title: L-3,4-Dihydroxyphenylalanine as a neurotransmitter candidate in the central nervous system.
abstract: Historically, 3,4-dihydroxyphenylalanine (DOPA) has been believed to be an inert amino acid that alleviates the symptoms of Parkinson's disease by its conversion to dopamine via the enzyme aromatic L-amino acid decarboxylase. In contrast to this generally accepted idea, we propose that DOPA itself is a neurotransmitter and/or neuromodulator, in addition to being a precursor of dopamine. Several criteria, such as synthesis, metabolism, active transport, existence, physiological release, competitive antagonism, and physiological or pharmacological responses, must be satisfied before a compound is accepted as a neurotransmitter. Recent evidence suggests that DOPA fulfills these criteria in its involvement mainly in baroreflex neurotransmission in the lower brainstem and in delayed neuronal death by transient ischemia in the striatum and the hippocampal CA1 region of rats.
authors.affiliation: Department of Pharmacology, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. ymisu@zd5.so-net.ne.jp
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Misu
authors.forename: Kunio
authors.initials: K
authors.lastname: Kitahama
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Goshima
mesh_terms: D002490:Central Nervous System / Q000378:metabolism / Q000502:physiology; D004295:Dihydroxyphenylalanine / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D006801:Humans; D018377:Neurotransmitter Agents / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology
chemical_list: D018377:Neurotransmitter Agents; D004295:Dihydroxyphenylalanine