Jungmann, CarolinHoughton, Caroline GauguinNielsen, Frederik GothPackeiser, Eva-MariaKörber, HannaReichler, Iris M.Balogh, OrsolyaGoericke-Pesch, Sandra2022-11-102022-11-102022-11-06Jungmann, C.; Houghton, C.G.; Nielsen, F.G.; Packeiser, E.-M.; Körber, H.; Reichler, I.M.; Balogh, O.; Goericke-Pesch, S. Involvement of Oxytocin and Progesterone Receptor Expression in the Etiology of Canine Uterine Inertia. Int. J. Mol. Sci. 2022, 23, 13601.http://hdl.handle.net/10919/112567An altered oxytocin and progesterone receptor (<i>OXTR</i> and <i>PGR</i>, respectively) expression was postulated in canine uterine inertia (UI), which is the lack of functional myometrial contractions. <i>OXTR</i> and <i>PGR</i> expressions were compared in uterine tissue obtained during C-section due to primary UI (PUI; <i>n</i> = 12) and obstructive dystocia (OD, <i>n</i> = 8). In PUI, the influence of litter size was studied (small/normal/large litter: PUI-S/N/L: <i>n</i> = 5/4/3). Staining intensity in immunohistochemistry was scored for the longitudinal and circular myometrial layer and summarized per dog (IP-Myoscore). Mean P4 did not differ significantly between PUI (<i>n</i> = 9) and OD (<i>n</i> = 7). <i>OXTR</i> and <i>PGR</i> expressions (ratios) were significantly higher in PUI (<i>OXTR</i>: <i>p</i> = 0.0019; <i>PGR</i>: <i>p</i> = 0.0339), also for <i>OXTR</i> in PUI-N versus OD (<i>p</i> = 0.0034). A trend for a higher <i>PGR</i> IP-Myoscore was identified (PUI-N vs. OD, <i>p</i> = 0.0626) as well as an influence of litter size (lowest <i>PGR</i>-Myoscore in PUI-L, <i>p</i> = 0.0391). In conclusion, PUI was not related to higher P4, but potentially increased <i>PGR</i> availability compared to OD. It remains to be clarified whether <i>OXTR</i> is upregulated in PUI due to a counterregulatory mechanism to overcome myometrial quiescence or downregulated in OD due to physiological slow <i>OXTR</i> desensitization associated with an advanced duration of labor. Identified <i>OXTR</i> differences between myometrial layers indicate the need for further research.application/pdfenCreative Commons Attribution 4.0 Internationaldogdystociauterine inertiaoxytocin receptorprogesterone receptorArticle - Refereed2022-11-10https://doi.org/10.3390/ijms232113601