AJP - Gastrointestinal and Liver Physiology, Vol 256, Issue 1 220-G225, Copyright © 1989 by American Physiological Society

ARTICLES

Age and cortisone alter host responsiveness to cholera toxin in the developing gut

S. H. Chu, I. G. Ely and W. A. Walker
Combined Program in Pediatric Gastroenterology and Nutrition, Children's Hospital, Boston, Massachusetts.

To assess the influence of immaturity on the responsiveness of enterocytes to specific pathogens, a dose-response curve for cholera toxin (CT)-induced fluid secretion was determined in the proximal small intestine of rats at 2 and 4 wk of age. The suckling rat was approximately 50 times more sensitive to CT in triggering the secretory response than the weaned rat, when estimated by the medium-effective dose (ED50, 0.8 vs. 38.9 nM). Cortisone, known to promote enterocyte maturation, when injected into suckling rats, decreased host sensitivity approximately 1,000 times. Neither age nor cortisone decreased the receptor binding of 125I-labeled CT to intestinal microvillus membranes. In contrast, cortisone treatment caused a threefold increase in receptor density from 14.5 to 43.0 pmol/mg protein. The enzyme responsible for the sodium pump, Na+-K+-ATPase, showed a threefold increase in activity both after weaning and after a cortisone treatment. These data indicate that the immature gut exhibited an increased host sensitivity to CT stimulation that was not correlated with initial receptor binding but was related to a lowered Na+-K+-ATPase activity, suggesting that an underdeveloped sodium pump may be partially responsible for the high incidence of secretory diarrhea in neonates.

This article has been cited by other articles:

				L. Lu, S. Khan, W. Lencer, and W. A. Walker Endocytosis of cholera toxin by human enterocytes is developmentally regulated Am J Physiol Gastrointest Liver Physiol, August 1, 2005; 289(2): G332 - G341. [Abstract] [Full Text] [PDF]

				J. Pacha Development of Intestinal Transport Function in Mammals Physiol Rev, October 1, 2000; 80(4): 1633 - 1667. [Abstract] [Full Text] [PDF]

				U. Shah and W. A. Walker Adverse Host Responses to Bacterial Toxins in Human Infants J. Nutr., February 1, 2000; 130(2): 420 - 420. [Abstract] [Full Text]