Effect of chronic ethanol administration on hepatic eNOS activity and its association with caveolin-1 and calmodulin in female rats

2005 ◽  
Vol 289 (3) ◽  
pp. G579-G585 ◽  
Author(s):  
Xu Wang ◽  
Abdel A. Abdel-Rahman
Keyword(s):  
Nitric Oxide ◽  
Liver Injury ◽  
Female Rats ◽  
Ethanol Administration ◽  
Inhibitory Protein ◽  
Dynamic Interactions ◽  
Excessive Alcohol Consumption ◽  
Caveolin 1 ◽  
Hepatic Expression ◽  
Enos Activity

Although chronic and excessive alcohol consumption is associated with liver disease, the mechanism of alcoholic liver injury is still not clear. Whether reduced hepatic production of nitric oxide, which is evident in models of liver injury, is associated with alcohol-induced liver injury has not been investigated. We measured nitric oxide synthase (NOS) activity in the liver of pair-fed rats receiving liquid diet with or without alcohol [3% (vol/vol)] for 12 wk. Compared with control rats, hepatic NOS activity was significantly reduced in alcohol-treated rats along with the evidence of liver injury. Interestingly, there was no difference in the hepatic expression of endothelial NOS (eNOS) between ethanol-fed and pair-fed rats. We then tested the hypothesis that an imbalance between the binding of eNOS with inhibitory and stimulatory proteins may underlie the reduced activity of eNOS because eNOS catalytic activity is regulated partly through dynamic interactions with the inhibitory protein caveolin-1 and the stimulatory protein calmodulin. We found that hepatic caveolin-1 was markedly increased in alcohol-treated rats compared with control rats, whereas calmodulin remained unaltered. The binding of caveolin-1 and calmodulin with eNOS was increased and decreased, respectively, in alcohol-treated rats. Our results suggest that chronic alcohol intake attenuates hepatic eNOS activity by increasing the expression of the inhibitory protein caveolin-1 and enhancing its binding with eNOS.

scholarly journals Role of nitric oxide in hepatic microvascular injury elicited by acetaminophen in mice

2004 ◽  
Vol 286 (1) ◽  
pp. G60-G67 ◽  
Author(s):  
Yoshiya Ito ◽  
Edward R. Abril ◽  
Nancy W. Bethea ◽  
Robert S. McCuskey
Keyword(s):  
Nitric Oxide ◽  
Liver Injury ◽  
Cell Injury ◽  
Parenchymal Cell ◽  
Protective Role ◽  
Hepatic Expression ◽  
Inos Inhibitor ◽  
Microcirculatory Disturbances

Nitric oxide (NO) is suggested to play a role in liver injury elicited by acetaminophen (APAP). Hepatic microcirculatory dysfunction also is reported to contribute to the development of the injury. As a result, the role of NO in hepatic microcirculatory alterations in response to APAP was examined in mice by in vivo microscopy. A selective inducible NO synthase (iNOS) inhibitor,l- N6-(1-iminoethyl)-lysine (l-NIL), or a nonselective NOS inhibitor, NG-nitro-l-arginine methyl ester (l-NAME), was intraperitoneally administered to animals 10 min before APAP gavage. l-NIL suppressed raised alanine aminotransferase (ALT) values 6 h after APAP, whereas l-NAME increased those 1.7-fold. Increased ALT levels were associated with hepatic expression of iNOS. l-NIL, but not l-NAME, reduced the expression. APAP caused a reduction (20%) in the numbers of perfused sinusoids. l-NIL restored the sinusoidal perfusion, but l-NAME was ineffective. APAP increased the area occupied by infiltrated erythrocytes into the extrasinusoidal space. l-NIL tended to minimize this infiltration, whereas l-NAME further enhanced it. APAP caused an increase (1.5-fold) in Kupffer cell phagocytic activity. This activity in response to APAP was blunted by l-NIL, whereas l-NAME further elevated it. l-NIL suppressed APAP-induced decreases in hepatic glutathione levels. These results suggest that NO derived from iNOS contributes to APAP-induced parenchymal cell injury and hepatic microcirculatory disturbances. l-NIL exerts preventive effects on the liver injury partly by inhibiting APAP bioactivation. In contrast, NO derived from constitutive isoforms of NOS exerts a protective role in liver microcirculation against APAP intoxication and thereby minimizes liver injury.

scholarly journals Endothelial Nitric Oxide Synthase and Its Negative Regulator Caveolin-1 Localize to Distinct Perinuclear Organelles

2002 ◽  
Vol 50 (6) ◽  
pp. 779-788 ◽  
Author(s):  
Roland Govers ◽  
Peter van der Sluijs ◽  
Elly van Donselaar ◽  
Jan-Willem Slot ◽  
Ton J. Rabelink
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Golgi Complex ◽  
Endothelial Nitric Oxide Synthase ◽  
Direct Interaction ◽  
Negative Regulator ◽  
Caveolin 1 ◽  
Enos Activity ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Caveolin-1 is a member of a subset of intracellular proteins that regulate endothelial nitric oxide synthase (eNOS) activity. In caveolae, caveolin-1 inhibits eNOS activity via a direct interaction with the enzyme. Previous work has indicated that both eNOS and caveolin-1 are also localized at the perinuclear Golgi complex. Whether caveolin-1 is involved in eNOS regulation in this cell compartment is unknown. Here we studied the localization of eNOS and caveolin-1 in the perinuclear region of primary bovine aortic endothelial cells. By immunofluorescence microscopy we show that both eNOS and caveolin-1 co-localize with Golgi markers. On treatment of the cells with the microtubule-depolymerizing drug nocodazole, the Golgi complex is scattered and caveolin-1 is found in vesicles at the periphery of the cell, while eNOS is localized at large structures near the nucleus. The nocodazole-induced redistribution of eNOS is similar to that of cis-, medial-, and trans-Golgi markers, while the caveolin-1 redistribution resembles that of sec22, a marker for the intermediate compartment. The localization of eNOS and caveolin-1 at distinct perinuclear compartments that behave differently in the presence of nocodazole indicates that eNOS activity is not regulated by caveolin-1 in the Golgi complex.

l-Arginine improves endothelial function, independently of arginine uptake, in aortas from chronic renal failure female rats

2014 ◽  
Vol 306 (4) ◽  
pp. F449-F456 ◽  
Author(s):  
Nachum Nesher ◽  
Inna Frolkis ◽  
Doron Schwartz ◽  
Tamara Chernichovski ◽  
Sharon Levi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Renal Failure ◽  
Chronic Renal Failure ◽  
Serum Levels ◽  
Female Rats ◽  
Ultrastructural Changes ◽  
Cationic Amino Acid ◽  
Enos Activity ◽  
Arginine Transport ◽  
Arginine Uptake

Endothelial cell dysfunction (ECD) is a common feature of chronic renal failure (CRF). Defective nitric oxide (NO) generation due to decreased endothelial nitric oxide synthase (eNOS) activity is a crucial parameter characterizing ECD. Decreased activity of cationic amino acid transporter-1 (CAT-1), the selective arginine transporter of eNOS, has been shown to inhibit eNOS in uremia. Recently, we failed to demonstrate a decrease in glomerular arginine transport in uremic female rats (Schwartz IF, Grupper A, Soetendorp H, Hillel O, Laron I, Chernichovski T, Ingbir M, Shtabski A, Weinstein T, Chernin G, Shashar M, Hershkoviz R, Schwartz D. Am J Physiol Renal Physiol 303: F396–F404, 2012). The current experiments were designed to determine whether sexual dimorphism which characterizes glomerular arginine transport system in uremia involves the systemic vasculature as well and to assess the effect of l-arginine in such conditions. Contractile and vasodilatory responses, ultrastructural changes, and measures of the l-arginine-NO system were performed in thoracic aortas of female rats subjected to ⅚ nephrectomy. The contractile response to KCl was significantly reduced, and acetylcholine-induced vasodilation was significantly impaired in aortas from CRF dames compared with healthy rats. Both of these findings were prevented by the administration of arginine in the drinking water. The decrease in both cGMP generation, a measure of eNOS activity, and aortic eNOS and phosphorylated eNOS abundance observed in CRF rats was completely abolished by l-arginine, while arginine transport and CAT-1 protein were unchanged in all experimental groups. Arginine decreased both serum levels of advanced glycation end products and the asymmetrical dimethylarginine/arginine ratio and restored the endothelial ultrastructure in CRF rats. In conclusion. arginine administration has a profound beneficial effect on ECD, independently of cellular arginine uptake, in CRF female rats.

scholarly journals Effect of dietary sodium on vasoconstriction and eNOS-mediated vascular relaxation in caveolin-1-deficient mice

2008 ◽  
Vol 294 (3) ◽  
pp. H1258-H1265 ◽  
Author(s):  
Luminita H. Pojoga ◽  
Tham M. Yao ◽  
Sumi Sinha ◽  
Reagan L. Ross ◽  
Jeffery C. Lin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Vascular Function ◽  
Sodium Intake ◽  
Dietary Sodium ◽  
Vascular Relaxation ◽  
Enos Expression ◽  
Vascular Contraction ◽  
Caveolin 1 ◽  
Enos Activity

Changes in dietary sodium intake are associated with changes in vascular volume and reactivity that may be mediated, in part, by alterations in endothelial nitric oxide synthase (eNOS) activity. Caveolin-1 (Cav-1), a transmembrane anchoring protein in the plasma membrane caveolae, binds eNOS and limits its translocation and activation. To test the hypothesis that endothelial Cav-1 participates in the dietary sodium-mediated effects on vascular function, we assessed vascular responses and nitric oxide (NO)-mediated mechanisms of vascular relaxation in Cav-1 knockout mice (Cav-1−/−) and wild-type control mice (WT; Cav-1+/+) placed on a high-salt (HS; 4% NaCl) or low-salt (LS; 0.08% NaCl) diet for 16 days. After the systolic blood pressure was measured, the thoracic aorta was isolated for measurement of vascular reactivity and NO production, and the heart was used for measurement of eNOS expression and/or activity. The blood pressure was elevated in HS mice treated with NG-nitro-l-arginine methyl ester and more so in Cav-1−/− than WT mice and was significantly reduced during the LS diet. Phenylephrine caused vascular contraction that was significantly reduced in Cav-1−/− (maximum 0.25 ± 0.06 g/mg) compared with WT (0.75 ± 0.22 g/mg) on the HS diet, and the differences were eliminated with the LS diet. Also, vascular contraction in response to membrane depolarization by high KCl (96 mM) was reduced in Cav-1−/− (0.27 ± 0.05 g/mg) compared with WT mice (0.53 ± 0.12 g/mg) on the HS diet, suggesting that the reduced vascular contraction is not limited to a particular receptor. Acetylcholine (10−5 M) caused aortic relaxation in WT mice on HS (23.6 ± 3.5%) and LS (23.7 ± 5.5%) that was enhanced in Cav-1−/− HS (72.6 ± 6.1%) and more so in Cav-1−/− LS mice (93.6 ± 3.5%). RT-PCR analysis indicated increased eNOS mRNA expression in the aorta and heart, and Western blots indicated increased total eNOS and phosphorylated eNOS in the heart of Cav-1−/− compared with WT mice on the HS diet, and the genotypic differences were less apparent during the LS diet. Thus Cav-1 deficiency during the HS diet is associated with decreased vasoconstriction, increased vascular relaxation, and increased eNOS expression and activity, and these effects are altered during the LS diet. The data support the hypothesis that endothelial Cav-1, likely through an effect on eNOS activity, plays a prominent role in the regulation of vascular function during substantial changes in dietary sodium intake.

Effects of calcium channel antagonists on LPS-induced hepatic iNOS expression

1999 ◽  
Vol 277 (2) ◽  
pp. G351-G360 ◽  
Author(s):  
Shamimunisa B. Mustafa ◽  
Merle S. Olson
Keyword(s):  
Nitric Oxide ◽  
Liver Injury ◽  
Calcium Channel ◽  
Mrna Expression ◽  
Time Course ◽  
Inos Expression ◽  
Inos Mrna ◽  
Calcium Channel Antagonists ◽  
Hepatocellular Injury ◽  
Inhibitory Protein

The onset of liver injury is a pivotal event during endotoxemia. Lipopolysaccharide (LPS) activates the Kupffer cells (KC), the resident macrophages of the liver, to generate an abundance of inflammatory substances, including nitric oxide (NO). Elevated levels of NO are thought to contribute to the propagation of liver injury during sepsis. Calcium, a major second messenger in several cellular signaling events, is required by the KC for the generation of inducible nitric oxide synthase (iNOS). The purpose of this study was to determine whether calcium channel antagonists limit hepatic injury and iNOS expression in vivo following LPS exposure and to evaluate their effects on the regulation of iNOS expression in cultured KC. In rats subjected to LPS for 6 h, the serum alanine aminotransferase (ALT) level was elevated significantly; this response was accompanied by an increase in iNOS mRNA formation in the intact liver. Pretreatment of rats with calcium channel antagonists (i.e., diltiazem, nifedipine, or verapamil) before LPS exposure attenuated the serum ALT level and iNOS mRNA expression in the liver. Pretreatment of cultured KC with calcium channel antagonists for 1 h followed by the addition of LPS markedly repressed iNOS protein and mRNA expression. Time-course studies revealed that calcium channel antagonists were most effective at inhibiting LPS-induced iNOS mRNA formation by KC when added before LPS. Treatment of KC with calcium channel antagonists prior to the addition of LPS decreased nuclear levels of the p65 subunit of nuclear factor-κB and prevented the LPS-dependent degradation of the inhibitory protein IκBα. Thus our findings indicate that under endotoxemic conditions calcium channel antagonists limit hepatocellular injury that is accompanied by an inhibition of LPS-mediated iNOS expression in rat liver KC.

scholarly journals Gut Microbial Trimethylamine is Elevated in Alcohol-Associated Hepatitis and Contributes to Ethanol-Induced Liver Injury in Mice

2022 ◽  
Author(s):  
Robert N Helsley ◽  
Tatsunori Miyata ◽  
Anagha Kadam ◽  
Varadharajan Venkateshwari ◽  
Naseer Sangwan ◽  
...  
Keyword(s):  
Liver Injury ◽  
Gut Microbiome ◽  
Ethanol Administration ◽  
Microbial Metabolite ◽  
Gut Microbes ◽  
Hepatic Expression ◽  
Small Molecule Inhibition ◽  
Liver Transcriptome ◽  
Liquid Chromatography Tandem Mass ◽  
The Impact

Background:There is mounting evidence that microbes resident in the human intestine contribute to diverse alcohol-associated liver diseases (ALD) including the most deadly form known as alcohol-associated hepatitis (AH). However, mechanisms by which gut microbes synergize with excessive alcohol intake to promote liver injury are poorly understood. Furthermore, whether drugs that selectively target gut microbial metabolism can improve ALD has never been tested. Methods: We used liquid chromatography tandem mass spectrometry to quantify the levels of microbe and host choline co-metabolites in healthy controls and AH patients, finding elevated levels of the microbial metabolite trimethylamine (TMA) in AH. In subsequent studies, we treated mice with non-lethal bacterial choline TMA lyase (CutC/D) inhibitors to blunt gut microbedependent production of TMA in the context of chronic ethanol administration. Indices of liver injury were quantified by complementary RNA sequencing, biochemical, and histological approaches. In addition, we examined the impact of ethanol consumption and TMA lyase inhibition on gut microbiome structure via 16S rRNA sequencing. Results: We show the gut microbial choline metabolite trimethylamine (TMA) is elevated in AH patients and correlates with reduced hepatic expression of the TMA oxygenase flavin-containing monooxygenase 3 (FMO3). Provocatively, we find that small molecule inhibition of gut microbial CutC/D activity protects mice from ethanol-induced liver injury. CutC/D inhibitor-driven improvement in ethanol-induced liver injury is associated with distinct reorganization of the gut microbiome and host liver transcriptome. Conclusions: The microbial metabolite TMA is elevated in patients with AH, and inhibition of TMA production from gut microbes can protect mice from ethanol-induced liver injury.

scholarly journals Fat-1 Transgenic Mice With Augmented n3-Polyunsaturated Fatty Acids Are Protected From Liver Injury Caused by Acute-On-Chronic Ethanol Administration

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeffrey Warner ◽  
Josiah Hardesty ◽  
Ying Song ◽  
Rui Sun ◽  
Zhongbin Deng ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Liver Disease ◽  
Liver Injury ◽  
Polyunsaturated Fatty Acids ◽  
Dietary Fatty Acids ◽  
Ethanol Administration ◽  
Protective Effects ◽  
Hepatic Expression ◽  
N3 Polyunsaturated Fatty Acids ◽  
Pai 1

Alcohol-associated liver disease (ALD) is the leading cause of liver disease worldwide, and alcohol-associated hepatitis (AH), a severe form of ALD, is a major contributor to the mortality and morbidity due to ALD. Many factors modulate susceptibility to ALD development and progression, including nutritional factors such as dietary fatty acids. Recent work from our group and others showed that modulation of dietary or endogenous levels of n6-and n3-polyunsaturated fatty acids (PUFAs) can exacerbate or attenuate experimental ALD, respectively. In the current study, we interrogated the effects of endogenous n3-PUFA enrichment in a mouse model which recapitulates features of early human AH using transgenic fat-1 mice which endogenously convert n6-PUFAs to n3-PUFAs. Male wild type (WT) and fat-1 littermates were provided an ethanol (EtOH, 5% v/v)-containing liquid diet for 10 days, then administered a binge of EtOH (5 g/kg) by oral gavage on the 11th day, 9 h prior to sacrifice. In WT mice, EtOH treatment resulted in liver injury as determined by significantly elevated plasma ALT levels, whereas in fat-1 mice, EtOH caused no increase in this biomarker. Compared to their pair-fed controls, a significant EtOH-mediated increase in liver neutrophil infiltration was observed also in WT, but not fat-1 mice. The hepatic expression of several cytokines and chemokines, including Pai-1, was significantly lower in fat-1 vs WT EtOH-challenged mice. Cultured bone marrow-derived macrophages isolated from fat-1 mice expressed less Pai-1 and Cxcl2 (a canonical neutrophil chemoattractant) mRNA compared to WT when stimulated with lipopolysaccharide. Further, we observed decreased pro-inflammatory M1 liver tissue-resident macrophages (Kupffer cells, KCs), as well as increased liver T regulatory cells in fat-1 vs WT EtOH-fed mice. Taken together, our data demonstrated protective effects of endogenous n3-PUFA enrichment on liver injury caused by an acute-on-chronic EtOH exposure, a paradigm which recapitulates human AH, suggesting that n3-PUFAs may be a viable nutritional adjuvant therapy for this disease.

scholarly journals Caveolin-1 mediates endotoxin inhibition of endothelin-1-induced endothelial nitric oxide synthase activity in liver sinusoidal endothelial cells

2009 ◽  
Vol 297 (5) ◽  
pp. G930-G939 ◽  
Author(s):  
Willson Kwok ◽  
Sang Ho Lee ◽  
Cathy Culberson ◽  
Katarzyna Korneszczuk ◽  
Mark G. Clemens
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Nitric Oxide Synthase ◽  
Molecular Mechanism ◽  
Endothelial Nitric Oxide Synthase ◽  
Liver Sinusoidal Endothelial Cells ◽  
Caveolin 1 ◽  
Enos Activity ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Endothelin-1 (ET-1) plays a key role in the regulation of endothelial nitric oxide synthase (eNOS) activation in liver sinusoidal endothelial cells (LSECs). In the presence of endotoxin, an increase in caveolin-1 (Cav-1) expression impairs ET-1/eNOS signaling; however, the molecular mechanism is unknown. The objective of this study was to investigate the molecular mechanism of Cav-1 in the regulation of LPS suppression of ET-1-mediated eNOS activation in LSECs by examining the effect of caveolae disruption using methyl-β-cyclodextrin (CD) and filipin. Treatment with 5 mM CD for 30 min increased eNOS activity (+255%, P < 0.05). A dose (0.25 μg/ml) of filipin for 30 min produced a similar effect (+111%, P < 0.05). CD induced the perinuclear localization of Cav-1 and eNOS and stimulated NO production in the same region. Readdition of 0.5 mM cholesterol to saturate CD reversed these effects. Both the combined treatment with CD and ET-1 (CD + ET-1) and with filipin and ET-1 stimulated eNOS activity; however, pretreatment with endotoxin (LPS) abrogated these effects. Following LPS pretreatment, CD + ET-1 failed to stimulate eNOS activity (+51%, P > 0.05), which contributed to the reduced levels of eNOS-Ser1177 phosphorylation and eNOS-Thr495 dephosphorylation, the LPS/CD-induced overexpression and translocation of Cav-1 in the perinuclear region, and the increased perinuclear colocalization of eNOS with Cav-1. These results supported the hypothesis that Cav-1 mediates the action of endotoxin in suppressing ET-1-mediated eNOS activation and demonstrated that the manipulation of caveolae produces significant effects on ET-1-mediated eNOS activity in LSECs.

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