Alteration of chromatin-modifying enzyme expression in pre-ovulatory follicles in adult cows gestated under high temperature-humidity index

ORMAECHEA N; SCHLEGEL S; NOTARO US; CHIARAVIGLIO JA; ANGELI E; ORTEGA HH; REY F; SALVETTI NR; RODRÍGUEZ FM

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencias. SAIC, SAB, AAFE, AACyTAL; 2023

Incattle, gonadal development and gametogenesis occur during gestation. Whendairy cows suffer high temperature and humidity conditions at pregnancy, thefertility of their offspring can be compromised. This could be consequence ofvariations in expression of proteins involved in follicular growth anddevelopment, which are regulated by different enzymes acting on chromatinstructure, such methylating DNA enzymes. The aim of the study was to analyzethe expression of DNA Methyltransferases (DNMTs) in preovulatory follicles ofcows gestated under different environmental conditions. Adult Argentinean Holsteincows (n=24) gestated under different THI conditions during their in uterodevelopment were used. Ovariansamples were obtained by ovariectomy after estrous synchronization and gene and proteinexpression of DNMTs (DNMT1, DNMT3a and DNMT3b) was determined by RT-PCR andimmunohistochemistry in pre-ovulatory follicle. Gestation was divided into twoperiods (P1: 0-150 days; P2: 151 days-birth); and three trimesters (T1: 0-90days; T2: 91-180 days; T3: 181-birth days) in which the exposure to highTemperature-Humidity Index (THI) was considered. Negative associations betweenDNMT1, DNMT3a expression in granulosa cells of preovulatory follicles and THI inT3 and P2 were observed. Instead, positive associations between DNMT3a ingranulosa cells and THI in T1 were detected. Besides, DNMT3b expression intheca interna were positively associated to high THI during all gestation. Thisdata suggests that exposure to high THI during intrauterine developmentinfluences the expression of genes and proteins associated with epigeneticmodifications and may affect the expression of molecules critical for thedevelopment and function of pre-ovulatory follicles in adult life.