Estrogen receptor beta expression fluctuates during the estrous cycle contributing to the balance of the pituitary cell proliferation

PEREZ, PABLO; PETITI JUAN PABLO; WAGNER IGNACIO; SABATINO MARÍA EUGENIA; DE PAUL ANA LUCIA; TORRES, ALICIA; GUTIERREZ SILVINA

Granada

Congreso; 16 Congress of the Spanish Society of Neuroscience; 2015

Spanish Society of Neuroscience

17β-estradiol (E2) levels fluctuate during the estrous cycle regulating pituitary cell proliferation through its specific estrogen receptors (ER) α and β. Although an important number of studies have demonstrated the function of ERα in pituitary cell proliferation, the role of ERβ in the growth of pituitary cells is not well known. This background leads us to study the expression of ERβ during the estrous cycle and analyze if this subtype of ER modulates the expression of cell cycle regulators.Pituitary glands from female Wistar rats at different stages of the estrous cycle (proestrus, estrus and diestrus) and GH3 cells transfected to over-expression of ERβ (GH3β+) were used. E2 and the agonists of ERα (PPT) and ERβ (DPN) were employed. ERα and β expression was quantified by flow cytometry, cyclin D1 and CDK4 expression was detected by Western Blot and the GH3 proliferation was analyzed by BrdU technique. The statistical analysis used was ANOVA-Tukey. 34.12 ± 7.7 % of pituitary cells obtained from rats in diestrus expressed ERβ, 35.4 ± 2.5 % were ERβ+ in the proestrus, with a decrease in the ERβ expression in estrus, with an 18.79 ± 1.1% of ERβ+. However, ERα levels were similar during the estrous cycle. In pituitary cells from rats in proestrus and estrus the cyclin D1 levels were increased in relation to those found in diestrus. Over-expression of ERβ in GH3 cells decreased the pituitary cell proliferation and the cyclin D1 level expression.These results indicate that ERβ levels in the pituitary gland fluctuate during the estrous cycle and suggest that its expression is modulated by E2. The ERβ exerts an inhibitory role on the anterior pituitary cell proliferation with participation of the cyclin D1, adjusting the cell population and its functionality to the body's requirements.