Transcriptomic changes in the ovine caruncular endometrium following imbalanced nutrition and FSH-induced ovarian hyperstimulation
Imbalanced nutrition and exogenous gonadotrophins affect uterine function and morphology. In sheep, FSH-induced superovulation causes morphological alterations in the uterus, leading, i.e., to an increase in lipid droplets. Similarly, depending on diet, FSH treatment alters the expression of estrogen and progesterone receptors and of adhesion molecules. To broad the knowledge regarding imbalanced nutrition and carry-over effects of superovulation induced with FSH in the caruncular endometrium, deep RNA sequencing (NGS, RNA-Seq) was applied, followed by functional analysis. Ewes (n = 3-5/group) were divided as follows: control fed (CF), overfed (OF), and underfed (UF), and each group was further treated with FSH (superovulated (SOV)) or saline (negative controls (CONT)). Samples were collected on day 10 of diestrus. Furthermore, samples from CF_CONT were collected on day 5 to assess time-dependent changes. The 1484 differentially expressed genes (DEGs, P < 0.01, FDR < 0.05) identified between CF_CONT animals at days 5 and 10 were associated with increased immune activity and cellular metabolic processes and decreased cellular proliferation. In CONT animals, unbalanced nutrition (i.e., both OF and UF) was associated with enrichment of terms associated with cell adhesion and differentiation, immune response and angiogenesis. As for carry-over effects of FSH, higher number of DEGs were found for CF animals (1374), than in OF (168) or UF (18) samples, associated with dysregulation of cell cycle and hormonal sensitivity. The absence of genes concomitantly affected by SOV at all different feeding regimes suggested multidirectional and body condition-dependent effects of FSH in caruncular transcriptome. Both body condition and SOV appear to affect the homeostasis of the ovine caruncles, possibly involving the modulation of uterine receptivity. Overall design: A total of 29 ewes were used in the present work. Ewes (n=3-5/group) were divided into control fed (CF, 100% of National Research Council requirements ), overfed (OF, 200% of National Research Council requirements), and underfed (UF, 60% of National Research Council requirements), with each group further divided between superovulated (SOV; FSH, 5mg/injection on day 13, 4mg/injection on day 14 and 3mg/injection on day 15 of estrus cycle.) or control (C; saline, 10 ml of 0.9% NaCl in water ). Samples were collected on days (d) 5 and 10 of diestrus in the next estrous cycle.