Objective    To study the effect of leptin at different concentrations on phosphorylation of insulin receptors in human trophoblast cells and its role in molecular mechanism underlying insulin receptor signal transduction.     Methods      Trophoblast cells from artificially aborted embryo were cultured in vitro and divided into blank control group

100 μg/L leptin group

250 μg/L leptin group and 500 μg/L leptin group. After incubated for 24 h

phosphorylation of insulin receptors was detected by Western blotting.     Results     The phosphorylation of insulin receptor β subunit in trophoblast cells was significantly lower in 100 μg/L leptin group

250 μg/L leptin group and 500 μg/L leptin group than in control group (P0.05)

which decreased with the increasing concentration of leptin. The phosphorylation of insulin receptor protein in trophoblast cells was 1.216 2±0.032 2 in control group

and 1.056 7±0.042 4

0.957 6±0.026 8

0.734 2±0.038 8

respectively

in 100 μg/L leptin group

250 μg/L leptin group

and 500 μg/L group.     Conclusion    Leptin is correlated with insulin receptor signal transduction. Inhibition of phosphorylation in cell membrane insulin receptor β subunit may be one of the mechanisms underlying insulin receptor signal transduction.