Is DOPA a neurotransmitter?
Historically, 3,4-dihydroxyphenylalanine (DOPA) has been considered 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 in baroreflex neurotransmission.
Misu
Yoshimi
Y
Yokohama City University, Shinobu Hospital, 31-1 Takahata, Ohmori, Fukushima 960-1101, Japan. ymisu@zd5.so-net.ne.jp
Goshima
Yoshio
Y
Miyamae
Takeaki
T
D000818:Animals; D017704:Baroreflex / Q000502:physiology; D004295:Dihydroxyphenylalanine / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D004298:Dopamine / Q000096:biosynthesis; D009474:Neurons / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D017552:Solitary Nucleus / Q000166:cytology / Q000378:metabolism
D018377:Neurotransmitter Agents; D004295:Dihydroxyphenylalanine; D004298:Dopamine