Multi-Omics Deciphers Divergent Mechanisms in Differentially Cardiac-Remodeled Yili Horses Under Conditions of Equivalent Power Output

Exercise performance is a critical trait for evaluating the economic and breeding value of working and athletic horses, with cardiac structure and function serving as essential physiological determinants of athletic capacity. This study aimed to investigate the multi-omics response mechanisms associated with varying degrees of cardiac remodeling under identical exercise intensity. Twenty 2-year-old Yili horses were selected and categorized based on echocardiographic parameters into a high cardiac remodeling group (BH; EDV > 500 mL, SV > 350 mL, EF > 66%) and a low cardiac remodeling group (BL; EDV < 450 mL, SV < 330 mL, EF < 64%). Blood samples were collected before and after the 1000 m constant-speed test (pre-test high cardiac remodeling group (BH, <i>n</i> = 10), post-test high cardiac remodeling group (AH, <i>n</i> = 10), pre-test low cardiac remodeling group (BL, <i>n</i> = 10), post-test low cardiac remodeling group (AL, <i>n</i> = 10)), and integrated metabolomic, transcriptomic, and miRNA profiling were conducted to systematically characterize molecular responses to exercise-induced stress. Metabolomic analysis identified a total of 1936 lipid metabolites, with the BH group exhibiting stronger post-exercise lipid mobilization and significant enrichment of sphingolipid signaling pathways. Transcriptomic and miRNA analyses further revealed that key miRNAs in the BH group, including miR-186, miR-23a/b, and the let-7 family, along with their target genes (e.g., GNB4, RGS5, ALAS2), were involved in fine regulation of cardiac electrophysiology, oxidative stress, and energy metabolism. Integrated analysis indicated that the AH vs. BH comparison uniquely enriched pathways related to glycine-serine-threonine metabolism and glycosylphosphatidylinositol (GPI)-anchor biosynthesis, whereas the AL vs. BL comparison showed unique enrichment of α-linolenic acid and arachidonic acid metabolism pathways. Ultimately, multi-omics integration identified that in the BH group, eca-let-7d, eca-let-7e, eca-miR-196b, eca-miR-2483, and eca-miR-98 regulate ALAS2 and, together with GCSH, influence the enrichment of lipids such as PS(17:0_16:1), PS(18:0_18:1), and PS(20:0_18:1). These lipids participate in glycine, serine, and threonine metabolism through complex pathways, collectively modulating energy supply, inflammatory responses, and muscle function during exercise. This study reveals the molecular mechanisms by which horses with high cardiac remodeling maintain energy homeostasis and myocardial protection during exercise.