Tight junction proteins of cerebral endothelial cells in early postnatal development

Resumo

The formation and functional plasticity of the blood–brain barrier are inextricably linked to the molecular events occurring in cerebral neurovascular unit during the embryonic and early postnatal development of the organism. To study the features of the barrier genesis under physiological conditions, as well as after perinatal hypoxia and stress in early life, tight junction proteins of cerebral endothelial cells (the number of JAM-, ZO1-, and CLDN5-positive cells) in rats at the age of 7 (P₇), 28 (P₂₈), and 70 (P₇₀) days were investigated. It was found that, under physiological conditions, the number of cells expressing JAM, ZO1, and CLDN5 slightly increase in the period from P₇ to P₇₀ in the cortex, hippocampus, and amygdala of the brain. After perinatal hypoxia, the number of cells expressing the proteins of tight junctions (JAM, CLDN5) is significantly increased to the age of P₂₈–P₇₀, while the number of ZO1⁺ cells in the same period of time is reduced. Early life stress causes an imbalance between the expression of ZO1 and other proteins of tight junctions, but these changes are opposite in direction.