Altered proliferation and apoptosis in preovulatory follicles in cows gestated under heat stress conditions

ORMAECHEA N; NOTARO US; CHIARAVIGLIO JA; CATTANEO MOREYRA ML; ORTEGA HH; REY F; SALVETTI NR; RODRÍGUEZ FM

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencias; 2022

Environmental conditions experienced by pregnantcows can affect the fertility of their daughters through changes at themolecular level in the ovary during development. In fact, the ovarianfollicular reserve is established during the fetal life and many factors canaffect the future fertility of the offspring. The aim of the study was toanalyze the expression of proliferation and apoptosis markers in preovulatoryfollicles of cows gestated under heat stress in different stages of pregnancy. Holstein cows (n=20) gestated under different environmentalconditions during their in utero development were used. Ovarian sampleswere obtained by ovariectomy and determination of proliferation (PCNA) andapoptosis (Caspase-3; BCL-2; BAX) in granulosa and theca interna layers of preovulatoryfollicles was done by immunohistochemistry. Gestation was divided into two periods(P1: 0-150 days; P2: 151 days-birth); and three trimesters (T1: 0-90 days; T2:91-180 days; T3: 181-birth days) in which the exposure to high Temperature-HumidityIndex (THI) was calculated. Positive associations between PCNA expression in thecainterna and THI during all gestation and particularly in the second trimester wereobserved. Caspase-3 expression in granulosa cells shown positive associationwith THI in the second period of gestation. Also, positive associations betweenexpression of BCL-2 in theca cells and high THI during all gestation, and inthe first period and second trimester of gestation were observed. Moreover, theexpression of BAX in theca interna were positively associated to high THI inthe first period of gestation. These data suggest that exposition to high THIduring in utero development can alter the expression of fundamental proteinsrelated to normal development of preovulatory follicles. In this sense changes duringearly development can influence the fertility of the cows through changes inthe balance in proliferation / apoptosis mechanisms in the dominant follicle.