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

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

Mar del Plata, Buenos Aires Argentina.

Congreso; Reunión Conjunta SAIC, SAI, FAIC, SAFIS 2022. LXVII Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC). 16 al 19 de noviembre de 2022.; 2022

SAIC

Environmental conditions experienced by pregnant cows can affect the fertility of their daughters through changes at the molecular level in the ovary during development. In fact, the ovarian follicular reserve is established during the fetal life and many factors can affect the future fertility of the offspring. The aim of the study was to analyze the expression of proliferation and apoptosis markers in preovulatory follicles of cows gestated under heat stress in different stages of pregnancy. Holstein cows (n=20) gestated under different environmental conditions during their in utero development were used. Ovarian samples were obtained by ovariectomy and determination of proliferation (PCNA) and apoptosis (Caspase-3; BCL-2; BAX) in granulosa and theca interna layers of preovulatory follicles 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-Humidity Index (THI) was calculated. Positive associations between PCNA expression in theca interna and THI during all gestation and particularly in the second trimester were observed. Caspase-3 expression in granulosa cells shown positive association with THI in the second period of gestation. Also,positive associations between expression of BCL-2 in theca cells and high THI during all gestation, and in the first period and second trimester of gestation were observed. Moreover, the expression of BAX in theca interna were positively associated to high THI in the first period of gestation. These data suggest that exposition to high THI during in utero development can alter the expression of fundamental proteins related to normal development of preovulatory follicles.In this sense changes during early development can influence the fertility of the cows through changes in the balance in proliferation / apoptosis mechanisms in the dominant follicle.