Analysis of the ovarian estrogen receptor alfa and beta in cows gestated under heat stress conditions

NOTARO US; HUBER E; RECCE S; DÍAZ PU; ORTEGA HH; REY F; SALVETTI NR; RODRIGUEZ FM

Mar del Plata

Congreso; LXII Reunión anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2018

Theeffects of adverse ambient conditions (number of days with temperature-humidityindex (THI) exceeding the comfort threshold: >72) on dairy cows can affectthe reproduction not only in a direct way, also in the progeny of the animalsthat were gestated under stress conditions. In fact, the ovarian follicularreserve is established during the first half of the fetal life (0-150 days) andmany factors can affect the future fertility of the offspring. Within thesefactors, Estrogen Receptors (ER) α and β are the most important regulators whichgene expression could be modulated. The aim of this study was to evaluate thegene and protein expression of ERα and ERβ in preovulatory follicles of animalsgestated under heat stress in different stages of pregnancy. Holstein cows(n=20) were divided in two groups: group 1 (cows gestated under heat stressbetween 0-150 days of pregnancy) and group 2 (cows gestated under heat stress between151days-end of pregnancy). Similar levels of ERα and β mRNA were detected byreal time PCR, in follicular wall of different groups analyzed (p>0.05). Forquantitative methylation analysis of the 5´UTR sequences of ERα and β, anAGENA?s MassARRAY platform was used. No differences were detected for any CpGanalyzed for both receptors (p>0.05). On the other hand, the protein expressionevaluated by immunohistochemistry show similar levels of ERα in granulosa andtheca interna of preovulatory follicles of the groups analyzed (p>0,05) anda higher expression of ERβ in granulosa and theca cells of preovulatoryfollicles of cows of Group 2 related to Group 1 (p<0.05). These data suggestthat changes in the expression of estrogen receptors, mainly ERβ, can lead toan altered response of steroid hormones, and thus contribute to ovarian alterationsin animals gestated under heat stress.