Rat milk and dietary long arginine3 insulin-like growth factor I promote intestinal growth of newborn rat pups.
Newborn rat pups were artificially reared by the pup in cup (PIC) method to determine whether dietary long arginine3 IGF-I (long R3 IGF-I), an IGF-I analog with high receptor affinity and low IGF binding protein (IGFBP) affinity, had efficacy on intestinal growth. IGF effects are mediated by IGFBP and receptor interactions, hence dietary-induced changes in intestinal IGF-II receptor patterns and IGFBP-3 message levels were investigated. Intestinal micrographs of pups fed rat milk replacer (RMR) for 3 d showed flattened villi with low cell counts and appeared similar to newborn intestines. Mother-fed (MF) controls and long R3 IGF-I-fed pups showed increased villi height and cell counts when compared with RMR pups, with long R3 IGF-I fed pups showing the greatest increase. At birth IGF-II-specific binding was not uniform in the intestine; specific binding was higher in the proximal intestinal section than in the distal intestinal section. However, after 3 d of MF treatment, specific binding had reversed and the distal section showed higher IGF-II-specific binding. Three days of RMR feeding did not change IGF-II-specific binding from that of the newborn pup. An IGFBP-3 message was identified in intestinal epithelium by in situ hybridization. Northern analysis of IGFBP-3 message showed a decline over time, but the change was not influenced by dietary treatments. In summary, milk-borne growth factors have the potential to affect intestinal growth within 3 d of treatment.
Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, USA.
M D
MD
Staley
C A
CA
Gibson
J F
JF
Herbein
C E
CE
Grosvenor
C R
CR
Baumrucker
D000818:Animals; D000831:Animals, Newborn; D005260:Female; D005527:Food, Fortified; D005786:Gene Expression Regulation; D006128:Growth / Q000502:physiology*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D008892:Milk; D051381:Rats; D017207:Rats, Sprague-Dawley; D017527:Receptor, IGF Type 2 / Q000378:metabolism*; D014158:Transcription, Genetic
D018972:Insulin-Like Growth Factor Binding Protein 3; D017527:Receptor, IGF Type 2; C085700:long R(3)-insulin-like growth factor-I; D007334:Insulin-Like Growth Factor I