GnRH system plays a pivotal role in human reproductive physiology. The expression and role of the GnRH system in ovarian granulosa cells is of special interest since these cells support and regulate the development of the oocyte. We investigated the mRNA expression of GnRH-I, GnRH-II and their common receptor (GnRHR) in HGL5, a human luteal granulosa cell line.

HGL5 cells were cultured according to various protocols. RNA samples were obtained from each experiment and analyzed by RT- PCR. Two sets of primers for GnRH-I and GnRH-II and five sets of primers for GnRHR were used. The primers for GnRHR covered a 989bp region of the cDNA and located at positions: 79-294; 321-366; 457-655; 468-796; 546-798. cDNA from hypothalamic tissue served as control. The authenticity of the PCR products was confirmed by sequencing.

GnRH-I and GnRH-II mRNA were detected in all cases. PCR products with the expected sizes for GnRHR were detected in hypothalamic but not in HGL5 cells. Only transcripts located in the region 79-294 were found. According to these findings, GnRH-I and GnRH-II are expressed by HGL5 cells. HGL5 possibly expresses a truncated form of GnRHR.