Nutritional and regulatory role of branched-chain amino acids in lactation.
Optimal growth and health of suckling neonates critically depend on milk production by their mothers. In both humans and animals, branched-chain amino acids (BCAA) are not only the major components of milk proteins but are also nitrogenous precursors for the synthesis of glutamate, glutamine, alanine, and aspartate in the mammary gland. These synthetic pathways, which are initiated by BCAA transaminase, contribute to the high abundance of free and peptide-bound glutamate, glutamine, aspartate and asparagine in milk.  In mammary epithelial cells, the carbon skeletons of BCAA can be partially oxidized via branched-chain alpha-ketoacid dehydrogenase to provide energy for highly active metabolic processes, including nutrient transport, protein turnover, as well as lipid and lactose syntheses. In addition, results of recent studies indicate that BCAA play regulatory roles in mammary metabolism.  For example, leucine can activate the mammalian target of rapamycin cell signaling pathway to enhance protein synthesis in mammary epithelial cells. Dietary supplementation with BCAA may have great potential to enhance milk synthesis by the lactating mammary gland, thereby improving neonatal survival, growth and development.
College of Animal Science and Technology, South China Agricultural University, Guangzhou, P R China. sgleijian@163.com
Jian
J
Lei
Dingyuan
D
Feng
Yongliang
Y
Zhang
Feng-Qi
FQ
Zhao
Zhenlong
Z
Wu
Ana
A
San Gabriel
Yoshiyuki
Y
Fujishima
Hisayuki
H
Uneyama
Guoyao
G
Wu
D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage / Q000378:metabolism*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D019587:Dietary Supplements; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D007774:Lactation / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism; D008892:Milk / Q000378:metabolism; D008894:Milk Proteins / Q000096:biosynthesis; D011247:Pregnancy; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
D000597:Amino Acids, Branched-Chain; D008894:Milk Proteins; D058570:TOR Serine-Threonine Kinases