Lectin binding patterns in developing rat colon.

Abstract

To evaluate qualitative changes in brush-border and goblet cell glycoconjugates during colonic development, rhodamine-conjugated lectins were applied to tissue from fetal (18-22 day), suckling (1-20 day), and weanling (22-26 day) rats. Tissue from the proximal and distal colon of each animal was incubated with Triticum vulgaris, Arachis hypogaea, Glycine max, or Ulex europeus agglutinin I. Formalin-fixed paraffin sections and unfixed frozen sections were coded, read blindly, and graded from negative (-) or weak (+) to intensely positive (4+). The results showed a unique developmental pattern for each lectin, although in all cases the adult binding pattern was established by weaning. Alterations in the binding pattern between paraffin and frozen sections were noted only for Arachis hypogaea and Glycine max. Minimal Glycine max binding was seen at any age in paraffin sections, although in frozen sections a weak but consistent supranuclear binding was seen in goblet cells of postnatal animals. In contrast, both the brush-border and goblet cells were intensely fluorescent after exposure to Triticum vulgaris. This fluorescence was present in both regions at all ages studied. Ulex europeus agglutinin I also labeled goblet cells in the fetal and neonatal colon, but late in the suckling period regional differences appeared. This resulted in a significant loss of labeled goblet cells distally and a restriction of Ulex europeus agglutinin I-positive cells to the base of the crypts proximally. Finally, Arachis hypogaea showed a transient brush-border binding in paraffin sections of the proximal colon before weaning, whereas frozen sections revealed a supranuclear localization in goblet cells in both regions after birth. These studies indicate significant changes in membrane-associated and goblet cell secretory glycoconjugates in the developing rat colon.