Estradiol would favor indirectly mammary gland elongation and side-branching by stimulating progesterone receptor expression in pregnant Lagostomus maximus (Rodentia, Chinchillidae).

MARÍA CLARA CORSO, SOFÍA PROIETTO, SANTIAGO ANDRÉS CORTASA, SCHMIDT ALEJANDRO RAÚL, PABLO IGNACIO FELIPE INSERRA, SANTIAGO ELÍAS CHARIF, VERÓNICA BERTA DORFMAN, ALFREDO DANIEL VITULLO; HALPERIN J

Ciudad Autonoma de Buenos Aires

Congreso; Reunión Conjunta de Sociedades de BioCiencias; 2017

SAIC, SAIB, SAA, SAI, SAB, SAB, SAFE, SAFIS, SAH y SAP

Prolactin (PRL), progesterone (P) and estradiol (E2) are majorregulators of mammary gland (MG) tissue remodeling throughoutthe repeated cycles of pregnancy-lactation-regression. Considering the atypical modulation of the hypothalamus-hypophysis-ovary axisof Lagostomus maximus we studied the relation among P and E2serum values, their MG-receptor expression levels (PR, ER andPRLR) and their relation with the MG-cell proliferation and MG-vascularization.P and E2 serum levels (ELISA) and mammary PRLR-,PR-, VEGF- and PCNA expressions (PCR and immunohistochemistry)were determined in 4 groups of adult vizcachas (resting,pregnant, lactating, regressing). Maximal levels of E2 and P wererecorded at pregnancy (p<0.005) when the GM reaches a great developmentevidenced by high levels of both VEGF and PCNA. Inorder to establish the importance of the ovarian steroids over PRLR,PR, VEGF and PCNA expressions, adult non-pregnant femaleswere ovariectomized (OVX) and treated with either E2 (OVX_E) orP (OVX_P). OVX animals were used as controls. Mammary PRLRimmunoreactive area in OVX_E dropped approximately to half ofthat detected in OVX group (p<0.005) suggesting that the expressionof this receptor is P dependent. On the contrary, the absenceof changes in the expression of VEFG and PCNA among the experimentalgroups could indicate that the regulation of these markers isnot under the direct and unique control of ovarian steroids but ratherthat they would coordinate their action with other factors (i.e. PRL)in MG-tissue remodeling. Interestingly, both PR gene expressionand PR immunoreactive area were notably lower in MG of OVX_Pcompared to both OVX_E and OVX groups (p<0.005) indicating therole of E2 in PR expression. Our data suggest that the increasedPR expression associated to the branching and elongation of theMG ductal tree at pregnancy may be indirectly stimulated by E2.Fundación Científica Felipe Fiorellino, CONICET-PIP110/14, MINCyT-PICT1281/2014