GSE126031
Gene expression profiling of the canine placenta during normal and antigestagen-induced luteolysis.
Next-generation sequencing (RNA-Seq) was performed on canine placenta Placental samples collected at natural prepartum luteolysis were compared with those samples obtained from dogs at mid-pregnancy stage. Furthermore, in order to better understand the involvement of P4 and PGR-dependent downstream regulatory mechanisms during initiation of parturition in the dog, samples derived from dogs in which prepartum luteolysis/abortion was induced with the antigestagen aglepristone at mid-pregnancy, were included. With this approach the aim was to acquire new information that could be translated to clinical and breeding practice for more accurate patient management. The sample set derived from antigestagen-treated dogs was compared with mid-pregnant non-treated group that served as non-treated control. Finally, to identify differences in molecular events occurring in the placenta prior to natural parturition and/or abortion, placental transcriptomes of both groups were compared. Overall design: Placentae from nine (n=9) clinically healthy, cross-breed bitches (aged 2-8 years) were included in this study. Animals were assigned to following experimental groups: 1) mid-gestation (days 35-40 of pregnancy; n=3); 2) natural prepartum luteolysis (n=3); 3) antigestagen-induced luteolysis (n=3). Dogs were mated 2 days after ovulation, which was determined by vaginal cytology and measurements of serum P4 concentrations (> 5ng/ml). Day of mating represented Day 0 of gestation. The time of natural prepartum luteolysis (Group 2) was ascertained by measurements of serum P4 beginning on day 58 of pregnancy, in 6h intervals. Under physiological conditions, parturition in dogs occurs 12-42h following the luteolytic P4 drop. Thus, when P4 levels dropped below 3ng/ml in three consecutive measurements indicating its prepartum decrease, the surgery was performed and the tissue samples were collected. Additionally, abortion was induced in bitches at mid-pregnancy (Group 3) using P4-receptor (PGR) blocker, aglepristone (Alizine®, Virbac, Bad Oldesloe, Germany) in dosage of 10 mg/kg bw, 2 times in 24h interval. The surgery and tissue collections were done 24h after the second treatment. All dogs used for the study were subjected to routine ovariohysterectomy. Following surgery, placentae were separated from uteri, rinsed with phosphate-buffered saline (PBS) and immersed in RNAlater® for 24h at +4°C. After 24h, tissue material was stored at -80°C until RNA isolation.