Abstract
Pinocytosis is the predominant route of penetration of macromolecules across the small bowel epithelium of newborn animals. We have developed a model system to study this process on jejunal mucosal explants using ricin. Ricin is a potent toxin which inhibits protein synthesis by a mechanism involving binding to galactose surface residues, internalization of its enzymatic component and inactivation of the 60 S ribosomal subunit. Protein synthesis (3H-leucine incorporation) in jejunal explants from fetal, suckling and adult rabbits was measured in organ culture following an initial exposure (30 min, 25°) to ricin (1-25 μg). The rate of inhibition of protein synthesis was age dependent (Fig). High in the fetus, it increased further to a maximum at day 6 postnatally, then decreased rapidly in suckling animals to adult levels at weaning. The high sensitivity to ricin during the colostral period may be related to the following factors currently under study: 1) colostral-milk components stimulating a high rate of endocytosis, 2) transitional maturation changes in membrane properties and 3) changes in sensitivity at the target ribosomal site. The model presented is useful to study modifiers and events influencing mucosal permeability in the developing small intestine.
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Olson, A., Torres-Pinedo, R. 277 CHANGES IN SENSITIVITY TO RICINUS COMMUNIS TOXIN (RICIN) OF RABBIT JEJUNUM DURING THE SUCKLING PERIOD. Pediatr Res 15 (Suppl 4), 486 (1981). https://doi.org/10.1203/00006450-198104001-00288
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DOI: https://doi.org/10.1203/00006450-198104001-00288