Berberine Alleviates Right Heart Dysfunction in MCT-Induced PAH Rats by Targeting Myocardial Mitochondrial Oxidative Phosphorylation
Authors: Bai Yu , Liu Zihua , Wang Xuyang , Lu Kangping , Deng Qiming , Hou Jingchen , Kessler John 
Published: May 2024

Background: Right ventricular failure (RVF) stands as a leading cause of mortality among pulmonary hypertension (PAH) patients. The underlying mechanisms contributing to Right Ventricular (RV) dysfunction remain enigmatic, with a conspicuous absence of effective treatments. RV functional deterioration is influenced by mitochondria oxidative phosphorylation and fatty acid oxidation. Berberine (BBR), a natural active compound extracted from Berberis vulgaris rhizomes, has shown promise for treating cardiovascular diseases due to its interactions with multiple intracellular targets. This study aimed to investigate the applicability and therapeutic effcacy of BBR in RVF and explore the mechanisms involved in its beneficial effects in monocrotaline (MCT)-induced PAH rats. Methods: Right ventricular hypertrophy (RVH) and RVF were induced via a single injection of MCT (60 mg/kg, ip) in Sprague-Dawley rats. BBR (4 mg/kg body weight per day) was administered through oral gavage. RVH and RVF were confirmed through transthoracic echocardiography (TTE). Transmission electron microscopy (TEM) was utilized to observe changes in cardiomyocyte and mitochondrial ultrastructure within the right ventricle tissue. Comparisons were made among Normal control (NC), RVH, RVH+BBR, RVF, and RVF+ BBR groups. RNA sequencing (RNA-seq) of right ventricle tissue was performed for both the NC (treated with normal saline, ip) and right ventricle dysfunction (RVH and RVF) groups. Gene Ontology and KEGG enrichment analyses were conducted using the R-package “Clusterprofiler.” RV transcriptome results were validated through qPCR and Western blot analysis. Results: Echocardiography and elevated ANP and BNP levels confirmed the presence of RVF following the development of MCT-induced PAH. TEM imaging revealed significant disruptions in mitochondrial ultrastructure, particularly in a subset of interfibrillar mitochondria, which exhibited swelling, disorganization, and reduced cristae density in RVH rats. These disruptions were even more pronounced in RVF rats. Transcriptomic profiles of RV tissue from RVH and RVF identified a total of 175 differentially expressed genes (DEGs). Gene Ontology and KEGG enrichment analyses pinpointed 38 genes associated with oxidative phosphorylation. qPCR demonstrated downregulation of mitochondrial oxidative phosphorylation-related genes (NDUFA2, NDUFA13, COX7B, COX6C, GSTK1, ECH1) in RVF. BBR ameliorated right heart function, leading to decreased RV internal diameter at end-diastole, a reduced RV hypertrophy index, and an increased RV fractional area change. This was accompanied by the recovery of ANP and BNP levels. Furthermore, after BBR application, the mitochondrial structure within RV tissue exhibited marked improvement. Lastly, Western blot analysis revealed that fatty acid oxidation-related proteins (Decr1, Acadm, Acacb, Hadh, Hadhb, Prkag3, Acaa2) were downregulated in right heart dysfunction, and BBR effectively mitigated the decline in oxidation-related protein levels in both RVH and RVF. Conclusion: In summary, our results underscore the critical role of BBR in preserving cardiac function from RVF in MCT-induced PAH rats. This preservation appears to occur through the upregulation of mitochondrial oxidative phosphorylation levels, ultimately enhancing energy metabolism within the mitochondria of RV cardiomyocytes in the right heart of PAH. This work is supported by Natural Science Foundation of Shandong Province(ZR2022MH052), China Postdoctoral Fund (NO.2021M691944) to XMY. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.