Exploration of Relationship between TGF β_1/ Smad7 Signaling Pathway and Ventricular Fibrosis in Spontaneously Hypertensive Rats

[Objective] To explore the correlation between TGFβ1/ Smad7 signaling and ventricular fibrosis in spontaneously hypertensive rats (SHRs). [Methods] Fourteen male SHRs and 14 Wister Kyoto (WKY) rats matched with the same age and sex, were divided into 2 groups respectively according to the aging of 14 weeks as well as 22 weeks. Tail-cuff pressure was investigated before and at the end of the test, and the left ventricular mass index (LVMI) was measured after autopsy of the animals. Collagen typeⅠ, type Ⅲ as well as hydroxyproline contents which reflect myocardial fibrosis was determined by using immunohistochemical analysis. RT-PCR and Western-blot were performed to detect the expression of TGF-1 and Smad7 in the heart. [Results] 14-weeks or 22-weeks SHRs showed significantly higher blood pressure than those of WKY rats matched with age (P 0.001). 22-weeks SHRs appeared higher blood pressure than that of 14-weeks SHRs (P 0.001). There were significantly higher LVMI, hydroxyproline contents, Collagen type Ⅰ and Ⅲ along with up-expression of TGF-1 and down-expression of Smad7 in 22-weeks SHRs comparing with 14-weeks SHRs. [Conclusion] In terms of myocardial fibrosis, there are high blood pressure, rich collagen type Ⅰ, type Ⅲ, hydroxyproline contents with up-expression of TGF-1 and down-expression of Smad7 during the development of heart remodeling in SHRs.