Estrogen and oxytocin receptors in the canine corpus luteum during pregnancy and parturition

Abstract

The expression of genes encoding the receptors for estrogen (ERαmRNA) and oxytocin (OTRmRNA) was studied in the corpus luteum during pregnancy and parturition in dogs. Real-time PCR was performed to quantify the levels of ERαmRNA and OTRmRNA in the corpus luteum of bitches during Early (up to 20 days of gestation), Mid (20 to 40 days) and Late Pregnancy (40 to 60 days), and Parturition (first stage of labor). The corpus luteum expressed mRNA for OTR, however ERα mRNA was not detected. There was a reduction of OTR mRNA expression in the corpus luteum from gestational Day 20 onward, which suggests an important role of OTR mRNA in the mechanism of pregnancy recognition in dogs. We concluded that the expression of OTR mRNA in canine corpus luteum vary over time, which support the idea that the sensitivity and response to hormone therapy can vary along the course of pregnancy and labor. Moreover, the canine CL lacks ERα mRNA expression during pregnancy.