Effects of rhBNP on myocardial fibrosis after myocardial infarction in rats

Purpose: We aimed to observe the effects and mechanism of rhBNP treatment on myocardial fibrosis (MF) after myocardial infarction (MI). Methods: SPF rats were separated into 3 groups: normal, MI (ligation of left coronary artery), and MI + rhBNP (recombinant human brain natriuretic peptide). Rats in MI + rhBNP group were given 30 μg/kg for 2 days before modeling and for 4 weeks after modeling. mRNA levels and the expression levels of TGF-β1 (transforming growth factor) and CTGF (connective tissue growth factor) in 3 groups were analyzed using the RT-qPCR and western blotting analysis, respectively. Furthermore, myocardial volume fraction (CVF) was analyzed using the Sirius Red F3B (SR) while the percentage of type I and III collagen in 3 groups were analyzed using the immunohistochemical staining. Results: Compared with the normal group, the levels of TGF-β1, CTGF, CVF, type I and III collagen were higher in MI group. However, mRNA levels of TGF-β1 and CTGF were significantly decreased in MI + rhBNP compared to MI groups. Expression of TGF-β1 was lower while that of CTGF was higher in MI + rhBNP group than that in MI group. Besides, CVF, and type I and III collagen were lower in MI + rhBNP group compared with MI group. Conclusion: rhBNP could significantly decrease the TGF-β1 and CTGF levels in post-MI so as to inhibit the type I and III collagen deposition in MF of post-MI. rhBNP will be benefit for the improvement of MF.