title: Circadian variation in R-THBP-induced enhancement of the ambulation-increasing effect of methamphetamine on mice.
abstract: 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP), a co-factor for tyrosine hydroxylase and tryptophan hydroxylase, induces the enhancement of ambulation-increasing effect of methamphetamine on mice. In this study, we investigated the circadian variation in the interaction between R-THBP and methamphetamine by changing the time-of-day of both methamphetamine administration and pretreatment with R-THBP. The mouse's ambulatory activity was measured by a tilting-type activity cage for 4 hr. In the daytime, but not in the nighttime, the ambulation-increasing effect of methamphetamine (1 and 2 mg/kg, s.c.) was significantly enhanced by the pretreatment with R-THBP (100 mg/kg, s.c., 2 or 6 hr before). These data indicate the possibility that peripherally administered R-THBP increases the biosynthesis of catecholamine especially in the daytime.
authors.affiliation: Department of Neuropsychiatry, Gunma University School of Medicine, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Ida
authors.forename: T
authors.initials: T
authors.lastname: Asami
authors.forename: H
authors.initials: H
authors.lastname: Kuribara
authors.forename: Y
authors.initials: Y
authors.lastname: Uchihashi
authors.forename: T
authors.initials: T
authors.lastname: Higuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Machiyama
authors.forename: S
authors.initials: S
authors.lastname: Tadokoro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology*; D004347:Drug Interactions; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D013997:Time Factors
chemical_list: D001708:Biopterins; D008694:Methamphetamine; C003402:sapropterin