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

Abstract

ContentsUterine 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 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 < .05), whereas there was no difference found between groups for kiss1. Except during the pre-implantation period, KP-10 expression was higher in the non-pregnant uterus compared to all gestational periods investigated, indicating a pregnancy-related downregulation. In the preimplantation period, KP-10 was present in larger vessels only, whereas the presence of GPR54 in vessels was found in all samples, with most labelling in the postimplantation period. KP-10 was present in superficial uterine glands, GPR54 in superficial and deep uterine glands of the post-implantation uterus. In myocytes, the highest staining for KP-10 was seen in the non-pregnant uterus, whereas the highest staining for GPR54 was seen in post-implantation and mid-gestation. Syncytiotrophoblast cells stained for both KP-10 and GPR54 in post-implantation and mid-gestation, with maximum intensity for GPR54 in the latter. We conclude that KP-10 and GPR54 are expressed in the canine uterus and trophoblast cells. However, during pregnancy, expression of both proteins seems to be differentially regulated.

Kisspeptin/GPR54 System: What Do We Know About Its Role in Human Reproduction?

“…Kp-10 increased intracellular Ca 2+ levels in isolated first trimester trophoblasts emphasizing Kp-10 as a paracrine/endocrine regulator in finetuning trophoblast invasion generated by the trophoblast itself [75]. Corroborating these results, the same was found in canine pregnant uterus and trophoblast cells [76].…”

Pre‐pubertal treatment with a GnRH agonist in bitches—Effect on the uterus and hormone receptor expression

“…The expression of kisspeptin receptor in the pre‐pubertal uterus of bitches has not been described before; only one study reports about the expression of kisspeptin and its receptor in the canine pregnant uterus and trophoblast cells (Schäfer‐Somi et al., ). However, since no control bitch was castrated before puberty, we cannot directly compare the results of those experimental bitches that did not enter oestrus during the observation period.…”

Kisspeptin and Glucose Homeostasis

“…53,54 The extent of placental kisspeptin release in animal models is unclear due to the lack of reliable assays; however, kisspeptin mRNA is expressed and increases through pregnancy in rodent and dog placenta, supporting placental kisspeptin release in other animals. [55][56][57] Thus, pregnancy represents a physiological state in which the islets are exposed to kisspeptin at elevated levels, which may be stimulatory.…”