Study on the expression of transforming growth factor-β1 in myocardial tissue and the concentration of serum B-type natriuretic peptide in myocardial remodeling of rats and the effects of Carvedilol intervention

Abstract

Objective To study the expression of transforming growth factor-β1 (TGF-β1) in myocardial tissue and the concentration of serum B-type natriuretic peptide (BNP) in myocardial remodeling of SD rats induced by isoproterenol (ISO) and the effects of carvedilol intervention. Methods According to random number table, 30 male SD rats were divided into 3 groups: (1)after 9 g/L saline was injected with 5 mL/(kg·d) for 10 days, 9 g/L saline was used at the dose of 10 mL/(kg·d) by way of gavage for 4 weeks in the control group (n=10); (2) after ISO was injected with 5 mg/(kg·d) for 10 days, 9 g/L saline was used at the dose of 10 mL/(kg·d) by way of gavage for 4 weeks in the model group (n=10); (3)after ISO was injected with 5 mg/(kg·d) for 10 days, carvedilol was used at the dose of 10 mg/(kg·d) by way of gavage for 4 weeks in the treatment group (n=10). Then, all the rats were killed and the cardiac weight index (CWI) was measured.The pathological changes of myocardial tissue were observed through HE staining and Masson staining.The mRNA expression of TGF-β1 was detected by adopting reverse transcription-polymerase chain reaction.The protein of TGF-β1 was detected by means of immunohistochemistry and Western blot.The concentration of serum BNP was tested by adopting enzyme-linked immuno sorbent assay. Results (1)Pathological changes by light microscope: no significant pathological changes were observed in myocardial tissue of the control group.The denaturization, hypertrophy, edema, necrosis of myocardial cells and collagen fibers increased in myocardial tissue of the model group were more serious than those of the treatment group.(2) CWI: CWI of the model group[(3.31±0.07) mg/g] was significantly higher than that of the treatment group[(3.03±0.04) mg/g], and CWI of the treatment group was significantly higher than that of the control group[(2.98±0.10) mg/g]. There was significant difference among 3 groups (F=54.383, P=0.000). There was also significant difference between any 2 groups (all P<0.01). (3) The level of TGF-β1 of myocardial tissue: the level of TGF-β1 of the model group was significantly higher than that of the treatment group, and the level of TGF-β1 of the treatment group was significantly higher than that of the control group by using three detection methods.There was significant difference among 3 groups (F=13.62, P=0.000). There was also significant difference between any 2 groups (all P<0.01). (4) The concentration of serum BNP: the concentration of serum BNP of the model group[(61.13±2.00) ng/L] was significantly higher than that of the treatment group[(57.08±1.52) ng/L], and the concentration of serum BNP of the treatment group was significantly higher than that of the control group[(51.56±1.80) ng/L]. There was significant difference among 3 groups (F=72.81, P=0.000). There also was significant difference between any 2 groups (all P<0.01). Conclusions The expression of TGF-β1 in myocardial tissue was up-regulated and the concentration of serum BNP was increased in myocardial remodeling of SD rats induced by ISO.The carvedilol intervention can down-regulate the expression of TGF-β1 and decrease the concentration of BNP, then inhibit myocardial remodeling, and improve cardiac function. Key words: Transforming growth factor-β1; B-type natriuretic peptide; Myocardial remodeling; Carvedilol