Hormonal profile prior to luteolysis modulates the uterine luminal transcriptome in the subsequent cycle in beef cross-bred cows§.

Abstract

Sex steroid concentrations modulate endometrial function and fertility in cattle. Our objective was to compare the post-estrus luminal transcriptome of cows that were exposed to contrasting concentrations of progesterone (P4) before luteolysis that displayed estrus and ovulated spontaneously. Cross-bred beef cows received either 1) a new CIDR and GnRH (d - 9; high progesterone treatment; HP4; n = 16) or 2) a previously used CIDR, PGF2α, and GnRH (low progesterone treatment; LP4; n = 24). All cows received PGF2α at CIDR removal (d - 2). Ovarian ultrasonography and blood collections were performed on d - 9, d - 2, d - 0.5, d 0 (day of observed estrus), d 4, d 7, and d 14 for measurement of ovarian structures, P4, and estradiol (E2). Luminal epithelial cells were collected using a cytology brush on d 4, d 7, and d 14 for RNAseq. On d - 2, CL area and concentrations of P4 were greater, while on d - 0.5 concentrations of E2 were decreased in HP4. Ovarian structures and hormonal concentrations were similar on d 4, d 7, or d 14 (P > 0.05). There were enriched pathways in HP4 related to activation and signaling of the innate immune system at d 4, downregulation in the network involved in the extracellular matrix remodeling at d 7, and exacerbated inflammatory response as well as differentiation and activation of macrophages at d 14 (Benjamini - Hochberg P-value ≤0.05). In conclusion, manipulation of pre-luteolysis sex steroid concentrations altered the post-estrus luminal transcriptome even though all cows showed estrus and ovulated spontaneously.