Impact of Aerobic Training on Transcriptomic Changes in Skeletal Muscle of Rats with Cardiac Cachexia

Abstract

Cardiac cachexia (CC) is an advanced stage of heart failure (HF) characterized by structural and functional abnormalities in skeletal muscle, leading to muscle loss. Aerobic training provides benefits; however, the underlying molecular mechanisms remain poorly understood. This study aimed to investigate the therapeutic effects of aerobic training on transcriptomic alterations associated with disease progression in cachectic skeletal muscle. HF was induced in male Wistar rats by a single monocrotaline injection (60 mg/Kg). Aerobic training consisted of 30 min treadmill running at ~55% of maximal capacity, 5×/week for 4 weeks. Assessments included body mass, right ventricle mass, skeletal muscle fiber size and exercise tolerance. RNA-seq analysis was performed on the medial gastrocnemius muscle. Sedentary cachectic rats exhibited 114 differentially expressed genes (DEGs) while exercised cachectic rats had only 18 DEGs. Enrichment pathways analyses and weighted gene co-expression network analysis (WGCNA) identified potential key genes involved in disrupted lipid metabolism in sedentary cachectic rats, which were not observed in the exercised cachectic rats. Validation of DEGs related to lipid metabolism confirmed that Dgat2 gene expression was modulated by aerobic training in CC rats. These findings suggest that aerobic training mitigates transcriptional alterations related to lipid metabolism in rats with CC, highlighting its therapeutic potential.

Keywords: exercise; metabolism; muscular remodeling; pulmonary arterial hypertension; transcriptome.

Figure 1

Summary of experimental design and representation of differentially expressed genes (DEG). (a) Animal model of cachexia, exercise intervention and skeletal muscle RNA-sequence analysis. Volcano Plots show DEGs based on their log fold change for the (b) sedentary (Sed vs. CC-Sed), and (c) exercise (Ex vs. CC-Ex); red dots are upregulated DEGs, blue dots are downregulated DEGs, and grey dots are non-significant DEGs. Heat maps represent some DEGs based on z-score for the (d) sedentary and (e) exercise comparisons. Sed: control sedentary; Ex: control exercised; CC-Sed: cardiac cachexia sedentary; CC-Ex: cardiac cachexia exercised.

Figure 2

Skeletal muscle histology. Left: Medial gastrocnemius cross-sectional area. Right: Representative gastrocnemius muscle sections. Laminin (white) was used as a membrane marker. Objective 20x. Sed: control sedentary group (n = 9); Ex: control exercised (n = 8); CC-Sed cardiac cachexia sedentary group (n = 7); CC-Ex: cardiac cachexia exercised group (n = 6). * Main effect of Disease.

Figure 3

Tree plot of enriched biological process GO terms clustered by semantic similarity of (a) sedentary (Sed vs. CC-Sed) and (b) exercise (Ex vs. CC-Ex).

Figure 4

Enriched network plots: GO Biological process from (a) sedentary (Sed vs. CC-Sed) and (b) exercise (Ex vs. CC-Ex). KEGG pathway analysis from (c) sedentary (Sed vs. CC-Sed) and (d) exercise (Ex vs. CC-Ex).

Figure 5

Weighted gene co-expression network analysis (WGCNA). (a) Scale of Independence with soft threshold power (red line); (b) Scale of mean connectivity; (c) Dendrogram highlighting color-coded module eigengenes identified by hierarchical clustering (ME); (d) Correlation between ME and morphometric and exercise intolerance variables. * p < 0.05; ** p < 0.001; *** p < 0.0001.

Figure 6

Network visualization of co-expression modules (a) MEbrown and (b) MEmagenta. Genes circled in black overlap with DEGs. Panels (c,d) show enriched GO-BPs shared between module eigengenes and DEGs for MEbrown and MEmagenta, respectively. The top three overlapping GO biological processes terms, as shown in Table 6, are highlighted. Square outlines indicate DEGs connected to the top three overlapping GO biological processes.

Figure 7

Validation of DEGs related to lipid metabolism in medial gastrocnemius muscle. Sed: control sedentary group; Ex: control exercised; CC-Sed cardiac cachexia sedentary group; CC-Ex: cardiac cachexia exercised group. * Main effect of Disease.