QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takenaka, A. Articles by Noguchi, T. Search for Related Content PubMed PubMed Citation Articles by Takenaka, A. Articles by Noguchi, T.

---

Articles

Dietary Restriction of Single Essential Amino Acids Reduces Plasma Insulin-Like Growth Factor-I (IGF-I) but Does Not Affect Plasma IGF-Binding Protein-1 in Rats

Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan

³To whom correspondence should be addressed. E-mail: noguchi{at}bio.m.u-tokyo.ac.jp

The effects of dietary restriction of a single essential amino acid (EAA) on insulin-like growth factor-I (IGF-I) and IGF-binding protein (IGFBP)-1 were investigated in rats. Rats were fed experimental diets containing amino acid (AA) mixtures in which the concentrations of all EAA were at levels recommended by the National Research Council (control), in which a single EAA was restricted to 20% of that of the control diets (Leu^-, Lys^-, Met^- or Thr^-), or in which the diet was devoid of amino acids (AA^-). To eliminate the effect of differences in energy intake, rats were fed the mean amount of food as consumed by the AA^- group on the previous day. Growth was significantly retarded in rats fed diets restricted in just one EAA compared with that of rats fed the control diet, and further growth retardation was observed in rats fed the AA^- diet. On the other hand, the plasma IGF-I concentrations in the groups with a single EAA restriction or in the AA^- group were 66% (P < 0.05) and 50% (P < 0.05) of that of the control group, respectively. The effect of any single EAA restriction was not significantly different from that of total AA deprivation. The plasma IGFBP-1 concentration in the control group did not differ from that of rats fed diets with the single EAA restrictions except for methionine restriction, but it was 6-fold greater in the AA^- group. Differences in plasma IGFBP-1 concentration under these conditions could be explained by differences in hepatic IGFBP-1 mRNA contents. Based on these results, we conclude that restriction of single EAA does not affect IGFBP-1 synthesis in vivo, although the deprivation of a single EAA has been reported to increase IGFBP-1 production in hepatocyte cultures. Our results also indicated that a single EAA restriction decreased IGF-I production but did not affect IGFBP-1 production. The present study suggests that not only plasma IGF-I, but also IGFBP-1, affects the magnitude of growth retardation in vivo.

KEY WORDS: • essential amino acid • insulin-like growth factor–binding protein-1 • mRNA • rats

This article has been cited by other articles:

				B. Meissner, M. Boll, H. Daniel, and R. Baumeister Deletion of the Intestinal Peptide Transporter Affects Insulin and TOR Signaling in Caenorhabditis elegans J. Biol. Chem., August 27, 2004; 279(35): 36739 - 36745. [Abstract] [Full Text] [PDF]

				K. Kita, K. Nagao, N. Taneda, Y. Inagaki, K. Hirano, T. Shibata, M. A. Yaman, M. A. Conlon, and J.-i. Okumura Insulin-Like Growth Factor Binding Protein-2 Gene Expression Can Be Regulated by Diet Manipulation in Several Tissues of Young Chickens J. Nutr., February 1, 2002; 132(2): 145 - 151. [Abstract] [Full Text] [PDF]