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KMID : 0613820080180070931
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Journal of Life Science
2008 Volume.18 No. 7 p.931 ~ p.939
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Responses of Plasma IGF-1, IGFBPs and Hepatic GH Receptor to Growth Hormone Releasing Peptides (GHRP)-2 Administration and Energy Level in Wethers
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Lee Hong-Gu
Jin Young-Cheng
Hidari Hisashi
Choi Yun-Jaie
Kim Seon-Ku
Shin Teak-Soon
Cho Byung-Wook
Kim Yong-Gyun
Kim Keun-Ki
Son Hong-Joo
Lee Sang-Mong
Park Hyean-Cheal
Kang Han-Seok
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Abstract
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The purpose of this study was to determine the effect of energy supplement on responses of plasma insulin-like growth factor (IGF)-1 and IGF binding proteins (IGFBPs) to growth hormone-releasing peptide-2 (GHRP-2) administration in normal protein-fed wethers, and to observe the effect of GHRP-2 treatment on hepatic growth hormone (GH) receptor in well-fed wethers. Plasma IGF-1 and 39-42 kDa IGFBP-3 during the HENP (CP, crude protein 0.34 and TDN, total digestible nutrients 1.83 ㎏/day DM, dry matter intake) treatment period were higher than in the LENP (CP 0.32 ㎏ and TDN 0.87 ㎏/day DM intake) period (P＜0.05). The response of GH was stimulated by GHRP-2 (12.5 ㎍/㎏ body weight/day) administration during both of the feed treatment periods (P＜0.05). The area under curve (AUC) increment and average concentration of GH (0-180 min) with GHRP-2 administration was higher during HENP treatment than LENP treatment (P＜0.01). During the HENP treatment period from day 1 to day 7 of twice daily GHRP-2 treatment, the plasma IGF-1 increment was increased on days 2, 6 and 7 of GHRP-2 administration (P＜0.05). On the basis of ligand blotting, the proportions of plasma 39-43 kDa IGFBP-3 during the HENP treatment period only showed a significant difference on days 6 and 7 with GHRP-2 administration. No significant difference in the specific binding of 125I-labeled oGH to hepatic membranes was detected between the saline and GHRP-2 treatments of the HENP-fed wethers. These results suggest that the nutritional balance between energy and protein may affect the endogenous GH / IGF-1 axis as well as plasma IGFBP-3 levels.
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KEYWORD
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Dietaryenergy, growthhormone-releasingpeptide-2(GHRP-2), insulin-likegrowthfactor-1(IGF-1), IGFbindingproteins(IGFBPs), wether
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