Abstract: Nitric oxide (NO) is a key regulator of maternal and fetal homeostasis during pregnancy.Moreover,NO is also an important substance in promotes maternal cardiovascular changes,fetal development and growth,and adaptation to intrauterine and extrauterine life.Arginine (Arg) and homoarginine (h-Arg) are a pair of homologous amino acids.h-Arg is a non-essential cationic amino acid which can be synthesized by lysine catabolism or amino transfer of its precursor Arg.They have similar functions in the physiological and biochemical aspects during pregnancy,because they are both metabolic products of NO.Supplementation of Arg or h-Arg during the gestation period can increase the content of NO in pregnant sow.NO can increases the attachment of embryos,reduces embryonic death and enhances fetal development by regulating the production of hormones,angiogenesis and increasing the supply of nutrients,and then improving the intrauterine growth restriction (IUGR) and reproductive performance of sow.As the pregnancy progresses,body oxidative metabolism has been increased,and a large amount of free radicals are produced.NO produced by Arg or h-Arg metabolism up-regulates the Nrf2 pathway and stimulates the expression of genes involved in glutathione (GSH) metabolism,enhances the antioxidant capacity of the sow,and ensures the healthy development of the gestational body and the fetus.In this paper,the authors focus on the supplement of Arg or h-Arg during the gestation period of sows,and discuss the functions of improving the IUGR and reproductive performance,enhancing the antioxidant capacity and the possible mechanisms of their common substrate——NO.This review is respected to provide theoretical support for the application of Arg and h-Arg on pregnant sows.

Key words: arginine (Arg); homoarginine (hArg); NO; pregnant sow