Evaluation of ovarian glucocorticoid receptor α expression in cows gestated under heat stress conditions.

HUBER EMILIA; NOTARO ULISES; RECCE SEBASTIÁN; ORTEGA HUGO HÉCTOR; SALVETTI NATALIA RAQUEL; REY FLORENCIA ; RODRÍGUEZ FERNANDA MARIEL

Mar del Plata

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC), LXVI Reunión anual de la SAI; Reunión anual de la SAFIS; con la participación de la SAV y Asociacion Argentina de Nanomedicinas (NANOMEDAR).; 2018

SAIC

Adverse ambient conditions (temperature-humidity index (THI) exceedingthe comfort threshold (72) for 3 or more days) on dairy cowscan affect reproduction not only in a direct way, also in the progenyof animals that are gestated under these stress conditions. In fact,the ovarian follicular reserve is established during the first half of thefetal life (0-150 days) and many factors can affect the future fertilityof the offspring. Under stress situations, nervous system triggers asignaling cascade with a final secretion of glucocorticoids (GCs). Itis known that GCs exert actions in the ovary, mainly through the GCreceptor α (GRα). In this study, we evaluated gene expression ofGRα in preovulatory follicles of cows gestated under heat stress indifferent stages of gestation, and epigenetic mechanisms that couldregulate gene expression. Holstein cows (n=20) were divided in twogroups: group 1 (cows gestated under heat stress between 0-150days of gestation) and group 2 (cows gestated under heat stressbetween 151 days-end of gestation). Higher levels of GRα were detectedby Real Time PCR in follicular wall of preovulatory folliclesof group 1 relative to group 2 (p<0,05). For quantitative methylationanalysis of the 5? UTR region of the GR gene, an AGENA?s MassARRAYplatform was used. Similar levels of methylation were foundin both groups for every CpG analyzed. These data suggest thatdifferential expression of GRα could be related to an altered ovarianresponse to GCs in cows gestated under heat stress in first half ofgestation. However, we could not confirm that this variation is due todifferential methylation of the GR gene.