Expression and immunolocalization of the oxytocin receptor in human lactating and non-lactating mammary glands
Source: Human Reproduction, Volume 13, Number 9, September 1998 , pp. 2645-2653(9)
Publisher: Oxford University Press
Abstract:The milk ejection reflex is mediated by the release of pituitary oxytocin and its interaction with specific receptors within the mammary gland. Although up-regulation of the oxytocin receptor during lactation has been shown for the rat mammary gland by ligand binding assay, investigation of the receptor expression in human breast at the molecular level has not yet been carried out in detail. Here we report the expression and immunolocalization of the oxytocin receptor in the human breast. It appears that the expression level of the receptor-specific mRNA is not significantly elevated during lactation and the protein remains at a relatively low level. However, this lack of increase may be only a dilution effect because of the high level of milk protein expression. Immunohistochemistry and immunoelectron microscopy using three anti-oxytocin receptor antibodies raised against different epitopes of the receptor indicated the presence of receptor immunoreactivity only to a very limited extent in the myoepithelial cells; more specific expression appeared to occur in the ductal/glandular epithelium in both the non-lactating as well as lactating breast. This finding was also confirmed in a New World monkey, the common marmoset (Callithrix jacchus). These results suggest that, at least for human and marmoset, in addition to - or even instead of - myoid cells, the ductal/glandular epithelium is also a target for oxytocin action, not only during lactation but also in the non-lactating breast. Thus, there may be other physiological effects of oxytocin besides direct myoid cell contraction in the breast.
Key words:ductal glandular epithelium/lactation/mammary gland/myoepithelium/oxytocin receptor
Document Type: Research Article
Affiliations: 1: Department of Obstetrics and Gynecology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan 2: Second Department of Surgery, Osaka University Medical School, Suita, Osaka 565, Japan 3: Department of Reproductive Biology, Deutsches Primatenzentrum, Gottingen, Germany 4: Department of Anatomy, Kansai College of Oriental Medicine, Kumatori, Osaka 590-04, Japan 5: Institute for Hormone and Fertility Research, University of Hamburg, Hamburg, Germany 6: Department of Pathology, School of Allied Health Science, Faculty of Medicine, Osaka University, Suita, Osaka 565, Japan
Publication date: September 1998
- Human Reproduction features full-length, peer-reviewed papers reporting original research, clinical case histories, as well as opinions and debates on topical issues. Papers published cover the scientific and medical aspects of reproductive physiology and pathology, endocrinology, andrology, gonad function, gametogenesis, fertilization, embryo development, implantation, pregnancy, genetics, genetic diagnosis, oncology, infectious disease, surgery, contraception, infertility treatment, psychology, ethics and social issues. The highest scientific and editorial standard is maintained throughout the journal along with a rapid rate of publication.