[Effect of Combined Intervention of Electroacupuncture and Astragaloside IV on Myocardial Hypertrophy and TGF-β 1/Smad Signaling in Rats with Myocardial Fibrosis].

Objective: To observe the effect of combined intervention of electroacupuncture (EA) and astragaloside IV(ASIV) on cardiac hypertrophy and transforming growth factor β 1 (TGF-β 1)/Smad signaling in isoproterenol (ISO) induced cardiac hypertrophy rats, so as to investigate its underlying mechanisms in improving myocardial fibrosis.
Methods: A total of 50 SD rats were randomly divided into 5 groups: normal control, model (ISO), Propranolol (PRO)，ASIV and EA＋ASIV groups ( n ＝10 in each group). The myocardial fibrosis model was established by intraperitoneal injection (i.p.) of ISO (10 mg·kg ^－1 ·d ^－1 ), once daily for 30 days. Rats of the control group were given normal saline (i.p.), those of the PRO group given with PRO (40 mg·kg ^－1 ·d ^－1 , gavage), and those of the ASIV and EA＋ASIV groups were treated by gavage of ASIV (40 mg·kg ^－1 ·d ^－1 ), once daily for 30 days. EA (20 Hz, 6 V) was applied to bilateral "Neiguan" (PC 6) for 10 min, once every day for 30 d. The heart mass index (HMI, whole heart weight/body weight) and left ventricular (LV) mass index (LVMI, weight of the LV/body weight) were calculated to assess the state of cardiac hypertrophy. The enzyme linked immunosorbent assay (ELISA) was used to determine the levels of procollagen I carboxy-terminal propeptide (PICP，a marker of extracellular matrix remodeling) and carboxyterminal telopeptide of type I collagen (ICTP, a metabolite of type I collagen) in serum, and Western blot was used to test protein contents of TGF- β 1, Smad 2 / 3, Smad 4, Smad 7 in the left ventricle tissue of the heart.
Results: After modeling, the HMI and LVMI, serum PICP and ICTP contents and the expression levels of myocardial TGF-β 1, Smad 2/3 and Smad 4 proteins were significantly increased in the model (ISO) group ( P <0.05), suggesting a deposition of collagen and cardiac hypertrophy, and were considerably decreased in PRO, ASIV and EA＋ASIV groups after the intervention ( P <0.05). The expression level of myocardial Smad 7 protein was significantly lower in the model group than in the normal control group ( P <0.05), and significantly up-regulated in PRO, ASIV and EA＋ASIV groups ( P <0.05). Sirius Red staining of the left ventricular myocardium showed a dense deposition of collagen and a severer myocardial fibrosis in the model group, and a relatively lighter fibrosis in the PRO, ASIV and EA＋ASIV groups. The therapeutic effects of EA＋ASIV were comparable to those of PRO, and were significantly superior to those of ASIV in down-regulating HMI, serum ICTP, and myocardial Smad 2/3 and Smad 4 expression and up-regulating Smad 7 protein ( P <0.05). There were no significant differences among the PRO, ASIV and EA＋ASIV groups in LVMI, PICP and TGF-β 1 levels, and between the PRO and EA＋ ASIV groups in HMI, ICTP, Smad 2/3, Smad 4 and Smad 7 levels ( P > 0.05).
Conclusions: EA stimulation of PC 6 combined with ASIV can relieve cardiac hypertrophy and myocardial fibrosis in rats, which may be associated with its effects in regulating myocardial TGF-β 1/Smad signaling pathway.