Effect of saponins extracted from Panax japonicas on inhibiting myocardial fibrosis by TGF-β1/Smad3 signaling pathway in aging rats

Abstract

To investigate the amelioration effect of saponins extracted from Panax japonicas (SPJ) on myocardial fibrosis in natural aging rats and its mechanisms, male SD rats aged 18 months were randomly divided into 3 groups (aging model group, low-dose SPJ group and high-dose SPJ group), with 10 rats in each group. SPJ groups were given SPJ at different doses (10, 60 mg·kg⁻¹·d⁻¹) consecutively for 6 months, meanwhile, aging model group was treated with the equal volume of saline for 6 months until 24 months old. Another 10 rats aged 6 month were used as young control group. The changes of myocardial morphological were observed by haematoxylin-eosin (HE) staining. Masson staining was used to observe the changes of collagen deposition in rat hearts. RT-PCR was used to detect the mRNA expression levels of myofibroblast marker α-SMA, collagen-related protein COL1α2, COL3α1 and matrix metalloproteinase MMP2, MMP9. Western blot was used to test the changes of the protein expressions of TGF-β1, p-Smad3, IL-1β and TNF-α in heart tissues. SPJ can effectively improve the arrangement of myocardial fibers, decrease inflammatory infiltration and reduce collagen deposition in aging rats. SPJ can effectively down-regulate the mRNA expression levels of COL1α2, COL3α1, α-SMA, MMP9, MMP2 and inhibit the protein expressions of TGF-β1, p-Smad3, TNF-α, IL-1β in the natural aging heart tissues. SPJ can effectively alleviate myocardial fibrosis in natural aging rats, and its mechanisms was related to the inhibition of the protein expressions of TGF-β1, p-Smad3 and the reduction of myocardial inflammation in rat hearts.