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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The objective of this study was to isolate, purify, culture, and characterize myoepithelial cells from bovine mammary glands. Myoepithelial cells were separated from other mammary and blood cells after collagenase digestion and centrifugation using metrizoate-ficoll gradients. Myoepithelial cells were identified by their characteristic morphology and cloned using selective detachment. They contained many densely packed myofilaments, very few cytoplasmic organelles, elongated surface projections, and a dense, irregularly shaped nuclei. Some cells were as large as 1.2 mm in culture. Myoepithelial cells contained an extensive network of cytoskeletal proteins, including alpha-smooth muscle actin, alpha-actinin, and vimentin. When cultured, they tended to repel one another and never grew as closely associated cells. The myoepithelial nature of these cells was verified by showing that they contracted in response to oxytocin, bound oxytocin, and did not produce casein. Myoepithelial cells from fetal and lactating glands grew very well in culture. Active division of myoepithelial cells could be maintained for at least 3 mo, and cells could be serially subcultured at least seven times. The successful isolation and culture of bovine mammary myoepithelial cells make utilization of these cells possible in order to study their role in mammary growth and differentiation and milk ejection.
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PMID:Bovine mammary myoepithelial cells. 1. Isolation, culture, and characterization. 147 4

The effects of culture supernatants conditioned by the growth of Staphylococcus aureus M60 on in vitro growth and functional properties of bovine mammary myoepithelial cells were examined. Myoepithelial cell proliferation was reduced by Staph. aureus M60 culture supernatants. Exposure of myoepithelial cells to culture supernatants of isogeneic mutants of Staph. aureus M60 that produced either alpha or beta toxins reduced proliferation, but to a lesser extent than supernatants from the wild type strain. Thus, alpha and beta toxins may play some role in affecting myoepithelial cell proliferation. Of the cells tested, 42% contracted following addition of oxytocin (10(-7) M) in the culture medium. Treatment of myoepithelial cells for 15 min with Staph. aureus M60 supernatants, prior to addition of oxytocin in the culture medium, increased the number of cells that contracted to 92%. Exposure of cells for 3 h to the same supernatant, prior to addition of oxytocin in the culture medium, abolished oxytocin responsiveness, had no effect on immunolocalization of actin and vimentin, but affected the localization of alpha-actinin within myoepithelial cells. Treatment of myoepithelial cells for 3 h with a combination of purified staphylococcal proteinases XVI and XVII-B abolished oxytocin responsiveness and mimicked the effect of the Staph. aureus culture supernatant. We conclude that Staph. aureus M60 culture supernatant affected proliferation and functional properties of myoepithelial cells.
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PMID:Effects of Staphylococcus aureus products on growth and function of bovine mammary myoepithelial cells in vitro. 856 28

Peritubular myoid cells, surrounding the seminiferous tubules in the testis, have been found in all mammalian species, but their organization in the peritubular interstitial tissue varies by species. In laboratory rodents, including rats, hamsters and mice, only one layer of myoid cells is seen in the testis. The cells in these animals are joined by junctional complexes as are epithelial cells. On the other hand, several cellular layers exist in the lamina propria of the seminiferous tubule in the human and some other animals. Myoid cells contain abundant actin filaments which are distributed in the cells in a species-specific manner. In the rat, the filaments within one myoid cell run both longitudinally and circularly to the long axis of the seminiferous tubule, exhibiting a lattice-work pattern. The arrangement of the actin filaments in the cells changes during postnatal development, and the disruption of spermatogenesis, such as cryptorchidism, seems to affect further the arrangement of the filaments. Other cytoskeletal proteins, including myosin, desmin/vimentin and alpha-actinin, are also found in the cells. Myoid cells have been shown to be contractile, involved in the transport of spermatozoa and testicular fluid in the tubule. Several substances (prostaglandins, oxytocin, TGF beta, NO/cGMP) have been suggested to affect the contraction of the cell, though the mechanisms of the contraction are still unknown. Recent in vitro studies have demonstrated that the cells secrete a number of substances including extracellular matrix components (fibronectin, type I and IV collagens, proteoglycans) and growth factors (PModS, TGF beta, IGF-I, activin-A). Some of these substances are known to affect the Sertoli cell function. Furthermore, it has been reported that myoid cells contain androgen receptors and are involved in retinol processing. Considering all this, it is evident that peritubular myoid cells not only provide structural integrity to the tubule but also take part in the regulation of spermatogenesis and the testicular function. Their precise roles, however, remain to be solved.
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PMID:Peritubular myoid cells in the testis: their structure and function. 872 59

This study sought to investigate the presence of oxytocin receptors and the possible biological role of oxytocin as an effective factor in the differentiation of embryonic stem cells (ESCs) into cardiomyocytes. Mouse ESCs were cultivated in hanging drops to form embryoid bodies (EBs). The EBs were then treated with and without oxytocin (experimental and control groups). Up to 30 days after plating, contraction and beating frequency were monitored and evaluated daily. The growth characteristics of the ESC-derived cardiomyocytes were assessed by cardioactive drugs, immunocytochemistry, transmission electron microscopy (TEM) and reverse transcription-polymerase chain reaction (RT-PCR). In the experimental group, the percentage of the EBs with spontaneous contraction was significantly increased from 17th day onward. The spontaneous beating frequency of each EB in both groups was also changed with cardioactive drugs such as Bay K, carbachol, isopernaline and phenylephrine. However, in the experimental group, changes with isopernaline were more pronounced at the early and intermediate stages of cardiomyocyte development. The beating cells of both groups, stained positive with anti alpha-actinin, desmin, cardiac troponin I and connexin antibodies, and revealed similar ultrastructural features. Oxytocin receptors were detected on the ESCs and derived-differentiated cells. In addition, cardiac-specific genes such as cardiac alpha- and beta-myosin heavy chain, myosin light chain-2v, and atrial natriuretic factor were also detected in the ESC-derived differentiated cells of both groups. In the experimental group, all the specific genes, with the exception of alpha-myosin heavy chain, were more pronounced at the early stage of cardiomyocyte development. In conclusion, oxytocin has receptors on undifferentiated ESCs and derived differentiated cells, and in spite of better improvement of the EBs with spontaneous contraction, it can only promote the early maturation of ESC-derived cardiomyocytes in terms of chronotropic responses and expression of cardiac-specific genes, and have no effect on ultrastructural characteristics of cardiomyocytes in any stage of development.
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PMID:Effects of oxytocin on cardiomyocyte differentiation from mouse embryonic stem cells. 1703 84

Oxytocin (OT), a hormone recently identified in the heart, induces embryonic and cardiac somatic stem cells to differentiate into cardiomyocytes (CM), possibly through nitric oxide (NO). We verified this hypothesis using P19 cells and P19 Clone 6 derivatives expressing a green fluorescent protein (GFP) reporter linked to cardiac myosin light chain-2v promoter. OT treatment of these cells induced beating cell colonies that were fully inhibited by N,G-nitro-L-arginine-methyl-ester (L-NAME), an inhibitor of NO synthases (NOS), partially reduced by 1400W, an inhibitor of inducible NOS, and ODQ, an inhibitor of NO-sensitive guanylyl cyclases. The NO generator S-nitroso-N-acetylpenicillamine (SNAP) reversed the L-NAME inhibition of cell beating and GFP expression. In OT-induced cells, L-NAME significantly decreased transcripts of the cardiac markers Nkx2.5, MEF2c, alpha-myosin heavy chain, and less, GATA4, endothelial NOS, and atrial natriuretic peptide, as well as the skeletal myocyte (SM) marker myogenin. Image analysis of OT-induced P19Cl6-GFP cells revealed ventricular CM coexpressing sarcomeric alpha-actinin and GFP, with some cells exclusively expressing alpha-actinin, most likely of the SM phenotype. The OT-mediated production of CM, but not SM, was diminished by L-NAME. In P19 cells, exogenously added OT stimulated the expression of its own transcript, which was reduced in the presence of L-NAME. Surprisingly, L-NAME alone decreased the expression of anti-stage specific embryonic antigen-1 marker of the undifferentiated state and induced some beating colonies as well as GFP in P19Cl6-GFP cells. Collectively, our data suggest that the pleiotropic action of NO is involved in the initiation of CM differentiation of P19 cells and maintenance of their undifferentiated state.
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PMID:Nitric oxide signaling in oxytocin-mediated cardiomyogenesis. 1713 63