The effect of hyperglycemia on brain capillary permeability in the lizard, Anolis carolinensis. A freeze-fracture analysis of blood-brain barrier pathology

摘要: Abstract The anatomical basis of the blood-brain barrier in American chameleon, Anolis carolinensis , is system tight intercellular junctions that occurs between apposed endothelial cells brain capillaries. Under normal physiological conditions, capillaries cortex these animals remain sealed by interendothelial zonulae occludentes and, consequently, escape exogenous tracer proteins such as horseradish peroxidase (HRP) into extracellular compartment central nervous prevented. Systemic injection 2.7 mg d -glucose chameleons results increased capillary permeability, evidenced HRP or Trypan blue spaces neuropil. Freeze-fracture analysis endothelia glucose-hyperglycemic lizards revealed no alteration ridge and groove construction junctions, indicating although interface becomes leaky during severe hyperglycemia, occludents are not affected. Evidence obtained this study strongly supports notion permeability result amplified transendothelial transport. effect manifest facilitated formation chains pinocytotic vesicles derived from luminal surface cells, which fuse to create open trans-endothelial conduits. It likely channels traverse a response could allow temporarily unrestricted passage wide range molecules, some potentially toxic, CNS milieu. This first report unequivocally document with freeze-cleave techniques, abnormally elevated levels blood sugar can affect permeability. finding suggests similar consequences may be expected diabetic hyperglycemia humans.