Immunohistochemical and gene expression studies of oestrogen, progesterone, oxytocin and prostaglandin F2alpha receptors in the bovine uterus during the post-partum period

The early post-partum (p.p.) period is one of the most critical for health and reproductive performance in dairy cows. Hormones and their corresponding receptors play a significant role in regulating post-partum uterine activity. Thirty-two tissue samples of the bovine intercaruncular uterine wall were collected during caesarean section (n = 16) and from euthanized cows in the first 3 weeks p.p. (n = 16). Ten of them were diagnosed with metritis. Immunohistochemistry (IHC) was performed for hormone receptors of oxytocin (OXTR), prostaglandin F2α (PTGFR), oestrogen (ESR1) and progesterone (PGR). Tissue sections were examined for positive staining and staining intensities at nine tissue localizations. Additionally, quan-titative real-time reverse transcription-polymerase chain reaction (RT-qPCR) for the mRNAs of those receptors was performed for the p.p. samples for each endometrium and myometrium. Hormone re-ceptor expression was detected via RT-qPCR and IHC in all time pe-riods. There was no difference in the occurrence of OXTR apart from two localizations, whereas PTGFR protein showed a decline over time p.p. for several localizations. RT-qPCR showed an increase over time p.p. for endometrial PTGFR expression. ESR1 protein showed an increase over time in IHC in all tissue layers as well as ESR1 mRNA showed an increase over time in the endometrium. PGR appearance in IHC was strongest on day 0 and decreased at most sites p.p. Lower values for uteri of cows diagnosed with metritis compared to those without metritis could only be verified for ESR1 in one localization but not via RT-qPCR. The results indicate that the localization of the studied receptors changes during the p.p. period. Only very few ef-fects of metritis were observed.