Significance of human striatal D-neurons: implications in neuropsychiatric functions.
The human striatum, especially its ventral part, the nucleus accumbens (Acc), contains numerous nonmonoaminergic aromatic L-amino acid decarboxylase (AADC) [=dopa decarboxylase (DDC)] neurons (D-neurons). AADC is the second-step synthesizing enzyme for monoamines and is also the rate-limiting enzyme of phenylethylamine (PEA) synthesis. D-neurons may participate in the manifestation of efficacy of pharmacotherapy for Parkinson's disease by taking up monoamine precursors including L-dopa or droxidopa (L-threo-DOPS) and by converting them to dopamine or noradrenaline, respectively. Although previous studies have shown that AADC activity was elevated in the striatum of drug-naive schizophrenia, the number of striatal D-neurons was reduced in autopsy brains of schizophrenia. It is unclear whether or not such reduction of striatal D-neurons implies downregulation. Possible pluripotentiality of D-neurons, including compensatory functions against aging and degeneration, was discussed based on recent published works.
Ikemoto
Keiko
K
Clinical Research Institute, National Minami Hanamaki Hospital, 500 Suwa, Hanamaki, Iwate, 025-0033, Japan. ikemoto@shanamaki.hosp.go.jp
D000818:Animals; D000978:Antiparkinson Agents / Q000627:therapeutic use; D004296:Dopa Decarboxylase / Q000502:physiology*; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008032:Limbic System / Q000502:physiology; D001523:Mental Disorders / Q000503:physiopathology*; D017072:Neostriatum / Q000166:cytology / Q000502:physiology* / Q000503:physiopathology; D009422:Nervous System Diseases / Q000188:drug therapy / Q000503:physiopathology*; D009474:Neurons / Q000201:enzymology / Q000502:physiology*
D000978:Antiparkinson Agents; D007980:Levodopa; D004296:Dopa Decarboxylase