REGION-SPECIFIC EFFECTS OF OVARIAN HORMONES ON ESTROGEN-RECEPTOR IMMUNOREACTIVITY

THE cell groups in which nuclear estrogen receptor (ER) expressing neu rons are found have unique, often coordinated, functions. Regulation o f ER content may be one mechanism through which feedback responses can be adjusted to match the function of a specific brain region and phys iological circumstance. In these immunocytochemical experiments, estro gen decreased staining intensity for ER in the ventrolateral hypothala mus and bed nucleus of the stria terminalis, but not in the periventri cular preoptic area. ER staining intensity was further decreased by pr ogesterone, following estrogen, but not in all brain regions. These re sults suggest that ER is regulated by estrogen in a region-specific ma nner. Furthermore, inhibition of responses to estrogen by progesterone may involve progesterone-induced downregulation of ERs.