Blood-brain Barrier Permeability

Research Areas | Products | Background | Related Information

The blood-brain barrier (BBB) is a network of specialized endothelial cells which form a physical barrier between the central nervous system (CNS) and systemic circulation. Key functions of the BBB include:

Restricting entry of pathogens, large molecules, and hydrophilic substances into the brain
Protecting the brain from rapid ionic and metabolic fluctuations
Maintaining CNS integrity and function
Supplying essential nutrients through selective transporters
Facilitating waste removal

Explore Our Interactive Blood-Brain Barrier Overview

Blood-brain Barrier Research Areas

Adhesion Molecules	Cytoskeletal Filaments and Associated Proteins	Extracellular Matrix and Related Molecules	Nitrosylating Molecules
Cytokines and Receptors	Endothelial Cell Differentiation Markers	Nitric Oxide Signaling

Products for Blood-brain Barrier Research

Cell Adhesion Molecules

Protease-activated Receptors

Multidrug Transporters

RAGE (AGER)

RAGE Antagonists

Background

Blood-brain Barrier Anatomy and Physiology

Vessels of the BBB are composed of tight junctions between specialized endothelial cells, as well as pericytes, astrocyte end feet, microglia, and a basement membrane made from extracellular matrix proteins. Aquaporins enable the transport of water across the BBB.

Molecules entering the brain must be lipid soluble, less than 400 Daltons, and not substrates of active efflux transporters (AET). Molecules that do not meet these requirements only pass the BBB if they are transported by carrier-mediated transporters (CMT) or through receptor-mediated transport (RMT). Waste products and small molecules that are too large or too hydrophilic to permeate the BBB exit the brain as substrates of AET.

Blood-brain Barrier and Disease

Conditions such as inflammation, infection, traumatic brain injury, or ischemic stroke can compromise BBB integrity, making it more permeable for large and hydrophilic molecules. Breakdown of the BBB is associated with the progression of neurological diseases like Alzheimer’s disease (AD) and Parkinson’s disease (PD).

The limited permeability of the BBB also complicates treatment of brain infections and cancers. While it prevents bacterial entry, it also blocks the entry of antibodies and antibiotics. Additionally, drugs like chemotherapeutics are expelled from brain cells via multidrug transporters.