Abstract: Abstract: Objective To study the effect of paeonol (PAE) and panax notoginseny saponins (PNS) on the expressions of collagenⅠand Ⅲ protein and mRNA in rats with acute myocardial infarction (AMI), and to explore the molecular mecha⁃ nism of improving myocardial fibrosis. Methods The rat model of AMI was made using the left anterior descending coro⁃ nary branch ligation．According to the intervention rats were divided into model group, PAE (8 mg/kg) group, PNS (40 mg/ kg) group, PAE (4 mg/kg)+PNS (20 mg/kg) group, PAE (8 mg/kg)+ PNS (40 mg/kg) group and captopril positive control group (10 mg/kg). Sham operation group, only wear line without ligation. The left ventricular mass index (LVMI) was detected after treatment for 28 d. Masson staining was used to observe changes of myocardial fibrosis. Western blot assay and RT-PCR technique were used to detect protein and mRNA expression levels of collagenⅠand Ⅲ. Results The values of LVMI were increased in model group compared with those of sham operation group and treatment groups. Compared with PAE group and PNS group, values of LVMI were significantly decreased in PAE (4 mg/kg)+PNS (20 mg/kg) group and PAE (8 mg/kg)+ PNS (40 mg/kg) group. There was a more significant decrease in formula high dose group (P < 0.01). The model group showed pathological change. There were different degrees of improvement in pathological structure in all treatment groups, more sig⁃ nificant improvement was found in formula low dose group, formula high dose group and captopril positive control group. There were different degrees of increase in expressions of collagenⅠand Ⅲ protein and mRNA in model group compared with those of sham operation group and treatment groups. Compared with PAE group and PNS group, the protein and mRNA expression levels of collagenⅠand Ⅲ were significantly decreased in formula low dose group and formula high dose group, more significant decreased was found in formula high dose group (P < 0.05). Conclusion Compound of paeonol and PNS can improve myocardial fibrosis in myocardial infarction rats, which may be related with reduced expressions of collagenⅠ and Ⅲprotein and mRNA.

Key words:  myocardial infarction, drug therapy, combination , myocardial fibrosis, disease models, animal, collagen typeⅠ, collagen type Ⅲ, Paeonol , Panax notoginseng saponins