Related Experiment Videos
Pathways into, through, and around the fluid-brain barriers.
1Department of Surgery, University of Maryland School of Medicine, Baltimore 21201.
NIDA Research Monograph
|January 1, 1992
Summary
Substances can enter the central nervous system (CNS) via multiple pathways. Research shows blood-brain barrier (BBB) endothelia actively transport substances, suggesting a significant brain-blood barrier function.
Area of Science:
- Neuroscience
- Cell Biology
- Physiology
Background:
- The blood-brain barrier (BBB) regulates substance entry into the central nervous system (CNS).
- Extracellular pathways and perivascular clefts complicate the study of substance transport across the BBB.
- Previous assumptions about limited endocytic activity in BBB endothelia are being challenged.
Purpose of the Study:
- To investigate the mechanisms of blood-borne substance transport across the BBB.
- To clarify the role of endocytosis and transcytosis in BBB function.
- To differentiate BBB transport from blood-cerebrospinal fluid (CSF) barrier transport.
Main Methods:
- Review of available biochemical and morphological data on BBB endothelia.
- Analysis of endocytic activity at the luminal and abluminal surfaces of BBB endothelia.
- Comparison of transport mechanisms at the BBB and the blood-CSF barrier.
Main Results:
- BBB endothelia exhibit significant endocytic activity, contradicting prior beliefs.
- Evidence supports transcytosis of proteins and peptides across cerebral endothelia.
- Asymmetrical endocytic activity suggests a unidirectional brain-blood barrier, not bidirectional BBB trafficking.
- Choroid plexus epithelia show bidirectional transcytosis, unlike the BBB.
Conclusions:
- The BBB actively transports substances via transcytosis, challenging previous notions.
- A functional brain-blood barrier, deterring bidirectional transfer, is significant.
- The choroid plexus facilitates bidirectional transport, distinct from the BBB's mechanisms.