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The blood–brain barrier is formed by the brain capillary endothelium and excludes from the brain 100% of large-molecule neurotherapeutics and more than 98% of all small-molecule drugs. [28] Overcoming the difficulty of delivering therapeutic agents to specific regions of the brain presents a major challenge to treatment of most brain disorders.
The blood–brain barrier is formed by special tight junctions between endothelial cells lining brain blood vessels. Blood vessels of all tissues contain this monolayer of endothelial cells, however only brain endothelial cells have tight junctions preventing passive diffusion of most substances into the brain tissue. [1]
Coating these polymeric nanoparticle devices with different surfactants can also aid BBB crossing and uptake in the brain. Surfactants such as polysorbate 80, 20, 40, 60, and poloxamer 188, demonstrated positive drug delivery through the blood–brain barrier, whereas other surfactants did not yield the same results. [2]
L-DOPA, a precursor of dopamine that crosses the blood–brain barrier, is used in the treatment of Parkinson's disease. For depressed patients where low activity of the neurotransmitter norepinephrine is implicated, there is only little evidence for benefit of neurotransmitter precursor administration.
The blood–cerebrospinal fluid barrier (BCSFB) is a fluid–brain barrier that is composed of a pair of membranes that separate blood from CSF at the capillary level and CSF from brain tissue. [14] The blood–CSF boundary at the choroid plexus is a membrane composed of epithelial cells and tight junctions that link them. [14] There is a CSF ...
Long-chain fatty acids cannot cross the blood–brain barrier, but the liver can break these down to produce ketone bodies. However, short-chain fatty acids (e.g., butyric acid, propionic acid, and acetic acid) and the medium-chain fatty acids, octanoic acid and heptanoic acid, can cross the blood–brain barrier and be metabolised by brain cells.
The VOLT is one of the three sensory circumventricular organs providing information to other brain regions. [6] [10] VOLT capillaries do not have a blood–brain barrier, and so neurons in this region can respond to circulating factors present in the systemic circulation. [11] [9]
These form the ventricular system of the brain: [8] The neural stem cells of the developing brain, principally radial glial cells, line the developing ventricular system in a transient zone called the ventricular zone. [9] The prosencephalon divides into the telencephalon, which forms the cortex of the developed brain, and the diencephalon.