

Hepatoprotective and Antioxidant Activity of Linden (Tilia platyphyllos L.) Infusion Against Ethanol-Induced Oxidative Stress in Rats

The present study was carried out to evaluate the hepatoprotective effect and antioxidant role of infusion prepared from linden flowers (LF) against ethanol-induced oxidative stress. The hepatoprotective and antioxidant role of the plant’s infusion against ethanol-induced oxidative stress was evaluated by measuring liver damage serum biomarkers, aspartate aminotransferase (AST), alanine aminotransferase, lactate dehydrogenase (LDH), total protein, total albumin, and total cholesterol level; ADS such as GSH, GR, SOD, GST, CAT and GPx, and MDA contents in various tissues of rats. Rats were divided into four experimental groups: I (control), II (20 % ethanol), III (2 % LF), and IV (20 % ethanol + 2 % LF). According to the results, the level of serum marker enzymes, AST and LDH, was significantly increased in group alcohol and group LF as compared to control group, whereas decreased in group IV as compared to ethanol group. With regard to MDA content and ADS constituents, MDA contents of alcohol group in all tissues, except for erythrocytes and heart, and in brain, kidney, and spleen of LF group significantly increased compared to control group, whereas LF beverage extract supplementation did not restore the increased MDA towards close the control level. In addition, while ethanol caused fluctuation in antioxidant defense system constituents level as a result of oxidative stress condition in the rats, it could have not been determined the healing effects of the LF against these fluctuations. The results indicated that LF beverage extract could not be as important as diet-derived antioxidants in preventing oxidative damage in the tissues by reducing the lipid oxidation or inhibiting the production of ethanol-induced free radicals in rats.     

The effects of zinc supplementation on metabolic profile and oxidative stress in overweight/obese patients with non-alcoholic fatty liver disease: A randomized,double-blind,placebo-controlled trial

BackgroundEvidence indicates the positive effects of zinc on insulin resistance and oxidative stress in metabolic syndrome or diabetes. Non-alcoholic fatty liver disease (NAFLD) is the main hepatic manifestation of insulin resistance and metabolic syndrome. The present study is the first clinical trial that evaluated the effects of zinc supplementation on metabolic and oxidative stress status in overweight/obese patients with NAFLD undergoing calorie- restriction diet. Methods: Fifty six overweight/obese patients with confirmed mild to moderate NAFLD using ultrasonography were randomly allocated to receive 30 mg elemental zinc supplement (n = 29) or placebo (n = 27) along with weight loss diet for 12 weeks. Serum levels of zinc, homeostasis model of assessment-estimated insulin resistance (HOMA-IR), lipid profile, serum superoxide dismutas1 (SOD1) and malondialdhyde (MDA) levels were assessed.ResultsSerum levels of insulin, SOD1, MDA and HOMA-IR were improved in the treatment group (p < 0.05). Within group comparison showed significant reduction in serum FBS, HbA_1C, TC, LDL-c and TG in the treatment group. Conclusion: Zinc supplementation for three months improved insulin resistance and oxidative stress status in overweight/obese NAFLD patients with no beneficial effects on lipid profiles over weight loss diet. Registration ID in IRCT (IRCT NO: 20181005041238N1).     

Effect of Zinc Supplementation on Antioxidant Activity in Young Wrestlers

This study aims to examine the effect of zinc supplementation on free-radical formation and antioxidant system in individuals who are actively engaged in wrestling as a sport. The study registered a total of 40 male subjects, of whom 20 were wrestlers and 20 were sedentary individuals. The subjects were equally allocated to four groups: group 1, zinc-supplemented sportsmen group; group 2, sportsmen group without supplementation; group 3, zinc-supplemented sedentary group; group 4, sedentary group without supplementation. Blood samples were collected from all subjects twice, once at the beginning of the study and once again at the end of 8-week procedures. The blood samples collected were analyzed to determine the levels of malondialdehyde (MDA), serum glutathione (GSH), serum glutathione peroxidase (GPx) activity, serum superoxide dismutase (SOD) activity (ELISA colorimetric method) and zinc (colorimetric method). No difference was found between MDA levels of the study groups in the beginning of the study. The highest MDA value at the end of the study was obtained in group 4 (p < 0.01). MDA levels in group 2 were established to be significantly higher than those in groups 1 and 3 (p < 0.01). GSH level, GPx, and SOD activities and zinc level measured in the beginning of the study were not different between groups. Measurements performed at the end of the study showed that groups 1 and 3 (zinc-supplemented groups) had the highest GSH level, GPx, and SOD activities and zinc level (p < 0.01). These parameters were not different in the groups without supplementation (groups 2 and 4). Results obtained at the end of the study indicate that zinc supplementation prevents production of free radicals by activating the antioxidant system. In conclusion, physiologic doses of zinc supplementation to athletes may beneficially contribute to their health and performance.     

Oxidative stress and damage in liver, but not in brain, of Fischer 344 rats subjected to dietary iron supplementation with lipid-soluble [(3,5,5-trimethylhexanoyl)ferrocene

Accumulation of iron probably predisposes the aging brain to progressive neuronal loss. We examined various markers of oxidative stress and damage in the brain and liver of 3- and 24-month-old rats following supplementation with the lipophilic iron derivative [(3,5,5-trimethylhexanoyl)ferrocene] (TMHF), which is capable of crossing the blood-brain barrier. At both ages, iron concentration increased markedly in the liver but failed to increase in the brain. In the liver of TMHF-treated young rats, levels of alpha- and gamma-tocopherols and glutathione (GSH) were also higher. In contrast, the brain displayed unaltered levels of the tocopherols and GSH. Malondialdehyde (MDA) level was also higher in the cerebrospinal fluid (CSF) and the liver but not in the brain. In old rats, the absence of an increase in iron concentration in the brain was reflected by unaltered concentrations of GSH, tocopherols, and MDA as compared to that in untreated rats. In the aging liver, concentrations of GSH and MDA increased with TMHF treatment. Morphological studies revealed unaltered levels of iron, ferritin, heme oxygenase-1 (HO-1), nitrotyrosine (NT), or MDA in the brains of both young and old rats treated with TMHF. In contrast, TMHF treatment increased the level of HO-1 in Kupffer cells, NT in hepatic endothelial cells, and MDA and ferritin in hepatocytes. Although these results demonstrated an increase in the biochemical markers of oxidative stress and damage in response to increasing concentrations of iron in the liver, they also demonstrated that the brain is well protected against dietary iron overload by using iron in a lipid-soluble formulation.     

鹿茸多肽对缺铁性贫血大鼠的治疗作用及机制研究

摘要 目的：研究鹿茸多肽（PAP）对缺铁性贫血（IDA）大鼠的治疗作用并探讨其可能机制。方法：使用缺铁饲料诱导IDA大鼠模型,将40只IDA大鼠随机分为模型组（灌胃等体积的生理盐水）,Low-PAP组、Medium-PAP组和High-PAP组（分别灌胃30、60和120 mg/kg的PAP）,每组10只,另选取10只正常饲料喂养的同龄健康大鼠作为对照组（灌胃等体积的生理盐水）。每天灌胃1次,疗程为4周。末次给药24 h后,测量各组大鼠的体重、肝脏和脾脏指数,对肝脏和脾脏组织进行苏木素伊红（HE）染色。通过ELISA法检测血红蛋白（Hb）和促红细胞生成素（EPO）含量,通过比色法检测血清铁（SI）含量,通过透射电子显微镜观察肝脏和脾脏线粒体超微结构。使用相应试剂盒检测血清氧化应激指标水平。通过Western blot检测骨髓转铁蛋白受体（TFR）蛋白表达水平。结果：与模型组相比,Low-PAP组、Medium-PAP组和High-PAP组大鼠体重均升高,肝脏和脾脏指数均降低（P<0.05）,且大鼠的肝脏和脾脏形态和线粒体超微结构明显改善,Hb、EPO和SI水平均升高（P<0.05）。与模型组相比,Low-PAP组、Medium-PAP组和High-PAP组大鼠的血清超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GSH-PX）水平均升高,而丙二醛（MDA）降低（P<0.05）。与模型组相比,Low-PAP组、Medium-PAP组和High-PAP组大鼠的骨髓TFR蛋白相对表达量降低（P<0.05）。结论：本研究表明PAP可有效减轻IDA大鼠的临床症状,促进红细胞生成,增强造血功能,改善铁代谢,提高抗氧化能力,促进线粒体合成。     

The Evaluation of the Oxidative Stress Parameters in Nondiabetic and Diabetic Senile Cataract Patients

The aim of the present study was to evaluate the copper (Cu), zinc (Zn), malondialdehyde (MDA), glutathione (GSH), and advanced oxidation protein products (AOPP) levels and superoxide dismutase (SOD) activities in diabetic senile cataract. Ten patients with diabetic senile cataract and ten patients with nondiabetic senile cataract (control group) were included in this study. AOPP, MDA, and GSH levels and SOD activity were measured by a spectrophotometric method. Serum, lens Cu, and Zn levels were measured by an atomic absorption spectrophotometric method. Both the lens and serum Zn and Cu levels between the two groups were not significantly different (p > 0.05). GSH, AOPP, and MDA levels and the SOD activities in the diabetic senile cataract group were significantly increased as compared to the control group (p < 0.05). Oxidative stress is one of the major factors which may lead to the early cataract formation. Oxidative events are of great importance in diabetic complications and, particularly in the lens, may have a role in the pathogenesis of cataract associated with diabetes mellitus as exhibited in this study.     

Increases of Calcium,Phosphorus, and Magnesium in Both the Right and Left Fibrous Trigones of Human Heart with Aging

We previously reported that reduced platelet endogenous antioxidant enzymes activities are related to the low plasma zinc level in patients with end-stage renal failure (ESRF). In this study, we attempt to evaluate whether dietary zinc deprivation reduces the activities of endogenous antioxidant and then enhances oxidative stress in the unstimulated platelet of normal and 5/6 nephrectomized (Nx) rats because increased platelet oxidative stress is suggested to involve in the incidence of thrombotic and atherosclerotic diseases. Male Sprague–Dawley rats (n = 48) were fed a zinc-deficient diet and deionized distilled water for 1 week to induce reduction of plasma zinc level. Half of the rats continued on this diet for 4 weeks as zinc-deplete group, and the other half were maintained on the same diet but with zinc-supplemented water (120 mg/L zinc sulfate solution) to correct the reduction of plasma zinc level as zinc-replete group. Half of each group underwent 5/6 Nx, while the other half underwent sham operation. Another 12 normal rats were fed standard rat chow (containing 23.4% protein and 50 ppm zinc) and drank deionized distilled water as normal control rats. In zinc-deplete rats including sham-operated and 5/6 Nx rats exhibited lower endogenous antioxidant enzymes activities such as reduced glutathione (GSH), superoxide dismutase (SOD), and glutathione peroxidase (GPX) and higher malondialdehyde (MDA) levels than normal control rats in the unstimulated platelets. However, in zinc-replete rats including sham-operated and 5/6 Nx rats have a normal endogenous antioxidant enzymes activity and normal MDA levels in the unstimulated platelets. We suggest that in uremia, the low plasma zinc level may be a risk factor for thrombotic and atherosclerotic diseases because it reduces the activities of endogenous antioxidant enzymes and increases oxidative stress in the unstimulated platelet. Supported by grant 92-117 from Taipei Veterans General Hospital     

Acute and/or chronic stress models modulate CuZnSOD and MnSOD protein expression in rat liver

Cellular protection against oxidative stress is afforded by the enzyme superoxide dismutase (SOD). In this study, the protein levels of copper–zinc SOD (CuZnSOD) in the cytosolic and nuclear fraction, manganese SOD (MnSOD) in the mitochondrial, and cytosolic fraction and cytochrome c (cyt c) in the liver of male rats exposed to 2 h of acute immobilization (IM) or Cold stress, 21 days chronic isolation or their combinations (chronic/acute stress) were examined. The serum corticosterone (CORT) level was measured, as an indicator of stress stimuli. Both acute stressors with elevated CORT levels caused a decrease of mitochondrial MnSOD, while acute IM resulted in redistribution of the CuZnSOD protein level between the cytosolic and nuclear fraction. Chronic isolation, during which the CORT level was close to control value, resulted in an increase of cytosolic CuZnSOD, whereas a decrease of MnSOD in mitochondrial and its corresponding increase in cytosol fraction was found. In both combined stress regimes, an increase of the CuZnSOD and MnSOD levels in the cytosolic fraction was recorded whereby increase of the CORT level was observed only in the chronic isolation followed by acute IM. The data indicate that acute and/or chronic stress models have different degrees of influence on serum CORT and SOD subcellular protein levels. Increased cytosolic CuZnSOD protein level under chronic isolation suggests that state of oxidative stress may also exist under CORT level similar to the basal value. The presence of MnSOD and cyt c in the cytosolic fraction could serve as useful parameters for mitochondrial dysfunction.     

Can we reduce oxidative stress with liver transplantation?

BackgroundThe aim of this study was to determine the levels of lipid peroxidation (MDA) and antioxidants such as reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) in the blood serum of patients with cirrhosis and liver transplantation.MethodsIn this study, serum malondialdehyde acid (MDA) levels, superoxide dismutase (SOD), reduced glutathione (GSH), and catalase (CAT) activities were measured spectrophotometrically and compared to the results of the healthy control group.ResultsSOD, CAT and GSH activities were significantly decreased in the patient groups compared to the healthy control group (p<0.05). MDA levels were significantly higher in the patient group compared to the healthy control group (p <0.05).ConclusionsIn conclusion, this study demonstrated that oxidative stress may play an important role in the development of liver cirrhosis and in liver transplantation. This study is the first one to show how MDA, SOD, CAT and GSH levels change in liver cirrhosis and liver transplantation, while further studies are essential to investigate antioxidant enzymes and oxidative stress status in patients with cirrhosis and liver transplantation.     

Psychological Stress Expands Low Molecular Weight Iron Pool in Cerebral Cortex,Hippocampus, and Striatum of Rats

We have previously demonstrated that psychological stress (PS) can cause iron to accumulate in the cerebral cortex, hippocampus, and striatum of rats. However, why iron accumulates and in what oxidation state iron it accumulates in the brain of PS-exposed rats has not been well elucidated. In the present study, we investigated the influence of PS on the low molecular weight iron pool (LMWIP) in the rat brain. The results showed that: (1) PS significantly expanded LMWIP in the cerebral cortex, hippocampus, and striatum in rats; (2) PS caused derangement of pyramidal cells and reduced the layers of pyramidal CA1 and CA2 neurons; (3) PS exposure greatly lowered the expression of ferritin (Fn) and hephaestin (HP) in the rat cortex and hippocampus; and (4) PS decreased superoxide dismutase, glutathione peroxidase, and glutathione level and increased malondialdehyde level in the cerebral cortex, hippocampus, and striatum in rats. These results indicated that PS could expand LMWIP significantly, which may be attributed to PS-induced decrease in Fn, HP expression, and the subsequent reduction in iron storage and utilization, and expansion of LMWIP could in turn lead to aggravation of oxidative damage.     

Oxidative stress and antioxidant response to subacute and subchronic iron overload in Wistar rat

Iron saccharate complex ISC is an iron supplement used to optimize erythropoiesis in cases of iron deficiencies. Because of the lack of major mechanisms of iron excretion, excess iron unbound to protective molecules is believed to be involved in catalyzing the generation of reactive oxygen species and induction of oxidative stress. This study employed ISC for the purpose of inducing iron overload and hence investigating the consequent iron toxicity, lipid peroxidation and antioxidant extent in a murine species. Male Wistar rats were given iron as intraperitoneal injections of ISC in subacute (0.2 mg Fe kg^?1 for 2 weeks) and subchronic (0.1 mg Fe kg^?1 for 4 weeks) doses. In iron-overloaded rats, enhanced hepatic iron accumulation (P > 0.001) attended by increased serum concentrations of malondialdehyde (MDA) (P > 0.001) and activities of antioxidant enzymes (superoxide dismutase SOD, catalase CAT and glutathione peroxidase GPx) (P > 0.001) was pointed out. The demonstrated antioxidant boost is attributed to a sense of equilibrium prompted by the potential of iron-induced oxidative stress to modify antioxidant defense capacity and to modulate susceptibility to oxidative stress. Rats seemed to constantly suffer from oxidative stress based on the consistent rise in MDA that was not overwhelmed by the elevated antioxidant input. The current findings are of informative value in drawing attention to the health hazards of applying higher doses of the commercially used iron supplement ISC. Data are virtually significant in elucidating the higher magnitude of subchronic than subacute iron overload in initiating oxidative stress and antioxidant defense. Both pathways proceeded in a time-dependent rather than dose-dependent manner.     

Effect of Selenium Supplementation on Lipid Peroxidation,Antioxidant Enzymes,and Lactate Levels in Rats Immediately After Acute Swimming Exercise

The present study aims to evaluate the effect of selenium supplementation on lipid peroxidation and lactate levels in rats subjected to acute swimming exercise. Thirty-two adult male rats of Sprague–Dawley type were divided into four groups. Group 1, control; group 2, selenium-supplemented; group 3, swimming control; group 4, selenium-supplemented swimming group. The animals in groups 2 and 4 were supplemented with (i.p.) 6 mg/kg/day sodium selenite for 4 weeks. The blood samples taken from the animals by decapitation method were analyzed in terms of erythrocyte-reduced glutathione (GSH), serum glutathione peroxidase (GPx) and superoxide dismutase (SOD), and plasma malondialdehyde (MDA) and lactate using the colorimetric method, and serum selenium values using an atomic emission device. In the study, the highest MDA and lactate values were found in group 3, while the highest GSH, GPx and SOD values were obtained in group 4 (p < 0,001). Group 2 had the highest and group 3 had the lowest selenium levels (p < 0,001). Results of the study indicate that the increase in free radical production and lactate levels due to acute swimming exercise in rats might be offset by selenium supplementation. Selenium supplementation may be important in that it supports the antioxidant system in physical activity.     

Role of soy isoflavone in preventing aging changes in rat testis: Biochemical and histological studies

Testicular function and structure harmed by ageing. Goal of this research was to assess preventive actions of soy isoflavone oral administration for 8 weeks on testes of old male albino rats, and potential mechanisms of action. Adult control (N = 10) and elderly control (N = 10) rats were fed usual diet, while aged treatment group (N = 10) gave oral 100 mg/kg soy isoflavone daily for 8 weeks. ELISA kits were used to measure testosterone levels and oxidative stress indicators [malonaldehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD)] in serum. Aging produced functional and structural testicular changes and decreased ki67 proliferative marker immunoexpression versus adult control rats due to enhancement of oxidative stress. Soy isoflavone exerted protective effect on testicular function and structure as assessed by increase serum levels of testosterone and preserved histological structure and immune-expression features. These protected effects due to isoflavone antioxidant properties proved by decrease in serum values of MDA, while GSH and SOD were elevated after treatment. These data demonstrated protective effects of isoflavone against age changes in rat testes, by reducing oxidative stress and increasing antioxidants and testicular ki67 proliferative marker immunoexpression.     

Protective effects of crocin on biochemistry and histopathology of experimental periodontitis in rats

ABSTRACT

We investigated the effectiveness of crocin for preventing oxidative damage in experimentally produced periodontitis. We used three groups of 10 female Wistar rats divided into: control (C); experimental periodontitis (EP), experimental periodontitis + crocin (Cr-EP). Malondialdehyde (MDA), glutathione (GSH), total antioxidant status (TAS), total oxidant status (TOS) and superoxide dismutase (SOD) and catalase (CAT) enzyme activities were measured. We examined histopathology and inflammatory cell infiltration in gingiva and periodontal ligament. MDA and TOS levels, and SOD and CAT activities increased significantly in rats with induced periodontitis compared to the control group, while GSH and TAS levels were decreased significantly compared to the control group. Histopathologic examination revealed inflammatory cell infiltration in gingiva epithelium and subepithelial connective tissue in the EP group. Histological damage was reduced significantly after crocin treatment compared to the EP group. Crocin supplementation may help reduce oxidative damage to periodontal tissues.     

Effect of zinc on the lipid peroxidation and the antioxidant defense systems of the alloxan-induced diabetic rabbits

The effects of oral zinc supplementation on lipid peroxidation and the antioxidant defense system of alloxan (80-90 mg/kg)-induced diabetic rabbits were examined. Forty-five New Zealand male rabbits, 1 year old, weighing approximately 2.5 kg, were allocated randomly and equally as control, diabetic, and zinc-supplemented diabetic groups. After diabetes was induced, zinc-supplemented diabetic rabbits had 150 mg/L of zinc as zinc sulfate (ZnSO(4)) in their drinking tap water for 3 months. The feed and water consumption was higher in diabetic groups than (P<0.01) healthy rabbits. The body weight was lower in diabetic rabbits compared to control. The blood glucose levels were higher in diabetic groups than controls. The elevated plasma malondialdehyde (MDA) levels were determined in the diabetic group (P<0.01). The glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), and ceruloplasmin levels in the diabetic group were decreased by the effect of diabetes but there was no difference between zinc-supplemented diabetic and control rabbits. Serum zinc concentrations were lower in diabetic rabbits but iron (Fe) and copper (Cu) levels in sera were not different among the groups. As a result, it was concluded that daily zinc supplementation could reduce the harmful effects of oxidative stress in diabetics.     

补锌对酒精性肝病的影响及其分子机制

目的:本研究是为了观察饮食补充锌减轻酒精性肝病损伤的作用及与HNF-4α的关系。方法:选用成年C57BL/6小鼠40只,按随机数字表分为4组(n=10):正常对照组、酒精中毒组、正常补锌组及酒精补锌组,用不同饮食喂养6个月处死,在正常补锌组和酒精补锌组小鼠饮用水中加入硫酸锌,使锌的含量达到75 mg/L。取各组小鼠肝组织进行病理切片及增殖细胞核抗原(PCNA)免疫组织化学染色,RT-PCR检测肝细胞核因子-4α(HNF-4α)含量,Western blot检测肝组织HNF-4α蛋白表达,检测"肝组织超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量"。结果:酒精中毒组小鼠HNF-4α转录及表达均明显低于正常对照组,差异具有统计学意义(P<0.05),该组小鼠MDA含量增高,SOD活性下降与正常对照组相比差异有统计学意义(P<0.05);而酒精补锌组小鼠PCNA阳性肝细胞数目及HNF-4α蛋白表达水平明显高于酒精中毒组,差异有统计学意义(P<0.05),该组小鼠SOD活性增加,MDA下降,与酒精中毒组相比差异有统计学意义(P<0.05)。结论:长期酒精喂养导致小鼠氧化还原失衡,而补锌可逆转该状态。我们推测饮食补锌可能是通过增加HNF-4α的转录及表达而增强酒精喂养小鼠的肝再生,因此,饮食补锌可能对酒精性肝病有较好的影响。     

The effect of iron and/or zinc diet supplementation and termination of this practice on the antioxidant status of the reproductive tissues and sperm viability in rats

AimsThe aim of this study was to investigate the effect of iron or/and zinc supplementation and termination of this treatment on the antioxidant defence of the male reproductive system and sperm viability in rats.MethodsThe study consisted of 3 stages: I) 4-week adaptation to the diets (C-control or D-iron deficient); II) 4-week iron and/or zinc supplementation (10-times more than in the C diet of iron: CSFe, DSFe; zinc: CSZn, DSZn; or iron and zinc: CSFeZn, DSFeZn; and III) 2-week post-supplementation period (the same diets as during stage I). Parameters of antioxidant status (total antioxidant capacity and SOD, GPx, and CAT activiy), oxidative damage (lipid and protein peroxidation), and sperm viability were measured.ResultsSimultaneous iron and zinc supplementation compared to iron supplementation (CSFeZn vs CSFe) increased SOD activity in the testes and decreased the level of malondialdehyde in the epididymis after stage II, and increased the percentage of live sperm after stage III. After discontinuation of the iron and zinc supplementation and a return to the control diet, the following was observed a decrease of SOD activity in the testes and GPx activity in the epididymis, and a increase malondialdehyde concentration in prostates. After stage III, in DSFeZn vs DSFe rats, an increase of SOD and CAT activity in the epididymis was found.ConclusionZinc supplementation simultaneous with iron may protect the male reproductive system against oxidative damage induced by high doses of iron and may have a beneficial effect on sperm viability. The effect of this supplementation was observed even two weeks after the termination of the intervention.     

Reactive oxygen species in pregnant rats: effects of exercise and thermal stress

With the aim of evaluating the effect of interaction between physical training or exercise only during pregnancy and thermal stress on oxidative stress, and antioxidant mechanism sedentary pregnant rats (PS), exercised pregnant rats only during pregnancy (PE) and trained rats submitted to also exercise during pregnancy (PT) were compared (N=63). Exercise sessions consisted of swimming at 80% of maximal work load supported into water at 28 degrees C (hypothermia, PS 28, PE28, PT28) or 35 degrees C (thermal neutrality, PS35, PE35, PT35) or 39 degrees C (hyperthermia, PS39, PE39, PT39), for 30 min. The initial body weight in all groups of rats was from 177 to 207 g. On the 20th day of pregnancy, 24 h after the last immersion or swimming session venous blood was collected to determine oxidative stress. Plasma concentrations of means malondialdehyde (MDA) values measured as thiobarbituric acid reactive substances (TBARS); total glutathione (GSH) and vitamin E were determined. The oxidative stress index was calculated from the ratio TBARS/GSH and TBARS/Vitamin E. TBARS did not change on the group PE at different temperatures of water; TBARS were higher for PS28 than PS35 and PS39; PT35 had higher values than PT28 and PT39. For GSH, PS39 was lower than PS35; PE28 was higher than PE35 and PE39 and PT35 were lower than PT28 and PT39. Plasma concentration of vitamin E did not present any difference for sedentary rats at different water temperatures, but for PE28, the values were lower than for PE35 and PE39, whereas PT39 was lower than PT35 and PT28. In relation to TBARS/GSH, it was verified an increase in oxidative stress for PS28 (in relation to PS35 and PS39), PE35, and PT35 (in relation to PE28 and PE39 or PT28 and PT39); regarding the ratio TBARS/vitamin E, the highest values were obtained at 35 degrees C for PS and PT groups and at 39 for PE group. These results have shown the great complexity of the interaction between physical training, thermal stress and pregnancy. Apparently, hypothermia produces large index of oxidative stress only in sedentary rats, but this index was greater at 35 degrees C in relation to extreme temperatures for trained rats. These results have suggested that physical training allows a more efficient activation of antioxidant mechanisms under thermal stress.