Effects of Boron on Fat Synthesis in Porcine Mammary Epithelial Cells

This study aimed to investigate the effect of boron on porcine mammary epithelial cells (PMECs) survival, cell cycle, and milk fat synthesis. PMECs from boron-treated groups were exposed to 0-80 mmol/L boric acid concentrations. Cell counting kit-8 and flow cytometry assays were performed to assess cell survival and the cell cycle, respectively. Triacylglycerol (TAG) levels in PMECs and culture medium were determined by a triacylglycerol kit while PMECs lipid droplet aggregation was investigated via oil red staining. Milk fat synthesis-associated mRNA levels were determined by quantitative real-time polymerase chain reaction (qPCR) while its protein expressions were determined by Western blot. Low (0.2, 0.3, 0.4 mmol/L) and high (> 10 mmol/L) boron concentrations significantly promoted and inhibited cell viabilities, respectively. Boron (0.3 mmol/L) markedly elevated the abundance of G2/M phase cells. Ten mmol/L boron significantly increased the abundances of G0/G1 and S phase cells, but markedly suppressed G2/M phase cell abundance. At 0.3 mmol/L, boron significantly enhanced ERK phosphorylation while at 0.4, 0.8, 1, and 10 mmol/L, it markedly decreased lipid droplet diameters. Boron (10 mmol/L) significantly suppressed ACACA and SREBP1 protein expressions. The FASN protein levels were markedly suppressed by 0.4, 0.8, 1, and 10 mmol/L boron. Both 1 and 10 mmol/L markedly decreased FASN and SREBP1 mRNA expressions. Ten mmol/L boron significantly decreased PPARα mRNA levels. Low concentrations of boron promoted cell viability, while high concentrations inhibited PMECS viabilities and reduced lipid droplet diameters, which shows the implications of boron in pregnancy and lactation.