Early nutrition and intestinal transport function: effect of low-cholesterol diet.

Intestinal structure and function change with aging and with manipulation of the diet. The present study was undertaken to assess the absorption of selected nutrients and the morphologic characteristics of the intestine of weaning rabbits fed chow for 2, 4, or 6 weeks, and to determine the effect of feeding a low-cholesterol diet (LCD) for 2 weeks on these changes. Over the 6-week period in the chow-fed rabbits, an increase was seen in the jejunal villus height, villus surface area, and mucosal surface area, whereas in the ileum no change occurred in the villus height, and a decrease in the mucosal surface area was seen. Feeding LCD for 2 weeks had no effect on the jejunal or ileal mucosal surface area, and returning to chow for 2 weeks after 2 weeks of the low-cholesterol diet (LCD-C) also had no effect on mucosal surface area. Food consumption was lower in animals fed LCD than in animals fed chow, but body weight gain was unchanged. With an in vitro technique, the jejunal, ileal, and colonic uptake of lipids was shown to change over 6 weeks in animals fed chow, with a decline in the value of the incremental change in free energy (integral of delta Fw----I) associated with the uptake of medium-chain fatty acids, and an increase in the uptake of dodecanol, suggesting lower effective resistance of the intestinal unstirred water layer. The jejunal and ileal uptake of glucose and leucine fell from 2 to 6 weeks of age. Feeding LCD for 2 weeks was associated with marked changes in transport: in the jejunum there was increased uptake of fatty acids (FA) 6:0, 8:0, 12:0, 14:0, and 16:0, dodecanol, glucose, and galactose, and reduced uptake of FA 10:0 and 18:0, cholic acid, and leucine. Feeding LCD abolished the site-related differences in integral of delta FW----I, and reduced the early age-related fall in integral of delta FW----I in the ileum and colon. With LCD-C some of the changes in uptake were returned to normal, whereas for others new abnormalities became apparent. Thus, (1) the intestinal structure and transport function of young growing rabbits undergoes complex alterations, with the direction and magnitude of the absorption changes depending on the probe and the intestinal site; (2) feeding LCD for 2 weeks alters the age-related process of intestinal development.(ABSTRACT TRUNCATED AT 400 WORDS)