Remodeling of membrane-bound glycoproteins containing alpha-D-galactose in the cerebral endothelial cells of rats during blood-brain barrier maturation and alteration.

In the course of the development of cerebral endothelia, the lectin labelling of alpha-D-galactosyl residues on the luminal front of the endothelial cells was gradually increased but that on the abluminal surface was concomitantly attenuated. In the latter, the isolectin (GSA I-B4) decoration was totally diminished with the maturation of the brain. Associated with this change, the end feet of astrocytes resting on the endothelia became lectin positive. Numerous cytoplasmic vacuoles, Golgi apparatus, vesicles and tubule-like structures were strongly labelled in the cerebral endothelia in the early stages of development but only sparse vacuoles and vesicles remained lectin-stained in the mature cerebral endothelia. Labelled pericytes closely associated with the wall of blood vessels, displayed a lectin binding pattern similar to that of the developing cerebral endothelia. Following the blood-brain barrier damage induced by a cold lesion, the altered cerebral endothelia that were surrounded by densely-stained macrophages/microglia or pericytes remained unstained with the isolectin. Present results suggest that during blood-brain barrier maturation, the brain endothelia develop a functional polarity whereby their membrane glycoprotein is down regulated. The membrane glycoprotein, however, underwent remodeling when the blood-brain barrier was disrupted.