Blood-Brain Barrier: The Ultimate Defence Being Breached
The blood-brain barrier (BBB) is a highly selective semi-permeable vascular boundary formed by specialised brain endothelial cells connected by exceptionally tight junctions, supported by pericytes and astrocytic end-feet — collectively creating a structural and biochemical barrier that rigorously regulates the passage of molecules from the systemic circulation into the central nervous system. This biological security system is the primary reason the brain can maintain the precise biochemical environment required for neural function, excluding pathogens, large molecules, and most hydrophilic compounds whilst facilitating the transport of glucose, amino acids, and lipid-soluble molecules via specific carrier proteins. The BBB is not inviolable: heavy metals including aluminium, mercury, and lead cross it via mimicry of essential metal transport; glyphosate increases BBB permeability by disrupting tight junction proteins; chronic systemic inflammation elevates BBB permeability through cytokine-mediated mechanisms; and radiofrequency electromagnetic fields activate voltage-gated calcium channels in endothelial cells — collectively creating conditions under which neurotoxic compounds that should be excluded from brain tissue gain access and accumulate.
