IGF alters jejunal glucose transporter expression and serum glucose levels in immature rats

Milk-borne insulin-like growth factors (IGFs) enhance nutrient absorption in the immature intestine, which is characterized by low levels of glucose oxidation. We therefore hypothesized that feeding a rat milk substitute (RMS) devoid of growth factors to rat pups would lower serum glucose levels rel...

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Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2002-12, Vol.52 (6), p.R1450-R1460
Main Authors: LANE, Robert H, DVORAK, Bohuslav, MACLENNAN, Nicole K, DVORAKOVA, Katerina, HALPERN, Melissa D, PHAM, Tho D, PHILIPPS, Anthony F
Format: Article
Language:English
Subjects:
Biological and medical sciences
Cell division
Fundamental and applied biological sciences. Psychology
Glucose
Intestine. Mesentery
Rodents
Vertebrates: digestive system
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Summary:Milk-borne insulin-like growth factors (IGFs) enhance nutrient absorption in the immature intestine, which is characterized by low levels of glucose oxidation. We therefore hypothesized that feeding a rat milk substitute (RMS) devoid of growth factors to rat pups would lower serum glucose levels relative to dam-fed control rats and that supplementation of RMS with physiological doses of either IGF-I or IGF-II would normalize serum glucose levels via increased jejunal glucose transporter 2 (GLUT2) and high-affinity Na+-glucose cotransporter (SGLT1) expression. We found lower serum glucose concentrations in RMS-fed pups; in contrast, serum glucose levels in the IGF-supplemented pups were similar to those of dam-fed controls. RT-PCR and laser scanning confocal microscopy similarly demonstrated that IGF supplementation increased expression of jejunal glucose transporters. Further experiments demonstrated that IGF supplementation altered mRNA levels of key mitochondrial enzymes without altering jejunal lactase activity. We conclude that IGF-I and IGF-II supplementation increases serum glucose levels in the immature rat pup fed artificial formula and alters gene expression of the jejunal glucose transporters. [PUBLICATION ABSTRACT]
ISSN:0363-6119
1522-1490