| Project/Area Number |
62560073
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
応用生物化学・栄養化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NOGUCHI Tadashi Faculty of Agric., The Univ. of Tokyo Professor, 農学部, 教授 (50011937)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Somatomedin C / Insulin-like growth factor-I / Protein nutrition / Whole-body protein synthesis rate / somatomedin C-mRNA / 必須アミノ酸欠乏 / ソマトメジンレセプタ- / ソマトメジンC-mRNA / ポリメラ-ゼ連鎖反応 / メチオニン欠乏 / リジン欠乏 / メッセンジャーRNA / アミノ酸欠乏 / ノザンブロットハイブリダイゼーション / 必須アミノ酸 / デキサメタゾン / ストレプトゾトシン / 糖尿病 |
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| Research Abstract |
Somatomedin C (or insulin-like growth factor-I, IGF-I) is a peptide hormone, the structure of which is known to be similar to insulin. However, IGF-I shows biological properties distinct from insulin. IGF-I has been elucidated to be produced mainly by liver under the control of growth hormone and nutritional status of animals. However, the effect of dietary proteins has not been studied extensively. This work was plained to elucidate the effect of dietary proteins on plasma immunoreactive (ir) IGF-I concentration, the mode of association of IGF-I with plasma IGF-binding proteins, and the correlation between plasma ir-IGF-I concentration and whole body protein synthesis rate.
Nutritional quality of dietary proteins affected plasma ir-IGF-I extensively. The rats fed a casein diet showed the highest ir-IGF-I concentration and those given a protein- free diet, the lowest. Plasma ir-IGF-I of rats fed a gluten or corn gluten weal diet showed the intermediate values. Supplementation of lysine and threonine to the gluten diet or tryptophan and lysine to the corn gluten meal diet increased plasma ir-IGF-I concentration significantly.
Nutritional value of dietary proteins also affected the mode of association of IGF-I with IGF-binding proteins. IGF-I in the plasma of rats fed casein diet was found primarily in the 150 kDa fraction. However, significantly lower amount of IGF-I was found in this fraction in the rats given the protein-free diet.
The rats fed the protein-free diet contained lower amount of IGF-I-mRNA in liver compared with those fed the casein diet.
These results clearly show the important role of IGF-I in protein or amino acid nutrition of man and other animals.
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