Dopamine D1 receptor activation ameliorates ox-LDL-induced endothelial cell senescence via CREB/Nrf2 pathway.

Endothelial cell senescence is involved in endothelial dysfunction and aging-related vascular diseases. The D1-like dopamine receptor (DR1), a number of G-protein-coupled receptors, is currently under consideration as a potential therapeutic target for the prevention of atherosclerosis. However, the role of DR1 in regulating ox-LDL-stimulated endothelial cell senescence remains unknown. Here, we found that the elevated Prx hyperoxidation and reactive oxygen species (ROS) levels in ox-LDL-treated Human umbilical vein endothelial cells (HUVECs) were observed, suppressed by DR1 agonist SKF38393. Increased proportion of senescence-associated ß-galactosidase (SA-ß-gal) positive staining cells and activated p16/p21/p53 pathway in ox-LDL-treated HUVECs were significantly abolished by DR1 activation. In addition, SKF38393 increased the phosphorylation of cAMP response element-binding protein (CREB) at serine-133, nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and expression of HO-1 in HUVECs. In contrast, adding H-89, a PKA inhibitor, diminished the effects of DR1 activation. Further studies performed with DR1 siRNA confirmed that DR1 was involved in CREB/Nrf2 pathway. Taken together, DR1 activation reduces ROS production and cell senescence by upregulating CREB/Nrf2 antioxidant signaling in ox-LDL-induced endothelial cells. Thus, DR1 could be a potential molecular target to counteract oxidative stress-induced cellular senescence.

DR1 Activation Inhibits the Proliferation of Vascular Smooth Muscle Cells through Increasing Endogenous H2S in Diabetes.

Tissue ischemia and hypoxia caused by the abnormal proliferation of smooth muscle cells (SMCs) in the diabetic state is an important pathological basis for diabetic microangiopathy. Studies in recent years have shown that the chronic complications of diabetes are related to the decrease of endogenous hydrogen sulfide (H2S) in diabetic patients, and it has been proven that H2S can inhibit the proliferation of vascular SMCs (VSMCs). Our study showed that the endogenous H2S content and the expression of cystathionine gamma-lyase (CSE), which is the key enzyme of H2S production, were decreased in arterial SMCs of diabetic mice. The expression of PCNA and Cyclin D1 was increased, and the expression of p21 was decreased in the diabetic state. After administration of dopamine 1-like receptors (DR1) agonist SKF38393 and exogenous H2S donor NaHS, the expression of CSE was increased and the change in proliferation-related proteins caused by diabetes was reversed. It was further verified by cell experiments that SKF38393 activated calmodulin (CaM) by increasing the intracellular calcium ([Ca2+]i) concentration, which activated the CSE/H2S pathway, enhancing the H2S content in vivo. We also found that SKF38393 and NaHS inhibited insulin-like growth factor-1 (IGF-1)/IGF-1R and heparin-binding EGF-like growth factor (HB-EGF)/EGFR, as well as their downstream PI3K/Akt, JAK2/STAT3 and ERK1/2 pathways. Taken together, our results suggest that DR1 activation up-regulates the CSE/H2S system by increasing Ca2+-CaM binding, which inhibits the IGF-1/IGF-1R and HB-EGF/EGFR pathways, thereby decreasing their downstream PI3K/Akt, JAK2/STAT3 and ERK1/2 pathways to achieve the effect of inhibiting HG-induced VSMCs proliferation.

Sodium hydrosulfide inhibiting endothelial cells injury and neutrophils activation via IL-8/CXCR2/ROS/NF-κB axis in type 1 diabetes mellitus rat.

AIMS: Hydrogen sulfide (H2S) prevents endothelial cells injury. However, the complicated mechanism of sodium hydrosulfide (NaHS, a donor that produces H2S) which inhibits the endothelial cells injury which correlated the activation of neutrophil in the type 1 diabetes mellitus (T1DM) rats has not been previously investigated. METHODS AND RESULTS: In the experiment, the T1DM animal model was established, the IL-1ß, IL-8 were determined by western blotting and ELISA, the expressions of the Bax and Bcl-2 of endothelial cells and the CXCR2, CSE, phosphor-IκBα and NF-kB of neutrophils were measured by western blotting. Additionally, the concentration of serum dsDNA was tested by PicoGreen commercial Kits, changes in the H2S concentration of neutrophils were determined by Multiskan spectrum microphate spectrophotometer, the cellular ROS levels of neutrophils were detected by DCFH-DA staining and flow cytometry. The IL-1ß, IL-8 concentration and expression increased, the endothelial cells injury which stimulated by high glucose and the concentration of dsDNA in serum increased, the expression of CXCR2, phosphor-IκBα and NF-kB increased while the expression of CSE and concentration of H2S decreased in neutrophils in the T1DM group compared to the control group. NaHS significantly inhibited the injury of endothelial cell, the production of ROS in neutrophils, reversed the expressions of CXCR2, CSE, phosphor-IκBα and NF-κB and decreased concentration of dsDNA in serum which were caused by T1DM. CONCLUSIONS: Our results demonstrated that the donor of H2S inhibits endothelial cells injury and neutrophils activation via the IL-8/CXCR2/ROS/NF-κB axis in T1DM rat.

DR1 activation promotes vascular smooth muscle cell apoptosis via up-regulation of CSE/H2 S pathway in diabetic mice.

The important role of hydrogen sulfide (H2 S) as a novel gasotransmitter in inhibiting proliferation and promoting apoptosis of vascular smooth muscle cells (VSMCs) has been widely recognized. The dopamine D1 receptor (DR1), a G protein coupled receptor, inhibits atherosclerosis by suppressing VSMC proliferation. However, whether DR1 contributes to VSMC apoptosis via the induction of endogenous H2 S in diabetic mice is unclear. Here, we found that hyperglycemia decreased the expressions of DR1 and cystathionine-γ-lyase (CSE, a key enzyme for endogenous H2 S production) and reduced endogenous H2 S generation in mouse arteries and cultured VSMCs. DR1 agonist SKF38393 increased DR1 and CSE expressions and stimulated endogenous H2 S generation. Sodium hydrosulfide (NaHS, a H2 S donor) increased CSE expressions and H2 S generation but had no effect on DR1 expression. In addition, high glucose (HG) increased VSMC apoptosis, up-regulated IGF-1-IGF-1R and HB-EGF-EGFR, and stimulated ERK1/2 and PI3K-Akt pathways. Overexpression of DR1, the addition of SKF38393 or supply of NaHS further promoted VSMC apoptosis and down-regulated the above pathways. Knock out of CSE or the addition of the CSE inhibitor poly propylene glycol diminished the effect of SKF38393. Moreover, calmodulin (CaM) interacted with CSE in VSMCs; HG increased intracellular Ca2+ concentration and induced CaM expression, further strengthened the interaction of CaM with CSE in VSMCs, which were further enhanced by SKF38393. CaM inhibitor W-7, inositol 1,4,5-trisphosphate (IP3 ) inhibitor 2-APB, or ryanodine receptor inhibitor tetracaine abolished the stimulatory effect of SKF38393 on CaM expression and intracellular Ca2+ concentration. Taken together, these results suggest that DR1 up-regulates CSE/H2 S signaling by inducing the Ca2+ -CaM pathway followed by down-regulations of IGF-1-IGF-1R and HB-EGF-EGFR and their downstream ERK1/2 and PI3K-Akt, finally promoting the apoptosis of VSMCs in diabetic mice.

Exogenous hydrogen sulfide protects from endothelial cell damage, platelet activation, and neutrophils extracellular traps formation in hyperhomocysteinemia rats.

Hydrogen sulfide (H2S) prevents endothelial cells damage and P-selectin of platelets promotes neutrophils extracellular traps (NETs) formation. However, how sodium hydrosulfide (NaHS), a donor that produces H2S regulates the activation of platelets and whether H2S inhibits the formation of neutrophils extracellular traps in hyperhomocysteinemia rats have not been previously investigated. The morphological and ultrastructural alterations of endothelial cells (ECs) and platelets were tested by transmission electron microscopy. The expressions of P-selectin of platelets were determined by flow cytometry. Additionally, the cellular ROS and the H2S level were detected by DCFH-DA staining and H2S probe, the expressions of Bax and Bcl-2 in arteries and cultured ECs from rat thoracic aortas and the phosphor-p38 mitogen-activated protein kinase (MAPK), CSE and CBS of platelets were measured by western blotting. The NETs formations, the concentration of DNA in serum and supernatant of cultured neutrophils stimulated with platelet-rich plasma (PRP) were tested by Sytox Green and PicoGreen commercial Kits. The vascular ECs damaged, the expression of P-selectin of platelets and NETs formation increased; the concentration of DNA in serum and supernatant of cultured neutrophils stimulated with PRP also increased; the expression of Bax increased while Bcl-2 decreased in arteries, the phosphor-p38 MAPK of platelets increased while CSE and CBS have no statistically significant changes in the HHcy group compared to the control group. In the cultured ECs, the ROS level increased while the H2S level decreased after 48 and 72 h treatment by HHcy; the expression of Bcl-2 decreased while Bax increased after 72 h treatment by HHcy. NaHS significantly inhibited the ECs injured, cellular ROS production, platelet activation and NETs formation, reversed the expressions of Bax, Bcl-2, phosphor-p38 MAPK, P-selectin and the increased concentration of DNA in serum and supernatant of cultured neutrophils which caused by high homocysteine. Our results demonstrate that the donor of H2S inhibits the platelets activation and NETs formation, which concerts the protection of ECs in hyperhomocysteinemia.

DR1 activation reduces the proliferation of vascular smooth muscle cells by JNK/c-Jun dependent increasing of Prx3.

Vascular smooth muscle cells (VSMCs) proliferation is a key process in atherosclerosis. However, little is known about the underlying mechanisms, leading to a lack of effective therapy. This study was to investigate whether dopamine receptor 1 (DR1) is involved in the VSMCs proliferation and related mechanisms. A7r5 cells were treated with oxidized low-density lipoprotein (ox-LDL, 10, 20, 50, 100, 200 µg/mL) in the presence or absence of the SKF38393 (DR1agonist), SCH23390 (DR1antiagonist), SP600125 (JNK inhibitor), PD98059(ERK1/2 inhibitor) or NAC (ROS inhibitor). Cell proliferation and related signaling pathway were evaluated. The expression of DR1 was negatively correlated with increasing of cell proliferation caused by ox-LDL. Cell proliferation and ROS generation in response to ox-LDL were prevented by DR1 agonist or over-expression. The peroxiredoxins protein (Prx1, 2, 3, 5, 6) were increased in A7r5 cells treated with ox-LDL; however, only Prx3 dramatically increased after activation of DR1 compared with ox-LDL group, which is related to activation of JNK/c-Jun pathway. In addition, ERK is associated with the restraining effects of DR1 activation. DR1 activation inhibits VSMCs proliferation primarily by JNK/c-Jun dependent increasing of Prx3, suggesting DR1 a potential target for the prevention of vascular proliferation disease.

Spermine and spermidine reversed age-related cardiac deterioration in rats.

Aging is the most important risk factor for cardiovascular disease (CVD). Slowing or reversing the physiological impact of heart aging may reduce morbidity and mortality associated with age-related CVD. The polyamines, spermine (SP) and spermidine (SPD) are essential for cell growth, differentiation and apoptosis, and levels of both decline with age. To explore the effects of these polyamines on heart aging, we administered SP or SPD intraperitoneally to 22- to 24-month-old rats for 6 weeks. Both treatments reversed and inhibited age-related myocardial morphology alterations, myocardial fibrosis, and cell apoptosis. Using combined proteomics and metabolomics analyses, we identified proteins and metabolites up- or downregulated by SP and SPD in aging rat hearts. SP upregulated 51 proteins and 28 metabolites while downregulating 80 proteins and 29 metabolites. SPD upregulated 44 proteins and 24 metabolites and downregulated 84 proteins and 176 metabolites. These molecules were mainly associated with immune responses, blood coagulation, lipid metabolism, and glutathione metabolism pathways. Our study provides novel molecular information on the cardioprotective effects of polyamines in the aging heart, and supports the notion that SP and SPD are potential clinical therapeutics targeting heart disease.

Thioredoxin 2 Offers Protection against Mitochondrial Oxidative Stress in H9c2 Cells and against Myocardial Hypertrophy Induced by Hyperglycemia.

Mitochondrial oxidative stress is thought to be a key contributor towards the development of diabetic cardiomyopathy. Thioredoxin 2 (Trx2) is a mitochondrial antioxidant that, along with Trx reductase 2 (TrxR2) and peroxiredoxin 3 (Prx3), scavenges H2O2 and offers protection against oxidative stress. Our previous study showed that TrxR inhibitors resulted in Trx2 oxidation and increased ROS emission from mitochondria. In the present study, we observed that TrxR inhibition also impaired the contractile function of isolated heart. Our studies showed a decrease in the expression of Trx2 in the high glucose-treated H9c2 cardiac cells and myocardium of streptozotocin (STZ)-induced diabetic rats. Overexpression of Trx2 could significantly diminish high glucose-induced mitochondrial oxidative damage and improved ATP production in cultured H9c2 cells. Notably, Trx2 overexpression could suppress high glucose-induced atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) gene expression. Our studies suggest that high glucose-induced mitochondrial oxidative damage can be prevented by elevating Trx2 levels, thereby providing extensive protection to the diabetic heart.

Calcium sensing receptor initiating cystathionine-gamma-lyase/hydrogen sulfide pathway to inhibit platelet activation in hyperhomocysteinemia rat.

Hyperhomocysteinemia (HHcy, high homocysteine) induces the injury of endothelial cells (ECs). Hydrogen sulfide (H2S) protects ECs and inhibits the activation of platelets. Calcium-sensing receptor (CaSR) regulates the production of endogenous H2S. However, whether CaSR inhibits the injury of ECs and the activation of platelets by regulating the endogenous cystathionine-gamma-lyase (CSE, a major enzyme that produces H2S)/H2S pathway in hyperhomocysteinemia has not been previously investigated. Here, we tested the ultrastructure alterations of ECs and platelets, the changes in the concentration of serum homocysteine and the parameters of blood of hyperhomocysteinemia rats were measured. The aggregation rate and expression of P-selectin of platelets were assessed. Additionally, the expression levels of CaSR and CSE in the aorta of rats were examined by western blotting. The mitochondrial membrane potential and the production of reactive oxygen species (ROS) were measured; the expression of phospho-calmodulin kinases II (p-CaMK II) and Von Willebrand Factor (vWF) of cultured ECs from rat thoracic aortas were measured. We found that the aggregation rate and the expression of P-selectin of platelets increased, and the expression of CaSR and CSE decreased in HHcy rats. In the ECs of HHcy group, the ROS production increased and the mitochondrial membrane potential decreased markedly, the expression of CSE and the p-CaMK II increased after treatment with CaSR agonist while decreased upon administration of U73122 (PLC-specific inhibitor) and 2-APB (IP3 Receptor inhibitor). CaSR agonist or NaHS significantly reversed the ECs injured and platelet aggregation caused by hyperhomocysteinemia. Our results demonstrate that CaSR regulates the endogenous CSE/H2S pathway to inhibit the activation of platelets which concerts the protection of ECs in hyperhomocysteinemia.

Sulfiredoxin involved in the protection of peroxiredoxins against hyperoxidation in the early hyperglycaemia.

As a direct consequence of hyperglycaemia, the excessive generation of ROS is central to the pathogenesis of diabetic cardiomyopathy. We hypothesize that stimulation of high glucose (HG) results in an increased sulfiredoxin (Srx) expression, which regulates ROS signaling through reducing the hyperoxidized peroxiredoxins (Prxs). We show that hyperoxidized Prxs were initially reduced in the preliminary stage but then dramatically increased in advanced stage and these changes corresponded to a significant increase of Srx expression in the heart of diabetic rats. These time-dependent changes were also confirmed in neonatal cardiomyocytes and H9c2 cells treated with HG. Moreover, the reduction rate of hyperoxidized Prxs was greatly improved in the HG 24h group, which had an elevated expression of Srx. Our data also show that HG-induced AP1 activation and Srx expression were almost abolished by JNK inhibitor and N-acetylcysteine (NAC). In addition, siRNA-Srx suppressed HG-induced ANP and ß-MHC gene expression. These observations suggest that activation of AP1 induced by HG is important for the expression of Srx and the reduction of hyperoxidized Prxs in cardiomyocytes. This Srx induction maybe is the pivotal compensatory protection mechanism against oxidative stress in diabetes or hyperglycaemia. Most interestingly, hyperoxidized Prxs/Srx pathway may be involved in the cardiac hypertrophy signaling of diabetes.

Suppression of calcium­sensing receptor ameliorates cardiac hypertrophy through inhibition of autophagy.

The calcium-sensing receptor (CaSR) releases intracellular calcium ([Ca2+]i) by accumulating inositol phosphate. Changes in [Ca2+]i initiate myocardial hypertrophy. Furthermore, autophagy associated with [Ca2+]i. Autophagy has previously been demonstrated to participate in the hypertrophic process. The current study investigated whether suppression of CaSR affects the hypertrophic response via modulating autophagy. Isoproterenol (ISO) was used to induce cardiac hypertrophy in Wistar rats. Hypertrophic status was determined by echocardiographic assessment, hematoxylin and eosin, and Masson's staining. The protein expression levels of CaSR and autophagy level were observed. Changes of hypertrophy and autophagy indicators were observed following intravenous injection of a CaSR inhibitor. An ISO­induced cardiomyocyte hypertrophy model was established and used determine the involvement of GdCl3. [Ca2+]i was determined using Fluo­4/AM dye followed by confocal microscopy. The expression levels of various active proteins were analyzed by western blotting. The size of the heart, expression levels of CaSR and autophagy level were markedly increased in hypertrophic myocardium. In addition, the present study demonstrated that the indicators of hypertrophy and autophagy were effectively suppressed by CaSR inhibitor. Furthermore, similar effects were demonstrated in neonatal rat hypertrophic cardiomyocytes treated with ISO. It was also observed that CaSR regulates the Ca2+/calmodulin­dependent protein kinase kinase ß (CaMKKß)­AMP­activated protein kinase (AMPK)­mammalian target of rapamycin (mTOR) signaling pathway induced by ISO in cardiomyocytes. Furthermore, the AMPK inhibition significantly reduced the autophagy level following CaSR stimulation (P<0.05). The results of the present demonstrated that inhibition of CaSR may ameliorate cardiac hypertrophy induced by ISO and the effect may be associated with the inhibition of autophagy and suppression of the CaMKKß­AMPK­mTOR signaling pathway.

[Effects of activation of dopamine type I receptor on the produc-tion of NO/NOS in ox-LDL activated THP-1 cells].

OBJECTIVE: To study the effect of excited dopamine type I receptor on the production of nitric oxide/nitric oxide synthase(NO/NOS)in ox-LDL activated THP-1 cells and the possible mechanism. METHODS: Cultured THP-1 cells activated by PMA were randomly assigned in the following groups:control group (control), oxidized low density lipoprotein group (ox-LDL), dopamine receptor 1(DR1) agonist group (SKF), DR1 antagonist group (SCH), ERK blocker group (PD98059). Oil Red O staining was used to identify the accumulation of cellular lipid. The levels of NO and NOS in the supernatant of THP-1 were assayed by nitrate reductase method. The protein expression of DR1, p-ERK and ERK were obtained by Western blot and immunity fluorescence. RESULTS: After 48 h of incubation of ox-LDL, accumulation of lipid in the cytoplasm was found in most THP-1 cells. Compared with control group, DR1 protein expression was reduced in ox-LDL-induced cells(P<0.01). Activation of DR1 agonist decrease the production of NO and iNOS(P<0.01), and PD98059 partly reversed the above effect. CONCLUSIONS: Activation of DR1 can inhibit the production of NO/NOS in ox-LDL-induced THP-1 cells, which may be related with ERK pathway.

Calhex231 Ameliorates Cardiac Hypertrophy by Inhibiting Cellular Autophagy in Vivo and in Vitro.

BACKGROUND/AIMS: Intracellular calcium concentration ([Ca2+]i) homeostasis, an initial factor of cardiac hypertrophy, is regulated by the calcium-sensing receptor (CaSR) and is associated with the formation of autolysosomes. The aim of this study was to investigate the role of Calhex231, a CaSR inhibitor, on the hypertrophic response via autophagy modulation. METHODS: Cardiac hypertrophy was induced by transverse aortic constriction (TAC) in 40 male Wistar rats, while 10 rats underwent a sham operation and served as controls. Cardiac function was monitored by transthoracic echocardiography, and the hypertrophy index was calculated. Cardiac tissue was stained with hematoxylin and eosin (H&E) or Masson's trichrome reagent and examined by transmission electron microscopy. An angiotensin II (Ang II)-induced cardiomyocyte hypertrophy model was established and used to test the involvement of active molecules. Intracellular calcium concentration ([Ca2+]i) was determined by the introduction of Fluo-4/AM dye followed by confocal microscopy. The expression of various active proteins was analyzed by western blot. RESULTS: The rats with TAC-induced hypertrophy had an increased heart size, ratio of heart weight to body weight, myocardial fibrosis, and CaSR and autophagy levels, which were suppressed by Calhex231. Experimental results using Ang II-induced hypertrophic cardiomyocytes confirmed that Calhex231 suppressed CaSR expression and downregulated autophagy by inhibiting the Ca2+/calmodulin-dependent-protein kinase-kinase-ß (CaMKKß)­ AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) pathway to ameliorate cardiomyocyte hypertrophy. CONCLUSIONS: Calhex231 ameliorates myocardial hypertrophy induced by pressure-overload or Ang II via inhibiting CaSR expression and autophagy. Our results may support the notion that Calhex231 can become a new therapeutic agent for the treatment of cardiac hypertrophy.

[Effects and mechanisms of low concentration dopamine on hydrogen peroxide-induced apoptosis in cultured neonatal rat cardiomyocytes].

OBJECTIVE: To study the effects of low concentration dopamine(DA) on hydrogen peroxide-induced apoptosis in cultured rat cardiomyocytes as well as the possible molecular mechanisms. METHODS: Cultured neonatal rat cardiomyocytes were randomly divided into the following groups: control group (control), hydrogen peroxide group (H2O2), pretreated with low concentration dopamine ( DA + H2O2), dopamine receptor l(DR1) antagonist group (DR1 + DA + H2O2), dopamine receptor 2(DR2) antagonist group (DR2 + DA + H2O2). The cell apoptosis was then assessed by MTT and flow cytometry. The cellular ultrastructure changes were observed by transmission electron micro- scope. The activity of lactate dehydrogenase(LDH )and superoxide dismutase (SOD) in cell medium was analyzed by colorimetry. The protein expressions of Cytochrone c, Caspase 3 and Caspase 9 were obtained by Western blot. RESULTS: Compared with hydrogen peroxide group, low concentration dopamine(10 µmol/L) decreased the apoptosis rate and the expression of protein of apoptosis related protein, enhanced SOD activity, decreased LDH activity. DR1 antagonist SCH-23390 treatment inhibited dopamine induced cardiac protective effect. DR2 antagonist haloperido treatment had no changes compared with dopamine group. CONCLUSION: Above findings indicate that low concentration dopanine inhibits apoptosis induced by hydrogen peroxide in neonatal rat cardiomyocytes, which is partly associated with the activation of DR1.

The efficacy and mechanism of apoptosis induction by hypericin-mediated sonodynamic therapy in THP-1 macrophages.

PURPOSE: To investigate the sonoactivity of hypericin (HY), together with its sonodynamic effect on THP-1 macrophages and the underlying mechanism. MATERIALS AND METHODS: CCK-8 was used to examine cell viability. Confocal laser scanning microscopy was performed to assess the localization of HY in cells, reactive oxygen species (ROS) generation, and opening of the mitochondrial permeability transition pore (mPTP) after different treatments. Apoptosis was analyzed using Hoechst-propidium iodide and transmission electron microscopy. Mitochondrial membrane potential (ΔΨm) collapse was detected via fluorescence microscopy. Lipoprotein oxidation was determined in malondialdehyde (MDA) assays. Western blotting was conducted to determine the translocation of BAX and cytochrome C and the expression of apoptosis-related proteins. RESULTS: HY was sublocalized among the nuclei and the mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosome in the cytosol of THP-1 macrophages. Under low-intensity ultrasound irradiation, HY significantly decreased cell viability and induced apoptosis. Furthermore, greater ROS generation, higher MDA levels, and greater ΔΨm loss were observed in the sonodynamic therapy (SDT) group. Both ROS generation and MDA levels were significantly reduced by the ROS scavenger N-acetyl cysteine (NAC) and the singlet oxygen scavenger sodium azide. Most of the loss of ΔΨm was inhibited by pretreatment with NAC, sodium azide, and the mPTP inhibitor cyclosporin A (CsA). mPTP opening was induced upon SDT but was reduced by pretreatment with bongkrekic acid, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium, CsA, and NAC. Western blot analyses revealed translocation of BAX and cytochrome C, downregulated expression of Bcl-2, and upregulated expression of cleaved caspase-9, cleaved caspase-3, and cleaved poly(ADP-ribose) polymerase in the SDT group, which were reversed by NAC. CONCLUSION: HY mediated SDT-induced apoptosis in THP-1 macrophages via ROS generation. Then, the proapoptotic factor BAX translocated from the cytosol to the mitochondria, increasing the ratio of BAX/Bcl-2, and the mPTP opened to release cytochrome C. This study demonstrated the great potential of HY-mediated SDT for treating atherosclerosis.

Constitutive BDNF/TrkB signaling is required for normal cardiac contraction and relaxation.

BDNF and its associated tropomyosin-related kinase receptor B (TrkB) nurture vessels and nerves serving the heart. However, the direct effect of BDNF/TrkB signaling on the myocardium is poorly understood. Here we report that cardiac-specific TrkB knockout mice (TrkB(-/-)) display impaired cardiac contraction and relaxation, showing that BDNF/TrkB signaling acts constitutively to sustain in vivo myocardial performance. BDNF enhances normal cardiomyocyte Ca(2+) cycling, contractility, and relaxation via Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Conversely, failing myocytes, which have increased truncated TrkB lacking tyrosine kinase activity and chronically activated CaMKII, are insensitive to BDNF. Thus, BDNF/TrkB signaling represents a previously unidentified pathway by which the peripheral nervous system directly and tonically influences myocardial function in parallel with ß-adrenergic control. Deficits in this system are likely additional contributors to acute and chronic cardiac dysfunction.

Sodium hydrosulfide attenuates hyperhomocysteinemia rat myocardial injury through cardiac mitochondrial protection.

Hydrogen sulfide (H2S) plays an important role during rat myocardial injury. However, little is known about the role of H2S in hyperhomocysteinemia (HHcy)-induced cardiac dysfunction as well as the underlying mechanisms. In this study, we investigated whether sodium hydrosulfide (NaHS, a H2S donor) influences methionine-induced HHcy rat myocardial injury in intact rat hearts and primary neonatal rat cardiomyocytes. HHcy rats were induced by methionine (2.0 g/kg) and the daily administration of 80 µmol/L NaHS in the HHcy + NaHS treatment group. At the end of 4, 8, and 12 weeks, the ultrastructural alterations and functions of the hearts were observed using transmission electron microscopy and echocardiography system. The percentage of apoptotic cardiomyocytes, the mitochondrial membrane potential, and the production of reactive oxygen species (ROS) were measured. The expressions of cystathionine-γ-lyase (CSE), Bax and Bcl-2, caspase-3, phospho-endothelial nitric oxide synthase and the mitochondrial NOX4 and cytochrome c were analyzed by Western blotting. The results showed the cardiac dysfunction, the ultrastructural changes, and the apoptotic rate increase in the HHcy rat hearts. In the primary neonatal rat cardiomyocytes of HHcy group, ROS production was increased markedly, whereas the expression of CSE was decreased. However, treatment with NaHS significantly improved the HHcy rat hearts function, the ultrastructural changes, and decreased the levels of ROS in the primary neonatal rat cardiomyocytes administrated with HHcy group. Furthermore, NaHS down-regulated the expression of mitochondrial NOX4 and caspase-3 and Bax and inhibited the release of cytochrome c from mitochondria. In conclusion, H2S is involved in the attenuation of HHcy myocardial injury through the protection of cardiac mitochondria.

Real-time detection of intracellular reactive oxygen species and mitochondrial membrane potential in THP-1 macrophages during ultrasonic irradiation for optimal sonodynamic therapy.

Reactive oxygen species (ROS) elevation and mitochondrial membrane potential (MMP) loss have been proven recently to be involved in sonodynamic therapy (SDT)-induced macrophage apoptosis and necrosis. This study aims to develop an experimental system to monitor intracellular ROS and MMP in real-time during ultrasonic irradiation in order to achieve optimal effect in SDT. Cultured THP-1 derived macrophages were incubated with 5-aminolevulinic acid (ALA), and then sonicated at different intensities. Intracellular ROS elevation and MMP loss were detected in real-time by fluorospectrophotometer using fluorescence probe DCFH-DA and jc-1, respectively. Ultrasound at low intensities (less than 0.48W/cm(2)) had no influence on ROS and MMP in macrophages, whereas at an intensity of 0.48W/cm(2), ROS elevation and MMP loss were observed during ultrasonic irradiation. These effects were strongly enhanced in the presence of ALA. Quantitative analysis showed that ROS elevation and MMP loss monotonically increased with the rise of ultrasonic intensity between 0.48 and 1.16W/cm(2). SDT at 0.48 and 0.84W/cm(2) induced mainly apoptosis in THP-1 macrophages while SDT at 1.16W/cm(2) mainly cell necrosis. This study supports the validity and potential utility of real-time ROS and MMP detection as a dosimetric tool for the determination of optimal SDT.

Synthesis and chemical and biological comparison of nitroxyl- and nitric oxide-releasing diazeniumdiolate-based aspirin derivatives.

Structural modifications of nonsteroidal anti-inflammatory drugs (NSAIDs) have successfully reduced the side effect of gastrointestinal ulceration without affecting anti-inflammatory activity, but they may increase the risk of myocardial infarction with chronic use. The fact that nitroxyl (HNO) reduces platelet aggregation, preconditions against myocardial infarction, and enhances contractility led us to synthesize a diazeniumdiolate-based HNO-releasing aspirin and to compare it to an NO-releasing analogue. Here, the decomposition mechanisms are described for these compounds. In addition to protection against stomach ulceration, these prodrugs exhibited significantly enhanced cytotoxcity compared to either aspirin or the parent diazeniumdiolate toward nonsmall cell lung carcinoma cells (A549), but they were not appreciably toxic toward endothelial cells (HUVECs). The HNO-NSAID prodrug inhibited cylcooxgenase-2 and glyceraldehyde 3-phosphate dehydrogenase activity and triggered significant sarcomere shortening on murine ventricular myocytes compared to control. Together, these anti-inflammatory, antineoplasic, and contractile properties suggest the potential of HNO-NSAIDs in the treatment of inflammation, cancer, or heart failure.

An animal model of atherosclerotic plaque disruption and thrombosis in rabbit using pharmacological triggering to plaques induced by perivascular collar placement.

INTRODUCTION: Limited availability of suitable animal model of plaque disruption and thrombosis has hampered the study of mechanism and preclinical evaluation of plaque-stabilizing therapies. This study aims to develop an animal model of atherosclerotic plaque disruption and thrombosis in rabbit femoral artery. METHODS: Silastic collars were placed around the bilateral femoral arteries of rabbits, which had been fed with atherogenic diet for 7 days. After 28 days on the same diet, the rabbits received pharmacological triggering by intraperitoneal injection of Russell's viper venom (RVV, 0.15 mg/kg) followed by intravenous injection of histamine (0.02 mg/kg), and the animals were then processed for imageological and histological examinations. RESULTS: Perivascular collar placement of the femoral artery in high-cholesterol-fed rabbits for 28 days induced marked intimal hyperplasia, which was a lipid- and collagen-rich lesion that contained substantial amount of macrophages and smooth muscle cells. Subsequent histological analysis showed that the pharmacological triggering evoked plaque disruption and platelet- and fibrin-rich thrombi in the collared femoral arteries. CONCLUSION: We demonstrated, for the first time, a rabbit model of plaque disruption and thrombosis induced by the combination of perivascular collar placement, RVV, and histamine injections. This model can be rapidly formed, easily operated, and site controlled.