Fig. 1.

Dopaminergic presynaptic phenotype at striatal dopamine synapses. (A and B) Immunofluorescence labeling for TH (A) and DAT (B) in the striatum. Cx, cortex; NA, nucleus accumbens; St, striatum. (C) Triple immunofluorescence for TH (red), DAT (green), and VMAT2 (blue) in ultrathin (100 nm) cryosections showing their extensive overlap (arrows). (D and E) Double-label postembedding immunoelectron microscopy for GABA [Ø (diameter) = 10-nm colloidal gold particles] and VIAAT (D, Ø = 15 nm) or TH (E, Ø = 15 nm). GABA (arrows) is concentrated on VIAAT⁺ GABAergic terminals forming symmetric synapses (NT-GABA, red terminal), but not detected in VIAAT⁻ glutamatergic terminals forming asymmetric synapses (NT-Glu, blue) or TH⁺ dopaminergic terminals (NT-DA, green) forming symmetric synapses. Arrowhead pairs indicate the synaptic membrane. Dn, dendrite; NT, nerve terminal; Sp, spine. (F) The density of immunogold labeling for GABA (particles per 1 μm²) in dopaminergic (DA), GABAergic (GABA), and glutamatergic (Glu) terminals. (G and I) Double-label postembedding immunogold microscopy for TH (Ø = 15 nm) and CAST (G, Ø = 10 nm) or Nrxn (I, Ø = 10 nm). Immunogold labeling (arrows) for CAST and Nrxn is observed beneath the presynaptic membrane of TH⁺ dopaminergic terminals. (H and J) The mean density of immunogold particles per 1 μm of synaptic membrane for CAST (H) and Nrxn (J) at dopaminergic, GABAergic, and glutamatergic synapses in wild-type (H and J, open columns) and CAST-KO (H, filled columns) mice. In F, H, and J, numbers of terminals analyzed are indicated above each column, and error bars on columns represent SEM. *P < 0.05 (unpaired t test). [Scale bars: 1 mm (A and B), 2 μm (C), and 100 nm (D, E, G, and I).]