| Project/Area Number |
06454112
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied animal science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAKAI Senkiti Univ.of Tokyo, Dept.of Agriculture, Associate Professor, 農学部, 助教授 (80114487)
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| Co-Investigator(Kenkyū-buntansha) |
AOKI Fugaku Univ.of Tokyo, Dept.of Agriculture, Assistant Professor, 農学部, 助手 (20175160)
KOHMOTO Kaoru Univ.of Tokyo, Dept.of Agriculture, Professor, 農学部, 教授 (30011894)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥6,500,000)
Fiscal Year 1995: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1994: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Keywords | Casein / Mammary gland / Lactation / Gene expression / Gene regulation / Prolactin receptor / プロラクチン / RT-PCR / 競合的RT-PCR / 泌乳開始 / 泌乳の維持 / ホルモン受容体 / メッセンジ-RNAの測定 / メッセンジ-RNAの合成 / メッセンジャーRNAの分解 |
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| Research Abstract |
In the present experiments, the author examined the regulation of prolactin receptor gene expression at various reproductive stages of the mouse mammary gland. In order to determine the level of prolactin receptor and casein mRNAs, the author constructed the competitive reverse-transcription and polymerase chain reaction using the chimeric and competitor DNAs. The results obtained in this study were as follow. (a). The expression of the prolactin receptor gene is controlled dominantly by prolactin, estradiol and progesterone at virgin and early pregnancy. The high concentration of progesterone inhibited the increasing action of prolactin and estradiol. (b). The expression of the prolactin receptor gene occurs about 8 hr prior to parturition and is a trigger for lactogenesis. During mid to late pregnancy, progesterone inhibited directly the initiation of lactation. (c). On day 5 of lactation. the level of prolactin receptor mRNA decreased in time-dependent manner following the removal of pups. Its level was minimal at 12 hr of weaning and low levels were maintained until of 48 hr. At 24 of weaning, foster pups were supplyed. The level of prolactin receptor mRNA returned to that of the 0 hr-weaned control within 6 hr, In case of casein mRNA,the changing profile was essentially similar to that of prolactin receptor mRNA.(d). The rates of degradation and synthesis of prolactin receptor mRNA were estimated by the 24 hr-weaning or by the 6 hr-resuckling, respectively, as described in (c). The active synthesis of prolactin receptor mRNA was found on day 1 of lactation, and that of casein synthesis was on day 10 of lactation. The levels of the two mRNAs changed primarily in relation to their rates of mRNA synthesis.
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