From the Guidelines
The primary function of the Blood-Brain Barrier (BBB) is to protect the brain by preventing the influx of harmful solutes, comprising astrocytes, pericytes, and endothelial cells that form a selective diffusion barrier with transmembrane efflux pumps. This barrier is crucial for maintaining the brain's stable environment necessary for proper neural function. The BBB's structure and function allow it to control what substances can enter the brain from the bloodstream, enabling essential nutrients like oxygen, glucose, and certain amino acids to enter the brain while blocking potentially harmful substances, toxins, pathogens, and many medications 1.
The BBB's components, including tight junctions between endothelial cells, astrocytes, pericytes, and basement membrane, work together to form the neurovascular unit, which is essential for the barrier's function. However, certain conditions like inflammation, stroke, or traumatic brain injury can temporarily disrupt the BBB, potentially allowing harmful substances to enter the brain. Additionally, systemic administration of chemotherapeutic agents can induce oxidative stress, damaging BBB structures and increasing permeability, which can lead to neurotoxicity and cognitive impairment 1.
Key aspects of the BBB's function include:
- Preventing the entry of harmful substances into the brain
- Allowing essential nutrients to enter the brain
- Forming a selective diffusion barrier with transmembrane efflux pumps
- Comprising astrocytes, pericytes, and endothelial cells
- Being susceptible to disruption by certain conditions or chemotherapeutic agents, which can lead to increased permeability and potential neurotoxicity 1.
Overall, the BBB plays a critical role in maintaining the brain's health and function, and its disruption can have significant consequences, including cognitive impairment and neurotoxicity.
From the Research
Function of the Blood-Brain Barrier (BBB)
The Blood-Brain Barrier (BBB) is a semipermeable and extremely selective system that separates blood from the brain's extracellular fluid, playing a vital role in regulating the transport of necessary materials for brain function and protecting it from foreign substances in the blood that could damage it 2. The main functions of the BBB can be summarized as follows:
- Regulating the transport of necessary materials for brain function 2, 3
- Protecting the brain from foreign substances in the blood that could damage it 2, 3, 4
- Maintaining the homeostatic microenvironment of the brain 5
- Controlling the influx and efflux transport of nutrients and toxic materials 3, 4, 5
Structural Components and Regulation
The BBB is composed of brain microvascular endothelial cells, astrocytes, pericytes, neurons, and basement membrane, which work together to ensure proper function of the central nervous system (CNS) 4. The structural components of the BBB, such as tight junction proteins, adherens junctions, and junctional proteins, control the barrier permeability 3, 5. The regulation of the BBB is complex and involves various factors, including chemical mediators, non-physicochemical factors, and inflammation 5.
Importance of the BBB in Health and Disease
The BBB plays a critical role in maintaining the health of the CNS, and its dysfunction is implicated in various neurological diseases, such as Alzheimer's disease, ischemia, tumors, multiple sclerosis, and Parkinson's disease 4. Understanding the structure, function, and regulation of the BBB is essential for the development of therapeutics to improve the BBB function in health and disease 2, 3, 6, 4, 5.