Kisspeptin-10 and the G protein-coupled receptor 54 are differentially expressed in the canine pregnant uterus and trophoblast cells

Abstract

Uterine tissue was collected from bitches after ovariohysterectomy at different times after ovulation. Samples were assigned to four groups: metestrous non-pregnant, day 10–12, n = 4; pre-implantation, day 10–12, n = 9; post-implantation, day 18–25, n = 13; mid-gestation, day 30–40, n = 7. RT-qPCR detection was performed for kiss1 and the G protein-coupled receptor 54 (GPR54, specific receptor for kisspeptin). In addition, immunohistochemistry was performed for detection of kisspeptin-10 (KP-10), GPR54, as well as pan-cytokeratin and vimentin. The latter two were included to differentiate the different placental cell types. The percentage of positive stained cells was evaluated, and an immunoreactivity score (IRS) was obtained by multiplying the labelling intensity score (0–3) with the percentage of immunolabelled cells (range: 0–300). In non-pregnant and pre-implantation tissues, gene expression was highly variable for kiss1 and GPR54. Expression of GPR54 was higher before embryo adhesion than during post-implantation and mid-gestation (p