Differential regulation of ovarian anti-müllerian hormone (AMH) by estradiol through α- and β-estrogen receptors.

BACKGROUND: Anti-müllerian hormone (AMH) is a member of the TGF-β family, which limits follicle maturation. Recently serum AMH has been recognized as a useful diagnostic and prognostic tool in human reproductive endocrinology.
OBJECTIVE: The aim of this study was to investigate the regulation of human ovarian AMH by estradiol and FSH.
METHODS: AMH mRNA were quantified by real time RT-PCR in human granulosa cells (GC). AMH transcription was studied in KK1 GC cotransfected with estrogen receptors (ER)-β or ERα, and normal human AMH promoter-luciferase construct (hAMH-luc) or mutated AMH promoter reporter constructs. Binding sites for estradiol (estrogen response element half-site) and steroidogenic factor 1 were disrupted by targeted mutagenesis. The level of ER in GC was determined by quantitative RT-PCR and Western blotting.
RESULTS: In KK1 cells, estradiol up-regulated and inhibited hAMH-luc in the presence of ERα and ERβ respectively. Disruption of estrogen response element half-site and/or steroidogenic factor 1 binding sites did not modify ERβ-mediated effect of estradiol on hAMH-luc, whereas it affected that conveyed by ERα. The FSH enhancement of hAMH-luc was abolished by estradiol in cells overexpressing ERβ. When both ER were transfected, estradiol inhibited hAMH-luc or had no effect. Estradiol repressed AMH mRNAs in human GC, which express a little more ERα than ERβ mRNA.
CONCLUSIONS: Our results show that AMH expression can be differentially regulated by estradiol depending on the ER and suggest that its decrease in GC of growing follicles, which mainly express ERβ, and during controlled ovarian hyperstimulation is due to the effect of estradiol.