Mammalian gonadotropin-releasing hormone (termed GnRHⅠ) is a decapeptide that plays key role in the process of reproduction. In addition to its well-known endocrine function, it has become evident that GnRHⅠ and the second GnRH subtype (termed GnRHⅡ) are potentially important autocrine and/or paracrine regulators in placental trophoblast cells. The effects of GnRHⅠ and GnRHⅡ on trophoblastic cell invasion were investigated in human choriocarcinoma cell line (JEG-3) by the methods of invasion assay, RNA interference, Western blot and Real-time PCR. The data revealed that exogenous native peptide of these two forms of GnRH significantly induced the expression of typeⅠ GnRH receptor (GnRHRⅠ) in JEG-3 cells. The specific siRNA for GnRHRⅠ was capable of blocking the invasion-promoting effect of GnRHⅠ, but did not influence the effect of GnRHⅡ. The data suggested that the two hormones may be elicited by distinct receptors. Interference of the activities of ERK and JNK was capable of attenuating GnRHⅠ and Ⅱ-induced MMP-2 expression and trophoblast invasion, indicating that activation of ERK and JNK are required in both GnRHⅠ and GnRHⅡ-mediated MMP-2 production and invasion-promoting effect in human trophoblastic cells.