ABSTRACT
Background: The cellular and molecular mechanisms of cardioprotective effects of Vitamin D are poorly understood. Given the essential role of sirtuin-3 (SIRT3) as an endogenous negative regulator of cardiac hypertrophy, this study was designed to investigate the effect of 1, 25-dihydroxyvitamin D3 (calcitriol) on hypertrophy markers and SIRT3 mRNA and protein levels following angiotensin II induced - hypertrophy in cardiomyoblast H9c2 cells. Methods: Rat cardiomyoblast H9c2 cells were treated for 48 hr with angiotensin II alone (Ang group) or in combination with 1, 10 and 100 nM of calcitriol (C + Ang groups). Intact cells served as control (Ctl). The cell area was measured using methylene blue staining. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and SIRT3 transcription levels were measured by real time RT-PCR. SIRT3 protein expression was evaluated using western blot technique. Results: The results showed that in Ang group cell size was increase by 128.4 ± 15% (P < 0.001 vs. Ctl) whereas in C100 + Ang group it was increased by 21.3 ± 6% (P < 0.001 vs. Ang group). Calcitriol pretreatment decreased ANP mRNA level significantly (P < 0.05) in comparison with Ang group (Ang: 75.5 ± 15%, C100 + Ang: 19.2 ± 9%). There were no significant differences between Ang group and cells pretreated with 1 and 10 nM of calcitriol. SIRT3 at mRNA and protein levels did not change significantly among the experimental groups. Conclusions: In conclusion, pretreatment with calcitriol (100 nM) prevents Ang II-induced hypertrophy in cardiomyoblast H9c2 cells. This probably occurs through other pathways except SIRT3 upregulation.
Subject(s)
Angiotensin II/metabolism , Calcitriol/pharmacology , Cardiomegaly , Myocytes, Cardiac , RNA, Messenger/metabolism , Angiotensin II/chemistry , Animals , Myocytes, Cardiac/drug effects , RNA, Messenger/chemistry , RatsABSTRACT
PURPOSE: Sirtuin-3 (SIRT3) deacetylase protects the heart against oxidative stress via survival factors upregulation. Clinical and experimental studies have demonstrated that activation of systemic and local renin-angiotensin system (RAS) is implicated in ischemia-induced cardiac injury. However, the relation between RAS and SIRT3 in pathophysiology of myocardial ischemia reperfusion is unknown. In this study, the cardiac transcription and expression of SIRT3 levels was examined in response to ischemia reperfusion in untreated and losartan treated rats. METHODS: Rats were divided into control group, losartan group (L), and ischemia reperfusion (IR) groups with (L+IR) or without losatran pretreatment. Some rats were included as sham-operated and saline groups. IR was induced by left anterior descending artery occlusion. SIRT3 protein levels were determined by Western blot technique. The genes expression was specified by real-time RT-PCR. Arrhythmias were assessed according to the Lambeth conventions. RESULTS: In L+IR group a significant reduction was noted in the number of ventricular ectopic beats (VEBs) and episodes of ventricular tachycardia (VT) (VEBs: P<0.001; VT: P<0.01 vs. IR). In IR group, SIRT3 protein level was decreased in the ischemic tissue by 26.7±5.9% (P<0.01 vs. Control). However, in the non-ischemic tissue the changes of SIRT3 protein content were not significant. In L+IR group SIRT3 protein levels in the ischemic part of Left ventricle were significantly different from IR group (P<0.001). SIRT3 mRNA level did not change significantly among the experimental groups. Thioredoxin-1 and catalase transcription level was increased in L+IR group compared to IR group (P<0.01). CONCLUSION: A decreased SIRT3 protein levels subsequent to IR might be a novel signaling mechanism involved in IR injury. Losartan at non-hypotensive dose exerts anti-ischemic effects in part by normalizing the SIRT3 protein level and upregulating the survival factors encoding genes transcription in ischemic tissue of the heart.
Subject(s)
Cardiotonic Agents/pharmacology , Losartan/pharmacology , Myocardial Reperfusion Injury/drug therapy , Sirtuin 3/genetics , Animals , Blotting, Western , Cardiotonic Agents/administration & dosage , Catalase/genetics , Dose-Response Relationship, Drug , Gene Expression Regulation/drug effects , Losartan/administration & dosage , Male , Myocardial Reperfusion Injury/physiopathology , RNA, Messenger/metabolism , Rats , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction , Thioredoxins/genetics , Up-Regulation/drug effectsABSTRACT
The aim of this study was to assess the effect of combined 1,25-dihydroxyvitamin D (1,25 D) and resveratrol on cardiac arrhythmias, infarct size, and transcription of catalase, thioredoxin-1 and B-cell lymphoma 2 (Bcl-2), following myocardial ischemia-reperfusion (IR) in male rats. Ligation of coronary artery was performed in rats (n = 6 per group) without any treatment (IR group), pretreated with 0.1 µg/kg/day of 1,25 D (1,25 D + IR), 1 mg/kg/day of resveratrol (Res + IR) or a combination (1,25 D + Res + IR) for 14 days. Arrhythmias were analyzed according to the Lambeth conventions, and infarct size was measured by 2,3,5-triphenyl-2H-tetrazolium chloride staining. Expression of prosurvival genes was evaluated by real-time polymerase chain reaction. In the 1,25 D + Res + IR group the mean infarct size was 17.6 ± 3.5 %, which was significantly less than that in the IR, 1,25 D + IR, and Res + IR groups (p < 0.001). Although the single therapy of either 1,25 D or resveratrol did not change the incidence of arrhythmias significantly, a reduction in the number of ventricular ectopic beats was noted in group 1,25 D + Res + IR (179.19 ± 58.87, p < 0.001 vs IR; p < 0.05 vs Res + IR; p < 0.01 vs Vit D + IR). Combination of 1,25 D and resveratrol increased transcription of catalase by 119 ± 37 % (p < 0.001 vs IR, p < 0.01 vs Res + IR, p < 0.001 vs 1,25 D + IR). Our study showed that combination of a non-hypotensive dose of 1,25 D and resveratrol can be a novel and effective strategy for protecting against ischemia.
