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Pimobendan attenuates pressure overload-induced myocardial hypertrophy by inhibiting the MAPKs pathway

ABSTRACT: Background: Although myocardial hypertrophy is an essential component of heart’s response to many forms of stress, prolonger excessive hypertrophy contributes importantly to the pathogenesis of heart disease. The pimobendan is a drug that both inhibits phosphodiesterase 3 (PDE3) and acts as a calcium sensitizer, which has been used to treat heart failure. The effects of pimobendan on myocardial hypertrophy is controversial. Objective: This study aims to evaluate the therapeutic effect of pimobendan on myocardial hypertrophy. Methods: Mice were treated with low oral doses of pimobendan (1mg/kg/d) for 4 weeks after transaortic constriction. Heart structure and function was assessed using ultrasound, hemodynamic measurements and histology combined with biochemical assessments of myocardial hypertrophy. We also examined the effects of pimobendan (100 µM) on hypertrophy in cultured neonatal rat cardiomyocytes (NRCMs) induced by 50 µM phenylephrine (PE). Results: The doses pimobendan used in our studies had no effect on baseline contractility. Nevertheless, pimobendan administration of mice subjected to TAC decreased heart weights (normalized to either tibia length or body weight) ventricular wall thickness, cardiomyocyte sizes, myocardial fibrosis and the levels of a number of key myocardial hypertrophy markers (WHICH ONES). In cultured neonatal cardiomyocytes, pimobendan attenuated the PE-induced hypertrophy. In both hypertrophy models pimobendan reduced the phosphorylation levels of several essential proteins in the MAPK pathway, PI3K-AKT pathway, and calcineurin signaling pathway. Conclusion: Low pimobendan may attenuate myocardial hypertrophy. Although the underlying mechanisms remain to be elucidated, the MAPK pathway is likely to play a role.

ORGANISM(S): Mus musculus

PROVIDER: GSE182501 | GEO | 2023/07/01

REPOSITORIES: GEO

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Project description:Aims: Pathological cardiac hypertrophy induced by activation of the renin–angiotensin–aldosterone system (RAAS) is one of the leading causes of heart failure. However, in current clinical practice, the strategy for targeting the RAAS is not sufficient to reverse hypertrophy. Here, we investigated the effect of prostaglandin E1 (PGE1) on angiotensin II (AngII)-induced cardiac hypertrophy and potential molecular mechanisms underlying the effect. Methods and Results: Adult male C57 mice were continuously infused with AngII or saline and treated daily with PGE1 or vehicle for two weeks. Neonatal rat cardiomyocytes were cultured to detect AngII-induced hypertrophic responses. We found that PGE1 ameliorated AngII-induced cardiac hypertrophy both in vivo and in vitro. The RNA sequencing (RNA-seq) and expression pattern analysis results suggest that Netrin-1 (Ntn1) is the specific target gene of PGE1. The protective effect of PGE1 was eliminated after knockdown of Ntn1. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the PGE1-mediated signaling pathway changes are associated with the mitogen-activated protein kinase (MAPK) pathway. PGE1 suppressed AngII-induced activation of the MAPK signaling pathway, and such an effect was attenuated by Ntn1 knockdown. Blockade of MAPK signaling rescued the phenotype of cardiomyocytes caused by Ntn1 knockdown, indicating that MAPK signaling may act as the downstream effector of Ntn1. Furthermore, inhibition of the E-prostanoid (EP)3 receptor, as opposed to the EP1, EP2, or EP4 receptor, in cardiomyocytes reversed the effect of PGE1, and activation of EP3 by sulprostone, a specific agonist, mimicked the effect of PGE1. Conclusion: In conclusion, PGE1 ameliorates AngII-induced cardiac hypertrophy through activation of the EP3 receptor and upregulation of Ntn1, which inhibits the downstream MAPK signaling pathway. Thus, targeting EP3, as well as the Ntn1–MAPK axis, may represent a novel approach for treating pathological cardiac hypertrophy.

Project description:Cardiomyocytes exhibit differential growth patterns throughout development. In fetal life the increase in cardiac mass is associated with hyperplastic growth and cardiomyocyte proliferation. The majority of fetal cardiomyocytes are also mononucleated. During the early neonatal period in mice there is a switch from hyperplastic to hypertrophic growth of cardiomyocytes. This period is characterized by bi-nucleation and polyploidization of cardiomyocyte nuclei and a decreased capacity for cardiomyocytes to proliferate and complete cytokinesis. Increases in myocardial mass occur predominantly via hypertrophic growth. Adult mammalian cardiomyocytes are generally accepted to have little or no proliferative capacity and to be terminally withdrawn from the cell cycle. The vast majority of adult murine cardiomyocytes are bi-nucleated. The present study sought to accurately establish the growth pattern of cardiomyocytes throughout development in mice and identify genes associated with the switch from hyperplastic to hypertrophic growth. These cell cycle associated genes are crucial to the understanding of the mechanisms of bi-nucleation, polyploidization and hypertrophy in the neonatal period. Cardiomyocytes were FACS sorted from the hearts of ED11-12 embryos, neonatal day 3-4 and adult (10 week) eGFP ?-MHC mice whereby GFP expression is driven constitutively by the ?-MHC promoter. Gene analyses identified genes whose expression was predicted to be particular to day 3 -4 neonatal cardiomyocytes, compared to embryonic or adult cells. Cell cycle associated genes are crucial to the understanding of the mechanisms of bi-nucleation and hypertrophy in the neonatal period, and offer attractive candidates for manipulation. Total RNA obtained from isolated cardiomyocytes from ED11-12; Neonatal day 3-4 and adult timepoints compared with each other. Several hearts per sample, RNA was pooled within samples. FACS samples were prepared in the following manner: embryonic, neonatal and adult hearts were dissected and dissociated to single cell solution with Liberase Blendzyme 3 (0.1 mg/ml) (Roche Diagnostics), washed and spun down and resuspended in cardiomyocyte isolation buffer (130 mM NaCl; 5 mM KCl; 1.2 mM KH2PO4; 6 mM HEPES; 5 mM NaHCO3; 1 mM MgCl2; 5 mM Glucose).

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Pimobendan attenuates pressure overload-induced myocardial hypertrophy by inhibiting the MAPKs pathway

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