1997 Fiscal Year Final Research Report Summary
Mechanism of Parathyroid Hormone-Related Protein Secretion on Three-Dimensional Culture of Bovine Mammary Cells
| Project/Area Number |
08660369
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Basic veterinary science/Basic zootechnical science
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| Research Institution | Rakuno Gakuen University |
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Principal Investigator |
OKADA Hiroyuki Rakuno Gakuen University, Department of Veterinary Pathology, Associate Professor, 獣医学部, 助教授 (50166419)
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| Co-Investigator(Kenkyū-buntansha) |
NAKADA Ken Rakuno Gakuen University, Department of Veterinary Obstetrics and Gynecology, As, 獣医学部, 講師 (10241069)
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| Project Period (FY) |
1996 – 1997
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| Keywords | parathyroid hormone-related protein / cytokine / mammary gland / bovine |
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| Research Abstract |
Various hormones and cytokines are present in milk. However, precise information on the mechanism in the mammary gland is still unclear. Parathyroid hormone-related protein (PTHrP) is produced by the lactating mammary gland and is present in milk in a biologically active form. This investigation was performed to determine the effect of epidermal growth factor (EGF) and transforming growth factor (TGF) -beta on parathyroid hormone-related protein secretion by three dimensional culture of bovine mammary cells in vitro. Mammary acini were isolated from lactating mammary glands of cows at 1-6 weeks after calving. Fresh or cryopreserved mammary acini were cultured within collagen gels and on collagen coated culture inserts or plastic dishes. PTHrP production was measured by N-terminal radioimmunoassay. PTHrP mRNA expression from cultured bovine mammary cells was determined by northern analysis. PTHrP production in the culture medium as well as PTHrP mRNA expression was increased by treatment with EGF and TGF-beta in dose dependent manner. Total PTHrP secretion in an apical direction remained at levels, whereas secretion in a basal direction remained at high levels in a membrane insert cultured system. These data demonstrated that the mammary cell from lactating cows could be cultured in vitro and secreted PTHrP in a regulated manner. These results also indicate that EGF and TGF-beta may be important factors in the regulation of PTHrP secretion in the mammary gland. The pathophysiological role of PTHrP is uncertain. Myoepithelial cells situated in the basal position of mammary alveoli act on the alveolar contraction. PTHrP could play a role in the regulation of milk or milk components into the alveolar lumen. In conclusion, this in vitro model will be useful to investigate the function and regulation of PTHrP in the lactating mammary gland.
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