Adaptive changes of intestinal cellular retinol-binding protein, type II following jejunum-bypass operation in the...

To examine whether the amount of intestinal cellular retinol-binding protein, type II (CRBP(II)) exhibits an adaptive change in a shortened jejunum, the distal end of 5-cm proximal-jejunal segment of 2-mth-old rats was joined to the proximal end of the ileum by an end-to-end anastomosis (jejunum-bypass operation). Three weeks after the operation, the amounts of CRBP(II) in proximal jejunum, proximal ileum and distal ileum were determined using a monospecific antiserum by enzyme-linked immunosorbent assay. The jejunum-bypass operation led to a 2-fold increase in the total amounts of CRBP(II) in proximal ileum where hyperplasia occurred; this elevation was in parallel to the increase of total proteins and DNA contents. in the proximal jejunum preceding the bypassed segment, the CRBP(II) level per unit DNA increased by 80%. The jejunum-bypass operation changed neither hepatic total retinol content, nor serum concentrations of retinol and retinol binding protein as compared with the sham-operation, suggesting that retinol absorption was elevated in the shortened small intestine. These results suggest that the increase in CRBP(II) content following jejunum-bypass might be an adaptive response to an enhancement of retinol absorption.