NO在实验性大鼠颈动脉瘤发展中的作用

目的建立一种新的颈动脉动脉瘤模型,观察iNOS在实验性动脉瘤组织局部的表达情况和选择性iNOS抑制剂氨基胍对动脉瘤增大和对血清NO水平的影响。方法50只SD大鼠随机分为3组,应用弹性蛋白酶灌注颈总动脉建立颈动脉梭形动脉瘤模型。A组给予氨基胍干预;B组给予生理盐水;C组为阴性对照。测量颈总动脉直径和血清硝酸盐含量。应用HE、免疫组化和原位杂交评价动脉瘤的病理特征和iNOS的局部表达特点。结果选择性iNOS抑制剂可以明显抑制动脉瘤增大的程度和血清硝酸盐水平。诱导的动脉瘤病理特征和外形与人动脉瘤组织相似,主要表现为动脉瘤壁明显增厚,内弹力膜和弹性膜全部消失,平滑肌细胞层变薄和消失。中膜和外膜管壁大量的炎症细胞浸润,氨基胍明显抑制iNOS的表达。结论应用弹性蛋白酶灌注颈动脉可以在大鼠诱导出梭形动脉瘤。动脉瘤的增大与局部升高的NO有关。     

Neuroprotective activity of cannabinoid receptor‐2 against oxidative stress and apoptosis in rat pups having experimentally‐induced congenital hypothyroidism

In this study, it was aimed to show the cannabinoid receptor‐2 (CB2) role, which is a part of neuroprotective endocannabinoidal system, against increasing nitric oxide synthetase (iNOS, eNOS) levels and the apoptotic activity (caspase‐3, caspase‐9, and DNA in situ fragmentation) within the postnatal critical period in pups of pregnant rats with artificially induced maternal thyroid hormone (TH) deficiency. Each of the three groups established comprised one male and two female rats, and they were coupled. Their pups were used. In the first two groups, the mothers were treated with 0.025% MMI during the critical period of the pregnancy. In the third group, as the control group, the mothers and pups were not treated. Euthanasia was applied to the pups in Group I on Day 10, and to the pups in Groups II and III on Day 21. In the biochemical analyses, total T4 levels of both mothers and pups in Group I and II were found to be lower than those of the control group. Histopathologically, karyopyknosis in migrating neurons and demyelinization were observed in both groups. Caspase‐3 and −9 expressions and TUNEL reactions showed parallelism to these findings. eNOS and iNOS activities were also increased in Groups I and II. CB2 receptor activity was observed in the fore and mid brain in Group I, and in the whole brain in Group II. In conclusion, apoptosis was triggered via oxidative stress in hypothyroid pups. Accordingly, neuroprotective activity of CB2 receptors were motivated spontaneously to resist to CNS lesions during the first 3 weeks of postnatal period. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1334–1347, 2017     

Effects of aminoguanidine against renal ischaemia-reperfusion injury in rats

Aminoguanidine is an inhibitor of nitric oxide synthase (NOS), with high selectivity for the inducible isoform (iNOS). In addition to being an inhibitor of NOS, aminoguanidine also exhibits antioxidant activity. Recent studies suggest that aminoguanidine reduces ischaemia-reperfusion (I/R)-induced damage. However, the role of aminoguanidine, in renal injury associated with I/R remains unknown. This study was designed to investigate the effects of aminoguanidine on renal I/R injury. There were three groups of eight rats each. I/R was induced by occlusion of the left renal vessels for 60 min, followed by 24 h reperfusion in rats. Malondialdehyde (MDA) levels, a stable metabolite of the free radical-mediated lipid peroxidation cascade, were found to be significantly higher in the I/R group (30.3 +/- 0.1 nmol g(-1) tissue) than in the control group (10 +/- 0.05 nmol g(-1)). Aminoguanidine (100 mg kg(-1)) administration to rats significantly reduced the MDA values. We also demonstrated that I/R leads to structural change but aminoguanidine did not reverse this change. Aminoguanidine, according to the biochemical finding is protective but histopathological findings did not reveal protection against I/R injury in kidney. The effects of aminoguanidine on I/R-induced damage remain a subject for future investigations.     

Inducible types of cyclooxygenase and nitric oxide synthase in adaptive cytoprotection in rat stomachs.

Roles of cyclooxygenases (COX-1 and COX-2) and nitric oxide (NO) synthases (nNOS and iNOS) in adaptive cytoprotection induced by 20 mM taurocholate dissolved in 50 mM HCl (TC) were investigated in rat stomachs. Intragastric administration of 0.6 N HCl caused haemorrhagic damage in the stomach. These lesions were prevented by pretreatment of the animals with TC p.o. 0.5 h before 0.6 N HCl, and a significant protection persisted for more than 5 h. The protection afforded by TC given 0.5 h before HCl was almost totally reversed by indomethacin and slightly mitigated by N(G)-nitro-L-arginine methyl ester (L-NAME) but not affected by NS-398 or aminoguanidine. By contrast, the mucosal protective action of TC given 5 h before HCl was significantly reversed by NS-398, L-NAME and aminoguanidine as well as indomethacin. Mucosal prostaglandin E2 (PGE2) contents were significantly increased for over 5 h after TC, while luminal NOx output tended to elevate at 0.5 h and be significantly increased at 5 h after TC. The increased PGE2 generation observed 0.5 h after TC was attenuated only by indomethacin, while that observed 5 h after TC was inhibited by NS-398 as well as indomethacin. On the other hand, the NOx output determined at 5 h after TC was significantly reduced by both L-NAME and aminoguanidine. The expression of mRNA for both COX-2 and iNOS was apparently detected in the stomach from 3 h after TC treatment. These results suggest that TC induced adaptive cytoprotection in the rat stomach against 0.6 N HCl, the effect lasting for over 5 h, and the underlying mechanism differs depending on the period after the irritation. The early phase is mediated mainly by COX-1/PGs, while the later phase is mediated by iNOS/NO, in addition to prostaglandins (PGs) produced by both COX-1 and COX-2.     

Protective role of polyphenols in cyclosporine A-induced nephrotoxicity during rat pregnancy.

The aim of this study was to evaluate the adverse effects of cyclosporine A (CsA) toward renal morphogenesis and to test the renoprotective natural antioxidants such as provinol (PV). Pregnant rats were divided into four groups. Group I was injected SC with olive oil. Group II was treated with oral administration of PV and was used as control. Group III animals were injected SC daily with CsA, and group IV animals were injected daily with CsA and PV for 21 days of pregnancy. Five pups per litter were killed and the kidneys removed and treated by morphological and immunohistochemical (IHC) methods. IHC analysis considered two proteins responsible for nephrotoxicity in adult rats: inducible nitric oxide (iNOS) and matrix metalloproteinase-2 (MMP2). Pregnancy outcomes among CsA-treated rats demonstrated a reduced number of pups. Pups that were exposed antenatally to CsA presented several pathologic findings in all immature parenchyma and an increase in iNOS and MMP2 expression. These side effects were not observed in kidney of litters born from CsA + PV-treated mothers. Our study indicates that CsA induces morphological alterations in renal parenchyma of neonates and that PV plays a protective role against these side effects.     

Enteroaggregative Escherichia coli infection induces IL-8 production via activation of mitogen-activated protein kinases and the transcription factors NF-κB and AP-1 in INT-407 cells

Multiple mucosal immune factors, such as TNF-α and IL-1β, are thought to be key mediators involved in inflammatory bowel disease. We evaluated the role of the pro-inflammatory cytokine TNF-α on nitric oxide synthase (NOS) expression in indomethacin-induced jejunoileitis in rats. Jejunoileitis was induced in rats with subcutaneous injections of indomethacin (7.5 mg/kg) 24 h apart for two consecutive days, and animals were randomized into four groups. Group 1 received only indomethacin. Group 2 was treated with a daily dose of phosphodiesterase (PDE) inhibitor (theophylline or pentoxifylline) by oral gavage for 2 days before and 4 days after indomethacin. Group 3 received a single dose of anti-TNF-α monoclonal antibody (TNF-Ab, IP) 30 min before indomethacin. Group 4 was treated with 1 h hyperbaric oxygenation (HBO₂) for 5 days after indomethacin. Rats were sacrificed at 12 h or 4 days after final indomethacin injection. PDE inhibitor, TNF-Ab, or HBO₂ treatment significantly decreased indomethacin-induced ulceration, myeloperoxidase activity, and disease activity index. Although indomethacin significantly increased serum TNF-α and nitrate/nitrite (NOx) concentrations above control values at 12 h, inducible NOS (iNOS) expression was detected only at day 4. Serum IL-1β levels did not change at 12 h but increased 4-fold after 4 days. Indomethacin had no effect on constitutive NOS. Treatment with PDE inhibitor, TNF-Ab, or HBO₂ significantly reduced serum/tissue TNF-α, IL-1β, NOx, and iNOS expression. Our data show TNF-α plays an early pro-inflammatory role in indomethacin-induced jejunoileitis. Additionally, down-regulation of NOx by PDE inhibitors, TNF-Ab, or HBO₂ suggests that TNF-α modulates iNOS expression.     

Exendin-4 对糖尿病脑缺血再灌注大鼠脑组织中MMP-9 表达的影响

目的:通过观察Exendin-4对糖尿病大鼠脑缺血再灌注后脑梗死体积百分比及脑组织中金属基质蛋白酶-9及基质金属蛋白酶抑制剂-1的变化,探讨Exendin-4对糖尿病大鼠脑缺血再灌注损伤的保护作用机制。方法:选用SD大鼠,给予链脲佐菌素(streptozocin,STZ)建立糖尿病大鼠模型后,随机分为A组:糖尿病对照组(n=6);B组:模型组(n=6);C组:Exendin-4低剂量组(n=6);D组:Exendin-4中剂量组(n=6);E组:Exendin-4高剂量组(n=6)。常规喂养6周后,A组给予假手术处理,B、C、D及E组采用线栓法制作大鼠大脑中动脉缺血90 min再灌注模型,24 h后处死大鼠取脑组织,采用2,3,5一氯化三苯四唑(2,3,5-triphenyltetrazolium chloride,TTC)染色测算脑梗死体积百分比;同时分别采用Western Blot法及RT-PCR测量脑组织中的MMP-9及TIMP-1表达量。结果:脑缺血再灌注能致脑组织中MMP-9及TIMP-1表达量增高,各组与A组比较,有显著差异(P<0.05);给予Exendin-4处理后脑组织中MMP-9及TIMP-1表达增高程度及脑梗死体积百分比明显降低,与B组比较有显著差异(P<0.05)。结论:Exendin-4对糖尿病大鼠脑缺血再灌注损伤有保护作用,其机制可能与抑制MMP-9及TIMP-1的表达有关。     

Selective head cooling with hypothermia suppresses the generation of platelet-activating factor in cerebrospinal fluid of newborn infants with perinatal asphyxia

Hypoxic-ischemic encephalopathy (HIE) remains one of the most important neurologic complications in the newborn. Several experimental and clinical studies have shown that hypothermia is the most effective means known for protecting the brain against hypoxic-ischemic brain damage. Furthermore, recent data have suggested that platelet-activating factor (PAF) could play a pathophysiologically important role in the progression of hypoxic-ischemic brain injury. The aim of the present study was to investigate the role of head cooling combined with minimal hypothermia in short-term outcome of infants with perinatal asphyxia. In addition, we have examined the effect of head cooling combined with minimal hypothermia on PAF concentrations in cerebrospinal fluid (CSF) after hypoxic-ischemic brain injury. The group of asphyxiated infants (Group 1) consisted of 21 full-term (gestational age >37 weeks). These infants were randomized and divided into either a standard therapy group (Group 1a; n=10) or cooling group (Group 1b; n=11). Head cooling combined with minimal hypothermia (rectal temperature 36.5-36 degrees C) was started as soon as practicable after birth. The infants were cooled for 72h and then were rewarmed at 0.5 degrees C/h. The control group (Group 2) consisted of seven full-term infants and none of these infants showed any sign of asphyxia. To measure PAF concentration in CSF, CSF with lumbar puncture was collected into tubes immediately before the cooling (1-3h after birth) and again after 36h. We had no evidence of severe adverse events related to hypothermia. In Group 1a, two infants died after 72h of life; however, all newborn infants in Group 1b survived. Convulsion required treatment in three infants of standard therapy group (1a); none of the infants in Group 1b had clinical seizure activity. Abnormal EEG patterns were found in four infants of Group 1a; no EEG abnormalities were noted in Group 1b (P<0.05). On admission (before cooling), PAF concentration in CSF of asphyxiated infants was found to be significantly higher when compared with that of control (P<0.001). Mean PAF concentration before initiation of the study was similar in the two asphyxiated groups (Group 1a vs. 1b) (P>0.05). Obtained PAF level in CSF after 36h, showed a profound decline in cooling group of infants compared to Group 1a infants (P<0.01). In conclusion, the present study suggests that cerebral cooling with minimal hypothermia started soon after birth has no severe adverse effects during 72-h cooling period and that short-term outcome of infants are encouraging. Our results also support the hypothesis PAF an important mediator in hypoxic-ischemic brain injury and demonstrate that head cooling combined with minimal hypothermia reduces the normal increase in PAF following hypoxic-ischemic brain injury in full-term infants.     

Dual action of nitric oxide in pathogenesis of indomethacin-induced small intestinal ulceration in rats.

We investigated the pathogenic role of nitric oxide (NO) in indomethacin-induced intestinal ulceration in rats. Nonfasting animals responded to a single administration of indomethacin (10 mg/kg, s.c.), resulting in multiple hemorrhagic lesions in the small intestine, mostly the jejunum and ileum. The damage was first observed 6 hr after indomethacin, the severity increasing progressively with time up to 24 hr later, accompanied with the gene expression of inducible NO synthase (iNOS) and the increase of nitrite and nitrate (NOx) contents in the mucosa. The ocurrence of damage was significantly prevented when iNOS induction was inhibited by dexamethasone given either once 0.5 hr before or twice 0.5 hr before and 6 hr after indomethacin. Likewise, aminoguanidine (a relatively selective iNOS inhibitor) reduced the severity of damage, irrespective whether given twice or as a single injection 6 hr after indomethacin. By contrast, the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) exhibited a biphasic effect, depending on the time of administration; the pre-administration worsened the damage, while the later administration reduced the severity of these lesions, yet both responses occureed in a L-arginine-sensitive manner. Pre-administration of L-NAME, but not aminoguanidine, significantly decreased NOx production in the intestinal mucosa of normal rats, while the increase of NOx production following indomethacin was significantly suppressed by the later administration of aminoguanidine as well as L-NAME. These results suggest that NO exerts a dual action in the pathogenesis of indomethacin-induced intestinal ulceration; NO generated by cNOS is protective against indomethacin, by maintaining the integrity of intestinal mucosa, while NO derived by iNOS plays a key pathogenic role in the ulcerogenic process.     

大鼠肢体缺血/再灌注后肺损伤及一氧化氮合酶的变化与意义

目的：研究大鼠肢体缺血／再灌注后急性肺损伤时,内皮型一氧化氮合酶（eNOS）和诱导型一氧化氮合酶（i-NOS）的表达及其在急性肺损伤发生中的作用。方法：雄性Wistar大鼠于后肢根部阻断血流后松解（4h／4h）,分别给予L-Arg和氨基胍（AG）预先干预,分为control、IR、L-Arg和AG组,免疫组织化学方法检测肺组织中iNOS和eNOS的表达,同时检测肺组织中MDA、MPO、W／D和NO2^-／NO3^-值,肺组织形态学观察以评价肺损伤的程度。结果：与control组比较,I／R组eNOS表达降低,iNOS表达增强,MDA、MPO、W／D和NO2^-／NO3^-值增加。肺组织充血、炎细胞浸润,肺泡腔渗液;与I／R组比较,L-Arg组eNOS、iNOS表达无明显变化,NO2^-／NO3^-增加。MDA、MPO、W／D降低,肺组织损伤有减轻趋势,AG组eNOS表达无明显变化,iNOS活性降低,NO2^-／NO3^-减少,MDA、MPO、W／D增加,肺组织损伤有加重趋势。结论：肢体缺血／再灌注急性肺损伤过程中,iNOS表达增加,NO生成增多,在肺损伤发生中有一定的保护作用。     

Neuroprotective effects of MK 801 and hypothermia used alone and in combination in hypoxic-ischemic brain injury in neonatal rats.

Although accumulating evidence suggests that increased extracellular glutamate concentrations may play an important role in hypoxic-ischemic brain injury, dopamine and other catecholamines also seem to be involved. The N-methyl-D-aspartate receptor antagonist MK 801 and moderate hypothermia (32-34 degrees C) are each known to be neuroprotective, but their combined effect on the release and metabolism of neurotransmitters is unknown. Seven-day-old pups (n: 150) underwent right common carotid artery ligation to induce hemispheric ischemia, and were later subjected to 120 minutes of hypoxia with 8% O2 and 92% N2O. Half the rats (Group I, n: 74) were subjected to normothermic conditions throughout the hypoxic period. Moderate hypothermia (30-32 degrees C) was induced in the other pups (Group II, n: 76) immediately after artery occlusion, and was maintained throughout the hypoxic period. Prior to inducing hypoxia, half of the rats in each group (Groups IA and IIA) received vehicle solution (0.9% NaCI) and the other rats (Groups IB and IIB) received MK 801 (0.5 mg/kg) subcutaneously at 45 and 120 minutes after occlusion. Intracerebral temperature was recorded every 15 minutes after occlusion. Infarct area (n: 40) was calculated after staining with 2% 2,3,5 triphenyltetrazolium chloride. Neuronal damage (n: 42) was assessed by quantifying CA1-CA3 neuronal loss at five hippocampal levels. The amount of damage to the monoamine system of the corpus striatum was determined based on the dopamine and 3,4 dihydroxyphenylacetic acid levels in the corpus striatum in both hemispheres (n: 46), as measured by high-pressure liquid chromatography and compared with normal control pups' values (n: 10). The normothermia/saline-treated pups had significantly larger infarct areas than the MK 801 only, hypothermia only, or MK 801/hypothermia combination groups. Neuropathological examination and striatal tissue monoamine data also confirmed marked neuronal damage in this group. Although MK 801 treatment alone resulted in significantly smaller infarct area and less tissue damage than was observed in the normothermia/saline-treated group, the moderate hypothermia and the MK 801/hypothermia combination treatment groups both exhibited better neuronal protection, especially in the corpus striatum. The rats that received combined treatment also had a significantly lower mortality rate.     

Upregulation of iNOS by COX-2 in muscularis resident macrophage of rat intestine stimulated with LPS

We investigated the effect of lipopolysaccharide (LPS) on the induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in muscularis resident macrophages of rat intestine in situ. When the tissue was incubated with LPS for 4 h, mRNA levels of iNOS and COX-2 were increased. The majority of iNOS and COX-2 proteins appeared to be localized to the dense network of muscularis resident macrophages immunoreactive to ED2. LPS treatment also increased the production of nitric oxide (NO), PGE(2), and PGI(2). The increased expression of iNOS mRNA by LPS was suppressed by indomethacin but not by N(G)-monomethyl-L-arginine (L-NMMA). The increased expression of COX-2 mRNA by LPS was affected neither by indomethacin nor by L-NMMA. Muscle contractility stimulated by 3 microM carbachol was significantly inhibited in the LPS-treated muscle, which was restored by treatment of the tissue with L-NMMA, aminoguanidine, indomethacin, or NS-398. Together, these findings show that LPS increases iNOS expression and stimulates NO production in muscularis resident macrophages to inhibit smooth muscle contraction. LPS-induced iNOS gene expression may be mediated by autocrine regulation of PGs through the induction of COX-2 gene expression.     

Effect of nitric oxide on phagocytic activity of lipopolysaccharide-induced macrophages: possible role of exogenous L-arginine

Among the antimicrobial mechanisms associated with macrophages, NO produced by iNOS plays a major role in intracellular killing, but the relationship between NO and phagocytic activity after injection of inflammatory agents into the peritoneal cavity is not clear. The aim of the present study was to investigate the effect of nitric oxide (NO) on macrophage function after treatment with intraperitoneal lipopolysaccharide (LPS) and the role of exogenous L-arginine administration in this event. Six experimental groups and one control group, each consisting of seven Wistar rats were used: Group I: Control; Group II: LPS; Group III: LPS+L-arginine; Group IV: LPS+L-arginine+Aminoguanidine; Group V: LPS+Aminoguanidine; Group VI: L-arginine; Group VII: Aminoguanidine. Macrophage phagocytic activity and total plasma nitrite levels were increased in the LPS group. In the LPS+L-arginine group, both the phagocytic activity and total plasma nitrite levels showed large increases. Administration of aminoguanidine (AG), a specific iNOS inhibitor, abolished macrophage phagocytic activity and total plasma nitrite levels in the LPS and LPS+L-arginine groups. As a result, we showed that NO produced by macrophages has a role not only in intracellular killing, but also in phagocytic activity.     

Increased production of nitrotyrosine in lung tissue of rats with radiation-induced acute lung injury

The purposes of this study were 1) to identify the nitric oxide (NO) synthase (NOS) isoform responsible for NO-mediated radiation-induced lung injury, 2) to examine the formation of nitrotyrosine, and 3) to see whether nitrotyrosine formation and lung injury are reduced by an inducible NOS (iNOS) inhibitor, aminoguanidine. The left hemithorax of rats was irradiated (20 Gy), and the degree of lung injury, the expression of NOS isoforms, and the formation of nitrotyrosine and superoxide were examined after 2 wk. iNOS mRNA was induced, and endothelial NOS mRNA was markedly increased in the irradiated lung. Nitrotyrosine was detected biochemically and immunohistochemically. Aminoguanidine prevented acute lung injury as indicated by decreased protein concentration and lactate dehydrogenase activity in bronchoalveolar lavage fluid and improved NMR parameters and histology. Furthermore, the formation of nitrotyrosine was significantly reduced in the aminoguanidine group. We conclude that iNOS induction is a major factor in radiation-induced lung injury and that nitrotyrosine formation may participate in the NO-induced pathogenesis.     

Histological study of the protective effect of melatonin on neural cells after neonatal hypoxia-ischemia

To minimize as much as possible the neurological consequences from hypoxic-ischemic (HI) brain injury, neuroprotective strategies are urgently required. In this sense, there is growing interest in the neuroprotective potential of melatonin after perinatal asphyxia, due to its high efficacy, low toxicity and ready cross through the blood-brain barrier. Twenty six Wistar rats at postnatal day 7 were randomly assigned to: two hypoxic-ischemic groups: pups with the left common carotid artery ligated and then submitted to hypoxia (HI group) and animals that received a dose of 15 mg/kg melatonin just after the hypoxic-ischemic event and repeated twice with an interval of 24 hours (HI+MEL group). Pups without ischemia or hypoxia were used as controls (Sham group). Seven days after surgery, brains were collected and coronal sections Nissl-stained, TUNEL-labeled, or MBP- and GFAP-immunolabeled prior to determining brain infarct area, quantify surviving neurons and evaluate oligodendroglial injury and reactive astrogliosis. The number of surviving neurons showing a well preserved architecture in HI+MEL group was similar to that observed in the Sham group. Moreover, TUNEL-positive cells only appeared in the HI group. The ratio of left-to-right hemispheric MBP immunostaining showed a significant decrease in the HI group in comparison with Sham pups, which was restored after melatonin administration. Melatonin also reduced reactive gliosis. Thus, our results suggest that treatment with melatonin after neonatal hypoxia-ischemia led to a neuroprotective effect reducing cell death, white matter demyelination and reactive astrogliosis.     

延迟5分钟剖宫产造全脑缺氧缺血新生大鼠模型

目的建立围产期全脑缺氧缺血性损伤的新生大鼠模型。方法 SD雌性大鼠妊娠21 d时,颈椎脱臼法处死,用止血钳夹闭双侧子宫角血管5 min后,剖宫产取出新生大鼠,交由代乳鼠喂养。结果造模组雌性大鼠9只,共娩出新生大鼠91只,出生3 d内死亡7只,死亡率7.7%。新生大鼠出生第2天进行翻身实验,第14天进行悬吊实验和斜坡实验,造模组和其余各组均有显著性差异。新生大鼠出生后21 d,取脑组织切片行HE染色,显示大脑皮层典型的缺氧缺血性损伤,与正常组相比,可见神经细胞明显的病理形态学改变。结论采用延迟5min剖宫产和代乳鼠喂养的方法,操作简便,并结合行为学测试筛选行为异常者,可建立稳定可靠、可供长期实验使用的围产期全脑缺氧缺血性损伤的新生大鼠模型。     

重复+10Gz暴露对大鼠心肌自由基代谢的影响及低G预适应和茶多酚的保护作用

目的:观察重复 Gz暴露是否引起心肌自由基代谢异常以及低G预适应和天然抗氧化剂茶多酚(TP)的防护作用.方法:32只雄性Wistar大鼠随机分为4组(n=8):A组,仅受 1Gz 作用5 min; B组, 10Gz峰值暴露5 counts/d,每次30 s, 10Gz作用间隔为 1Gz 1 min,每周三天,共三周; C组,实验日先受到 2Gz 作用5 min,1 h后同B组处理;D组,实验日灌胃给予TP 200 mg/kg,1 h后同B组处理.于末次 Gz暴露的次日上午将各组大鼠断头处死,迅速取心脏用于以下指标测定:超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量、免疫组化和半定量反转录PCR(RT-PCR)技术测定Cu,Zn-SOD和诱生型一氧化氮合酶(iNOS)含量和其mRNA表达.结果:与A组(对照组)相比,B组心肌线粒体MDA水平和iNOS酶含量显著增加(P<0.05),与B组相比,C组心肌线粒体SOD活性明显升高,C、D组的iNOS酶含量明显降低(P<0.05).各组Cu,Zn-SOD含量、mRNA表达和iNOS mRNA表达无明显差异.结论:重复 Gz暴露引起大鼠心肌自由基代谢异常,主要导致线粒体氧化损伤,低G预适应和TP具有一定的防护作用,其中以低G预适应的效果更佳.     

Modulation of iNOS activity in age-related cardiac dysfunction

Based on the role of inducible nitric oxide synthase (iNOS) in heart failure, we hypothesized that the elevated expression of iNOS compared to young mice in the myocardium contributes to the age-related decline of left ventricular (LV) function. Cardiac iNOS mRNA and protein expression was singularly identified in old, wild type (WT) male mice (I6-month) and not in young WT male mice (6-month). Characterized with in vivo pressure-volume loops analysis, an age-related LV dysfunction was found in the old WT mice. The LV dysfunction of the aged mice was modified to that of the younger mice by the specific iNOS inhibitors, aminoguanidine (AMG, 10 mg/Kg, i.v. or infusion, n = 15) and S-methyl-isothiourea (MITU, 3 mg/Kg, i.v. n = 7), and declined with L-arginine (10 mg/Kg, i.v. n = 7). All three drugs had no effects on the LV function of young WT mice or old iNOS knockout (KO) mice. The NOx and cGMP levels were significantly higher only in the old WT mice (n = 6) and cGMP levels decreased to normal with AMG administration. In conclusion, these results suggested that the iNOS/NO/cGMP pathway may contribute to ventricular dysfunction during the aging process and that inhibition of iNOS activity significantly improved heart function in aged mice.     

Mechanism for increase in tracheobronchial blood flow induced by hyperventilation of dry air in dogs

To test whether the consistent increase in tracheal and bronchial blood flow observed in dogs during hyperventilation of dry air might be the result of release of mediators such as vasodilatory prostaglandins or neuropeptides, we studied two groups of anesthetized mechanically ventilated dogs. Group 1 (n = 6) was hyperventilated for four 30-min periods with 1) warm humid air (38-40 degrees C, 100% relative humidity), 2) warm dry air (38-40 degrees C, 0% relative humidity), 3) warm humid air, and 4) warm dry air. After period 2, a loading dose of indomethacin (4 mg/kg iv) was given over 15 min followed by a constant infusion (4 mg.kg-1.h-1). Group 2 (n = 10) was hyperventilated for four 15- to 20-min periods by use of the protocol described above. After period 3 (group 2a) or period 2 (group 2b), topical 4% lidocaine hydrochloride solution was instilled into the trachea and main stem bronchi. Five minutes before the end of each period of hyperventilation, cardiac output and vascular pressures were measured. To determine airway blood flow, differently labeled radioactive microspheres were injected into the left atrium. After the last measurements, dogs were killed and the lungs excised. Blood flow to the trachea, main stem bronchi, and parenchyma (group 1 only) was calculated. Results showed that hyperventilation of dry air produced a significant increase in blood flow to the trachea and bronchi (period 2). In group 1, this increase was attenuated (P less than 0.02) after administration of indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)     

白藜芦醇后处理对大鼠脑缺血再灌注损伤海马CA1区Bax、Bcl-2的影响

摘要 目的：探讨白藜芦醇后处理对大鼠脑缺血再灌注损伤Bax、Bcl-2表达的影响。方法：清洁级雄性SD大鼠60只随机分为假手术组（n=12）、I/R组（n=12）、白藜芦醇组（n=36）,白藜芦醇组按不同剂量分为低剂量、中剂量、高剂量组（10 mg/kg、20 mg/kg、40 mg/kg）,每组12只。假手术组：仅暴露大鼠颈外动脉,不做缺血处理;I/R组：采用改良线栓法制备大鼠大脑中动脉缺血再灌注损伤模型（缺血2 h,再灌注24 h）;白藜芦醇组：造模方法同I/R组,在大鼠缺血2h后,将不同剂量白藜芦醇腹腔注射入大鼠体内,比较各组SD大鼠神经功能缺损评分、采用Western blotting法、免疫组化法对大鼠脑组织缺血侧海马CA1区Bax和Bcl-2表达进行比较。结果：白藜芦醇低、中、高剂量组神经功能缺损评分均低于I/R组,随着白藜芦醇剂量的增加,神经功能缺损评分逐渐降低,其中白藜芦醇高剂量组神经功能缺损评分降低最为明显;白藜芦醇组与I/R组相比,不同剂量白藜芦醇组Bax表达逐渐减少,而Bcl-2表达明显增加,其中以白藜芦醇高剂量组改变最为明显。结论：高剂量白藜芦醇可以降低大鼠神经功能缺损评分,减轻脑缺血再灌注损伤,对大鼠脑缺血再灌注损伤具有保护作用,其机制与Bax、Bcl-2的表达有关。