Dietary arginine supplementation altered expression of IGFs and IGF receptors in weaning piglets

Abstract

Young piglets have a high requirement of arginine for growth and metabolic function, but the sow milk or endogenous synthesis cannot provide enough arginine for maximal growth. Dietary Arginine supplementation can improve the immunity of early-weaned piglets and enhance the skeletal muscle synthesis for growth. The insulin-like growth factor (IGF) signaling pathway is an important regulatory factor in regulating fetal and placental growth, proliferation, differentiation, migration and aggregation, and inhibits apoptosis of mammalian cells. However, how the insulin-like growth factor system expression altered in piglets with dietary arginine supplementation, and whether arginine plays a role in IGF system secretion is little noticed. This study was conducted to investigate the effect of dietary arginine supplementation in modulation IGF system of weanling piglets. Twelve 21-day-old healthy piglets (Landrace×Yorkshire) with a mean body weight (BW) were assigned randomly to two treatments representing diets supplemented with 0.6% L-arginine and 1.23% L-alanine (isonitrogenous control). At 28 days of age, 12 piglets were killed and longissimus muscle, liver and kidney were collected. Components of IGF signaling pathway mRNA expression were examined in three tissues, IGF1 was increased in three tissues of arginine group (P<0.05). IGF2 was increased in muscle of arginine group. Both muscle and liver had a higher level of IGFBP5 with arginine supplementation (P<0.05). These data suggest an important role of arginine in modulation of IGF signal pathway and the involvement of IGF and IGF receptors in the improved growth performance.   Key words: L-Arginine, IGFs, early-weaned piglets.