Investigation of three doses of oral insulin-like growth factor-I on jejunal lactase phlorizin hydrolase activity and gene expression and enterocyte proliferation and migration in piglets.
In a previous study, oral IGF-I at 65 nM increased lactase phlorizin hydrolase (LPH) activity and villus height in piglets, however, the mechanisms were unknown. Herein, the response to a range of doses of IGF-I was investigated and we hypothesized that LPH and villus height would respond to oral IGF-I in a dose-dependent manner. Two 14-d experiments were conducted using cesarean-derived piglets. In experiment 1, piglets (n = 28) were fed formula containing 0, 33, 65, or 131 nmol/L (0, 0.25, 0.5, or 1.0 mg/L) recombinant human IGF-I. In experiment 2, 5'-bromodeoxyuridine was administered to piglets fed formula alone (n = 4) or containing 131 nmol/L IGF-I (n = 4). IGF-I did not affect body weight gain or intestinal weight or length. Jejunal villus height and LPH activity were significantly greater in piglets fed 131 nmol IGF-I/L than control piglets. Villus height and lactase activity in piglets fed the 33 and 65 nmol/L IGF-I doses were similar and intermediate between control and 131 nmol IGF-I/L. Jejunal mRNA expression and LPH polypeptide abundance were investigated in piglets receiving 0 or 131 nmol/L IGF-I. Steady state LPH mRNA abundance was significantly higher (p < 0.05) in IGF-I-treated piglets. The relative abundance of proLPH(h) was not significantly increased (p = 0.06) by IGF-I treatment. Mucosal DNA content and DNA synthesis were greater in piglets receiving 131 nmol IGF-I/L than control, however, enterocyte migration and mucosal protein content were unaffected. Thus, oral IGF-I increased jejunal LPH activity and LPH mRNA abundance and stimulated intestinal cell hyperplasia in normal piglets.
Houle
V M
VM
Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, USA.
Park
Y K
YK
Laswell
S C
SC
Freund
G G
GG
Dudley
M A
MA
Donovan
S M
SM
D000818:Animals; D002455:Cell Division; D002465:Cell Movement; D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D015870:Gene Expression; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D007413:Intestinal Mucosa / Q000737:chemistry; D007583:Jejunum / Q000166:cytology* / Q000201:enzymology* / Q000254:growth & development; D010694:Lactase-Phlorizin Hydrolase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D011506:Proteins / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D013552:Swine; D015430:Weight Gain
D011506:Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D004247:DNA; D010694:Lactase-Phlorizin Hydrolase