Expression and localization of growth hormone receptor in the oviduct of cyclic and pregnant pigs and mid-implantation conceptuses.
Previously it was shown that growth hormone (GH) and its receptor (GH-R) are involved in growth-promoting events during early embryonic development. However, it is still unknown if GH-induced GH-R signalling may support other functions within the oviduct. The purpose of our study was to analyse GH-R expression and localization in the porcine oviduct during different stages of the oestrus cycle and pregnancy (days 2-3 post inseminationem to days 65-71). As shown by reverse transcription polymerase chain reaction (RT-PCR), GH-R is expressed in the porcine oviduct during all stages of the oestrus cycle and pregnancy, respectively. Additionally, GH-R mRNA was detected in porcine conceptuses collected at day 18 of pregnancy. Using immunohistochemistry, GH-R was exclusively localized to the epithelium of the porcine oviduct throughout all segments examined. Localization of GH-R was mainly observed in the cytoplasm of ciliated epithelial cells. Generally, the number of GH-R-positive cells was elevated in the periovulatory phase of the oestrus cycle. Except for the isthmic epithelium, staining intensity of GH-R-positive cells was highest at oestrus and markedly reduced at met- and dioestrous stages. In infundibular and ampullar segments, percentage of GH-R-positive cells was significantly higher at days 2-3 post inseminationem compared to days 65-71 of pregnancy. Furthermore, in porcine conceptuses on day 18 of pregnancy GH-R protein expression was almost exclusively localized to trophectoderm. Our data suggest that GH-R mRNA and protein expression in the porcine oviduct throughout the oestrus cycle and pregnancy may suggest other activities of GH not described previously. Specifically, autocrine or paracrine GH-induced GH-R signalling may be linked to ciliated cell homeostasis of the porcine oviduct. Additionally, our results indicate that GH-R expression in the pig trophectoderm may be responsible for trophoblastic elongation.
Steffl
Martin
M
Department of Anatomy and Physiology of Domestic Animals, University of Hohenheim, Fruwirthstr. 35, 70599 Stuttgart, Germany. stefflma@uni-hohenheim.de
Schweiger
Markus
M
Mayer
Judith
J
Amselgruber
Werner M
WM
D000818:Animals; D004847:Epithelial Cells / Q000378:metabolism; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D010057:Oviducts / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism*; D013552:Swine / Q000378:metabolism / Q000502:physiology*
D011986:Receptors, Somatotropin