Effects of Ligustrazine on Myocardial Fibrosis in Rats with Pressure Overload

Objective: To investigate the effects of ligustrazine (Li) on myocardial fibrosis in rats with pressure overload. Methods: Pressure overload rat models were established by constricting the abdominal a-orta. Sixty-three SD rats were divided into 3 groups: Sham operated group (SOG, n = 21), operated group (OG, n = 21) and operated combined with ligustrazine group (OG+Li, n = 21). Each group was randomly assigned to seven time points: The 1st, 2nd, 4th, 7th, 14th, 21st and 30th day after operation. Three rats were included in each time point. Serial sections of cardiac tissues were examined and the morphological or morphometric analysis of the SOG, OG and OG+Li done by histopathological and computer image analyzer technique. Results: (1) It showed that there were reactive fibrosis (from the 4th day on after operation) and reparative fibrosis (from the 21st day on after operation) in the OG, while myocardial fibrosis in the OG+Li was alleviated. Though reactive fibrosis (from the 21st day on after operation) was shown, reparative fibrosis wasn't seen. (2) Perivascular collagen area (PVCA) in the OG (2. 09±0. 45) was significantly higher than SOG (0. 83±0.06) from the 1st day on after operation and then steadily increased, while in the OG+Li (1.16±0.06), it was significantly lower than OG at the same time; collagen volume fraction (CVF) in the OG (3.08±0. 56) significantly increased compared with the SOG (2. 78±0. 64) from the 2nd day on after operation and showed a trend of rapid ascending from the 21st day on after operation; and in the OG + Li (4.69±0.85), it was significantly decreased compared with the OG (7.56±0.88) from the 21st day on after operation, with all P<0.05. Conclusion: Ligustrazine could alleviate and postpone the accumulation of myocardial collagen and has protective effects on the heart.

The Effect of TanshinoneⅡ A upon the TGF-beta1/Smads Signaling Pathway in Hypertrophic Myocardium of Hypertensive Rats

To investigate the molecular mechanism by which Tanshinone Ⅱ A （TSN Ⅱ A） prevents left ventricular hypertrophy （LVH）, we examined the expression of AT1R, TGF-β1 and Smads gene in the hypertrophic myocardium of hypertensive rats with abdominal aorta constriction. LVH model was established by creating abdominal aorta constriction. Four weeks later, animals were randomly divided into 4 groups with 8 animals in each. One group was used as model control, the other three groups were treated with TSN ⅡA （20 mg/kg）, TSN ⅡA （10 mg/kg） and valsartan （10 mg/kg）, respectively. Another 8 SD rats were subjected to sham surgery and served as blank control. After 8- week treatment, the caudal artery pressure of the animals was measured. The tissues of left ventricle were taken for the measurement of the left ventricular mass index （LVMI） and pathological sectioning and HE-staining were used for determining the myocardial fiber dimension （MFD）. The mRNA expression of AT1R, protein expression of TGF-betal and activity of Smad-2, 4, 7 were detected by RT-PCR and Western blotting, respectively. Our results showed that （1） the blood pressure of rats treated with TSN Ⅱ A, either at high or low dose, was significantly higher than those in the control and valsartan-treated group （P〈0.01, P〈0.05）; （2） LVMI and MFD in TSN Ⅱ A and valsartan-treated rats were higher than those in the control group （P〈0.05） but significantly lower than those in the model control （P〈0.01）; （3） the high doses of TSN Ⅱ A and valsartan significantly down-regulated the mRNA expression of AT 1R and protein expression of TGF-beta l and Smad-3 in the hypertrophic myocardium （P〈0.01）, and TGF-betal in valsartan-treated animals was more significantly lower than that in rats treated with TSN Ⅱ A; （4） the two doses of TSN Ⅱ A and valsartan significantly up-regulated the protein expression of Smad-7 in the hypertrophic myocardium （P〈0.01）, and Smad-7 in the animals treated with high-dose TSN Ⅱ A was significantly higher than that in rats treated with valsartan. It is concluded that inhibition of myocardial hypertrophy induced by TSN ⅡA independent of blood pressure. The underlying mechanism might be the down-regulated expression of AT1R mRNA and Smad-3, increased production of Smad-7, and blocking effect of TSN Ⅱ A on TGF betal/Smads signal pathway in local myocardium.

Molecular mechanism of carvedilol on attenuating the reversion back towards fetal energy metabolism during the development of cardiac hypertrophy

Objective to explore the molecular mechanism of carvedilol effect on fetal energy metabolism during the development of cardiac hypertrophy. Methods Male Wistar rats were divided into the coarctation of abdominal aorta group (CAA), sham operation group (SH), and carvedilol intervention group (CAR+CAA, carvedilol 30mg·kg -1 ·day -1 orally) and carvedilol control group (CAR+SH). Hemodynamics, ventricular remodeling parameters, free fatty acid in blood serum and cardiac myocyte, RT PCR analysis of the expressions of Muscle Carnitine Palmitoyltransferase I (M CPT I) and Medium Chain Acyl CoA Dehydrogenase (MCAD) mRNA were measured in all rats at 16 week after operation. Results Left ventricular hypertrophy occurrd after operation 16 weeks in group of CAA, accompanying with plasma free fatty acids accumulation, and both the levels of M CPT I and MCADmRNA were decreased significantly ( P <0.05). Carvedilol can reduce the left ventricular hypertrophy induced by pressure overload. The gene expressions of rate limiting enzyme(M CPT I) and key enzyme of fatty acid (MCAD) were upregulated in the CAR+CAA group, comparing with CAA group ( P <0.05). There was no statistically significant difference between SH group and CAR + SH group. Pressure overload in CAA rats downregulates the gene expression of rate limiting enzyme and key enzyme of fatty acid oxidation. Conclusions The intervention with carvedilol may attenuates the reversion of the metabolic gene expression back towards fetal type through up regulating the expression of M CPT I and MCADmRNA. Thus, carvedilol may confer cardioprotective effects in heart failure partly by preserving of the normal metabolic gene regulation.

Effect of Yiqi Huoxue Recipe(益气活血方)on Cardiac Function and Ultrastructure in Regression of Pressure Overload-induced Myocardial Hypertrophy in Rats

Objective： To investigate the effect of Yiqi Huoxue Recipe （YHR, 益气活血方） on the cardiac function and ultrastructure during the regression of myocardial hypertrophy induced by pressure overload in rats. Methods： The model of myocardial hypertrophy was established by abdominal aortic banding. Eighty male Wistar rats were divided into six groups, the normal control group Ⅰ （n=20）, the normal control group Ⅱ（n=12）, the hypertension model group Ⅰ （n=12）, the hypertension model group Ⅱ （n=12）, the YHR group （n=12） and the Captopril group （n=12）. The observation was carried out in the normal control group Ⅰ and the hypertension model groupⅠ after 4 weeks of modeling, and the other four groups were observed after 16 weeks of modeling （12 weeks of administration）. The cardiac function was measured with a multichannel biological signal analysis system, and the myocardium ultrastructure was observed by a transmission electron microscope. Results： （1） Compared with the normal control group Ⅰ, the systolic blood pressure and cardiac coefficient （left ventricular weight/body weight） in the model Ⅰ group was higher （P〈0.05, P〈0.01）. （2） In the YHR group, cardiac coefficient and -dp/dtmax were lower, left ventricular systolic pressure and ＋dp/dtmin were higher when compared with the model group Ⅱ and the Captopril group （P〈0.05 or P〈0.01）. In the Captopril group, only cardiac coefficient was lower when compared with the mode group Ⅱ （P〈0.05）. （3） Compared with the normal control group Ⅱ, ＋dp/dtmax was higher （P〈0.01）, -dp/dtmax and isovolumetric contraction time （ICT） was lower （P〈0.05, P〈0.01） in both the YHR group and the Captopril group. （4） Results of the myocardium ultrastructure showed edema under myocardium plasmalemma, enlarged sarcoplasmic reticulum and T tube, and significantly enlarged intercalated disc of the cardiac muscle in the model groups. In the Captopril group, the extension of sarcoplasmic reticulum and T tube as well as the pathological changes of intercalated disc were lighter, with slight edema under the myocardium plasmalemma. In the YHR group, the expansion of the sarcoplasmic reticulum was less than in the Captopril group, part of the pathological changes of intercalated discs was slightly more severe than that in the Captopril group, the dissolution of nuclear chromatin was not found, which was similar to that of the Captopril group, and no injury of the nucleus was found, either. Conclusion： YHR could reverse myocardial hypertrophy in rats with abdominal aortic banding and improve the systolic and diastolic function of the left ventricle. The ultrastructure of the myocardium such as arcoplasmic reticulum, intercalated disc, and cell nucleus in abdominal aortic banding rats could be partly reversed by the recipe.