Título del libro: The Blood-Brain Barrier: New Research
Título del capítulo: Local and temporal regulation of the blood-brain barrier during normal and altered physiological states
Autores externos:
Idioma:
Inglés
Año de publicación:
2012
Resumen:
The blood-brain barrier (BBB) is a highly regulated system that maintains brain allostasis. BBB achieves its main function by transporting from blood to brain glucose, amino acids and other molecules needed for proper neural physiology, while extruding from the brain molecules derived from neural and glial metabolism that may have neurotoxic properties. BBB function is tightly regulated by local synaptic and glial activity; both nerve and glial cells release molecules that modify hemodynamic and permeability parameters at the BBB. Under normal physiological conditions, products released by neural activity, such as some neurotransmitter/neuromodulator molecules and byproducts of neural metabolism, exert vasodilator effects and induce changes in BBB permeability. Active neurons have been shown to release several molecules that quickly increase cerebral blood flow locally, with a concomitant rise in BBB permeability to glucose and other solutes. In order to achieve prolonged activity-related effects on cerebral blood-flow and vessel permeability astrocytes are needed. Astrocyte calcium waves induce the release of vasoactive molecules that exert long-term hemodynamic and permeability changes in local vessels. Under altered physiological conditions, BBB function is also modified in a brain region specific manner. The mediators of the changes are almost the same as those of the normal physiological state, but their effects are intensenly and prolonged. Stress, a state of disrupted allostasis, has been shown to increase BBB permeability to blood-borne potentially neurotoxic molecules through increased vesicle-mediated transport at adulthood and during early-life; the effects are observed in some cortical regions, the brain stem, cerebellum, hippocampus, basal ganglia, and cervical spinal cord. Both adult and early-life stress exerted its effects upon BBB through increased release of serotonin, corticotrophin-releasing hormone, and pro-inflammatory cytokines. Sleep restriction is another altered physiological state that is accompanied by increased BBB permeability to blood-borne potentially toxic molecules. In a rat model, sleep restriction to 4-hours per day increased BBB permeability to an albumin-bound dye in almost the whole brain; the mechanism of the increased vessel permeability may be sleep deprivation-related hyperthermia, increased pro-inflammatory cytokine production and maybe some byproduct of altered neural and glial function after chronic sleep restriction. In conclusion, BBB function is tightly regulated inclusive during altered physiological states, some brain regions are affected during stress exposure or sleep restriction but others are spared and have normal brain vessel permeability. More research is needed to clarify regional differences in BBB properties and to elucidate the temporal organization of the involved molecules. © 2012 by Nova Science Publishers, Inc. All rights reserved.
Entidades citadas de la UNAM:
ISBN:
9781621007661
Editorial:
Nova Science Publishers, Inc. Nombre de la publicación:
Local and temporal regulation of the blood-brain barrier during normal and altered physiological states
Página inicial:
1
Página final:
42
Tipo de producto:
Capítulo de un Libro
