Reaction of the blood–brain barrier structural elements to normobaric hypoxia in newborn rats

Abstract

Special focus is currently laid on the early postnatal period when an organism adapts actively to new living conditions and therefore becomes particularly vulnerable to adverse environmental factors. Among these adaptive processes, one of the most important is the development of homeostatic and, specifically, barrier mechanisms. The aim of this study was to explore the reaction of the hematoencephalic or blood–brain barrier (BBB) structural elements to perinatal normobaric hypoxia (the human incomplete pregnancy model). Using light and electron microscopies, it was demonstrated that after hypoxic exposure all the capillary wall components in the neocortex display structural changes which may underlie microcirculatory disorders and increased BBB permeability. Differentiation of the capillary wall basal membrane was found to occur during the early perinatal period, and the formation of its laminae (laminae rara et densa) serves a differentiation criterion. Hypoxic exposure was found not only to delay the basal membrane formation, but to induce a vesicular type of its degeneration.