Gonadotrophin stimulation of non-luteinized granulosa cells increases steroid production and the expression of enzymes involved in estrogen and progesterone synthesis.

BACKGROUND In regular IVF treatment, mature oocytes are collected with their luteinized granulosa cells (GCs). When in vitro maturation (IVM) of the oocytes is performed, non-luteinized GCs can be collected. We have investigated how these cells respond to gonadotrophin stimulation in culture. METHODS GCs were collected from patients undergoing IVM treatment and compared with GCs from IVF patients. The cells were stimulated with FSH and/or hCG. After 48 h, culture media were collected for hormone analysis, and RNA was isolated for gene expression analysis. RESULTS In IVM GCs, hCG and FSH alone and in combination induced significantly increased progesterone production, and FSH alone and in combination with hCG increased estrogen production. We also studied the gene expression of P-450aromatase and P-450scc and the receptors for FSH and LH. In non-luteinized GCs, the expression levels of P-450aromatase increased with all treatments, and P-450scc expression increased with the combined FSH and hCG treatment. LHR expression increased with FSH treatment, but the FSH receptor expression did not change with different treatments. CONCLUSIONS Non-luteinized GCs behaved differently from luteinized GCs in culture. The data help understand the final stages of maturation of human oocytes and follicles.