21 research outputs found

    Estrogen Receptor Ī² Is Required for Optimal cAMP Production in Mouse Granulosa Cells

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    Granulosa cells of preovulatory follicles differentiate in response to FSH, and this differentiation is augmented by estradiol. We have previously shown that FSH-mediated granulosa cell differentiation requires functional estrogen receptor-Ī² (ERĪ²) by demonstrating that the granulosa cells of ERĪ²āˆ’/āˆ’ FSH-treated mice are unable to maximally induce expression of the LH receptor (an indicator of granulosa cell differentiation) compared with ERĪ²+/+ controls. As a result, FSH-primed ERĪ²āˆ’/āˆ’ granulosa cells exhibit a reduced response to a subsequent ovulatory dose of LH. In this study, we further characterized the attenuated response of ERĪ²āˆ’/āˆ’ granulosa cells to stimulation by LH and FSH using isolated mouse granulosa cells and primary granulosa cell cultures. We observed a 50% reduction in cAMP levels in cultured ERĪ²āˆ’/āˆ’ granulosa cells exposed to LH compared with ERĪ²+/+ controls. We also observed an attenuated genomic response in granulosa cells isolated from FSH-primed ERĪ²āˆ’/āˆ’ mice compared with ERĪ²+/+ controls. Our data indicate that this attenuated response may result from inadequate levels of cAMP, because cAMP levels in cultured ERĪ²āˆ’/āˆ’ granulosa cells exposed to forskolin were approximately 50% lower than in ERĪ²+/+ granulosa cells. Phosphorylation of cAMP regulatory element binding protein, an indicator of protein kinase A activity, was also reduced in FSH-treated ERĪ²āˆ’/āˆ’ granulosa cells compared with ERĪ²+/+ controls. These are the first data to indicate that ERĪ² plays a role in the induction of the cAMP pathway in mouse granulosa cells and that disruption of proper ERĪ² signaling associated with this pathway may cause negative effects on ovulation and fertility
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