Effects of insulin on milk fat synthesis by regulating the expressions of srebp1 and mtor in bovine mammary epithelial cells

Due to the complexity of insulin in life activities, the role of insulin in mammalian lactation has not been well explained. To investigate the influence of insulin on milk fat synthesis, bovine mammary epithelial cells (BMECs) were cultured in treatment with insulin. We determined the content of Triglyceride (TG) in cell-free culture medium and found a notable increase in TG secrection. Lipid droplet staining study showed a consistent result. We also used real-time quantitative PCR and western blotting to detect the expression of signaling molecules related to milk fat synthesis. We found that insulin resulted in an obvious increase of SREBP-1, mTOR and lipogenic gene expression compared with the blank group. Taken together, our study reveals that insulin plays a significant role in milk fat synthesis.