Number of striatal D-neurons is reduced in autopsy brains of schizophrenics.
The human striatum, especially its ventral part, the nucleus accumbens, contains numerous neurons immunoreactive for aromatic L-amino acid decarboxylase (AADC, the second-step monoamine synthesizing enzyme, =DDC: dopa decarboxylase), but not for tyrosine hydroxylase (TH, the first-step catecholamine synthesizing enzyme) or tryptophan hydroxylase (TPH, the first-step serotonin synthesizing enzyme) (Neurosci Lett 232 (1997) 111-114). These AADC (+)/TH (-)/TPH (-) neurons are named as D-neurons (Jaeger CB, Ruggiero DA, Albert VR, Joh TH, Reis DJ. Immunocytochemical localization of aromatic-L-amino acid decarboxylase. In: Bjorklund A, Hokfelt T, editors. Classical transmission in the CNS, Part I, Handbook of chemical neuroanatomy, vol. 2. Amsterdam: Elsevier, 1984. pp. 387-418). The nucleus accumbens is one of the brain regions that is involved in the pathogenesis of schizophrenia. We examined the distribution of striatal D-neurons using AADC immunohistochemistry and postmortem brains obtained by legal and pathological autopsies (nine controls (27-75 years old) and nine schizophrenics (32-78 years old), postmortem interval to fixation (PMI): 2-30 h). Because the number of AADC-positive neurons per section had a tendency to reduce in the case with longer PMI, we analyzed specimens of five controls (27-64 years old) and six schizophrenics (51-78 years old) in which the PMI was less than 8 h. The number of AADC-positive neurons was reduced in the striatum of schizophrenics compared to that of controls. The reduction was significant in the nucleus accumbens (P<0.05, t-test). D-Neurons might be involved in the pathogenesis of schizophrenia. Further studies using sex-, age- and PMI-matched controls are essential.
Ikemoto
Keiko
K
Clinical Research Institute, National Minami Hanamaki Hospital, Hanamaki, Iwate, 025-0033, Japan. ikemoto@shanamaki.hosp.go.jp
Nishimura
Akiyoshi
A
Oda
Tatsuro
T
Nagatsu
Ikuko
I
Nishi
Katsuji
K
D000328:Adult; D000368:Aged; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000032:analysis*; D001921:Brain / Q000201:enzymology* / Q000473:pathology*; D016022:Case-Control Studies; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009474:Neurons / Q000201:enzymology* / Q000473:pathology*; D012559:Schizophrenia / Q000473:pathology*
D001142:Aromatic-L-Amino-Acid Decarboxylases