Enhanced growth of small bowel in transgenic mice expressing human insulin-like growth factor I.

Abstract

BACKGROUND & AIMS:

Growth hormone and insulin-like growth factor I (IGF-I) stimulate small bowel growth. The aim of this study was to analyze whether IGF-I mediates enterotrophic actions of growth hormone.

METHODS:

IGF-I transgenic mice that overexpress an IGF-I transgene driven by the mouse metallothionein I promoter and are growth hormone deficient were compared with wild-type littermates. Growth of small bowel, abundance and localization of messenger RNAs for the IGF-I transgene, and insulin-like growth factor-binding protein 3 were assayed.

RESULTS:

Small bowel length and mass were greater in IGF-I transgenic mice than in wild-type mice. Villus height, crypt depth, and crypt cell mitoses were greater in jejunum of transgenics than wild-type mice, but jejunal disacharidase activities were not increased. The transgene was expressed strongly in villus epithelial cells. Insulin-like growth factor-binding protein 3 messenger RNA was localized in the lamina propria. Regional expression of both correlated with the increase in mucosal mass.

CONCLUSIONS:

Effects of IGF-I overexpression on intestinal length and mucosal mass were similar to effects of growth hormone overexpression observed previously. Excess of IGF-I increased crypt cell proliferation, whereas excess of growth hormone did not increase crypt cell proliferation. IGF-I excess stimulated differentiation of intestinal epithelial cells less effectively than growth hormone excess.

• Authors: K Ohneda, M H Ulshen, C R Fuller, A J D'Ercole, P K Lund
• Journal: Gastroenterology (Gastroenterology) Vol. 112 Issue 2 Pg. 444-54 (Feb 1997) ISSN: 0016-5085 [Print] United States
• PMID: 9024298 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Insulin-Like Growth Factor Binding Protein 3
• RNA, Messenger
• Insulin-Like Growth Factor I
• Growth Hormone

Topics

• Animals
• Body Weight
• Cattle
• Energy Intake
• Gene Expression
• Growth Hormone (genetics)
• Humans
• Insulin-Like Growth Factor Binding Protein 3 (genetics)
• Insulin-Like Growth Factor I (genetics, metabolism)
• Intestinal Mucosa (growth & development, physiology)
• Intestine, Small (anatomy & histology, cytology, growth & development)
• Jejunum (metabolism)
• Mice
• Mice, Transgenic (genetics, metabolism, physiology)
• Mitosis
• Organ Size
• RNA, Messenger (metabolism)
• Reference Values
• Tissue Distribution