GSE130369
Transcriptional effects of prostaglandins inhibition in the early canine Corpus Luteum
The absence of luteolytic signal on non-pregnant bitches leads to the existence of a physiological pseudopregnancy maintained by a long lasting luteal function. During the diestrus, hormonal regulation of the canine CL changes. While in later stages prolactin is the main luteotropic hormone, in earlier stages the CL is independent from hypophysary hormones. At this time, prostaglandins are among the main luteotropic factors. In the present project, the aim was to further understand the effects of prostaglandins withdrawal on luteal function. In the present project, next generation sequencing (NGS), RNA-seq, was applied to explore the modulatory role of prostaglandins in the canine corpus luteum (CL) during the first half of diestrus. For this, transcriptome analysis of genes differently expressed in the CL of bitches treated in vivo with a COX2 inhibitor (Previcox, Merial) was performed. Additionally, by using just control samples, effects dependent on time were also explored and used as primary validation of results. Higher represented differentially expressed genes (DEG, p<0.01, FDR<0.1) in mature CL (days 20 and 30) referred to steroidogenesis, while in early CL (days 5 and 10) to proliferation and immune system. Then, treatment effects were investigated at each time point. No gene was concomitantly affected in all investigated groups. Thus, clearly, the effects were dioestrus stage-dependent. Higher numbers of DEG were found on day 20 (n=1741), mainly related to increased immune function, while on day 30 (n=552) they were related to decreased steroidogenesis and vascularization. Low numbers of DEG were found in early CL. Our results suggest the presence of strong compensatory effects in the early CL and multidirectional effects towards luteal gonadotropin-dependency after COX2-inhibition. Overall design: Bitches of various breeds and ages were observed for the onset of spontaneous estrus by vaginal cytology and P4 assay. The day of ovulation (day 0) was considered when circulation P4 levels exceeded 5ng/ml. The animals were then randomly assigned to four treatment groups and five control groups. Animals from treated groups (TG) received, orally, 10mg/kg of firocoxib (Previcox, Merial Ltd) for 5 (n=4), 10 (n=3), 20 (n=3) and 30 (n=3) days. Animals from control groups (CG) remained untreated for 5 (n=4), 10 (n=3), 20 (n=3) and 30 (n=3) days. Ovariohysterectomy was performed on the last day of treatment for collection of CL. To evaluate treatment-induced effects, analysis of differentially expressed genes was performed by comparing treated with control groups at each time-point (Days 5, 10, 20 and 30). Time-dependent effects were analyzed by comparing differently expressed genes on days 20+30 with days 5+10.