title: Methamphetamine-induced dopaminergic hyperactivity is not accompanied with increase in tyrosine hydroxylase mRNA of the rat midbrain.
abstract: Tyrosine hydroxylase (TH) mRNA was measured in the midbrain of rats treated repeatedly with methamphetamine (MAP). Male Sprague-Dawley rats were daily injected with MAP (5 mg/kg, i.p., once daily) or saline for 14 days. Progressive augmentation was observed in MAP-induced stereotyped behaviors. After one week of abstinence, the rats were decapitated and the brains were prepared for either in situ hybridization using non-radioactive cRNA probes or Northern blot analysis using 32P-labeled cDNA probes. In situ hybridization showed that the signals of TH mRNA were localized to the dopaminergic perikarya in the midbrain and were reduced in MAP-treated animals compared to the controls. Northern blot analysis revealed that the level of TH mRNA in the midbrain of MAP-treated rats was decreased by 37% compared to the controls, which was close to the statistical significance (P = 0.053). These results indicate that the dopaminergic hyperactivity caused by repeated MAP treatment is not associated with enhanced transcription of the TH gene.
authors.affiliation: Department of Molecular Medical Science, Tokyo Medical and Dental University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ishimaru
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: K
authors.initials: K
authors.lastname: Obata
authors.forename: F
authors.initials: F
authors.lastname: Fukamauchi
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D004298:Dopamine / Q000502:physiology*; D017403:In Situ Hybridization; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000201:enzymology*; D008694:Methamphetamine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013239:Stereotyped Behavior / Q000187:drug effects; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
chemical_list: D012333:RNA, Messenger; D008694:Methamphetamine; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine