Junbao Du

Role of Hydrogen Sulfide in the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

Objective—We explored the effect of hydrogen sulfide (H2S) on atherosclerotic progression, particularly on intracellular adhesion molecule-1 (ICAM-1) in apolipoprotein-E knockout (apoE−/−) mice and human umbilical vein endothelial cells (HUVECs). Methods and Results—ApoE−/− mice were treated with sodium hydrosulfide (NaHS) or DL-propargylglycine (PPG); HUVECs were pretreated with NaHS. Compared with control mice, apoE−/− mice showed decreased plasma H2S level and aortic H2S production but increased plasma ICAM-1 and aortic ICAM-1 protein and mRNA. Compared with apoE−/− mice, apoE−/−+NaHS mice showed increased plasma H2S level, but decreased size of atherosclerotic plaque and plasma and aortic ICAM-1 levels, whereas apoE−/−+PPG mice showed decreased plasma H2S level but enlarged plaque size and increased plasma and aortic ICAM-1 levels. NaHS suppressed ICAM-1 expression in tumor necrosis factor (TNF)-&agr;–treated HUVECs. NaHS inhibited I&kgr;B degradation and NF-&kgr;B nuclear translocation in HUVECs treated with TNF-&agr;. Conclusions—The vascular CSE/H2S pathway was disturbed in apoE−/− mice. H2S exerted an antiatherogenic effect and inhibited ICAM-1 expression in apoE−/− mice. H2S inhibited ICAM-1 expression in TNF-&agr;-induced HUVECs via the NF-&kgr;B pathway.

Therapeutic effects of ghrelin on endotoxic shock in rats.

We investigated the effects of ghrelin in a rat endotoxic shock model, and also observed the direct role of endotoxin on ghrelin generation in gastric mucosa. About 55% (11/20) of rats treated with lipopolysaccharide (5 mg/kg i.v.) alone died within 24 h of endotoxin injection. However, administration of ghrelin either at the same time as lipopolysaccharide injection (early treatment) or 12 h after lipopolysaccharide injection (late treatment) significantly decreased the mortality rate and ameliorated the hypotension seen in rats with endotoxic shock. Early and late treatment with ghrelin increased markedly the plasma glucose concentration and decreased the plasma lactate concentration. Early treatment with ghrelin attenuated significantly the deficiency in myocardial ATP content, but late treatment with ghrelin had no effect on myocardial ATP content. The plasma ghrelin level was significantly increased in the rats with endotoxin shock, and it increased further after ghrelin administration. Exposure of rat gastric mucosa in vitro to lipopolysaccharide (1.0 to 100 microg/ml) triggered the release of ghrelin from mucosa tissue in a dose- and time-dependent manner, meaning that lipopolysaccharide stimulated directly gastric mucosa to synthesize and secrete ghrelin. The results suggest that ghrelin could have therapeutic value for endotoxic shock.

Hydrogen Sulfide as a New Endogenous Gaseous Transmitter in the Cardiovascular System

Hydrogen sulfide (H(2)S) is a well-known toxic gas with the smell of rotten eggs. Recent studies have shown that H(2)S is generated in vivo in human and animal organisms and that it participates in many pathophysiological processes. H(2)S is produced endogenously in mammalian tissues from L-cysteine metabolism mainly by 3 enzymes: cystathionine beta-synthetase (CBS), cystathionine gamma-lyase (CSE) and 3-mercaptosulfurtransferase (MST). H(2)S may not only function as a neuromodulator in the central nervous system but it also relaxes gastrointestinal smooth muscles. More importantly, present evidence shows that H(2)S exerts regulatory effects on the pathogenesis of various cardiovascular diseases such as hypertension, pulmonary hypertension, shock and myocardial injury. The genomic basis of cystathioninuria in humans is 2 nonsense and 2 sense mutations in CSE. This review reveals that H(2)S is a new endogenous gaseous transmitter in the cardiovascular system.

Endogenously generated sulfur dioxide and its vasorelaxant effect in rats

AbstractAim:The present study was designed to explore the endogenous production and localization of the sulfur dioxide (SO2)/aspartate aminotransferase pathway in vascular tissues of rats and to examine its vasorelaxant effect on isolated aortic rings, as well as the possible mechanisms.Methods:The content of SO2 in the samples was determined by using high performance liquid chromatography with fluorescence detection. Aspartate aminotransferase activity and its gene expression were measured by an enzymatic method and quantitative RT–PCR, respectively. Aspartate aminotransferase mRNA location in aorta was detected by in situ hybridization. The vasorelaxant effect of SO2 on isolated aortic rings of the rats was investigated in vitro. L-type calcium channel blocker, nicardipine, and L-type calcium channel agonist, Bay K8644, were used to explore the mechanisms by which SO2 relaxed the aortic rings.Results:Aorta had the highest SO2 content among the vascular tissues tested (P<0.01). The aortic aspartate aminotransferase mRNA located in endothelia and vascular smooth muscle cells beneath the endothelial layer. Furthermore, a physiological dose of the SO2 derivatives (Na2SO3/NaHSO3) relaxed isolated artery rings slightly, whereas higher doses (1–12 mmol/L) relaxed rings in a concentration-dependent manner. Pretreatment with nicardipine eliminated the vasorelaxant response of the norepinephrine-contracted rings to SO2 completely. Incubation with nicardipine or SO2 derivatives successfully prevented vasoconstriction induced by Bay K8644.Conclusion:Endogenous SO2 and its derivatives have a vasorelaxant function, the mechanisms of which might involve the inhibition of the L-type calcium channel.

Regulatory effects of hydrogen sulfide on IL-6, IL-8 and IL-10 levels in the plasma and pulmonary tissue of rats with acute lung injury.

We examined the possible role of hydrogen sulfide (H2S) in the pathogenesis of oleic acid (OA)-induced acute lung injury (ALI) and its regulatory effects on the inflammatory response. Compared to control rats, the OA-treated rats had decreased partial pressure of oxygen in the arterial blood (PaO2) levels, an increased pulmonary wet/dry weight (W/D) ratio, increased index of quantitative assessment (IQA) score and increased frequency of polymorphonuclear (PMN) cells in the lung 2, 4 or 6 h after OA injection (0.1 ml/kg, intravenous injection). In addition, significantly increased IL-6, IL-8 and IL-10 levels together with decreased H2S levels were observed in the plasma and lung tissue of OA-treated rats compared to controls. Administration of the H2S donor sodium hydrosulfide (NaHS, 56 μmol/L, intraperitoneal injection) into OA-treated rats increased the PaO2 level, reduced the lung W/D ratio and infiltration of PMN cells, and alleviated the degree of ALI (measured by the IQA score). In addition, NaHS decreased IL-6 and IL-8 levels but increased IL-10 levels in the plasma and lung tissues, suggesting that H2S may regulate the inflammatory response during ALI via regulation of IL-6, IL-8 and IL-10. Thus, the down-regulation of endogenous H2S production might be involved in the pathogenesis of OA-induced ALI in rats.

Hydrogen Sulfide and Carbon Monoxide Are in Synergy with Each Other in the Pathogenesis of Recurrent Febrile Seizures

Summary1.The purpose of the present study was to investigate the interaction between hydrogen sulfide (H2S) and carbon monoxide (CO) during recurrent febrile seizures (FS)2.H2S and CO are important intra- and intercellular messengers, regulating various brain functions. Our recent studies showed that both of them alleviate the hippocampal damage induced by recurrent FS. In the present study, on a rat model of recurrent FS, we found that hydroxylamine (an inhibitor of cystathionine b-synthase, CBS) reduced CO level and downregulated heme oxygenase (HO-1) expression, while NaHS (a donor of H2S) elevated CO level and upregulated HO-1 expression. ZnPP-IX (an inhibitor of HO-1) decreased H2S formation and downregulated CBS expression, while hemin (which increases the production of endogenous CO) enhanced H2S formation and elevated CBS expression.3.Our data demonstrate that endogenous H2S and CO are in synergy with each other in recurrent FS.

Hydrogen sulfide regulates lung tissue-oxidized glutathione and total antioxidant capacity in hypoxic pulmonary hypertensive rats

AbstractAim:To investigate the modulatory effect of sudium hydrosulfide on lung tissue-oxidized glutathione and total antioxidant capacity in the development of hypoxic pulmonary hypertension (HPH).Methods:After 21 d of hypoxia, the mean pulmonary artery pressure was measured by cardiac catheterization. The plasma H2S level and production of H2S in the lung tissues were determined by using a spectrophotometer. The lung homogenates were assayed for total antioxidant capacity (T-AOC), superoxide dismutase (SOD), oxidized glutathione (GSSG), reduced glutathione and malonaldehyde by colorimetry. The mRNA level of SOD was analyzed by real-time PCR, and the SOD expression was detected by Western blotting.Results:In the hypoxia group, the plasma H2S concentration and H2S production in the lung was significantly decreased compared with the control group (187.2±13.1 vs 299.6±12.4 μmol/L; 0.138±0.013 vs 0.289±0.036 nmol·mg−1·min−1, P<0.01). The administration of sodium hydrosulfide could reduce the mean pulmonary artery pressure by 31.2% compared with the hypoxia group (P<0.01). Treatment with sodium hydrosulfide decreased GSSG, and the T-AOC level of the lung tissues was enhanced compared with the hypoxia group (P<0.05). There were no significant changes in the lung tissue SOD mRNA level, protein level, and its activity among the 3 groups.Conclusion:Oxidative stress occurred in the development of HPH and was accompanied by a decrease in the endogenous production of H2S in the lung tissues. H2S acted as an antioxidant during the oxidative stress of HPH partly as a result of the attenuated GSSG content.

Hydrogen Sulfide Attenuates Hyperhomocysteinemia-Induced Cardiomyocytic Endoplasmic Reticulum Stress in Rats

The mechanisms responsible for the cardioprotective effect of hydrogen sulfide (H(2)S) are unclear. The present study was designed to examine whether H(2)S could regulate hyperhomocysteinemia (HHcy)-induced cardiomyocytic endoplasmic reticulum (ER) stress. A rat model of HHcy was produced, and H9c2 cells (rat embryonic heart-derived cell line) were cultured. The plasma homocysteine was measured by using HPLC. Plasma H(2)S concentration and myocardial H(2)S production were measured with a sulfide-sensitive electrode. Confocal immunofluorescent analysis for cardiomyocytic C/EBP homologous protein (CHOP) was performed. Glucose-regulated protein 78 (GRP78), CHOP, and caspase 12 expressions by myocardial tissues and cleaved caspase 12 and p-eIF2alpha expressions by H9c2 cells were detected with Western blotting. The results showed that methionine overload induced HHcy, resulting in a marked cardiomyocytic ER stress, whereas endogenous production of H(2)S was reduced in rats with HHcy. H(2)S supplementation, however, decreased expressions of ER stress-associated proteins, including GRP78, CHOP, and caspase 12, by myocardial tissues in vivo. The inhibition of endogenous H(2)S production further enhanced cardiomyocytic ER stress, but H(2)S supplementation effectively antagonized the H9c2 cell CHOP, cleaved caspase 12 and p-eIF2alpha expressions induced by Hcy, thapsigargin, or tunicamycin in vitro. The results suggest that H(2)S can attenuate cardiomyocytic ER stress in HHcy-induced cardiomyocytic injury.

Effect of chronic hypoxia on contents of urotensin II and its functional receptors in rat myocardium.

Abstract The cyclic peptide urotensin II (UII) has recently been cloned in mammals and reported to constrict rat pulmonary arteries potently. An enhanced maximal response was shown in rats exposed to chronic hypoxia. The aim of this study was to investigate changes in plasma and myocardial UII levels and its receptor sites in crude sarcolemma of ventricles from chronic hypoxic rats. We observed that rats exposed to chronic hypoxia for 4 weeks developed pulmonary hypertension and right ventricular hypertrophy. Compared with controls, the UII content in hypoxic rats was increased by 97.5% (45.24 ± 7.1 vs. 22.9 ± 3.24 pg/mg protein, P < 0.01) in the right ventricle and 33.2% (24.89 ± 0.99 vs. 18.68 ± 2.04 pg/mg protein, P < 0.01) in the left ventricle, respectively. However, there was no significant difference in plasma (27.44 ± 3.11 vs. 27.82 ± 5.57 pg/ml, P > 0.05) and lung tissue levels (34.03 ± 4.63 vs. 33.74 ± 4.06 pg/mg protein, P > 0.05) between the control and hypoxic groups. The time course of the binding of [125I]UII to crude ventricular sarcolemma was specific and time dependent. Scatchard plot analysis of the data demonstrated that the maximal number of specific binding sites (Bmax) in both the right and left ventricles was upregulated in the hypoxic group. Moreover, Bmax in the right ventricular specimens was upregulated to a greater extent than in the left ventricle (increased by 114% and 25% in the right and left ventricles, respectively, compared with control group, P < 0.01). In contrast, the UII binding affinity in right and left ventricular membranes from hypoxic rats was decreased (the dissociation constant Kd) increased by 20% and 33%, respectively compared with controls, P < 0.01). These results indicate that UII may act as an autocrine and/or paracrine hormone rather than as a circulating hormone, playing important roles in the development of ventricular hypertrophy induced by chronic hypoxia, and that the pathophysiologi-cal significance of UII in pulmonary and cardiovascular alteration induced by chronic hypoxia deserves further investigation.

Modulating effect of hydrogen sulfide on gamma-aminobutyric acid B receptor in recurrent febrile seizures in rats

Hydrogen sulfide (H2S) is recognized as a new neuromodulator in regulating various brain functions. Some of our recent studies showed that H2S alleviates the hippocampal damage induced by recurrent febrile seizures (FS). In the present study, we used a rat model of recurrent FS and found that sodium sulfhydrate (NaHS, a donor of H2S) down-regulated the expression of c-fos and increased the expression of gamma-aminobutyric acid B receptor subunits 1 (GABA(B)R1) and 2 (GABA(B)R2). Hydroxylamine (an inhibitor of cystathionine b-synthase) up-regulated the expression of c-fos and down-regulated the expression of GABA(B)R2, but did not change the expression of GABA(B)R1. These results suggest that H2S plays a regulatory role through modulating GABA(B)R function in the pathogenesis of recurrent FS.