The genes encoding glucose transporter 4 (SLC2A4, GLUT4), insulin receptor (INSR) and glucocorticoid receptor (NR3C1) are considered regulators of energy metabolism that may influence fat content in skeletal muscle at different ages and breeds of pigs. In the study we performed analysis of expression of NR3C1, INSR and SLC2A4 genes in two skeletal muscle tissues: semimembranosus and longissimus dorsi muscle in gilts from three breeds of pigs that differed in intramuscular fat content: Duroc (DU), Pulawska (PUL) and Polish Large White (PLW) at 60, 90, 120, 150, 180 and 210 days after weaning. We also analyzed the expression of cortisol binding globulin (CBG) in the liver. Expression was analyzed with real time PCR (qPCR) using a relative quantification method. In blood, the concentration of cortisol, insulin and leptin were evaluated with radioimmunoassay. The concentration of metabolites (triglycerides and glucose) related to the changes of lipids content was also measured. We observed a significant relationship between the breed and the age of pigs and the expression of analyzed genes in muscle tissues (P < 0.01 for all analyzed genes) as well as with two hormones (for insulin P = 0.001; for cortisol P < 0.0001). Leptin level and metabolites in serum were not significant in the model (P > 0.05). The expression of analyzed genes (SLC2A4, INSR and NR3C1 in muscles and CBG in liver) strongly correlates with intramuscular fat content in pigs and is associated with age and breed.
Enhancement of porcine intramuscular fat content by overexpression of the cytosolic form of phosphoenolpyruvate carboxykinase in skeletal muscle
