Blood–brain barrier (BBB)

The blood–brain barrier (BBB) is a highly selective semipermeable border formed by endothelial cells lining the capillaries in the central nervous system. It regulates the movement of ions, molecules, and cells between the bloodstream and brain tissue to protect neural function. The BBB restricts most pathogens, large or hydrophilic molecules, immune factors, antibodies, and many drugs from entering the brain while allowing passive diffusion of small non-polar substances (such as oxygen or carbon dioxide) as well as active transport for essential nutrients like glucose[1][3][5]. Dysfunction or disruption of this barrier is implicated in various neurological diseases including multiple sclerosis, stroke, epilepsy, Alzheimer’s disease, infections such as meningitis or encephalitis, inflammation-related conditions, and other acute or chronic illnesses[3][5]. The BBB itself is not a single molecule but rather a complex physiological structure; thus it is not considered a therapeutic target in the conventional sense (e.g., receptor/enzyme/transporter), but its permeability can be modulated to enhance drug delivery to the CNS[6]. Note: "Blood-brain barrier permeability" refers to a property/phenomenon rather than an individual molecular target. Therefore, - is_target should be set to false. - is_incorrect should be set to true because this entry does not correspond to a specific molecule/receptor/protein that can serve directly as a drug target; instead it describes an emergent property resulting from cellular structures such as endothelial tight junction proteins (e.g., claudins), efflux transporters (e.g., P-glycoprotein), etc.[1][7]. - For structured data extraction purposes on molecular targets/receptors/enzymes/etc., use entries for specific components that regulate BBB permeability rather than "blood-brain barrier permeability" itself.

Other names

blood-brain barrierBBBblood brain barrier (no hyphens)