IUGR alters muscle fiber development and proteome in fetal pigs.

Intrauterine growth restriction (IUGR) may have permanent stunting effects on muscle growth and development of the progeny. However, underlying mechanisms are largely unknown. Recent studies comparing muscle fiber development and proteomes in IUGR and normal-body-weight (NBW) fetal pigs indicated that muscle fiber diameter were smaller in IUGR fetal pigs than in NBW fetal pigs on all three stages (d 60, d 90 and d 110) of gestation. Although the number of primary fibers did not differ between these two fetal groups on d 60 of gestation, the total number of muscle fibers in IUGR fetal pigs was lower on d 90 and 110 of gestation, when compared with NBW fetal pigs. Further proteomic analysis has shown that 37 proteins involved in energy supply and protein metabolism, structure and type of muscle fibers, proliferation and differentiation of muscle fibers, nutrient transport, intracellular environment, and tissue integrity were differentially expressed between IUGR and NBW fetal pigs. These novel findings provide some implications on the mechanisms of reduced growth and impaired development of skeletal muscle in IUGR piglets.