| Project/Area Number |
09660306
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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 |
Applied animal science
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| Research Institution | College of Bioresource Sciences, Nihon University |
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Principal Investigator |
SENSUI Naoto Nihon University, College of Bioresource Sciences Associate Professor, 生物資源科学部, 助教授 (10060120)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMURO Yutaka Nihon University, College of Bioresource Sciences Assitant Professor, 生物資源科学部, 専任講師 (10255119)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Estrogen / Lactation / Mammary Gland / Apoptosis / Prolactin Cell / Growth Hoemone Cell / Maternal Behavior / エストロジェン / 乳質 / ストレッチング |
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| Research Abstract |
The mechanisms of lactation depressive action by estrogen(E) were studied in mice and rats. The daily injection of E from day 3 of lactation for 10 days decreased litter weight gain. The weight and lactose contents of the mammary glands measured as an index of mammary glands secretary activity decreased markedly in E injected mice compared to the control. Administration of E to the mother was little effect on maternal behavior and suckling behavior of the litter in mice. The lactating mammary tissue section from mice injected E for 5 days or 10 days was stained with hematoxylin-eosin and examined histologically under microscope. The alveolar structure of the gland was maintained for 4*5 days after E injections whereas slight decrease in the number of alveolar and the quantity of milk in alveolus lumen and increase in the number of adepocytes in the mammary tissues were observed. However the alveolar structure of the glands was completely disrupted and the large number of adepocytes wer
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e infiltrated into the glands in 10 days E injected mice. Whether E induces apoptosis in the mammary glands is studied using some instances of apoptosis of mammary glands in mice. DNA laddering of mammary glands which is identified by ethidium bromide staining after agarose gel electrophoresis was detected 5 days after B injections, but not after 10 days. Apoptotic mammary cells were also detected by terminal deoxynucleotidyl transferese-mediated dUTP-biotin nick labeling method. Induction of c-myc, a protein associated with apoptotic cell death, was found in mammary tissues by E injections for 5 days. These results indicate that the induction of mammary gland involution by E, at least in part, is due to apoptosis. Because injected E to the mother is transported to their litters through milk, prolactin and growth hormone cells in the anterior pituitary glands of perinatal rats were cultured with E and examined development and proliferation of the cells. The result indicated that E stimulated the proliferation of prolactin cells but did not affect the proliferation of growth hormone cells in anterior pituitary glands. Less
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