Effect of Guizhitang with Different Proportions of Cinnamomi Ramulus and Paeoniae Alba Radix in Regulating TGF-β1/Smads Signaling Pathway and Chronic Inflammation and Alleviating Myocardial Fibrosis in Salt-sensitive Hypertensive Rats / 中国实验方剂学杂志

ABSTRACT

<b>Objective:To observe the effect of Guizhitang with different proportions of Cinnamomi Ramulus and Paeoniae Alba Radix on the expressions of transforming growth factor-<italic>β</italic>₁(TGF-<italic>β</italic>₁)/Smads signaling pathway and interleukin-10(IL-10), IL-6 and tumour necrosis factor-<italic>α</italic>(TNF-<italic>α</italic>)related inflammatory cytokines in salt-sensitive hypertensive rats, in order to explore the mechanism of Guizhitang in improving myocardial fibrosis in salt-sensitive hypertensive rats. <b>Method:Totally 40 male 6-week-old salt-sensitive rats were randomly divided into 5 groups the normal control group, the model group, the 1∶1(RC/peony)Guishao group, the 1∶2 Guishao group, and the 2∶1 Guishao group, with 8 in each group. The normal control group was fed with normal salt diet, while the other four groups were fed with high-salt diet. After 4 weeks of feeding, the rats were given intragastric administration, the normal control group and the model group were given the same amount of normal saline, and the 1∶1 Guishao group, the 1∶2 Guishao group and the 2∶1 Guishao group were given 4.0, 5.5, 5.5 g·kg^-1 of Guizhitang by gavage for 4 weeks. Blood pressure was measured once a week, left ventricular end systolic diameter(LVESD), left ventricular end diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF) and left ventricular short axis shortening fraction (LVFS) were detected by using echocardiogram. The pathological changes of myocardial morphology were observed by htoxylin eosin(HE)and Masson staining. The expressions of type Ⅰ and Ⅲ collagen in myocardial tissue of each group was detected by immunohistochemistry. The mRNA expression levels of IL-10, IL-6 and TNF-<italic>α</italic> in myocardial tissue of each group were detected by quantitative real-time fluorescence polymerase chain reaction(Real-time PCR). The protein expression levels of TGF-<italic>β</italic>₁, <italic>α</italic>-smooth muscle actin(<italic>α</italic>-SMA), Smad2, Smad3 and Smad7 in myocardial tissue of each group were detected by Western blot. <b>Result:Compared with the normal control group, the blood pressure was increased in the model group at 8-15 weeks, LVESD, LVEDD were increased in the model group, while LVFS, LVEF were decreased in the model group. The collagen volume fraction was increased, immunohistochemistry showed the expression levels of type Ⅰ and Ⅲ collagen were increased, mRNA expression levels of IL-10, IL-6 and TNF-<italic>α</italic> were increased, the protein expression levels of TGF-<italic>β</italic>₁, Smad2, Smad3 and <italic>α</italic>-SMA were increased, whereas the protein expression of Smad7 was decreased (<italic>P</italic><0.01). Compared with the model group, the blood pressure rise of each group of Guizhitang was delayed in 12-15 weeks, LVESD and LVEDD were decreased in Guizhitang group (<italic>P</italic><0.01), LVFS, LVEF were increased in Guizhitang group (<italic>P</italic><0.01), the collagen volume fraction was decreased in Guizhitang group (<italic>P</italic><0.01), and the expressions of type Ⅰ and Ⅲ collagen were decreased in Guizhitang group (<italic>P</italic><0.01). At the same time, the mRNA expression of IL-10 was increased in Guizhitang group (<italic>P</italic><0.05, <italic>P</italic><0.01), the mRNA expressions of IL-6 and TNF-<italic>α</italic> were decreased in Guizhitang group (<italic>P</italic><0.01), and the protein expressions of TGF-<italic>β</italic>₁, Smad2, Smad3 and <italic>α</italic>-SMA were decreased in Guizhitang group (<italic>P</italic><0.05, <italic>P</italic><0.01), and the protein expression of Smad7 was increased in Guizhitang group (<italic>P</italic><0.01). Compared with the 2∶1 Guishao group, the effect of the 1∶1 Guishao group in improving the above indicators was more obvious (<italic>P</italic><0.05, <italic>P</italic><0.01). <b>Conclusion:Guizhitang with different proportions of Ramulus Cinnamomi and Poeny can alleviate the degree of myocardial fibrosis in salt-sensitive hypertensive rats. The mechanism may be related to the regulation of TGF-<italic>β</italic>₁/Smads signaling pathway and the reduction of inflammatory response. Besides, the 1∶1 Guishao group showed the optimal effect in reducing inflammation and improving myocardial fibrosis.