Figure 8.

CB₁ is highly expressed in axons and terminals of medium spiny neurons and parvalbumin interneurons. Throughout this figure, CB₁ is pseudocolored in red. A, Single immunofluorescence for CB₁. Inset, Arrows and arrowheads indicate intense (putative inhibitory afferents) and weak (putative excitatory afferents) CB₁ immunolabeling, respectively. B1–H2, Semithin cryosections subjected to double immunofluorescence for CB₁ and terminal markers (green; B1,B2, vesicular GABA transporter VGAT; C1,C2, vesicular acetylcholine transporter VAChT; D1,D2, type 1 vesicular glutamate transporter VGluT1; E1,E2, type 2 vesicular glutamate transporter VGluT2; F1,F2, plasmalemmal dopamine transporter DAT; G1,G2, plasmalemmal serotonin transporter HTT; H1,H2, plasmalemmal norepinephrine transporter NET). Arrowheads and arrows indicate terminals judged to be positive and negative for CB₁, respectively. I1–J2, Double immunofluorescence for CB₁ and SP (green; I1, I2) or enkephalin (Enk) (green; J1, J2). Note low CB₁ contents in neuropeptide-carrying perikarya (arrows) and high CB₁ contents in neuropeptide-carrying axons (arrowheads). K1, K2, Triple immunofluorescence for CB₁, PV (green), and VGAT (blue). Note low CB₁ contents in PV-carrying perikarya (arrows) and high CB₁ contents in PV/VGAT-carrying terminals (arrowheads), the latter surrounding a putative MS neuron (asterisk) in a basket-like manner. Scale bars: A, I2, J2, K2, 10 μm; A′, B2, C2, D2, E2, F2, G2, H2, 2 μm.