Insulin and amino acids are critical regulators of neonatal muscle growth

Authors: Davis, Teresa

Submitted to: Nutrition Today
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2008
Publication Date: 7/1/2008
Citation: Davis, T.A. 2008. Insulin and amino acids are critical regulators of neonatal muscle growth. Nutrition Today. 43(4):143-149.

Interpretive Summary: Healthy newborns grow very rapidly, and their muscles grow at more rapid rates than the other tissues in their bodies. Using baby pigs as an animal model, our research showed that the muscles of newborns grow rapidly because the rate at which their muscles synthesize muscle protein increases profoundly when they eat. After eating, the rise in both amino acids, which are the building blocks of proteins, and the hormone insulin stimulates the synthesis of proteins in muscle. We have identified intracellular insulin and amino acid signaling proteins that regulate the synthesis of muscle proteins. We have also shown that the activity of these signaling proteins is elevated in muscle of the newborn and that the activity of these signaling proteins decreases with age. This information furthers the scientific understanding of the mechanisms underlying the response of different parts of the body to nourishment, and will help us find optimal ways of supporting the growth and development of babies.

Technical Abstract: Newborn humans and animals grow at very rapid rates because they very efficiently use the protein that they eat to increase body protein mass. This high efficiency of protein deposition in neonates is largely due to their ability to markedly increase the amount of protein synthesized in their muscles when they eat. This enhanced stimulation of muscle protein synthesis after eating is mediated by the rise in the hormone insulin and the rise in amino acids, which are the building blocks of protein. Intracellular signaling components that respond to insulin and amino acids have been identified, and these have been shown to be involved in the feeding-induced stimulation of protein synthesis in the skeletal muscle of the neonate. The enhanced activation of these intracellular signaling components in neonatal muscle contributes to the high rate of muscle protein synthesis and rapid gain in skeletal muscle mass in newborns.