2003 Fiscal Year Final Research Report Summary
Regulation for growth and differentiation of somatic cells by signals derived from oocytes
| Project/Area Number |
13460133
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Kyushu University |
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Principal Investigator |
HATTORI Masa-aki Kyushu University, Faculty of Agriculture, Prof, 農学研究院, 教授 (60175536)
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| Co-Investigator(Kenkyū-buntansha) |
KATO Yukio Meiji University, Faculty of Agriculture, Prof, 農学部, 教授 (30114177)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Nitric Oxide / Oocyte / Gene Expression / Cell Proliferation and Differentiation / Ovary / Hormone / Oocyte Maturation / Estrogen Receptor |
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| Research Abstract |
The endothelial type(NOS-3) of three isoforms of nitric oxide(NO) synthase occurs in porcine oocytes and granulose cells, but the regulation of NO synthesis in oocytes remains unknown. The present study was designed to evaluate steroid control in the process of oocyte NO synthesis. Cumulus-oocyte complexes(COCs), obtained from small-sized antral follicles of immature porcine ovaries, were cultured in estrogen-deprived medium, and the effect of steroids or steroid-free porcine follicular fluids on the NO release from oocytes was investigated. Oocytes that were isolated from cultured COCs were incubated with 1μM ionomycin. The NO metabolites were identified using a NO detector-high-pressure liquid chromatography system. Oocytes from COCs cultured with 10nM 17β-estradiol(E_2) released NO in response to ionomycin, whereas progesterone and testosterone had little effect on the synthesis of NO. An inhibitor of NOS suppressed the synthesis of NO. The maximal synthesis was observed after a 15 h-culture with E_2. However, oocytes freshly obtained from antral follicles did not response to ionomycin, and the E_2 action was suppressed by the addition of steroid-free follicular fluids. Analyses of RT-PCR and Western blotting showed that E_2 did not increase NOS-3 expression. In addition, estrogen receptor β was detected in oocytes and cumulus cells, and estrogen receptor a was detected only in cumulus cells. These findings suggest that oocyte NOS-3 is promoted for the synthesis of NO by E_2 without increases in NOS-3 expression, but the synthesis of NO is suppressed, at least in the oocytes of early antral follicles.
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