The lactation performance of sows plays a key role in pork production. The number of mammary cells and the number of nutrients available to those mammary cells are the main determinants of milk production. Hence, promoting the proliferation of mammary epithelial cells and enhancing the synthesis of milk-specific proteins in these cells are two effective ways to improve the lactation performance of mammals.

In recent years, studies have focused on nutritional and hormonal regulation of mammary gland metabolism. Emerging evidence has shown that Alpha-ketoglutarate (AKG), the carbon skeleton for the synthesis of glutamate and glutamine, can promote cell growth and protein synthesis through mechanistic targeting of rapamycin (mTOR). AKG may provide a novel strategy to enhance the lactation ability of mammary epithelial cells.

Recently, researchers in the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) used the porcine mammary epithelial cell model in vitro to explore the effect of AKG on lactation performance.

The team found AKG enhances the proliferation of porcine mammary epithelial cell and the expression of lactation-associated proteins. Results suggest that AKG may enhance the viability and proliferation of PMECs, and may also modulate intracellular signaling to promote the secretion of lactate and lactose. Thus, AKG may be beneficial for improving the lactation performance of mammals.

"The promotive effect of AKG on porcine mammary epithelial cell results from increases in protein synthesis and glucose metabolism through activating the crosstalk between ERS and mTOR signaling." said JIANG Qian, a doctoral researcher at ISA.

Their findings suggest that mTOR may phosphorylate a key protein in specific ERS pathways to up-regulate the activity of ERS-associated proteins. Even through, for applying the AKG into production practice,in vivo feeding studies are required to test this hypothesis. The feeding experiment is conducting in "Xin Wufeng" swine farm.

This research was supported by National Basic Research Program of China (2013CB127306), National Natural Science Foundation of China (31472107), the Chinese Academy of Sciences through its Hundred Talent Program, the Hubei Hundred Talent program, and Texas A&M AgriLife Research (H-8200).

The study entitled "alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells" has been published in the September issue of Amino Acids, details could be found at http://link.springer.com/article/10.1007/s00726-016-2249-5.

Contact: YAO Kang

E-mail: yaokang@isa.ac.cn

Institute of Subtropical Agriculture, Chinese Academy of Sciences