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Objectives: Preeclampsia is a severe disease whose pathogenesis is unclear. Agonistic antibodies against the angiotensin II receptor (AT1-AA) may be a novel risk factor in preeclampsia whose effects are undefined. Our aims were 1) to determine whether the titre of AT1-AAis increased in preeclampsia; 2) if so, to determine the mechanisms of AT1-AA in pathogenesis of preeclampsia. Methods: Sera obtained from preeclamptic women (n = 18) and normal pregnant women (n = 17) were applied to detect AT1-AA and purify IgG. The effects of AT1-AA on vascular smooth muscle activities were observed by using isolated rat aortic vascular ring. Results: 1) the titre of AT1-AA showed significant time-dependently increased in preeclampsia compared with normal pregnant women; 2) AT1-AA dose-dependently increased the vascular contractile tension. At the dose of 10-6mol/L, AT1-AA increased the peak systolic tension from 1.02±0.04g to 1.72±0.17g, which could be blocked by Losartan, an AT1 receptor blocker indicating that the effects were mediated by AT1eceptor. Nevertheless, these effects failed to well demonstrate when IgG from normal pregnant women were administered. Conclusion: Our study demonstrate that the titre of AT1-AA is markedly increased in preeclampsia; it could dose-dependently increase the contractile tension of the vascular ring suggesting that AT1-AA may be play a significant role in the pathogenesis of preeclampsia. [ABSTRACT FROM AUTHOR]

Objectives: The importance of agonistic antibodies against the angiotensin II receptor (AT1-AA) in the pathogenesis of preeclampsia has not been well researched. The aims of our study ware to 1) obtain direct evidence that the concentration of AT1-AA is increased in preeclampsia; 2) determine the effects of AT1-AA on ventricular ionic currents. Methds: Sera obtained from preeclamptic women (n = 18) were applied to detect AT1-AA and purify IgG and those collected from normal pregnant women (n = 17) were used as negative control. The effects of AT1-AA on rat ventricular ionic currents were studied by whole cell patch clamp techniques. Results: 1) the concentration of AT1-AA is time-dependently increased in preeclampsia compared with normal pregnant women. 2) AT1-AA could dose-dependently increase both IC a -L and IN a/C a current which blocked by losartan, a specific antagonist of AT1-receptor suggesting that the agonist-like activity of AT1-AA are mediated by stimulation of AT1-receptor. 3) AT1-AA decreased dose-dependently both Ito and 1 k1current which were also blocked by losartan, However these effects were not observed when IgG from normal pregnant women were administered. Conclusion: Our study provides direct evidence that the concentration of AT1-AA is markedly increased in preeclampsia; it has a remarkable positive inotropic effect on the heart, indicating that it may be play an important role in the pathogenesis of preeclampsia. [ABSTRACT FROM AUTHOR]

: Aims Hypercholesterolaemia and myeloperoxidase (MPO) overexpression are two well-recognized risk factors for ischaemic heart disease. Peroxisome proliferator-activated receptor-γ (PPARγ) agonists have recently been shown to reduce ischaemic heart injury in hypercholesterolaemic animals. However, whether PPARγ agonists may exert their cardioprotective effects by eliminating those risk factors that increase ischaemic injury remains unknown. : Methods and results Male New Zealand rabbits were fed with a normal or a high-cholesterol diet for 8 weeks, treated with vehicle or rosiglitazone (RSG, 3 mg/kg/day for the last 5 weeks) and subjected to myocardial ischaemia/reperfusion (1 h/4 h). MPO expression, activity, and distribution, cardiac caspase-3 activity, and myocardial infarct size were determined. Diet-induced hypercholesterolaemia caused a significant increase in neutrophil MPO expression/activity (7.2-/5.4-fold). Hypercholesterolaemia also tripled MPO activity in ischaemic/reperfused hearts when compared with rabbits fed with a normal diet. Surprisingly, MPO immunostaining was not only observed in perivascular and extracellular spaces in ischaemic/reperfused hearts, but also in cardiomyocytes. This intracardiomyocyte MPO staining was further intensified by hypercholesterolaemia. There is a strong positive correlation between cardiac MPO activity and caspase-3 activity, and treatment with an MPO inhibitor significantly reduced post-ischaemic caspase-3 activation. Treatment with RSG markedly inhibited hypercholesterolaemia-induced leucocyte MPO overexpression and activation, reduced MPO activity in ischaemic/reperfused hearts, decreased caspase-3 activity, and reduced myocardial infarct size (P < 0.01). : Conclusion Our results demonstrated that hypercholesterolaemia and MPO overexpression are causally related and that PPARγ agonists may have great therapeutic value in ischaemic heart disease patients with multiple complications such as hypercholesterolaemia and diabetes. [ABSTRACT FROM AUTHOR]

Objective: To determine whether the cardiac function of aged rats is more susceptible to ischemia/reperfusion injury than that of adult heart and, if so, to clarify the mechanisms. Methods: SD rats were randomly divided into 4 groups: normal adult group (5-6 months), normal old group (22-24 months), adult-myocardial ischemia/reperfusion (MI/R, the rats were subjected to 30 minutes of myocardial ischemia via ligating the left anterior descending coronary artery followed by 3 hours of reperfusion) group and old-MI/R group. The cardiac function of left ventricle was continuously measured. The content of total nitric oxide (NOx) and nitrotyrosine, and the expression of iNOS in myocardium were detected. Results: A significantly exacerbated cardiac reperfusion injury was found in old-MI/R group as evidenced by aggravated cardiac function compared with adult -MI/R group, especially the diastolic function. Aged hearts had a markedly increased basal NOx compared to young adult hearts (1.3 folds, P<0.05). Marked higher myocardial NOx contents, nitrotyrosine contents and iNOS expression was found in old-MI/R group than that in adult -MI/R group. Conclusion: Our results demonstrated that in aged hearts high levels of NO might form iNOS attributed to the increased susceptibility of ischemic-reperfusion injury in cardiac function. [ABSTRACT FROM AUTHOR]

Objective: To observe the effect of autoantibody against α1-adrenoceptor (α1-AR) on vasoconstriction. Methods: The synthetic peptide corresponding to the sequence of the second extracellular loop of the rat α1-AR was used as the antigen to screen the anti-α1-AR antibodies from the sera of immunized group and vehicle group by SA-ELISA. The IgGs from the positive sera were purified by affinity chromagraphy. The effects of antibody against α1-AR on the vasoconstriction of rats in vitro or blood pressure of rats in vivo were observed by tension of isolated thoracic aortic rings or tail-cuff method respectively. Results: In immunized group, the antibodies emerged at 3 weeks after initial immunization with the synthetic peptide, and reached the peak (1:5109±2.4) at 5 weeks, then persisted within 2 months; 3.5 months after immunization, the systolic blood pressure of the rats in immunized group was higher than that of vehicle group. The antibodies against α1-AR (10-6mol/L) increased the tension of isolated thoracic aortic ring from 1.06±0.08g to 1.88±0.06g (P<0.05, vs. control group),which is similar to the α1-AR agonist, phenylephrine (10-6mol/L), increased the tention from 1.04±0.07g to 2.26±0.03g. Conclusions: Our results demonstrated that the anti-α1-AR antibody exhibited remarkable effects of vascular contraction in vitro, and also can induce blood pressure increasing in vivo. Thus, autoantibody against α1-AR may play a role in both the initiation and maintenance of the hypertension. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether immunization with synthetic peptides corresponding to the second extracellular loop of the β1-adrenoceptor (β1-AR-ECu) may induce myocardial apoptosis in vivo, and if so, to determine whether apoptosis may contribute to cardiac dysfunction. Methods and Results: Adult male Wistar rats were immunized with synthetic peptides for 9 weeks. Anti-β1-AR antibody, cardiomyocyte apoptosis and cardiac function were determined. In the vehicle group, the antibody titer remained below 1:10 and no myocardial apoptosis and cardiac functional change were observed. However, in the immunized rats, a significant increase in anti-β1-AR antibody occurred 2 weeks after the immunization and peaked at week 3. A significant increase in caspase 3 occurred at week 3 and peaked at week 4, and severe cardiac dysfunction occurred 7 weeks. Treatment with Z-VAD-FMK, a broad-spectrum caspase inhibitor abolished myocardial apoptosis and improved cardiac function in the immunization rats. Conclusion: Our results demonstrated that stimulation with the antibody against β1-AR-ECu induces cardiomyocyte apoptosis in vivo contributing to cardiac dysfunction, and suggest that anti-apoptotic treatments may be a novel strategy in reducing multiple organ injury associated with immune response. [ABSTRACT FROM AUTHOR]

Objective: This study was designed to investigate the effects of pioglitazone, a PPARγ (peroxisome proliferator-activated receptory) agonist, on endothelial cell (EC) dysfunction in hypercholesterolemic rats and possible mechanism. Methods: Male Wistar rats were assigned to one of the following groups: control (C, normal diet); hypercholesterolemia (HC, high-cholesterol diet for 8 weeks); and HC treated with pioglitazone (10mg/kg/day for the last 4 weeks). EC function was determined by comparing vasorelaxation to Acetylcholine and acidified NaNO2. The expression of p-VASP(the phosphorylation of vasodilator-stimulated phosphoprotein) was detected by Western-blot. The level of TCh,TG and HDL-C in the serum was determined by kits. Results: Compared with the normal group, HC rats had increased level of TCh and TG obviously. Hypercholesterolemia caused a significant EC dysfunction (maximal relaxation to Ach: 50.51±2.45% vs. 99.73%±3.04% in C, P<0.01) and reduced p-VASP. Treatment with pioglitazone attenuated the high level of plasma lipid profiles, improved endothelium-dependent vasodilatation and preserved p-VASP. Conclusions: Our study suggests that pioglitazone may exert a significant vasoprotective effect in hypercholesterolemia rats by depressing the level of serum lipid profiles and improving NO bioavailability. [ABSTRACT FROM AUTHOR]

Objective To investigate the effects of pioglitazone, an agonist of peroxisome proliferator-activated receptor (PPAR) γ, on postischemic myocardial apoptosis in hypercholesterolemic (HC) rats. Methods Male Wistar rats were fed with normal or high cholesterol diets for 8 weeks. Four weeks after being fed a high cholesterol diet, HC rats were randomized to receive vehicle or pioglitazone during the remaining 4 weeks. At the end of 8 weeks, rats were then subjected to 30 min of coronary occlusion followed by 3 h of reperfusion. The myocardial infarct size, myocardial apoptosis, caspase-3 activity, nitric oxide (NO) contents and iNOS expression were measured by TTC staining, TUNEL assay, colorimetric assay, nitrate reductase assay and western-blotting. Results Compared with normal diet, HC had increased the myocardial infarct size (35±2% vs. 56±6%), caspase-3 activity, apoptotic cell death (15±3% vs. 22±2%), iNOS expression and NO contents (1.27±0.13¦Ìmol/gprot) (P<0.05). Treatment with pioglitazone in HC rats reduced the ischemia/reperfusion myocardial infarct size (39±2%), attenuated iNOS expression, NO contents (0.80±0.09¦Ìmol/gprot) and myocardial apoptosis (16±1%) (P <0.05). Conclusion Our results demonstrated that HC increased ischemia/reperfusion injury evidenced by aggravated cardiac dysfunction. In addition, pioglitazone could improve cardiac function and protect the heart injury after myocardial ischemia/reperfusion in HC rats. The PPARγ agonists may protect the heart from subsequent is ischemia/reperfusion-induced myocardial apoptosis. [ABSTRACT FROM AUTHOR]

Objective: Cardioprotection with postconditioning has been well demonstrated after a short period of reperfusion. This study was designed to investigate whether hypoxia inducible factor-1α (HIF-1α), the major transcription factor and key regulator of adoptive responses to hypoxia, was expressed during myocardial ischemia postconditioning (MIP). Methodes: Male adult rats undergoing 45 min left anterior descending artery occlusion were divided into MI/R (myocardial ischemia and reperfusion) group with 3 h of full reperfusion and MIP group with three l0 s cycles of reperfusion and re-occlusion applied at the onset of 3 h of reperfusion. The expression of HIF-1α was examined by immunohistochemistry and western blot. Myocardial infarct size was identified by Evans blue and TTC staining. Cardiomyocyte apoptosis was qualitatively analyzed by terminal dUTP nick end-labeling (TUNEL) assay. Result: Compared with MI/R group, treatment with MIP reduced myocardial infarct size (16.3±1.7% vs. 27.1±2.3%, P<0.05), decreased cardiomyocyte apoptosis (10.2±2.0% vs.18.2±3.7%, P<0.05). The expression of HIF-1α was significant increased with 1.4-fold in MIP groups versus MI/R groups. Conclusion: MIP has a protective effect on ischemic reperfused myocardium and the effect is intimately related to upregulation of HIF-1α. [ABSTRACT FROM AUTHOR]

The relaxin family peptides have been shown to exert several beneficial effects on the heart, including anti-apoptosis, antifibrosis, and anti-hypertrophy activity. Understanding their regulation might provide new opportunities for therapeutic interventions, but the molecular mechanism(s) coordinating relaxin expression in the heart remain largely obscured. Previous work demonstrated a role for the orphan nuclear receptor Nur77 in regulating cardiomyocyte apoptosis. We therefore investigated Nur77 in the hopes of identifying novel relaxin regulators. Quantitative real-time PCR (qRT-PCR) and enzymelinked immunosorbent assay (ELISA) data indicated that ectopic expression of orphan nuclear receptor Nur77 markedly increased the expression of latexin-3 (RLN3), but not relaxin-1 (RLN1), in neonatal rat ventricular cardiomyocytes (NRVMs). Furthermore, we found that the β-adrenergic agonist isoproterenol (ISO) markedly stimulated RLN3 expression, and this stimulation was significantly attenuated in Nur77 knockdown cardiomyocytes and Nur77 knockout hearts. We showed that Nur77 significantly increased RLN3 promoter activity via specific binding to the RLN3 promoter, as demonstrated by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assays. Furthermore, we found that Nur77 overexpression potently inhibited ISO-induced cardiomyocyte apoptosis, whereas this protective effect was significantly attenuated in RLN3 knockdown cardiomyocytes, suggesting that Nur77-induced RLN3 expression is an important mediator for the suppression of cardiomyocyte apoptosis. These findings show that Nur77 regulates RLN3 expression, therefore suppressing apoptosis in the heart, and suggest that activation of Nur77 may represent a useful therapeutic strategy for inhibition of cardiac fibrosis and heart failure. [ABSTRACT FROM AUTHOR]

Aging is regulated by conserved signaling pathways. The glycogen synthase kinase-3 (GSK-3) family of serine/ threonine kinases regulates several of these pathways, but the role of GSK-3 in aging is unknown. Herein, we demonstrate premature death and acceleration of age-related pathologies in the Gsk3a global KO mouse. KO mice developed cardiac hypertrophy and contractile dysfunction as well as sarcomere disruption and striking sarcopenia in cardiac and skeletal muscle, a classical finding in aging. We also observed severe vacuolar degeneration of myofibers and large tubular aggregates in skeletal muscle, consistent with impaired clearance of insoluble cellular debris. Other organ systems, including gut, liver, and the skeletal system, also demonstrated age-related pathologies. Mechanistically, we found marked activation of mTORC1 and associated suppression of autophagy markers in KO mice. Loss of GSK-3α, either by pharmacologic inhibition or Gsk3a gene deletion, suppressed autophagy in fibroblasts. mTOR inhibition rescued this effect and reversed the established pathologies in the striated muscle of the KO mouse. Thus, GSK-3α is a critical regulator of mTORC1, autophagy, and aging. In its absence, aging/senescence is accelerated in multiple tissues. Strategies to maintain GSK-3α activity and/or inhibit mTOR in the elderly could retard the appearance of age-related pathologies. [ABSTRACT FROM AUTHOR]