Impaired permeability of the blood-cerebrospinal fluid barrier in hyperphenylalaninaemia.
In hyperphenylalaninaemic rats the accumulation of 5-hydroxytryptophan (5-HTP) in the cerebrospinal fluid (CSF) could be shown in spite of the fact, that the 5-HTP levels of serum and brain remain constant. In vitro studies of the influx and efflux of 5-HTP and phenylalanine on isolated beef choroid plexus suggested that both aminoacids use the same carrier system. It is concluded that a high concentration of phenylalanine inhibits the re-uptake of 5-HTP by the endothelial cells of the choroid plexus. Additionally, an increased efflux of 5-HTP from choroid plexus leads to the accumulation of 5-HTP in the cerebrospinal fluid.
D006916:5-Hydroxytryptophan / Q000134:cerebrospinal fluid / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D001812:Blood-Brain Barrier; D001923:Brain Chemistry; D002417:Cattle; D002831:Choroid Plexus / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D010539:Permeability; D010649:Phenylalanine / Q000097:blood; D010661:Phenylketonurias / Q000097:blood / Q000134:cerebrospinal fluid* / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000032:analysis; D014364:Tryptophan / Q000032:analysis
D012701:Serotonin; D010649:Phenylalanine; D014364:Tryptophan; D006916:5-Hydroxytryptophan