Carr D B, Sesack S R
Departments of Neuroscience and Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
J Comp Neurol. 2000 Sep 18;425(2):275-83. doi: 10.1002/1096-9861(20000918)425:2<275::aid-cne9>3.0.co;2-z.
Dopamine (DA) afferents to the prefrontal cortex (PFC) play an important role in the cognitive functions subserved by this cortical area. Within the PFC, DA terminals synapse onto the distal dendrites of both local circuit neurons and pyramidal projection cells. We have previously demonstrated in the rat PFC that some of the dendrites and spines postsynaptic to DA terminals arise from pyramidal neurons that project to the nucleus accumbens. However, it is not known whether the pyramidal cells that give rise to callosal intercortical connections of the PFC also receive DA synaptic input. To address this question, retrograde tract tracing using an attenuated strain of pseudorabies virus (PRV-Bartha) was combined with immunocytochemistry for tyrosine hydroxylase (TH) to identify DA terminals in the PFC. Thirty-six to 40 hours following injection of PRV into the contralateral PFC, numerous callosal projection neurons were extensively labeled throughout their dendritic trees, with no evidence of PRV trans-synaptic passage. In tissue prepared for electron microscopy, labeling for PRV was distributed throughout pyramidal cell somata and extended into distal dendrites and dendritic spines. Some PRV-labeled dendrites and spines received symmetric synaptic input from terminals containing peroxidase labeling for TH. These results demonstrate that DA terminals synapse onto the distal dendrites of callosally projecting PFC neurons and suggest substrates through which DA may modulate interhemispheric cortical communication.
多巴胺（DA）传入前额叶皮质（PFC）在该皮质区域所支持的认知功能中发挥着重要作用。在PFC内，DA终末与局部回路神经元和锥体投射细胞的远端树突形成突触。我们之前在大鼠PFC中已证明，DA终末的一些突触后树突和棘来自投射到伏隔核的锥体神经元。然而，产生PFC胼胝体皮质间连接的锥体细胞是否也接受DA突触输入尚不清楚。为了解决这个问题，将使用减毒伪狂犬病病毒（PRV-Bartha）株进行的逆行束路追踪与酪氨酸羟化酶（TH）免疫细胞化学相结合，以识别PFC中的DA终末。将PRV注射到对侧PFC后36至40小时，大量胼胝体投射神经元在其整个树突树上被广泛标记，没有PRV跨突触传递的证据。在用于电子显微镜检查的组织中，PRV标记分布在锥体细胞的胞体中，并延伸到远端树突和树突棘。一些PRV标记的树突和棘接受了来自含有TH过氧化物酶标记的终末的对称性突触输入。这些结果表明，DA终末与胼胝体投射的PFC神经元的远端树突形成突触，并提示了DA可能调节半球间皮质通讯的底物。
