Wie altern Gefäße?  Mechanismen und klinische Implikationen

Altern ist ein wichtiger kardialer und vaskulärer Risikofaktor. Für das Gefäßaltern sind genetische, mechanische und hämodynamische Faktoren ausschlaggebend. So sind altersabhängige Veränderungen in Gefäßen, welche weniger Pulsatilität und Blutdruck ausgesetzt sind, wie Kapillaren und Venen, geringer oder abwesend. Vor allem in den großen Widerstandsgefäßen kommt es im Laufe des Alterns morphologisch zu einer Intima- und Mediaverdickung, verknüpft mit einer vermehrten Einlagerung von Matrixsubstanzen, und letztlich resultierend in verminderter Compliance der Gefäße. Es lassen sich Funktionsstörungen des Endothels nachweisen. Hier kommt es zu einer deutlichen Heraufregulierung der endothelialen Nitric Oxide Synthase (eNOS), welche für die Produktion des endogenen Vasodilatators Nitric Oxide (NO) verantwortlich ist. Paradoxerweise sind trotzdem die Vasorelaxationen im Alter vermindert, da es gleichzeitig zu einer erhöhten Produktion freier Radikale, im Besonderen Superoxid (O2-) kommt. O2- und NO bilden in einer schnell ablaufenden chemischen Reaktion Peroxinitrit (ONOO-), welches Proteine nitriert. Durch diese Nitrierung kommt es zur funktionellen Beeinträchtigung dieser Proteine, so dass verschiedene Signalübertragungswege, z.B. Tyrosilierung von Enzymen, blockiert werden. Primärer Ort der Bildung freier Sauerstoffradikale sind die endothelialen Mitochondrien. Bislang ungeklärt ist, ob der oxidative Stress als ein zentrales Ereignis des Gefäßalterns pharmakologisch beeinflussbar ist. Hier standen vor allem antioxidativ wirkende Vitamine im Mittelpunkt des Interesses. Überraschenderweise wird jedoch Vitamin E im Tiermodell vermehrt mit steigendem Alter in der aortalen Wand eingelagert, was im Rahmen eines altersassoziierten gegenregulatorischen Mechanismus zur Abwendung des vermehrten oxidativen Stresses erfolgt. Umgekehrt ist Vitamin C signifikant vermindert. Es bleibt abzuwarten, ob das Gefäßaltern durch Vitamin C oder andere Antioxidantien günstig beeinflusst werden kann. Für Statine und ACE-Hemmer wurden schon Wirkungen beschrieben, die mit Schlüsselmechanismen des Gefäßalterungsprozesses interferieren. Die Entwicklung therapeutischer Interventionen zur Verlangsamung des Gefäßalterns wird für das Auftreten von Herz- und Gefäßerkrankungen im Alter in Zukunft große Bedeutung haben.

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The protective effect of vitamin C, vitamin E and selenium combination therapy on ethanol-induced duodenal mucosal injury

Human & Experimental Toxicology ◽

10.1191/0960327104ht468oa ◽

2004 ◽

Vol 23 (8) ◽

pp. 391-398 ◽

Cited By ~ 11

Author(s):

M Koyuturk ◽

S Bolkent ◽

S Ozdil ◽

S Arbak ◽

R Yanardag

Keyword(s):

Nitric Oxide ◽

Vitamin E ◽

Nitric Oxide Synthase ◽

Vitamin C ◽

Protective Effect ◽

Neuronal Nitric Oxide Synthase ◽

Mucosal Injury ◽

The Other ◽

Absolute Ethanol ◽

Oxide Synthase

In this study, the effect of a combination of vitamin C, vitamin E and selenium on ethanol-induced duodenal mucosal damage in rats was investigated morphologi-cally and biochemically. The duodenal mucosal injury was produced by oral administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg) and selenium (0.5 mg/kg) for 3 days and absolute ethanol 1 hour after last antioxidant administration and were sacrificed 1 hour after absolute ethanol. Extreme degeneration in intestinal mucosa of rats given ethanol was observed morphologically. In addition, an increase in neuronal nitric oxide synthase immunoreactive areas was observed in the rats of the group given ethanol. On the other hand, a normal morphological appearance and a decrease in neuronal nitric oxide synthase immunoreactive areas were detected in the rats given ethanol+vitamin C+vitamin E+selenium. In the group to which ethanol was administered, an increase in serum cholesterol and a decrease in serum albumin levels were determined. On the other hand, in the group to which ethanol+vitamin C+vitamin E+selenium were administered, serum cholesterol value decreased, and the serum albumin level increased. As a result, we can say that the combination of vitamin C, vitamin E and selenium has a protective effect on ethanolinduced duodenal mucosal injury.

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Oxidative stress response in sugarcane

Genetics and Molecular Biology ◽

10.1590/s1415-47572001000100014 ◽

2001 ◽

Vol 24 (1-4) ◽

pp. 93-102 ◽

Cited By ~ 16

Author(s):

Luis Eduardo Soares Netto

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Molecular Weight ◽

Stress Response ◽

Nitric Oxide Synthase ◽

Vitamin C ◽

Antioxidant Defense ◽

Oxidative Stress Response ◽

Low Molecular Weight ◽

Oxide Synthase

Oxidative stress response in plants is still poorly understood in comparison with the correspondent phenomenon in bacteria, yeast and mammals. For instance, nitric oxide is assumed to play various roles in plants although no nitric oxide synthase gene has yet been isolated. This research reports the results of a search of the sugarcane expressed sequence tag (SUCEST) database for homologous sequences involved in the oxidative stress response. I have not found any gene similar to nitric oxide synthase in the SUCEST database although an alternative pathway for nitric oxide synthesis was proposed. I have also found several genes involved in antioxidant defense, e.g. metal chelators, low molecular weight compounds, antioxidant enzymes and repair systems. Ascorbate (vitamin C) is a key antioxidant in plants because it reaches high concentrations in cells and is a substrate for ascorbate peroxidase, an enzyme that I found in different isoforms in the SUCEST database. I also found many enzymes involved in the biosynthesis of low molecular weight antioxidants, which may be potential targets for genetic manipulation. The engineering of plants for increased vitamin C and E production may lead to improvements in the nutritional value and stress tolerance of sugarcane. The components of the antioxidant defense system interact and their synthesis is probably closely regulated. Transcription factors involved in regulation of the oxidative stress response in bacteria, yeast and mammals differ considerably among themselves and when I used them to search the SUCEST database only genes with weak similarities were found, suggesting that these transcription regulators are not very conserved. The involvement of reactive oxygen species and antioxidants in plant defense against pathogens is also discussed.

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Role of TLR-4/IL-6/TNF-α, COX-II and eNOS/iNOS pathways in the impact of carvedilol against hepatic ischemia reperfusion injury

Human & Experimental Toxicology ◽

10.1177/0960327121999442 ◽

2021 ◽

pp. 096032712199944

Author(s):

Mohamed IA Hassan ◽

Fares EM Ali ◽

Abdel-Gawad S Shalkami

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Inducible Nitric Oxide Synthase ◽

Liver Enzymes ◽

Ischemia Reperfusion ◽

Hepatic Ischemia ◽

Hepatic Ischemia Reperfusion ◽

Oxide Synthase ◽

Inducible Nitric Oxide

Aim: Hepatic ischemia/reperfusion (I/R) injury is a syndrome involved in allograft dysfunction. This work aimed to elucidate carvedilol (CAR) role in hepatic I/R injury. Methods: Male rats were allocated to Sham group, CAR group, I/R group and CAR plus I/R group. Rats subjected to hepatic ischemia for 30 minutes then reperfused for 60 minutes. Oxidative stress markers, inflammatory cytokines and nitric oxide synthases were measured in hepatic tissues. Results: Hepatocyte injury following I/R was confirmed by a marked increase in liver enzymes. Also, hepatic I/R increased the contents of malondialdehyde however decreased glutathione contents and activities of antioxidant enzymes. Furthermore, hepatic I/R caused elevation of toll-like receptor-4 (TLR-4) expression and inflammatory mediators levels such as tumor necrosis factor-α, interleukin-6 and cyclooxygenase-II. Hepatic I/R caused down-regulation of endothelial nitric oxide synthase and upregulation of inducible nitric oxide synthase expressions. CAR treatment before hepatic I/R resulted in the restoration of liver enzymes. Administration of CAR caused a significant correction of oxidative stress and inflammation markers as well as modulates the expression of endothelial and inducible nitric oxide synthase. Conclusions: CAR protects liver from I/R injury through reduction of the oxidative stress and inflammation, and modulates endothelial and inducible nitric oxide synthase expressions.

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Endothelial PPAR-γ provides vascular protection from IL-1β-induced oxidative stress

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00490.2015 ◽

2016 ◽

Vol 310 (1) ◽

pp. H39-H48 ◽

Cited By ~ 20

Author(s):

Masashi Mukohda ◽

Madeliene Stump ◽

Pimonrat Ketsawatsomkron ◽

Chunyan Hu ◽

Frederick W. Quelle ◽

...

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Endothelial Dysfunction ◽

Nitric Oxide Synthase ◽

Transgenic Mice ◽

Stress Responses ◽

Endothelial Nitric Oxide Synthase ◽

Ppar Γ ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Loss of peroxisome proliferator-activated receptor (PPAR)-γ function in the vascular endothelium enhances atherosclerosis and NF-κB target gene expression in high-fat diet-fed apolipoprotein E-deficient mice. The mechanisms by which endothelial PPAR-γ regulates inflammatory responses and protects against atherosclerosis remain unclear. To assess functional interactions between PPAR-γ and inflammation, we used a model of IL-1β-induced aortic dysfunction in transgenic mice with endothelium-specific overexpression of either wild-type (E-WT) or dominant negative PPAR-γ (E-V290M). IL-1β dose dependently decreased IκB-α, increased phospho-p65, and increased luciferase activity in the aorta of NF-κB-LUC transgenic mice. IL-1β also dose dependently reduced endothelial-dependent relaxation by ACh. The loss of ACh responsiveness was partially improved by pretreatment of the vessels with the PPAR-γ agonist rosiglitazone or in E-WT. Conversely, IL-1β-induced endothelial dysfunction was worsened in the aorta from E-V290M mice. Although IL-1β increased the expression of NF-κB target genes, NF-κB p65 inhibitor did not alleviate endothelial dysfunction induced by IL-1β. Tempol, a SOD mimetic, partially restored ACh responsiveness in the IL-1β-treated aorta. Notably, tempol only modestly improved protection in the E-WT aorta but had an increased protective effect in the E-V290M aorta compared with the aorta from nontransgenic mice, suggesting that PPAR-γ-mediated protection involves antioxidant effects. IL-1β increased ROS and decreased the phospho-endothelial nitric oxide synthase (Ser1177)-to-endothelial nitric oxide synthase ratio in the nontransgenic aorta. These effects were completely abolished in the aorta with endothelial overexpression of WT PPAR-γ but were worsened in the aorta with E-V290M even in the absence of IL-1β. We conclude that PPAR-γ protects against IL-1β-mediated endothelial dysfunction through a reduction of oxidative stress responses but not by blunting IL-1β-mediated NF-κB activity.

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