Impact of hormonal modulation at proestrus on ovarian responses and uterine gene expression of suckled anestrous beef cows

摘要

Background: This study evaluated the impact of hormonal modulation at the onset of proestrus on ovarian response and uterine gene expression of beef cows.Methods: A total of 172 anestrous beef cows were assigned to one of four groups according to the treatment with estradiol cypionate(ECP) and/or equine chorionic gonadotropin(eCG) [CON(n = 43), ECP(n = 43), eCG(n = 44)and ECP + eCG(n = 42)].Results: ECP-treated cows(ECP and ECP + eCG groups) presented greater occurrence of estrus(44.6% vs. 65.4%; P = 0.01) and pregnancy per AI [47.1% vs. 33.3%; P = 0.07], but similar progesterone(P4) concentration at subsequent diestrus than cows not treated with ECP(CON and eCG groups). Nonetheless, eCG-treated cows(eCG and ECP + eCG groups) presented larger follicle at timed AI(12.6 ± 0.3 vs. 13.5 ± 0.3 mm; P = 0.03), greater ovulation rate(96.5%vs. 82.6%; P = 0.008) and greater P4 concentration at d 6(3.9 ± 0.2 vs. 4.8 ± 0.2 ng/mL; P = 0.001) than cows not treated with eCG(CON and ECP groups). Next, cows with a new corpus luteum 6 d after TAI were submitted to uterine biopsy procedure. Uterine fragments [CON(n = 6), ECP(n = 6)] were analyzed by RNA-Seq and a total of 135 transcripts were differentially expressed between groups(73 genes up-regulated by ECP treatment). Subsequently,uterine samples were analyzed by q PCR(genes associated with cell proliferation). ECP treatment induced greater abundance of PTCH2(P = 0.07) and COL4 A1(P = 0.02), whereas suppressed EGFR(P = 0.09) expression. Conversely, eCG treatment increased abundance of HB-EGF(P = 0.06), ESR2(P = 0.09), and ITGB3(P = 0.05), whereas it reduced transcription of ESR1(P = 0.05). Collectively, supplementation with ECP or eCG at the onset of proestrous of anestrous beef cows influenced ovarian responses, global and specific endometrial gene expression.Conclusion: Proestrus estradiol regulate the endometrial transcriptome, particularly stimulating proliferative activity in the endometrium.