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

HUBER E; NOTARO, U; RECCE, S; ORTEGA HH; REY, F; R SALVETTI, NATALIA; RODRÍGUEZ, A.R

Mar del Plata

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2018

Sociedad Argentina de Investigación Clínica

Adverse ambient conditions(temperature-humidity index (THI) exceeding the comfort threshold (72) for 3 ormore days) on dairy cows can affect reproduction not only in a direct way, alsoin the progeny of animals that are gestated under these stress conditions. Infact, the ovarian follicular reserve is established during the first half ofthe fetal life (0-150 days) and many factors can affect the future fertility ofthe offspring.Under stress situations, nervous system triggers a signalingcascade with a final secretion of glucocorticoids (GCs). It is known that GCsexert actions in the ovary, mainly through the GC receptor α (GRα). In this study,we evaluated gene expression of GRα in preovulatory follicles of cows gestated underheat stress in different stages of gestation, and epigenetic mechanisms thatcould regulate gene expression. Holstein cows (n=20) were divided in twogroups: group 1 (cows gestated under heat stress between 0-150 days of gestation)and group 2 (cows gestated under heat stress between 151days-end of gestation).Higher levels of GRα were detected by Real Time PCR in follicular wall of preovulatoryfollicles of group 1 relative to group 2 (p<0,05). For quantitativemethylation analysis of the 5? UTR region of the GRα gene, an AGENA?s MassARRAYplatform was used. Similar levels of methylation were found in both groups forevery CpGanalyzed. These data suggest that differential expression of GRα couldbe related to an altered ovarian response to GCs in cows gestated under heatstress in first half of gestation. However, we could not confirm that thisvariation is due to differential methylation of the GR gene.