Linda R. Daniel

Age-related changes in jejunal glucose absorption in mice

Abstract Jejunal glucose absorption was determined in male mice aged 1, 2, 6, 12, and 18 months of age. Active and passive glucose transport was measured in vitro by estimating the uptake of 3-0-methyl-D-glucose by 1 mm jejunal rings in the presence and absence of phlorizin over a 5 min period. Passive glucose transport was found to be constant with increasing age. Active transport peaked at 2 months of age and the steadily declined. The reduction in active glucose transport rate between 2 and 18 months of age was approximately 50%. No corresponding changes were noted for jejunal villus or crypt dimensions, thickness of the jejunal musculature, or mucosal water and protein content. The age-related decrease in absorption is initiated before attainment of mature body weight. These results demonstrate that age specifically modifies active transport function in mouse jejunal mucosa without concomitant alterations in the structure of the jejunal wall.

The effect of long R3 insulin-like growth factor-I on jejunal glucose absorption in mice

Abstract Two experiments were conducted to determine the effects of long R 3 insulin-like growth factor (IGF)-I on jejunal glucose transport in mice. Jejunal rings from 4 mice were incubated for 10 min at 37°C in transport media containing 0, 150 or 500 ng long R 3 IGF-I/ml. Uptake of glucose measured during the last 5 min of incubation was similar among the three treatments. In the second experiment, 8 mice were subcutaneously injected once-daily with 0 or 150 μg long R 3 IGF-I/kg BW for 3 d. Treatment with long R 3 IGF-I did not affect jejunal glucose absorption. Weight of the stomach and small and large intestine were similar for both groups, however, treatment with long R 3 IGF-I reduced the length of the small intestine (P 3 IGF-I. Short-term administration of long R 3 IGF-I does not appear to cause alterations in intestinal absorption of glucose.