Melatonin ameliorates chronic renal failure-induced oxidative organ damage in rats

Chronic renal failure (CRF) is associated with oxidative stress that promotes production of reactive oxygen species (ROS). Melatonin, the chief secretory product of the pineal gland, was recently found to be a potent free radical scavenger and antioxidant. The aim of this study was to examine the role of melatonin in protecting the aorta, heart, corpus cavernosum, lung, diaphragm, and kidney tissues against oxidative damage in a rat model of CRF, which was induced by five of six nephrectomy. Male Wistar albino rats were randomly assigned to either the CRF group or the sham-operated control group, which had received saline or melatonin (10 mg/kg, i.p.) for 4 wk. CRF was evaluated by serum blood urea nitrogen (BUN) level and creatinine measurements. Aorta and corporeal tissues were used for contractility studies, or stored along with heart, lung, diaphragm, and kidney tissues for the measurement of malondialdehyde (MDA, an index of lipid peroxidation), protein carbonylation (PC, an index for protein oxidation), and glutathione (GSH) levels (a key antioxidant). Plasma MDA, PC, and GSH levels and erythrocytic superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status in CRF. In the CRF group, the contraction and the relaxation of aorta and corpus cavernosum samples decreased significantly compared with controls (P < 0.05-0.001). Melatonin treatment of the CRF group restored these responses. In the CRF group, there were significant increases in tissue MDA and PC levels in all tissues with marked reductions in GSH levels compared with controls (P < 0.05-0.001). In the plasma, while MDA and PC levels increased, GSH, SOD, CAT, and GSH-Px activities were reduced. Melatonin treatment reversed these effects as well. In this study, the increase in MDA and PC levels and the concomitant decrease in GSH levels of tissues and plasma and also SOD, CAT, GSH-Px activities of plasma demonstrate the role of oxidative mechanisms in CRF-induced tissue damage, and melatonin, via its free radical scavenging and antioxidant properties, ameliorates oxidative organ injury. CRF-induced dysfunction of the aorta and corpus cavernosum of rats was reversed by melatonin treatment. Thus, supplementing CRF patients with adjuvant therapy of melatonin may have some benefit.     

Melatonin improves cerebrovascular function and decreases oxidative stress in chronically hypoxic lambs

Chronic hypoxia during gestation and delivery results in oxidative stress and cerebrovascular dysfunction in the neonate. We assessed whether melatonin, a potent antioxidant and potential vasodilator, improves the cerebral vascular function in chronically hypoxic neonatal lambs gestated and born in the highlands (3600 m). Six lambs received melatonin (1 mg/kg per day oral) and six received vehicle, once a day for 8 days. During treatment, biometry and hemodynamic variables were recorded. After treatment, lambs were submitted to a graded FiO₂ protocol to assess cardiovascular responses to oxygenation changes. At 12 days old, middle cerebral arteries (MCA) were collected for vascular reactivity, morphostructural, and immunostaining evaluation. Melatonin increased fractional growth at the beginning and improved carotid blood flow at all arterial PO₂ levels by the end of the treatment (P < 0.05). Further, melatonin treatment improved vascular responses to potassium, serotonin, methacholine, and melatonin itself (P < 0.05). In addition, melatonin enhanced the endothelial response via nitric oxide‐independent mechanisms in isolated arteries (162 ± 26 versus 266 ± 34 AUC, P < 0.05). Finally, nitrotyrosine staining as an oxidative stress marker decreased in the MCA media layer of melatonin‐treated animals (0.01357 ± 0.00089 versus 0.00837 ± 0.00164 pixels/μm², P < 0.05). All the melatonin‐induced changes were associated with no systemic cardiovascular alterations in vivo. In conclusion, oral treatment with melatonin modulates cerebral vascular function, resulting in a better cerebral perfusion and reduced oxidative stress in the neonatal period in chronically hypoxic lambs. Melatonin is a potential therapeutic agent for treating cerebrovascular dysfunction associated with oxidative stress and developmental hypoxia in neonates.     

Melatonin reduces oxidative stress and increases gene expression in the cerebral cortex and cerebellum of aluminum-exposed rats

The pro-oxidant activity of aluminum (Al), the protective role of exogenous melatonin, as well as the mRNA levels of some antioxidant enzymes, were determined in cortex and cerebellum of rats following exposure to Al and/or melatonin. Two groups of male rats received intraperitoneal injections of Al lactate or melatonin at doses of 7 mg Al/kg/day and 10 mg/kg/day, respectively, for 11 wk. A third group of animals received concurrently Al lactate (7 mg Al/kg/day) plus melatonin (10 mg/kg/day) during the same period. A fourth group of rats was used as control. At the end of the treatment, the cerebral cortex and cerebellum were removed and processed to examine the following oxidative stress markers: glutathione transferase (GST), reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase, glutathione peroxidase (GPx), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as protein content. Moreover, gene expression of Cu-ZnSOD, MnSOD, GPx and CAT was evaluated by real-time RT-PCR. On the other hand, Al, Fe, Mn, Cu and Zn concentrations were determined in cortex and cerebellum of rats. Oxidative stress was promoted in both neural regions following Al administration, resulting from the pro-oxidant activity related with an increase in tissue Al concentrations. In contrast, melatonin exerted an antioxidant action which was related with an increase in the mRNA levels of the antioxidant enzymes evaluated. The results of the present investigation emphasize the potential use of melatonin as a supplement in the therapy of neurological disorders in which oxidative stress is involved.     

大鼠脑缺血／再灌注损伤热休克蛋白70表达及川芎嗪干预

目的研究大鼠脑缺血／再灌注时热休克蛋白（ＨＳＰ）７０表达及川芎嗪对ＨＳＰ７０表达的影响。方法采用ＳＤ大鼠左侧颈总动脉结扎并滴注生理盐水脑缺血／再灌注模型，以免疫细胞化学法检测２４只缺血／再灌注及川芎嗪干预大鼠脑缺血／再灌注３０ｍｉｎ时脑组织ＨＳＰ７０表达并与病理组织学改变进行对照研究。结果（１）非缺血侧脑组织无ＨＳＰ７０表达，缺血３０ｍｉｎ缺血侧大脑皮层可见ＨＳＰ７０表达；再灌注３０ｍｉｎ组仅１只大鼠（１／６）缺血侧大脑皮层有ＨＳＰ７０表达。（２）与单纯缺血大鼠相比，川芎嗪干预组缺血侧大脑皮层ＨＳＰ７０表达明显增强，计算机辅助图像半定量分析ＨＳＰ７０免疫阳性细胞数，分别为平均４３．５５±１２．５１个／片和８４．９５±１６．７个／片（Ｐ＜０．０１）。（３）缺血侧皮层神经细胞呈现轻度缺血改变，川芎嗪干预大鼠缺血损伤程度似有减轻。结论脑缺血时可诱导缺血脑细胞部分ＨＳＰ７０表达，川芎嗪干预可促使缺血大脑皮层ＨＳＰ７０表达明显增强，皮层神经细胞的缺血损伤有所减轻。     

Melatonin protects against Nickel‐induced neurotoxicity in vitro by reducing oxidative stress and maintaining mitochondrial function

Abstract: Nickel is a potential neurotoxic pollutant. Oxidative stress is supposed to be involved in the mechanism underlying nickel‐induced neurotoxicity. Melatonin has efficient protective effects against various oxidative damages in nervous system. The purpose of this study was to investigate whether melatonin could efficiently protect against neurotoxicity induced by nickel. Here, we exposed primary cultured cortical neurons and mouse neuroblastoma cell lines (neuro2a) to different concentrations of nickel chloride (NiCl₂) (0.125, 0.25, 0.5, and 1 mm ) for 12 hr or 0.5 mm NiCl₂ for various periods (0, 3, 6, 12, and 24 hr). We found that nickel significantly increased reactive oxygen species production and caused the loss of cell viability both in cortical neurons and neuro2a cells. In addition, nickel exposure obviously inhibited the mitochondrial function, disrupted the mitochondrial membrane potential (ΔΨm), reduced ATP production, and decreased mitochondrial DNA (mtDNA) content. However, each of these oxidative damages was efficiently attenuated by melatonin pretreatment. These protective effects of melatonin may be attributable to its roles in reducing oxidative stress and improving mitochondrial function in nickel‐treated nerve cells. Our results suggested that melatonin may have great pharmacological potential in protecting against the adverse effects of nickel in the nervous system.     

Melatonin counteracts oxidative stress in rats fed an ochratoxin A contaminated diet

The mycotoxin ochratoxin A (OTA) is a widespread contaminant in human and animal food products. It induces a wide range of toxic effects including lipid peroxidation through the generation of free radicals. The aim of this work was to evaluate the antioxidant effects of melatonin against OTA-induced oxidative stress in liver and kidney in rats. Treated animals were fed OTA-contaminated diet (3 mg/kg) for 15 days before, during and after melatonin administration (20 mg/kg bw). The results indicate that OTA caused severe effects typical to those reported in the literature for ochratoxicosis. Melatonin alone was effective in the improving food intake, body weight gain, serum total protein, albumin, the activities of alkaline phosphatase, G-glutamyl transferase and creatinine kinase and liver and kidney glutathione peroxidase, superoxide dismutase and malondialdehyde. Rats fed OTA-contaminated diet before, during or after melatonin administration showed a significant improvement in all tested parameters toward the normal values of the controls. This improvement was most pronounced in the group pretreated with melatonin. It is concluded that melatonin exhibits a preventive effect against OTA-induced oxidative stress through its role in the scavenging of free radicals and/or the prevention of lipid peroxidation.     

Melatonin reduces oxidative stress in erythrocytes and plasma of senescence-accelerated mice

It has been suggested that oxidative stress is a feature of aging. The goal of the present study was to assess the oxidant effects related to aging and the protective role of exogenous melatonin in senescence-accelerated mice (SAMP8). Two groups of SAMP8 mice (males and females) were compared with their respective control groups of SAMR1 mice (senescence-resistant inbred strain) to determine their oxidative status without melatonin treatment. Four other groups of the same characteristics were treated with melatonin (10 mg/kg/day) in their drinking water. The melatonin concentration in the feeding bottles was titrated according to water consumption and body weight (i.e. 0.06 mg/mL for 30 g of body weight and 5 mL/day of water consumption). The treatment began when animals were 1-month old and continued for 9 months. When mice were 10-month old, they were anesthetized and blood was obtained. Plasma and erythrocytes were processed to examine oxidative stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), thiobarbituric acid reactive substances (TBARS), and hemolysis. The results showed greater oxidative stress in SAMP8 than in SAMR1, largely because of a decrease in GSH levels and to an increase in GSSG and TBARS with the subsequent induction of the antioxidant enzymes GPX and GR. Melatonin, as an antioxidant molecule, improved the glutathione-related parameters, prevented the induction of GPX in senescent groups, and promoted a decrease in SOD and TBARS in almost all the groups.     

G-CSF干预对老龄慢性脑缺血大鼠模型认知改善与胶质细胞可塑性的影响

目的 探讨粒细胞集落刺激因子(G-CSF)干预后,慢性脑缺血老龄鼠学习记忆功能改善与海马胶质细胞可塑性改变的相关性.方法 12月龄雄性SD大鼠2VO术后饲养3个月,构建15月龄的2VO慢性脑缺血老龄鼠模型.分为2VO/G-CSF组(n=10)、2VO/NS组(n=7),Sham组(n=10).采用Morris水迷宫检测大鼠空间学习记忆能力,通过免疫组化和图像分析技术检测海马CA1区胶质细胞的数目及胞质突起长度.结果 水迷宫实验:2VO/NS组逃逸时间显著长于Sham组和2VO/G-CSF组(P＜0.01);2VO/NS组大鼠在平台象限的停留时间少于Sham组(P＜0.01)和2VO/G-CSF组(P＜0.05);2VO/NS组大鼠跨过平台区域的次数少于Sham组和2VO/G-CSF组(P＜0.01).HE染色发现G-CSF干预后海马CA1区锥体细胞排列层数增加,胞体增大.免疫组化染色:2VO/NS组海马CA1区GFAP阳性细胞少于Sham组和2VO/G-CSF组(P＜0.05).2VO/NS组大鼠GFAP阳性细胞胞质突起长度低于Sham组和2VO/G-CSF组(P＜0.05).认知功能与胶质细胞可塑性的相关分析:2VO/NS组、Sham组及2VO/G-CSF组海马CA1区胶质细胞的数量、胞质突起长度与空间记忆能力均呈正相关(P＜0.05).结论 慢性脑缺血可致老龄鼠的空间学习记忆能力明显受损,G-CSF可诱导海马锥体细胞增生及胶质细胞可塑性改变,有效改善空间学习记忆功能.其中,胶质细胞可塑性改变与空间记忆功能改善密切相关.     

Melatonin ameliorates low‐grade inflammation and oxidative stress in young Zucker diabetic fatty rats

The aim of this study was to investigate the effects of melatonin on low‐grade inflammation and oxidative stress in young male Zucker diabetic fatty (ZDF) rats, an experimental model of metabolic syndrome and type 2 diabetes mellitus (T2DM). ZDF rats (n = 30) and lean littermates (ZL) (n = 30) were used. At 6 wk of age, both lean and fatty animals were subdivided into three groups, each composed of 10 rats: naive (N), vehicle treated (V), and melatonin treated (M) (10 mg/kg/day) for 6 wk. Vehicle and melatonin were added to the drinking water. Pro‐inflammatory state was evaluated by plasma levels of interleukin‐6 (IL‐6), tumor necrosis factor‐α (TNF‐α), and C‐reactive protein (CRP). Also, oxidative stress was assessed by plasma lipid peroxidation (LPO), both basal and after Fe²⁺/H₂O₂ inducement. ZDF rats exhibited higher levels of IL‐6 (112.4 ± 1.5 pg/mL), TNF‐α (11.0 ± 0.1 pg/mL) and CRP (828 ± 16.0 µg/mL) compared with lean rats (IL‐6, 89.9 ± 1.0, P < 0.01; TNF‐α, 9.7 ± 0.4, P < 0.01; CRP, 508 ± 21.5, P < 0.001). Melatonin lowered IL‐6 (10%, P < 0.05), TNF‐α (10%, P < 0.05), and CRP (21%, P < 0.01). Basal and Fe²⁺/H₂O₂‐induced LPO, expressed as malondialdehyde equivalents (µmol/L), were higher in ZDF rats (basal, 3.2 ± 0.1 versus 2.5 ± 0.1 in ZL, P < 0.01; Fe²⁺/H₂O₂‐induced, 8.7 ± 0.2 versus 5.5 ± 0.3 in ZL; P < 0.001). Melatonin improved basal LPO (15%, P < 0.05) in ZDF rats, and Fe²⁺/H₂O₂‐ induced LPO in both ZL (15.2%, P < 0.01) and ZDF rats (39%, P < 0.001). These results demonstrated that oral melatonin administration ameliorates the pro‐inflammatory state and oxidative stress, which underlie the development of insulin resistance and their consequences, metabolic syndrome, diabetes, and cardiovascular disease.     

连朴清胃胶囊对脾胃湿热证慢性胃炎模型大鼠血清HSP-70及SIgA表达的影响

[目的]观察连朴清胃胶囊对慢性胃炎脾胃湿热证大鼠血清的热休克蛋白70（HSP-70）及分泌型免疫球蛋白A（SIgA）的影响,以探讨连朴清胃胶囊治疗慢性胃炎脾胃湿热证的治疗机理.[方法]70只SD大鼠,除正常组10只外,其余60只以2％水杨酸钠10 ml/（kg·d）灌胃,同时饲以高脂高糖高热饮食（20％蜂蜜水自由饮用,隔日灌服油脂10 g· kg-1·d-1,并与油脂隔日灌服白酒2 ml/200 g）并放在湿热环境中,连续20 d,制作慢性胃炎脾胃湿热证模型,将造模成功的60只大鼠按照随机数字表法分为模型组、连朴清胃胶囊高、中、低组、三九胃泰组、雷尼替丁组,灌胃给药10 d,末次给药后禁食16h后,心脏取血,运用ELASA法检测大鼠血清HSP-70及SIgA含量的变化.[结果]模型组HSP-70、SIgA水平高于正常组（P＜0.05）,连朴清胃胶囊高组、中组、低组、三九胃泰组、雷尼替丁组大鼠血清HSP 70、SIgA水平均高于模型组（P＜0.05）,且连朴清胃胶囊高、中、低组、三九胃泰组、雷尼替丁组大鼠一般情况较模型组明显改善,其中连朴清胃胶囊高、中组HSP-70、SIgA高表达及一般情况改善最为明显.[结论]连朴清胃胶囊可能通过诱导HSP-70及SIgA的高表达从而发挥对脾胃湿热型慢性胃炎的改善和治疗作用.     

Melatonin inhibits oxidative stress and apoptosis in fetal brains of hyperhomocysteinemic rat dams

Moderate hyperhomocysteinemia is a risk factor for neurodegenerative diseases and complications during pregnancy. Increased homocysteine levels during pregnancy may elevate developmental risk on fetal brain structure and function. However, little is known about the mechanism of action of homocysteine on the degeneration of the fetal brain. Hence in this study, we examined the effects of maternal hyperhomocysteinemia on oxidative stress and apoptosis in brain tissues and investigated whether administration of melatonin to the mother would prevent homocysteine-induced oxidative cerebral damage in pups. Hyperhomocysteinemia was induced in female rats by administration of methionine at a dose of 1 g/kg body weight dissolved in drinking water during pregnancy. Some animals received methionine plus 10 mg/kg/day melatonin subcutaneously throughout pregnancy. After delivery, the level of lipid peroxidation (malondialdehyde + 4-hydroxyalkenals) was determined in different subfractions of pup brains. Furthermore, DNA fragmentation, levels of Bcl-2 protein and p53 mRNA expression were determined to evaluate apoptosis. Significant elevation was found in the levels of lipid peroxidation in subcellular fractions of the brain of pups of hyperhomocysteinemic dams. Increased DNA fragmentation and p53 mRNA expression was observed in the brain of pups of homocysteine-treated rats, while a significant reduction was seen in the levels of anti-apoptotic Bcl-2 levels. Melatonin administration prevented markers of oxidative stress and biochemical signs of apoptosis. In conclusion, therapeutic administration of melatonin protects against the induction of oxidative stress and neural tissue injury and might prevent congenital malformations of fetal brain caused by maternal hyperhomocysteinemia.     

热休克蛋白70对心脏移植供心保护作用的实验研究

目的:本实验通过热休克预适应产生热休克蛋白70,研究其是否对心脏移植中的供心有保护作用。方法:建立大鼠异位心脏移植模型并随机分为6组:对照组,经热处理的R0h、R24h、R48h、R96h及R192h实验组。分别于移植后24h取出供心,测定供心中HSP70含量,同时测定受体血液中和供心组织中心肌酶学变化并观察供心组织超微结构的变化。结果:HSP70在R24h组中表达明显增高(P0.01),在R48h和R96h组中逐渐下降,在对照组、R0h组、R192h组表达无差异(P0.05)。同时,R24h组受体中的乳酸脱氢酶和肌酸激酶浓度最低,供心的炎症损伤最小。结论:热休克预适应可能是一种临床中切实可行的减轻心肌缺血缺氧损伤的方法。热休克预适应-HSP70-心肌保护作用之间存在时间-剂量-疗效的关联。     

Overexpression of heat shock protein 70 in stomach of stress-induced gastric ulcer-resistant rats

Expression of heat shock protein 70, induced by an antiulcer drug, provides protection against gastric ulcers. However, the mechanisms responsible for this protection are not known. The expression in ulcer-resistant, spontaneously hypertensive rats was 2.8-fold higher than in normotensive rats. One hour after restraint and water immersion stress, strong nuclear immunoreactivity was observed in nuclei of surface epithelial cells at the crest of gastric mucosal folds, the first site of ulceration, only in spontaneously hypertensive rats. Heat shock cognate protein 70, which is expressed in mucus-secreting cells, was not overexpressed in spontaneously hypertensive rats. Heat shock protein 70 expression was attenuated by chemical sympathectomy, which also resulted in abolition of the increase of mucosal blood flow and aggravation of ulcers. Our results indicate that overexpression of heat shock protein 70 in the stomach seems to protect against gastric ulcers through its cytoprotective effects on gastric mucosa by increasing mucosal blood flow.     

银杏叶提取物对大鼠心肌缺血再灌注损伤热休克蛋白表达的影响

目的:观察热休克蛋白70(HSP70)在心肌缺血再灌注损伤过程中的表达规律及银杏叶提取物(EGB)干预后的变化.方法:65只SD大鼠随机分为假手术组、模型组和治疗组.试验前30 min,治疗组大鼠腹腔注射银杏叶提取物50 mg/kg,结扎左冠状动脉前降支建立大鼠急性心肌缺血再灌注损伤模型.于再灌注不同时间点(1、3、6、12、24、48 h)取出心脏左前降支支配区的全层心肌组织,用免疫组织化学和Western Blot方法观察心肌HSP70的表达.结果:心肌缺血再灌注损伤时HSP70主要表达在心肌细胞和微血管上,表达水平随再灌注时间延长而增加,24 h时达高峰;与模型组相比,治疗组心肌组织HSP70表达水平明显上调,表达时间明显延长.结论:EGB促进HSP70在心肌表达增强和延长,可能与其提高心肌对缺血再灌注损伤的耐受性有关.     

七方胃痛胶囊对实验性胃溃疡大鼠一氧化氮与热休克蛋白70的影响

[目的]探讨中药七方胃痛胶囊抗溃疡的机制及提高溃疡愈合质量(QOUH)的应用价值.[方法]40只Wistar大鼠制作乙酸诱发大鼠胃溃疡模型后第3天随机分为4组:对照组,雷尼替丁胶囊组,七方胃痛胶囊大、小剂量组.用硝酸还原酶法检测血清一氧化氮(NO).取大鼠胃组织,测量溃疡面积.以免疫组化染色切片观测溃疡边缘黏膜组织炎症细胞数、新生血管数,并测定溃疡边缘黏膜组织热休克蛋白(HSP)70的表达情况.[结果]七方胃痛胶囊组的溃疡指数明显低于雷尼替丁组和对照组(P＜0.05,＜0.01);再生黏膜的新生血管数明显高于雷尼替丁组和对照组(P＜0.05,＜0.01);固有层炎症细胞浸润数明显低于雷尼替丁组和对照组(P＜0.01,＜0.05);血清NO溃疡边缘黏膜组织的HSP70水平均明显高于雷尼替丁组和对照组(P＜0.05,＜0.01).[结论]七方胃痛胶囊抗溃疡的作用机制与提高血清NO及溃疡边缘黏膜组织HSP70水平有关,且能降低溃疡指数与炎症细胞浸润,增加再生黏膜的新生血管生成,对于提高QOUH有一定的价值.     

Melatonin reduces lung oxidative stress in patients with chronic obstructive pulmonary disease: a randomized, double-blind, placebo-controlled study

Abstract: Chronic obstructive pulmonary disease (COPD), a major cause of death and disability, is attributed to an abnormal inflammatory response by the lungs to noxious substances, primarily from cigarette smoke. Although oxidative stress is regarded as central to the pathogenesis of COPD, very few studies have examined the effects of antioxidants in this condition. This was a randomized, double‐blind, placebo‐controlled study on the effects of melatonin in COPD. Thirty‐six consecutive patients with clinically stable moderate to very severe COPD (30 men; mean ± S.D. = 66.6 ± 7.8 yr) were randomized to receive 3 mg melatonin (N = 18) or placebo for 3 months. Oxidative stress was evaluated by 8‐isoprostane levels in exhaled breath condensate at baseline (T0) and after one (T1), two (T2), and three months (T3) of treatment. Additionally, exhaled breath condensate levels of IL‐8, dyspnea severity (Medical Research Council scale), lung function (spirometry), and functional exercise capacity (six min walk test) were compared at baseline and after treatment. Patients receiving melatonin showed a decrease in 8‐isoprostane (T0: mean ± S.E.M. = 20.41 ± 2.92 pg/mL; T1: 18.56 ± 2.68 pg/mL; T2: 12.68 ± 2.04 pg/mL; T3: 12.70 ± 2.18 pg/mL; P = 0.04; repeated measures ANOVA) with significant differences from baseline after 2 (P = 0.03) and 3 months (P = 0.01). Dyspnea was improved by melatonin (P = 0.01), despite no significant changes in lung function or exercise capacity. Placebo‐treated patients, but not those who were given melatonin, showed an increase in IL‐8 (P = 0.03). In summary, melatonin administration reduced oxidative stress and improved dyspnea in COPD. Further studies are necessary to determine the potential role for melatonin in the long‐term management of these patients.     

不同切肝量大鼠血清HSP70水平变化及其意义

目的观察不同切肝量大鼠血清HSP70水平的变化,并探讨其意义。方法将310只大鼠随机分为正常对照组10只、切肝组150只和谷氨酰胺（Gln）干预组150只。后两组又分为轻度、中度、重度切亚组各50只,分别建立不同切肝量手术创伤模型,干预组造模前经大鼠尾静脉注入Gln 0.75 g/kg。对照组只给予麻醉处理。检测对照组及其他两组术后2、8、12、24、48 h大鼠血清HSP70和肝功能指标。结果与正常对照组比较,切肝组和干预组血清HSP70于术后2 h开始升高,12 h达高峰,48 h仍较高;中、重度切肝组术后ALT、TB均增高,经Gln干预后均降低。结论手术创伤可导致大鼠血清HSP70水平明显升高;检测血清HSP70表达有助于诊断及预测手术创伤程度,术前诱导HSP表达对机体有保护作用。     

Melatonin improves cardiovascular function and ameliorates renal, cardiac and cerebral damage in rats with renovascular hypertension

Abstract:  The effect of melatonin was investigated in an angiotensin II-dependent renovascular hypertension model in Wistar albino rats by placing a renal artery clip (two-kidney, one-clip; 2K1C), while sham rats did not have clip placement. Starting either on the operation day or 3 wk after the operation, the rats received melatonin (10 mg/kg/day) or vehicle for the following 6 wk. At the end of the nineth week, after blood pressure (BP) and echocardiographic recordings were obtained, plasma samples were obtained to assay lactate dehydrogenase (LDH), creatine kinase (CK), antioxidant capacity (AOC), asymmetric dimethylarginine (ADMA), and nitric oxide (NOx) levels. In the kidney, heart and brain tissues, malondialdehyde (MDA) and glutathione (GSH) levels, superoxide dismutase (SOD), catalase (CAT), myeloperoxidase (MPO) and Na⁺-K⁺ ATPase activities were determined. 2K1C caused an increase in BP and left ventricular (LV) dysfunction. In hypertensive animals LDH, CK, ADMA levels were increased in plasma with a concomitant reduction in AOC and NOx. Moreover, hypertension caused a significant decrease in tissue SOD, CAT, and Na⁺, K⁺-ATPase activities and glutathione content, while MDA levels and MPO activity were increased in all studied tissues. On the other hand, both melatonin regimens significantly reduced BP, alleviated oxidative injury and improved LV function. In conclusion, melatonin protected against renovascular hypertension-induced tissue damage and improved cardiac function presumably due to both its direct antioxidant and receptor-dependent actions, suggesting that melatonin may be of therapeutic use in preventing oxidative stress due to hypertension.