title: Intracerebrally administered (6r)-l-erythro-tetrahydrobiopterin does not affect extracellular levels of dopamine and serotonin metabolites in rat striatum in vivo during measurement by brain micro-dialysis system.
abstract: By the use of the brain micro-dialysis technique combined with HPLC, the changes in the extracellular levels of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and a serotonin(5-HT) metabolite, 5-hydroxyindoleacetic acid (5-HIAA) were examined in the rat striatum before and after intracerebral injection of a vehicle or (6R)-l-erythro-tetrahydrobiopterin (6R-BH(4)), the natural form of the cofactor for the tryrosine hydroxylase and tryptophan hydroxylase. No apparent change after the 6R-BH, treatment was found in the levels of DA, DOPAC, HVA and 5-HIAA in the striatal dialysate. In contrast, the levels of total biopterin in both the operated (dialysis probe-implanted) and unoperated striatum of 6R-BH(4)-treated rats increased by 23- and 93-fold, respectively, when compared with those of the control, vehicle-treated rats. The results indicate that increased levels of the tetrahydrobiopterin cofactor may not affect the release of DA and the extracellular level of DA and 5-HT metabolites in the physiologically normal brain.
authors.affiliation: Nagoya University College of Medical Technology, Nagoya 461, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Nakahara
authors.forename: N
authors.initials: N
authors.lastname: Ozaki
authors.forename: N
authors.initials: N
authors.lastname: Kaneda
authors.forename: K
authors.initials: K
authors.lastname: Kiuchi
authors.forename: T
authors.initials: T
authors.lastname: Okada
authors.forename: T
authors.initials: T
authors.lastname: Ohta
authors.forename: T
authors.initials: T
authors.lastname: Nagatsu