Effect and mechanism of Poria cocos polysaccharides on myocardial cell apoptosis in rats with myocardial ischemia-reperfusion injury by regulating Rho-ROCK signaling pathway / 中国中药杂志

This study aimed to investigate the effect and underlying mechanism of Poria cocos polysaccharides(PCP) on myocardial cell apoptosis in the rat model of myocardial ischemia-reperfusion injury(MI/RI). Male SPF-grade SD rats were randomly divided into a sham group(saline), a model group(saline), low-and high-dose PCP groups(100 and 200 mg·kg~(-1)), and a fasudil group(10 mg·kg~(-1)), with 16 rats in each group. Except for the sham group, the other four groups underwent left anterior descending coronary artery ligation for 30 min followed by reperfusion for 2 h to establish the MI/RI model. The myocardial infarct area was assessed by TTC staining. Histological changes were observed through HE staining. Myocardial cell apoptosis was evaluated using TUNEL staining. Serum lactate dehydrogenase(LDH), creatine kinase MB(CK-MB), interleukin-1β(IL-1β) and IL-18 levels, myocardial superoxide dismutase(SOD) activity and malondialdehyde(MDA) levels were detected by ELISA. Protein expression of B-cell lymphoma 2(Bcl-2), Bcl-2 associated X protein(Bax), cleaved caspase-3, Ras homolog gene A(RhoA), myosin phosphatase target subunit 1(MYPT-1), phosphorylated MYPT-1(p-MYPT-1), and Rho-associated coiled-coil forming kinase 1(ROCK 1) were measured by Western blot. Pathological staining of myocardial tissue revealed that in the model group, there was focal necrosis of myocardial tissue, myocardial cell swelling, unclear boundaries, and neutrophil infiltration. These pathological changes were alleviated in the low-and high-dose PCP groups and the fasudil group. Compared with the model group, the low-and high-dose PCP groups and the fasudil group showed significantly reduced myocardial infarct area and myocardial cell apoptosis rate. Compared with the sham group, the model group exhibited elevated serum LDH, CK-MB, IL-1β and IL-18 levels, increased MDA levels, relative protein expression of Bax, cleaved caspase-3, RhoA, ROCK1 and p-MYPT-1, and decreased myocardial SOD levels and Bcl-2 protein expression. Compared with the model group, the PCP groups and the fasudil group showed lowered serum LDH, CK-MB, IL-1β and IL-18 levels, decreased MDA levels, relative protein expression of Bax, cleaved caspase-3, RhoA, ROCK1 and p-MYPT-1, and increased myocardial SOD levels and Bcl-2 protein expression. PCP exhibited a certain preventive effect on myocardial tissue pathological damage and myocardial cell apoptosis in MI/RI rats, possibly related to the inhibition of the Rho-ROCK signaling pathway activation, thereby reducing oxidative stress and inflammatory responses.

La inhibición de Rho quinasa post infarto mejora el remodelado y la función ventricular: mecanismos involucrados a nivel preclínico / Rho-kinase inhibition post myocardial infarction improves remodeling and systolic function: a preclinical study of intervening factors in a pre-clinical study

Resumen: Objetivo: Determinar algunos mecanismos moleculares por los cuales la activación de ROCK cardíaca post infarto del miocardio (IAM) participa en el remodelado y en deterioro de la función sistólica. Métodos: Determinación simultánea de niveles de proteínas blanco de ROCK cardíaca, de función sistólica in vivo del ventrículo izquierdo (VI) y de fibrosis e hipertrofia cardíaca en ratas con IAM en condiciones de inhibición de ROCK con fasudil. Resultados : Siete días post IAM la masa ventricular relativa aumentó significativamente en un 30% en el grupo MI y se redujo con fasudil. La disfunción sistólica VI mejoró significativamente con fasudil mientras que la activación de ROCK cardíaca se redujo a niveles del grupo control. El inhibidor de ROCK también redujo significativamente los niveles cardíacos elevados de las isoformas ROCK1 y ROCK2, de MHC-β y del colágeno miocárdico. En el grupo con IAM aumentaron significativamente los niveles de fosforilación de ERK 42 y ERK 44 (en 2 veces y en 63%, respectivamente), mientras que en el grupo IAM tratado con fasudil estos niveles fueron similares a los del grupo control. El IAM aumentó significativamente los niveles fosforilados del factor de transcripción GATA-4, que se normalizaron con el inhibidor de ROCK. Conclusiones: La disfunción sistólica post IAM se asoció fuertemente con la activación del ROCK cardíaca y con la fosforilación de proteínas río abajo de ROCK que promueven remodelado cardíaco como β-MHC y la vía ERK / GATA-4.

Abstracts: Objective: to determine some molecular mechanisms by which cardiac ROCK activation after myocardial infarction (MI) intervene in cardiac systolic function decline and remodeling. Methods: simultaneous measurement of different cardiac ROCK target proteins levels, in vivo left ventricular (LV) systolic function, myocardial fibrosis, and hypertrophy in rats with MI under ROCK inhibition with fasudil were performed. Results: seven days after MI the relative ventricular mass increased significantly by 30% in the MI groupand was reduced with fasudil. LV systolic dysfunction improved significantly with fasudil whereas at the same time cardiac ROCK activation was reduced to sham levels. The ROCK inhibitor also reduced increased cardiac levels of both ROCK1 and ROCK2 isoforms, β-MHC levels and myocardial collagen volume fraction decline. MI significantly increased phosphorylation levels of ERK 42 and ERK 44 by 2-fold and 63% respectively whereas in the fasudil-treated MI group these levels were similar to those in the sham group. MI significantly increased phosphorylated levels of the transcription factor GATA-4 which were normalyzed by the ROCK inhibitor. Conclusion: LV systolic dysfunction after MI was strongly associated to cardiac ROCK activation and subsequent phosphorylation of ROCK target proteins that promote ventricular remodeling, such as β-MHC and the ERK/GATA-4 pathway. ROCK inhibition with fasudil significantly improved systolic function, diminished myocardial fibrosis, and normalized β-MHC and ERK/GATA-4 phosphorylation levels.