Estrogens are crucial determinants in the regulation of anterior pituitary function and maintenance of tissue homeostasis. Estrogen actions in this gland are exerted through both classical and non-classical mechanisms of action. This review summarizes the expression of classical α- and β-estrogen receptors and variant isoforms of estrogen receptors in anterior pituitary cell subpopulations. We ...

It is now accepted that estrogens not only stimulate lactotrope proliferation but also sensitize anterior pituitary cells to proapoptotic stimuli. In addition to their classical mechanism of action through binding to intracellular estrogen receptors (ERs), there is increasing evidence that estrogens exert rapid actions mediated by cell membrane-localized ERs (mERs). In the present study, we exa...

The mechanisms that control the emergence of different anterior pituitary cells from a common stem cell population are largely unknown. The immortalized GHFT cells derived from targeted expression of SV40 T antigen to mouse pituitary display characteristics of somatolactotropic progenitors in that they express the transcription factor GHF-1 (Pit-1) but not growth hormone (GH) or prolactin (PRL)...

Prolactin secreting adenomas (prolactinomas) are the most prevalent form of pituitary tumors in humans. Prolactinomas have been linked to estrogen exposure in humans and animals. However, the mechanism by which estrogen increases mitogenesis in lactotropes, as well as other estrogen responsive cells, is not well understood. Given the complex nature of steroid hormones and their wide array of ac...

In addition to the circulating renin-angiotensin system (RAS), a local system has been postulated in the anterior pituitary because immunodetection of its components in various mammalian species. However, different cell types appear to be involved in different species, and there is no general consensus on the subcellular localization of prorenin, renin and angiotensinogen. In this ultrastructur...

Anterior pituitary cell turnover occurring during female sexual cycle is a poorly understood process that involves complex regulation of cell proliferation and apoptosis by multiple hormones. In rats, the prolactin (PRL) surge that occurs at proestrus coincides with the highest apoptotic rate. Since anterior pituitary cells express the prolactin receptor (PRLR), we aimed to address the actual r...

Prolactin-secreting adenomas (prolactinomas) are the most prevalent form of pituitary tumors in humans. Our knowledge of the formation of these tumors is limited. Experimental work in animal has uncovered that estradiol exposure leads to prolactinoma formation via orchestrated events involving dopamine D2 receptors, transforming growth factor-beta(TGF-beta) isoforms and their receptors, as well...