APStracts 3:0244G, 1996.

Continuous systemic infusion of igf-i or long [are3] igf-i, stimulates visceral organ growth and enhances proliferation of gastrointestinal tissues in suckling rats. Steeb, C. B., C. A. Shoubridge, D. R. Tivey, and L. C. Read. Child Health Research Institute and Cooperative Research Center for Tissue Growth and Repair, North Adelaide, South Australia, 50061 and Faculty of Agricultural and Natural Resource Sciences, The University of Adelaide, Glen Osmond, South Australia, 50642

APStracts 3:0244G, 1996.

This study describes developmental changes in gastrointestinal response to IGF-I peptide administration. Neonatal rats were infused with IGF-I or LR3IGF-I for 6.5 days starting on day 6 or 12 post partum. Peptides were delivered by mini-osmotic pumps at 0, 2, 5 or 12.5 [mu]g/g/day. IGF-I infusion increased plasma IGF-I levels in both age groups but stimulated body weight gain only in the older rats. Infusion of LR3IGF-I didn't change plasma IGF-I levels. Both peptides enhanced expression of IGFBP-1/2 and induced IGFBP-3 in the older rats. For both age groups, weights of the kidney and spleen increased by up to 85% and 76%, respectively. IGF-I treatment also stimulated gut weight and length by up to 60% and 32%, respectively, however, dose-dependency was observed in the older rats, only. LR3IGF-I was more potent for all growth parameters at both age groups. Histologically, thickening of the mucosa and muscularis externa was observed following infusion of IGF-I peptides. Thymidine labelling in the younger rats indicated that proliferative activity increased proportional with crypt cell growth. These results indicate that IGF-I peptides selectively stimulate growth of gastrointestinal tissues in suckling rats and the proximal gut was the most peptide responsive region.

Received 3 June 1996; accepted in final form 26 September 1996.
APS Manuscript Number G221-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996