Sustained Effects of a Single Injection of Ethanol on the Hypothalamic-Pituitary-Gonadal Axis in the Male Rat

The hormones responsible for regulating the hypothalamic-pituitary-gonadal axis are essential for proper reproductive function. Ethanol (EtOH) has been shown to exert its effects at all three levels of this axis. The present study defines striking differences in the time course of recovery of luteinizing hormone (LH) in gonadally intact, compared with, castrated male rats after acute EtOH administration. Serum levels of LH and testosterone were measured at various time points up to 2 weeks (1.5, 3, 24, 48, 72, 96, 168, and 336 hr) after a single intraperitoneal injection of either saline or 3 g/kg of EtOH in intact adult male rats. One EtOH injection significantly suppressed testosterone levels to as low as 20% (p < 0.01) of saline-injected intact rats. This occurred as early as 1.5 hr after EtOH administration (the first measured time point), and statistically significant suppression was sustained for 96 hr. Similarly, LH levels showed a significant decrease. However, this significant fall in LH did not begin until 3 hr (p < 0.05) and continued up to 96 hr (p < 0.01), with a gradual return to control levels at 168 and 336 hr after treatment. Despite the significant and prolonged fall in testosterone levels in the EtOH-treated intact rats, P-LH mRNA levels were inappropriately not elevated, as would be expected in the context of low circulating testosterone. However, at 168 and 336 hr, steady-state levels of P-LH mRNA were significantly higher than seen in saline-injected controls (p < 0.05 and p < 0.01, respectively), temporally correlating with the return of serum LH to control. LH levels in the castrated animals were significantly suppressed at 1.5 hr (p < 0.05) and 3 hr (p < 0.01) after EtOH treatment, compared with controls, yet they returned much more quickly by 24 hr after treatment. P-LH mRNA levels of castrated animals also showed a significant depression at 1.5 and 3 hr, and returned to control levels by 24 hr. In these rats, the hypothalamic LH-releasing hormone mRNA levels were not altered by a single EtOH injection at any time point. However, in the intact animals, there was a transient increase in LH-releasing hormone mRNA at 72 and 96 hr (p < 0.01 and p < 0.05, respectively) that may lead to the upregulation of β-LH mRNA expression. These studies indicate that EtOH causes prolonged decreases in important serum hormones that are essential to the reproductive axis of the adult male rat.     

Interaction of Ethanol and Nitric Oxide in the Hypothalamic-Pituitary-Gonadal Axis in the Male Rat

Ethanol (EtOH) exerts deleterious actions on reproductive function at all three levels: the hypothalamus, pituitary, and gonad (HPG). Nitric oxide (NO), a newly identified messenger molecular in a variety of biological systems, has been suggested as playing a role in HPG hormone regulation. NO stimulates luteinizing hormone releasing hormone secretion from the hypothalamus and has variable effects on luteinizing hormone release from the pituitary. NO is inhibitory to testosterone production, and it may also directly inhibit some steroidogenic enzymes. Related studies in the accompanying paper have demonstrated that inhibiting NO synthase (NOS) using various NOS inhibitors can prevent the EtOH-induced suppression of testosterone on the male HPG axis, and this action is mainly, although not entirely, due to a direct gonadal effect. To further investigate the role of NO in the HPG axis, we assessed the HPG NO-NOS system by determining NOS mRNA levels, protein levels, and enzyme activity in the presence and absence of EtOH. At the testicular level, EtOH's action did not appear to be mediated by increasing NO content. However, EtOH was able to potentiate NO'S suppressive effect on the testicular synthesis system. One locus where EtOH and NO interacted was at the steroidogenic enzyme level. N^Q-nitro- l -arginine methyl ester, a NOS inhibitor, was found to antagonize the EtOH-induced fall on P-450 17α-hydroxylase/C17-20 lyase mRNA levels when administered along with EtOH. EtOH had no apparent effect on the pituitary NO-NOS system and its effects on the hypothalamic NO-NOS system do not explain its ability to reduce luteinizing hormone releasing hormone secretion.     

Effects of Nitric Oxide Synthase Blockade on the Acute Response of the Reproductive Axis to Ethanol in Pubertal Male Rats

The effects of ethanol (EtOH) and nitric oxide (NO) are well known in the adult male rat reproductive axis. In the present study, we investigate the effects of EtOH, NO, and their interaction on key genes and reproductive hormone levels in mid- (45-day) and late pubertal (55-day) male rats. Using three different NO synthase blockers--N'omega-nitro-L-arginine methyl ester (L-NAME), N'omega-nitro-L-arginine (L-NA), and 7-nitroindazole--we show that it is possible to block, in part, some of the disruptive effects of EtOH. L-NAME totally prevented the EtOH-induced fall in serum testosterone in both 45- and 55-day-old rats (p < 0.05 and p < 0.001, respectively). On the other hand, the D-NAME, an inactive isomer of L-NAME, did not protect testosterone from suppression caused by EtOH. Similarly, L-NA and 7-nitroindazole prevented the suppression of testosterone caused by EtOH in 55-day-old animals (p < 0.001 L-NA and p < 0.05 for 7-nitroindazole), but not in the 45-day-old rats. Serum luteinizing hormone (LH) was significantly reduced by EtOH in all the studies in both age groups. L-NAME (but not D-NAME) and L-NA prevented this inhibition in 55-day-old animals (p < 0.001 for L-NAME and p < 0.01 for L-NA). However, only L-NA was able to prevent the effects of EtOH on LH in the 45-day-old rats. 7-Nitroindazole was unable to prevent the decrease in LH in either age group. Despite changes in the other reproductive hormones, there were no consistent changes in hypothalamic concentrations of either LH releasing hormone (LHRH) or its precursor, pro-LHRH. No treatment caused any change in steady-state levels of beta-LH mRNA. There were no consistent changes in pro-LHRH mRNA; but, interestingly, in 45-day-old rats, L-NA given with or without EtOH lead to a significant fall in LHRH gene expression. Our findings indicate that the acute suppressive effects of EtOH on the hypothalamic-pituitary-gonadal axis of the pubertal male rat can be at least partially prevented by NO synthase blockade.     

Ethanol Induced Changes in Superoxide Anion and Nitric Oxide in Cultured Microglia

Induction of oxidative stress has been implicated as a causative factor in fetal alcohol syndrome although the source of reactive oxygen species is not clear. One potential source is the microglia, the CNS macrophage, which generate superoxide anion as part of their normal immune function. Our data indicate that chronic exposure to ethanol alters the function of cultured neonatal hamster microglia by inducing superoxide anion production in resting (nonstimulated) cells. An increase in superoxide anion was seen at 24 or 48 hr of ethanol treatment but was not seen during acute exposures of up to 3 hr. This effect was dose dependent and was maximal at 20 mM ethanol. Treatment with ethanol did not directly activate the respiratory burst seen in microglia and did not act as a priming agent to enhance phorbol-ester-stimulated superoxide anion production. Lipopolysaccharide-mediated priming of microglial superoxide anion production was also not affected by exposure to 20 mM ethanol for 24 hr. Ethanol treatment, however, did depress nitric oxide (NO) levels in hamster microglia which had been stimulated to produce NO by polyinosinic:polycytidylic acid (poly I:C). Uptake of latex beads was increased by 24 hr of exposure to ethanol. The overall action of ethanol on neonatal hamster microglia is to shift the balance between the production of superoxide anion and NO. Because NO is protective to mammalian cells, these changes predict that oxidative stress in the CNS would be enhanced.     

The Role of Nitric Oxide in Ethanol-Induced Gastrointestinal Dysfunction

We recently showed that acute ethanol inhibits contractility of the lower esophageal sphincter (LES) and the lower esophageal body (LEB) both in vivo and in vitro. To evaluate the mechanism of this inhibitory effect of ethanol, we investigated the role of nitric oxide (NO) on contractility of isolated LES and LEB circular muscle strips using inhibitors of NO synthase (NOS), N ^G-itro- l -arginine methyl ester and N ^G-nitro- l -arginine. Ethanol significantly decreased LES basal tone. This effect was not mediated by NO, because inhibition was not prevented by inhibitors of NOS. Electrical field stimulation caused an On-response relaxation from LES strips, and an Off-response contraction from both LES and LEB strips. Inhibitors of NOS prevented the On-response relaxation of LES, but had no significant effect on LES Off-response contraction. Ethanol potentiated the On-response relaxation of the LES Off-response contraction. Ethanol potentiated the On-response relaxation of LES, but had no significant effect on Off-response contraction. Ethanol's potentiating effect of the On-response relaxation is NO-mediated, because it was abolished by NOS inhibitors. Ethanol also inhibited carbachol-induced LES contractility. This inhibitory effect was NO-mediated, because NOS inhibitors abolished it. Ethanol inhibited both the Off-response contraction and carbachol-induced contraction of LEB strips. These effects were not NO-mediated, because they were not affected by NOS inhibitor. These data suggest that NO is not a mediator for the inhibitory effect of ethanol on LEB contractility, and that NO seems to be a mediator of ethanol inhibition of some aspects of LES motor functions.     

清肠栓对溃疡性结肠炎大鼠一氧化氮和一氧化氮合酶活性的影响

目的：观察不同剂量清肠栓治疗溃疡性结肠（UC）的作用及其对一氧化氮（NO）和一氧化氮合酶（NOS）活性的影响。方法：将动物随机分成高、中、低剂量清肠栓组、SASP组、模型组、空白组,除空白组外其余5组动物分别用三硝基苯磺酸（TNBS）建立大鼠溃疡性结肠炎模型,连续用药2周后取结肠组织,采用改良的G法、分光光度法分别测定其NO含量和NOS活性。结果：模型组大鼠NO、NOS含量较空白组明显降低,其他各组均有不同程度的增高,尤其以清肠栓高剂量组的增高为明显。结论：TNBS急性损伤使结肠组织的NO、NOS活性发生改变,可能是UC发生的重要机制。中药复方清扬栓具有调控NO及NOS活性的作用,是有效治疗UC的可能机制之一。     

一氧化氮合酶抑制剂对实验性大鼠结肠炎疗效的研究

背景：炎症性肠病（IBD）中，诱生型一氧化氮合酶（iNOS）合成的高浓度一氧化氮（NO）与肠道炎症和疾病活动度相关。因此抑制iNOS为肠道炎症提供了新的治疗选择。目的：评估NOS抑制剂治疗进展期结肠炎的疗效。方法：予雌性Sprague．Dawlev大鼠含30mg三硝基苯磺酸（TNBS）的50％乙醇溶液0．85ml灌肠，诱导实验性结肠炎。7天后，将大鼠随机分成4组，每组7只，每天分别腹腔注射0．9％NaCl溶液1ml（造模组）、0．2mg／kg地塞米松（DX）、5mg／kg氨基胍（AG）和35mg／kgN-硝基-L-精氨酸甲酯（L-NAME）。另取4只正常大鼠作为正常对照组。通过肠道重量指数、溃疡面积、大体形态和组织学评分以及肠组织髓过氧化物酶（MPO）、丙二醛（MDA）、NOS和iNOS活性、血浆CD62P活性、血清NO含量测定评估疗效。结果：与造模组相比，DX组和AG组肠道重量指数、溃疡面积、大体形态和组织学评分以及肠组织MPO、MDA、NOS和iNOS活性、血浆CD62P活性、血清NO含量均显著降低，L-NAME组肠组织NOS和iNOS活性以及血清NO含量显著降低，但大体形态和组织学评分无改善。结论：选择性iNOS抑制剂AG能通过其抗炎作用减轻进展期肠道炎症，提示AG可作为IBD新的治疗选择，其疗效与DX相似。     

吡喹酮对血吸虫病肝纤维化小鼠血清NO及肝内iNOS活性的影响

目的:研究吡喹酮治疗血吸虫病肝纤维化小鼠前后血清一氧化氮及肝内诱导型一氧化氮合酶活性的变化。方法:制备血吸虫病肝纤维化小鼠模型,应用免疫组化染色方法和多媒体彩色病理图文分析系统定量观察吡喹酮治疗前后肝脏诱导型一氧化氮合酶含量的变化,并通过化学还原反应检测血清一氧化氮的水平变化。结果:吡喹酮治疗组肝内iNOS和血清NO的含量均低于感染组,P均小于0.01。结论:吡喹酮可显著降低血吸虫病肝纤维化小鼠肝脏诱导型一氧化氮合酶活性及血清NO含量而发挥抗血吸虫病肝纤维化的作用。     

Effect of Chronic Maternal Ethanol Administration on Nitric Oxide Synthase Activity in the Hippocampus of the Mature Fetal Guinea Pig

Nitric oxide is a novel messenger that is involved in neuronal cell-cell communication and seems to play a neurotrophic role in normal brain development Chronic prenatal ethanol exposure can produce central nervous system (CNS) teratogenesis, in which one of the target sites is the hippocampus. The main objective of our study was to test the following hypothesis: chronic matemal administration of an ethanol dosage regimen that produces CNS teratogenesis decreases nitric oxide synthase (NOS) activity in the fetal hippocampus. The ontogeny of NOS activity in the hippocampus of the developing guinea pig was further elucidated at two prenatal and two postnatal ages. The effects of chronic maternal oral administration of 4 g of ethanoVkg maternal body weight/day, isocaloric sucrose and pair feeding, or water [given as two equally divided doses 2 hr apart from gestational day (GD) 2 to GD 61] on body, brain, and hippocampal weights and hippocampal NOS activity were determined in the mature fetal guinea pig at GD 62 (term, about GD 68). NOS activity in the 25,000 × g supernatant fraction of hippocampal homogenate was measured using an optimized radiometric assay, based on the oxidation of l-[¹⁴C]arginine to l-[¹⁴C]citrulilne. For the chronic ethanol regimen, the matemai bid ethanol concentration at 1 hr after the second divided dose on OD 57 was 167 ± 45 mg/dI. Chronic matemal administration of ethanol decreased fetal body, brain, and hippocampai weights, compared with the isocaloric-sucrose/pair-fed and water treatment groups. The rate of l-[¹⁴C]cibulline formation and NOS activity in the fetal hippocampus were decreased in the ethanol treatment group, compared with the isocaioric-sucrose/ pair-fed and water treatment groups. There was no difference in the rate of l-[¹⁴C]citruIline formation, NOS activity, and fetal hippocampal and body weights between the isocaioric-sucrose/pair-fed and water treatment groups; however, fetal brain weight was decreased in the isocaloric-sucrose group, compared with the water group. Data of this study support the research hkothesis by demonstrating that chronic matemal administration of ethanol decreases fetal hippocampal NOS activity that is comlated with restricted growth of this brain region.     

急性心肌梗死大鼠心脏一氧化氮合酶表达的改变

目的 通过建立大鼠心肌梗死模型，观察急性心肌梗死对大鼠心脏内皮型一氧化氮合酶mRNA和诱导型一氧化氮合酶蛋白表达的影响。方法48只健康成年SD大鼠（体重200～250g）随机分为假手术组和缺血组，取1、2、8和24h四个不同时间点观察。采用开胸结扎冠状动脉左前降支建立心肌缺血模型，逆转录聚合酶链反应检测大鼠心肌梗死后1、2及24h三个时段缺血心肌内皮型一氧化氮合酶mRNA的表达；免疫组织化学染色检测冠状动脉结扎后8h缺血心肌诱导型一氧化氮合酶蛋白的表达。结果冠状动脉结扎后2h，缺血组大鼠缺血心肌组织内皮型一氧化氮合酶mRNA表达下降（P〈0．05），并持续至结扎后24h；结扎后24h组内皮型一氧化氮mRNA的表达与结扎后2h组相比无显著性差异（P〉0．05）。冠状动脉结扎后8h，梗死区存活心肌组织细胞诱导型一氧化氮合酶蛋白大量表达，而假手术组未见诱导型一氧化氮合酶蛋白表达。结论正常大鼠心肌组织有内皮型一氧化氮合酶基因表达，无诱导型一氧化氮合酶蛋白表达。在心肌梗死早期缺血心肌内皮型一氧化氮合酶mRNA表达减少。心肌急性缺血刺激早期诱导大鼠缺血心肌组织诱导型一氧化氮合酶蛋白大量表达。     

针刺疗法对实验性黄疸大鼠一氧化氮的影响

目的:观察针刺对实验性黄疸大鼠一氧化氮(NO)的影响.方法:采用一次性灌胃异硫氰酸萘酯(ANIT)中毒制备大鼠黄疸模型,以针刺疗法为治疗组,并与思美泰组作对照,观察其血清NO及丙氨酸氨基转移酶(ALT)、总胆红素(TBil)、γ-谷氨酰转肽酶(GGT)、碱性磷酸酶(ALP)和肝组织病理变化.结果:两种疗法均能显著改善大鼠NO及各项指标(P＜0.01),针刺组在某些方面优于思美泰组(P＜0.01).结论:针刺疗法能降低大鼠NO水平,抑制其对肝细胞的毒性作用,促进胆红素的正常代谢.     

L-精氨酸和氨基胍对糖尿病大鼠一氧化氮、一氧化氮合酶及肾功能的影响

目的探讨L-精氨酸和氨基胍对早期糖尿病大鼠一氧化氮、一氧化氮合酶活性及肾功能的影响。方法Wistar大鼠60只,检测其24 h尿蛋白排泄量、血清一氧化氮水平、总一氧化氮合酶和诱导型一氧化氮合酶及结构型一氧化氮合酶活性等5项指标。然后用链脲佐菌素60 mg/kg制备糖尿病大鼠模型,将糖尿病鼠随机分为糖尿病对照组、L-精氨酸组和氨基胍组。于8周末时再检测大鼠上述5项指标并进行统计分析。结果与造模前比较,糖尿病对照组在8周末时24 h尿蛋白排泄量(43.92±7.38 mg)、一氧化氮水平(42.2±6.92μmol/L)和诱导型一氧化氮合酶活性(19.75±3.85 kU/L)升高(P<0.01,P<0.05);L-精氨酸组24 h尿蛋白排泄量(100.47±43.42 mg)和一氧化氮水平(67.34±18.87μmol/L)显著升高(P<0.01);氨基胍组24 h尿蛋白排泄量(22.33±3.47 mg)增加(P<0.01),总一氧化氮合酶(23.34±3.10 kU/L)、诱导型一氧化氮合酶(14.84±1.98 kU/L)和结构型一氧化氮合酶(8.50±2.25 kU/L)降低(P<0.01,P<0.05)。与糖尿病对照组比较,8周末时L-精氨酸组24 h尿蛋白排泄量和一氧化氮均升高(P<0.05),总一氧化氮合酶、诱导型一氧化氮合酶和结构型一氧化氮合酶活性差异无显著性;氨基胍组与L-精氨酸组比较,上述5项指标均下降(P<0.05)。结论在糖尿病肾病早期应用L-精氨酸可增加血一氧化氮的合成,使24 h尿蛋白排泄量增加,损害肾功能;而早期应用氨基胍可降低血一氧化氮、一氧化氮合酶及24 h尿蛋白排泄量,保护肾功能。     

Binge Ethanol-Induced Brain Damage in Rats: Effect of Inhibitors of Nitric Oxide Synthase

Testing the possible role of endogenous nitric oxide (NO) in the neurotoxicity of ethanol, we examined how two different NO synthase (NOS) inhibitors affected the extent of cerebrocortical and olfactory neuronal damage in a modified "binge intoxication" rat model (Collins et al., Alcohol Clin. Exp. Res. 20:284–292, 1996). Male rats intragastrically fed ethanol (6.5 to 12 g/kg/day) in nutrient solution three times daily for 4 days also received N^G-nitro-L-arginine methyl ester by chronic intracerebroventricular infusion or 7-nitro-indazole by daily intraperitoneal injection; control rats were given nutrient solution only and/or vehicles. Blood ethanol levels did not differ among the ethanol-treated groups. The amount of ethanol-dependent neuronal degeneration in the entorhinal cortex, dentate gyrus, and olfactory bulb glomeruli—visualized with the de Olmos cupric silver stain and quantitatively assessed in the binge-intoxicated rats—was either unchanged or significantly increased by the NOS inhibitors. Although the efficacies of the inhibitors cannot be directly compared because various NOS forms were probably inhibited to differing extents, the results do not support the idea that endogenous NO is a neurotoxic mediator of ethanol's effects. Rather, NO may have a modest neuroprotectant role in this model of early brain damage induced by ethanol. In addition, the NOS that is localized histochemically as NADPH diaphorase was present primarily in regions and/or cells not damaged by binge ethanol treatment. Assuming that NADPH diaphorase represents most of the NO forming enzyme(s), this suggests a transcellular mechanism for NO. A further observation was that hippocampal CA pyramidal neuron degeneration was extensive in rats infused centrally with N^G-nitro-L-arginine methyl ester.     

氨氯地平对实验性兔动脉粥样硬化进程中一氧化氮合酶—一氧化氮和血红素氧合酶—一氧化碳系统的影响

目的探讨血红素氧合酶—一氧化碳和一氧化氮合酶—一氧化氮系统在动脉粥样硬化中的变化、相互关系及氨氯地平对动脉粥样硬化进程中血红素氧合酶—一氧化碳和一氧化氮合酶—一氧化氮的影响。方法家兔予以高胆固醇饮食8周,8周后停用高胆固醇饮食或另外给予喂饲氨氯地平进行药物干预8周。结果与对照组比较,模型组血脂水平明显升高,血清一氧化氮含量明显降低,血浆一氧化碳水平明显升高,血红素氧合酶1及诱导型一氧化氮合酶表达明显升高(P均<0.01)。与模型组比较,氨氯地平组血浆胆固醇、甘油三酯、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇差异无显著性(P>0.05);血清一氧化氮含量差异亦无显著性(P>0.05),血浆一氧化碳水平明显降低(P<0.01),血红素氧合酶1及诱导型一氧化氮合酶表达明显减少(P<0.01)。结论动脉粥样硬化进程中,血红素氧合酶—一氧化碳和一氧化氮合酶—一氧化氮系统显示出互补及代偿性调节作用,氨氯地平可以通过下调血红素氧合酶—一氧化碳和一氧化氮合酶—一氧化氮系统而延缓动脉粥样硬化的进程。     

Constitutive Expression of Inducible Nitric Oxide Synthase in the Normal Human Colonic Epithelium

Background: Inducible nitric oxide synthase (iNOS) in the human colon is considered expressed only in inflammatory states such as ulcerative or collagenous colitis. As subtle iNOS labelling was previously observed in some colonic mucosal biopsies from a heterogeneous group of controls with non-inflamed bowel, we studied whether bowel preparation with bisacodyl or polyethylene glycol prior to sigmoidoscopy might induce iNOS expression. Methods: Ten healthy, non-smoking male subjects were investigated. Mucosal biopsies were taken from the sigmoid colon prior to bowel preparation and again 12 h after rectal administration of bisacodyl or polyethylene glycol in randomized order. Expression of iNOS protein was quantified by Western blot analysis and localized by immunohistochemistry. Results: iNOS was expressed in the colonic mucosal biopsies from all subjects and localized in the epithelial cells, particularly at the luminal border of the epithelial cells and more pronounced in the crypt epithelium. The expression of iNOS was unaffected by bowel preparation with bisacodyl or polyethylene glycol. Conclusions: iNOS is constitutively expressed in the normal colonic epithelium. The results suggest that synthesis of iNOS protein is unaffected by bowel preparation with the secretagogue laxative, bisacodyl, or polyethylene glycol.     

Antagonism of Alcohol-Induced Suppression of Rat Testosterone Secretion by an Inhibitor of Nitric Oxide Synthase

To examine whether nitric oxide (NO) mediates the suppression of testosterone secretion by alcohol (ethanol), adult male rats were pretreated with a NO synthase inhibitor, N^G-nitro-L-arginine methyl ester (NAME), then treated with alcohol. Serum and testicular interstitial fluid (TIF) testosterone concentrations, serum luteiniring hormone (LH) concentrations, blood alcohol concentrations (BAC), and TIF volumes were measured 2 hr after alcohol treatment at a time of peak effects of alcohol and NAME on testosterone secretion. Pretreatment with NAME (30 or 100 mg/kg, subcutaneous) 30 min before alcohol treatment (0.5–3 g/kg, intraperitoneal) completely blocked the alcohol-induced suppression of testosterone secretion into the general circulation and into TIF without significantly altering blood alcohol concentrations (BAC) or TIF volumes. These results support the hypotheses that NO synthase inhibitors can antagonize alcohol induced suppression of testicular steroidogenesis, that alcohol interacts with arginine-NO synthase systems that regulate testicular steroidogenesis, and that NO is involved in mediating alcohol's testicular and reproductive effects.     

恒磁场对糖基化终产物作用下内皮细胞一氧化氮生成和一氧化氮合酶活性的影响

目的观察不同强度恒磁场对糖基化终产物作用下人脐静脉内皮细胞一氧化氮生成及一氧化氮合酶活性的影响。方法采用体外培养第3代人脐静脉内皮细胞,糖孵育法制备糖基化终产物修饰牛血清白蛋白。实验分为6组,即对照组、糖基化终产物修饰牛血清白蛋白(100μg/L)组及糖基化终产物修饰牛血清白蛋白+不同强度(1×10-4T、5×10-4T、10×10-4T2、0×10-4T)磁场组。各组细胞于培养及磁场作用24 h后收集标本,用Griess法检测培养上清中一氧化氮水平,并测定人脐静脉内皮细胞的一氧化氮合酶活性。结果糖基化终产物修饰牛血清白蛋白组一氧化氮含量和一氧化氮合酶活性较对照组明显降低(P<0.05)。1×10-4T、5×10-4T、10×10-4T和20×10-4T恒磁场组一氧化氮生成、一氧化氮合酶活性显著高于糖基化终产物修饰牛血清白蛋白组(P<0.05)。结论糖基化终产物修饰牛血清白蛋白可抑制人脐静脉内皮细胞的一氧化氮合酶活性和一氧化氮产生;1×10-4T~20×10-4T的恒磁场可呈强度依赖性拮抗糖基化终产物修饰牛血清白蛋白对一氧化氮生成的抑制效应。     

血红素氧合酶1—一氧化碳和一氧化氮合酶1—一氧化氮系统在动脉粥样硬化中的作用及其相关性研究

目的探讨血红素氧合酶1-一氧化碳和诱生型一氧化氮合酶-一氧化氮在动脉粥样硬化中的变化、相互关系及对动脉粥样硬化进程的影响. 方法家兔予以高胆固醇饮食(n=8)以及在高胆固醇饮食的同时经饮水给予L-精氨酸(n=8)或L-亚硝基精氨酸甲酯(n=8),或经腹腔注射血红素-L-赖氨酸盐(n=8)或锌原卟啉-9(n=8),共10周.结果与对照组比较,胆固醇组主动脉一氧化氮生成量显著减少,一氧化碳生成量则明显增加,一氧化氮合酶活性显著降低(P均<0.01),而血红素氧合酶1表达升高,主动脉斑块面积达40.2%±8.9%.与胆固醇组比较,外源性血红素-L-赖氨酸盐干预组的主动脉内膜斑块面积(26.6%±9.2%)明显缩小,主动脉一氧化碳的生成量和血红素氧合酶1的表达明显升高(P<0.01),但一氧化氮合酶活性和一氧化氮生成量较正常对照组显著降低(P<0.01),与胆固醇组比较则无显著性差异(P>0.05);与胆固醇组比较,外源性L-精氨酸组主动脉一氧化氮合酶活性显著升高, 一氧化氮生成量增加,主动脉斑块面积(28.1%±7.7%)明显缩小(P均<0.01),而血红素氧合酶1的表达和一氧化碳的生成较正常对照组明显升高,与胆固醇组比较则无显著性差异(P>0.05).与胆固醇组比较,血红素-L-赖氨酸盐干预组、L-精氨酸组的主动脉组织内c-myc及c-fos的mRNA和蛋白表达均显著降低(P均<0.01),而锌原卟啉组和L-亚硝基精氨酸甲酯组则无明显差异.结论动脉粥样硬化进程中,血红素氧合酶/一氧化碳和一氧化氮合酶/一氧化氮系统显示出互补及代偿性调节作用,血红素氧合酶系统通过对一氧化氮和一氧化氮合酶的调节和代偿机制抑制动脉粥样硬化病变的发展.     

褪黑素对内毒素血症大鼠胸主动脉诱导型一氧化氮合酶活性的影响

目的探讨诱导型一氧化氮合酶在褪黑素改善脂多糖诱导的体循环血管反应性失调中的作用。方法实验分为溶剂对照组、脂多糖组、脂多糖+褪黑素组和褪黑素组。制备离体胸主动脉环,应用血管张力检测技术检测各组血管环在诱导型一氧化氮合酶抑制剂氨基胍、或非特异性一氧化氮合酶抑制剂L-硝基精氨酸孵育前后对苯肾上腺素和乙酰胆碱的反应性变化;应用扫描电镜技术观察血管内皮超微形态学改变;酶法检测血管组织匀浆中诱导型一氧化氮合酶活性。结果褪黑素可显著改善脂多糖诱导的胸主动脉对缩血管剂苯肾上腺素的低反应性;氨基胍孵育后,脂多糖组和脂多糖+褪黑素组对苯肾上腺素的收缩反应分别提高了51.43%和24.53%,差异有显著性(P<0.01);与脂多糖组比较,脂多糖+褪黑素组的诱导型一氧化氮合酶活性显著降低(P<0.05)。结论褪黑素对诱导型一氧化氮合酶有一定的抑制作用,这可能是褪黑素改善内毒素血症大鼠的血管反应性失调的机制之一。