Expression and localization of growth hormone receptor in the oviduct of cyclic and pregnant pigs and mid-implantation conceptuses

Abstract

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.

Prolactin and growth hormone affect metaphase-II chromosomes in aging oocytes via cumulus cells using similar signaling pathways

“…Physiological levels of intratubular PRL and GH possibly derived from the circulation are presently unknown; however, follicular fluid containing both hormones flows into the oviduct following ovulation ( Lyons et al, 2006 ), permitting their local effects. The possibility for PRL and GH actions within the oviduct is also supported by evidence for the expression of the respective receptors in mammalian oviductal cells ( Shao et al, 2008 ; Steffl et al, 2009 ). It should be emphasized that concentrations of PRL and GH enhancing destructive changes of M-II chromosomes are 10 to 20 times higher than physiological ones.…”

The Clinical Application of Growth Hormone and Its Biological and Molecular Mechanisms in Assisted Reproduction

“…The gene expression of GH is not confined to the pituitary gland, since its mRNA and the protein that is coded by it are produced in many extrapituitary sites, such as testes and ovaries [5,6]. Substantial studies have shown the presence of GH/GHRs in the ovaries of various organisms, including fish, chicken, rats, mice, horses, pigs, monkeys, and humans [7][8][9][10][11][12][13]. The occurrence of GHRs in ovaries indicates that these organs are a target site of GH action.…”