title: Tetrahydrobiopterin precursor sepiapterin provides protection against neurotoxicity of 1-methyl-4-phenylpyridinium in nigral slice cultures.
abstract: Complex-I inhibition and oxidative processes have been implicated in the loss of nigral dopamine neurones in Parkinson's disease and the toxicity of MPTP and its metabolite MPP+. Tetrahydrobiopterin, an essential cofactor for tyrosine hydroxylase, may act as an antioxidant in dopaminergic neurones and protects against the toxic consequences of glutathione depletion. Here we studied the effects of manipulating tetrahydrobiopterin levels on MPP+ toxicity in organotypic, rat ventral mesencephalic slice cultures. In cultures exposed to 30 micro m MPP+ for 2 days, followed by 8 days 'recovery' in control medium, we measured dopamine and its metabolites in the tissue and culture medium by HPLC, lactate dehydrogenase release to the culture medium, cellular uptake of propidium iodide and counted the tyrosine hydroxylase-immunoreactive neurones. Inhibition of tetrahydrobiopterin synthesis by 2,4-diamino-6-hydroxypyrimidine had no significant synergistic effect on MPP+ toxicity. In contrast, the tetrahydrobiopterin precursor l-sepiapterin attenuated the MPP+-induced dopamine depletion and loss of tyrosine hydroxylase-positive cells in a dose-dependent manner with 40 micro m l-sepiapterin providing maximal protection. Accordingly, increasing intracellular tetrahydrobiopterin levels may protect against oxidative stress by complex-I inhibition.
authors.affiliation: Anatomy and Neurobiology, Institute of Medical Biology, University of Southern Denmark, Odense, Denmark.
authors.forename: Jakob Torp
authors.initials: JT
authors.lastname: Madsen
authors.forename: Pernille
authors.initials: P
authors.lastname: Jansen
authors.forename: Christian
authors.initials: C
authors.lastname: Hesslinger
authors.forename: Morten
authors.initials: M
authors.lastname: Meyer
authors.forename: Jens
authors.initials: J
authors.lastname: Zimmer
authors.forename: Jan Bert
authors.initials: JB
authors.lastname: Gramsbergen
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors* / Q000633:toxicity; D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism*; D002452:Cell Count; D002851:Chromatography, High Pressure Liquid; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D004298:Dopamine / Q000032:analysis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042967:Electron Transport Complex I; D007042:Hypoxanthines / Q000494:pharmacology; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology*; D009627:Nomifensine / Q000494:pharmacology; D011419:Propidium / Q000493:pharmacokinetics; D011621:Pteridines / Q000378:metabolism / Q000494:pharmacology*; D011622:Pterins; D051381:Rats; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis
chemical_list: D017077:Culture Media, Conditioned; D007042:Hypoxanthines; D018696:Neuroprotective Agents; D011621:Pteridines; D011622:Pterins; D009627:Nomifensine; D001708:Biopterins; D011419:Propidium; C016727:sepiapterin; D007770:L-Lactate Dehydrogenase; D014446:Tyrosine 3-Monooxygenase; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I; C017202:2,4-diaminohypoxanthine; C003402:sapropterin; D015655:1-Methyl-4-phenylpyridinium; D004298:Dopamine