| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1993: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
1.To cvaluate possible action of prostaglandins (PGs) and cstradiol-17beta(cstradiol) on the specific binding for oxytcin, cultured cells of bovine corpora lutea at mid luteal stage were examined for oxytocin (OT) receptors by a radioreceptor assay. The specific binding increased dose-dependently only with PGF2a, whereas PGE2, PGI2 or estradiol showed no effect. When PGF2a synthesis was inhibited by indomethacin for the last 28 h in culture, the specific binding for OT decreased significantly (P<0.01). On the other hand, the addition of arachidonic acid caused the significant increases of the specific binding for oxytoein and PGF2a secretion concomitantly (P<0.01). When protein kinase C (PKC) activity of the lutcal cell was inactivated before PGF2a stimulation, the specific binding for OT was not affected by the stimulation of PGF2a. These data suggest that PGF2a may be one of potent regulators for lutcal OT receptors in a paracrine and/or autocrine fashion, and that its action is medi
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ated by PKC.
2.To demonstrate the spceific receptors for OT in bovine granulosa cells, freshly prepared bovine granulosa cells from immature follicles or mature follicles were examined for OT receptors by a radioreceptor assay. The binding capacity in granulosa cells from immature follicle was significantly higher than from mature follicle (P<0.01). Furthermore, the binding affinity of OT receptors in granulosa cells from immature follicles was also significantly higher than from mature follicles. The results reveal the existence of specific binding sites for OT in bovine granlosa cells both from immature and mature follicles, and demonstrate that its characteristics are different between them.
3.To investigate the correlation between the luteinization and the characteristics of OT receptors, the binding for OT in the cultrued bovine granulosa cells were investigated. Although the binding affinity was not changed during the culture for 72h, as the cells were cultured longer, its binding capacities were decrcased with increasing the progesterone relcase in the medium. The results suggest that OT receptors decrease, as the granulosa cells are luteinized by. Less
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