blood-brain barrier; blood-CSF barrier; plasma-CSF barrier

Function

• the choroid plexus regulates nutrient, lipid & protein transport across the blood-CSF barrier
• opposes passage of most ions & large molecular weight compounds from the blood into the cerebrospinal fluid & brain tissue
• insulin can cross the blood brain barrier* & can penetrate the hippocampus

* insulin can be delivered through the nose to the brain, via a simple nasal spray

Structure

• continuous layer of endothelial cells connected by tight junctions
• similar capillaries are found in the retina, iris, inner ear & endoneurium of peripheral nerves
• in circumventricular organs, the blood brain barrier is absent; the endothelium is fenestrated
  • the blood-CSF barrier is provided by tight junctions between ependymal cells

Pathology

• breakdown of the blood brain barrier occurs in many neurodegenerative disorders
  • Alzheimer disease
  • Parkinson disease
  • Huntington disease
  • amyotrophic lateral sclerosis
  • multiple sclerosis
  • HIV-1-associated dementia
  • chronic traumatic encephalopathy

Comparative biology

• p16INK4a expressing (dubbed senescent) endothelial cells associated with compromised blood brain barrier in mice

More general terms

• vascular endothelium

Additional terms

• circumventricular organ

Component of

• brain