Insulin-like growth factor binding protein-2 gene expression can be regulated by diet manipulation in several tissues of young chickens.
The relationship between nutritional status and insulin-like growth factor binding protein-2 (IGFBP-2) gene expression in chickens was studied. Chickens (6 wk old) were food deprived for 2 d and then refed. IGFBP-2 mRNA in the brain was significantly decreased by food deprivation and levels did not increase when birds were refed for 24 h. Gizzard and hepatic IGFBP-2 mRNA levels were significantly increased by food deprivation and decreased by refeeding. Any nutrients tested decreased hepatic IGFBP-2 gene expression. In kidney, IGFBP-2 mRNA was detected but not influenced by food deprivation and refeeding. In another study, the influence of dietary protein source [isolated soybean protein vs. casein; crude protein (CP) 20%] and the supplementation of essential amino acids on IGFBP-2 gene expression of young chickens (5 wk old) was examined. The influence of feeding a low soybean protein diet (CP 5%) on tissue IGFBP-2 gene expression was also investigated. Hepatic IGFBP-2 mRNA was not detected in any group. Feeding the low protein diet for 7 d decreased brain IGFBP-2 mRNA level and increased gizzard IGFBP-2 level compared with chickens fed 20% protein diets. A significant interaction between protein source and amino acid supplementation was observed in gizzard IGFBP-2 mRNA level. In both casein-fed groups and in chickens fed 20% soybean protein diet without supplemental amino acids, the levels did not differ from one another or from the low protein diet-fed birds. The level was lower in chickens fed the amino acid-supplemented, 20% soybean protein diet. In conclusion, the response of IGFBP-2 gene expression to variations in nutritional status was rapid and different in several tissues of young chickens, which would help modulate the growth-promoting effect of circulating IGF-I by making the IGF-IGFBP complex.
Kita
Kazumi
K
Laboratory of Grassland Science, University Farm, Graduate School of Bioagricultural Sciences, Nagoya University, Togo, Aichi 470-0151, Japan. kitak@agr.nagoya-u.ac.jp
Nagao
Kenji
K
Taneda
Noriko
N
Inagaki
Yoshimi
Y
Hirano
Kazumi
K
Shibata
Takako
T
Yaman
M Aman
MA
Conlon
Michael A
MA
Okumura
Jun-ichi
J
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D004044:Dietary Proteins; D005508:Food Deprivation / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D005895:Gizzard, Avian / Q000378:metabolism; D007328:Insulin / Q000097:blood; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000235:genetics* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009752:Nutritional Status; D012333:RNA, Messenger / Q000378:metabolism
D004044:Dietary Proteins; D007328:Insulin; D018971:Insulin-Like Growth Factor Binding Protein 2; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I