Activities for leptin in bovine trophoblast cells.

Leptin is involved in various reproductive processes in humans and rodents, including placental development and function. The specific ways that leptin influences placental development and function in cattle are poorly understood. This work was completed to explore how leptin regulates hormone, cytokine and metalloprotease transcript abundance, and cell proliferation in cultured bovine trophoblast cells. In the first set of studies, cells were cultured in the presence of graded recombinant bovine leptin concentrations (0, 10, 50, 250 ng/mL) for 6 or 24 h. Transcript profiles were examined from extracted RNA. Leptin supplementation did not affect abundance of the maternal recognition of pregnancy factor, interferon-tau (IFNT), but leptin increased (P < 0.05) abundance of chorionic somatomammotropin hormone 2 (CSH2; ie, placental lactogen) at both 6 and 24 h at each concentration tested. At 24 h, the greatest CSH2 abundance (P < 0.05) was detected in cells supplemented with 50 ng/mL leptin. Transcript abundance of the remodeling factor, metalloprotease 2 (MMP2), was greater (P < 0.05) in leptin-treated cells at 24 h but not at 6 h. The 24 h MMP2 response was greatest (P < 0.05) at 250 ng/mL. Transcript abundance for MMP9 was not altered by leptin treatment. In a separate set of studies, cell proliferation assays were completed. Leptin supplementation did not affect bovine trophoblast cell line proliferation at any dose tested. In conclusion, leptin supplementation did not affect bovine trophoblast cell proliferation or IFNT expression, but leptin increases CSH2 and MMP2 transcript abundance. Both of these factors are involved with peri-implantation and postimplantation placental development and function, and this implicates leptin as a potential mediator of early placental development and function in cattle.