Metabolome and RNA-seq reveal discrepant metabolism and secretory metabolism profile in skeletal muscle between obese and lean pigs at different ages

Muscle and adipose tissues are regarded as important metabolic and secretory organs, which communicate with each other through secretory factors, also known as the "muscle-adipose axis". Secretory metabolites, as important mediators of muscle-adipose tissue crosstalk, regulating muscle differentiation, metabolic homeostasis and lipid deposition. Taoyuan Black pig (Chinese native breed, obese) originated in Taoyuan Count. Compared with lean Duroc pig, Taoyuan black pig has higher intramuscular fat content and slow myofiber proportion, and is known for excellent meat quality and richer peripheral fat deposition. Taoyuan black and Duroc pigs are also ideal animal models for studying mechanisms of muscle-adipose tissue interaction and metabolic diseases.

Using non-targeted metabolomics analysis of longissimus dorsi muscle at different ages, combined with lipid deposition phenotype data, the researchers identified age of 120 to 180 days as "window period" for lipid deposition and meat quality formation of Taoyuan black pig. Integrated metabolomics and transcriptome revealed that the metabolic differences of longissimus dorsi muscle between breeds and ages mainly reflected in the pathways related to energy, lipid, amino acid and protein metabolism. Subsequently, dozens of specific metabolites in longissimus dorsi muscle of Taoyuan black pigs at 180 d were identified. According to the sub-localization information of in HMDB database, differentially secretory metabolites significantly related to intramuscular fat content were identified. Among them, organic acid metabolites (fumaric acid, succinic acid, malic acid, gamma-aminobutyric acid), amino acid and peptide metabolites (L-glutamic acid, L-lysine) presented significant negative correlation, while lipid metabolites (2-Hydroxyisovaleric acid, carnitine) showed a significant positive correlation with intramuscular fat.

Focusing on metabolites mediating muscle-adipose tissue interaction, this study systematically analyzed the differences of muscle metabolism between obese and lean pigs, and provides potential dietary additives and intervention targets for nutritional regulation of lipid deposition and pork quality, as well as theoretical references for the study of metabolic diseases using pigs as animal models.