Objective: To identify adiponectin and its receptors (AdipoR1 and AdipoR2) in human granulosa cells (GC) and to study the effects of recombinant human adiponectin on P and E(2) secretion from these cells.
Design: The effects of recombinant human adiponectin on the secretion of P and E(2) by cultured human GCs were investigated.
Setting: Academic institutions.
Patient(s): Seventeen infertile and healthy women undergoing IVF.
Intervention(s): Primary human GC cultures stimulated with human recombinant adiponectin (5 microg/mL).
Main outcome measure(s): Determination of messenger RNA (mRNA) and protein expression of adiponectin and its receptors AdipoR1 and AdipoR2 in fresh human GCs by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblot, respectively. Measurement of P and E(2) levels in the conditioned media by RIA and determination of cell proliferation by tritied thymidine incorporation.
Result(s): Human GCs express adiponectin receptors AdipoR1 and AdipoR2 but not adiponectin. In primary human GCs, adiponectin increases P and E(2) secretion in response to insulin-like growth factor I (IGF-I). This was associated with an increase in the p450 aromatase protein level but not those of p450scc, 3 beta HSD, or StAR. Adiponectin treatment does not affect IGF-1-induced cell proliferation and basal steroidogenesis (no IGF-1 or FSH stimulation). Adiponectin rapidly stimulates MAPK ERK1/2 and p38 phosphorylation in primary human GCs.
Conclusion(s): Adiponectin receptors AdipoR1 and AdipoR2, but not adiponectin, are present in human GCs. Adiponectin increases IGF-1-induced P and E(2) secretion in primary human GCs.