Pituitary estrogen receptor alpha is involved in luteinizing hormone pulsatility at mid-gestation in the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha)

SOFÍA PROIETTO; LORENA YANKELEVICH; FEDERICO VILLARREAL; PABLO IGNACIO FELIPE INSERRA; SANTIAGO ELÍAS CHARIF; ALEJANDRO SCHMIDT; SANTIAGO ANDRÉS CORTASA; MARÍA CLARA CORSO; NOELIA PAULA DI GIORGIO; VICTORIA LUX- LANTOS; ALFREDO DANIEL VITULLO; JULIA HALPERIN; VERÓNICA BERTA DORFMAN

GENERAL AND COMPARATIVE ENDOCRINOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2018

0016-6480

The South American plains vizcacha, Lagostomus maximus, is a caviomorph rodent native from Argentina, Boliviaand Paraguay. It shows peculiar reproductive features like pre-ovulatory follicle recruitment during pregnancywith an ovulatory process at around mid-gestation. We have described the activation of the hypothalamic ?pituitary ? ovarian (HPO) axis during pregnancy. A progressive decrease of progesterone (P4) at mid-pregnancyelicits the delivery of gonadotropin-releasing hormone (GnRH) with the consequent secretion of follicle stimulatinghormone (FSH) and estradiol (E2) followed by luteinizing hormone (LH) release resulting in follicularluteinization and the P4 concentration recover. Pituitary gland is the central regulator of the HPO axis being E2 akey hormone involved in the regulation of its activity. In this work we analyzed the action of E2 on the pituitaryresponse to the GnRH wave as well as its involvement on LH secretion at mid-gestation in L. maximus. Theexpression of GnRHR at the pituitary pars distalis showed a significant decrease at mid-pregnancy compared toearly- and term-gestating females. ERα showed a significant increment from mid-gestation whereas ERβ did notshow variations throughout pregnancy; whereas the LH expression in the pituitary pars distalis showed a significantincrease at mid-gestation, concordantly with serum LH, which was followed by a decrease at termgestationwith similar values than at early-pregnancy. The number of cells with co-localization of ERα andGnRHR showed a decline at mid-pregnancy related to early- and term-gestation, whereas the cells with colocalizationof ERα and LH increased at mid- and term-pregnancy. On the other hand, ex vivo measuring of LHpulsatility showed a significant increment in the total mass of LH delivered at mid-pregnancy followed by adecrease at term-gestation. The stimulation of ERα with the PPT specific agonist induced a significant incrementin the total mass of LH released, whereas no changes were determined when ERβ was stimulated with its specificagonist MPP. These results suggest that LH pulsatility rise at mid-pregnancy would be enabled by the increase ofE2 acting through ERα.