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K. Ikemoto, K. Kitahama, A. Jouvet, A. Nishimura, K. Nishi, T. Maeda and R. Arai, “A Dopamine-Synthesizing Cell Group Demonstrated in the Human Basal Forebrain by Dual Labeling Immunohistochemical Technique of Tyrosine Hydroxylase and Aromatic L-Amino Acid Decarboxylase,” Neuroscience Letters, Vol. 243, No. 1-3, 1998, pp. 129-132. doi:10.1016/S0304-3940(98)00103-7

has been cited by the following article:

• TITLE: D-Cell Hypothesis: Pathogenesis of Mesolimbic Dopamine Hyperactivity of Schizophrenia

  AUTHORS: Keiko Ikemoto

  KEYWORDS: Dopamine; D-Neuron; Ventral Tegmental Area; Schizophrenia; TAAR1

  JOURNAL NAME: Journal of Behavioral and Brain Science, Vol.2 No.3, August 31, 2012

  ABSTRACT: In the present article, the author proposes a new “D-cell hypothesis” for mesolimbic dopamine (DA) hyperactivity of schizophrenia, of which relevant molecular mechanism has not yet been known. The “D-cell” is defined as “the non-monoaminergic aromatic L-amino acid decarboxylase (AADC)-containing cell”. The D-cell contains AADC but not dopaminergic nor serotonergic. D-cells produce trace amines, and also take up amine precursors and convert them to amines by decarboxylation. The author reported “dopa-decarboxylating neurons specific to the human striatum”, that is, “D-neurons” in the human striatum, and preliminarily the number reduction of D-neurons in the striatum and nucleus accumbens of postmortem brains of patients with schizophrenia. Trace amine-associated receptor, type 1 (TAAR1), a subtype of trace amine receptors, having a large number of ligands, including tyramine, β-phenylethylamine (PEA), and methamphetamine, is a target receptor for the latest neuroleptic discovery. Recent studies have shown that the decreased stimulation of TAAR1 on cell membranes or nerve terminals of DA neurons in the midbrain ventral tegmental area (VTA) increased firing frequency of VTA DA neurons. In brains of schizophrenia, dysfunction of neural stem cells in the subventricular zone of lateral ventricle may cause reduction of the number of D-neurons in the striatum and nucleus accumbens, and may result in decrease of trace amine synthesis. The decrease of stimulation of TAAR1 on terminals of VTA DA neurons caused by trace amine reduction may increase firing frequency of VTA DA neurons, and may finally cause mesolimbic DA hyperactivity. This innovative theory, “D-cell hypothesis” might explain mesolimbic DA hyperactivity in pathogenesis of schizophrenia.