The rodent ovary is regulated throughout the reproductive cycle to maintain normal cyclicity. Ovarian follicular development is controlled by changes in gene expression in response to the gonadotropins FSH and LH. The inhibin ␣-subunit gene belongs to a group of genes that is positively regulated by FSH and negatively regulated by LH. Previous studies established an important role for inducible cAMP early repressor (ICER) in repression of ␣-inhibin. These current studies investigate the

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... ms of repression by ICER. It is not clear whether all four ICER isoforms expressed in the ovary can act as repressors of the inhibin ␣-subunit gene. EMSAs demonstrate binding of all isoforms to the inhibin ␣-subunit CRE (cAMP response element), and transfection studies demon-I and II) generates ICER I, I␥, II, and II␥. ICER I and I␥