LH prevents AMH action via receptor downregulation in human primary granulosa lutein cells

Purpose: Gonadotropins and anti-Müllerian hormone (AMH) regulate reproductive development and ovarian function. While AMH plays a well-established role in early folliculogenesis by counteracting gonadotropins, luteinizing hormone (LH) becomes more active later, during the antral phase, when granulosa and theca cells express their respective receptors. There are hints suggesting the existence of an interplay between these hormones regulating granulosa cell functions at late stages of the folliculogenesis., but the mechanisms remain unclear. In this context, we explored whether gonadotropin LH can modulate AMH action in cells of ovarian origin. Methods: Primary human granulosa lutein cells isolated from in vitro fertilization (IVF) patients were pretreated with recombinant LH, followed by stimulation with recombinant AMH. AMH receptor type II (AMHR2) expression, AMH signaling activation, and the expression of AMH-responsive genes were assessed through RT-PCR, ELISA, and Western blotting. The involvement of the LH receptor was confirmed using siRNA-mediated knockdown. Results: Our findings showed that LH treatment downregulates AMHR2 transcripts and protein, impairing AMH-induced phosphorylation of small mothers against decapentaplegic (SMAD) 1, 5, and preventing osterix (OSX) and matrix metalloprotease 2 (MMP2) gene expression. Conclusions: These data are consistent with the possible interplay between gonadotropins and AMH in cells from antral/luteal stages and provide the molecular basis for further studies evaluating the impact of LH in modulating AMH signaling and follicular responsiveness during the antral stage.