Control mechanism of midbrain dopaminergic neurons by the limbic system.

我们采用顺行示踪结合免疫组织化学方法检测了中脑杏仁核纤维与酪氨酸羟化酶（TH）免疫反应（TH-ir）神经元之间的突触组织，TH催化了儿茶酚胺合成的限速步骤。生物素化右旋胺（BDA）注入中央杏仁核后，许多BDA标记的纤维和轴突终末分布在脑后野（RRF）。在黑质致密部（SNc）外侧也发现了一些标记纤维，而腹侧被盖区（VTA）只有少量标记纤维。thr样免疫反应神经元分布于RRA、SNc和VTA。在RRF中发现这些标记的轴突和神经元具有良好的重叠分布。在RRF内，bda标记的轴突与TH-ir神经元的树突和体细胞形成对称的突触接触。BDA注射到边缘下皮层（ILC）后，许多BDA标记的纤维和轴突终末分布在VTA和SNc的中间部分。TH-ir神经元嵌入bda标记轴突的神经丛中。在VTA内，bda标记的轴突与TH-ir神经元的树突形成不对称的突触接触。这些数据表明，RRF和VTA中的多巴胺能神经元分别接受来自ACe的抑制性输入和来自ILC的兴奋性输入。

We examined the synaptic organization between the amygdaloid fibers and the tyrosine hydroxylase(TH)-immunoreactive(TH-ir) neurons in the midbrain by using anterograde tracing combined with immunohistochemistry for TH, which catalyzes the rate-limiting step in the synthesis of catecholamines.After biotinylated dextranamine(BDA) injection into the central amygdaloid nucleus, many BDA-labeled fibers and axon terminals were distributed in the retrorubral field(RRF). Some labeled fibers were also found in the lateral part of the substantia nigra pars compacta(SNc) although there were only a few labeled fibers in the ventral tegmental area(VTA). TH-like immunoreactive(THir) neurons were distributed in the RRA,SNc and VTA. The good overlapping distribution of these labeled axons and neurons was found in the RRF. Within the RRF,BDA-labeled axons made symmetrical synaptic contacts with the dendrites and somata of TH-ir neurons.After BDA injection into the infralimbic cortex(ILC, many BDA-labeled fibers and axon terminals were distributed in the VTA and medialmost part of the SNc., where TH-ir neurons were embedded in the plexus of BDA-labeled axons. Within the VTA,BDA-labeled axons made asymmetrical synaptic contacts with the dendrites of TH-ir neurons.The data suggest that dopaminergic neurons in the RRF and VTA receive inhibitory inputs from the ACe and excitatory inputs from the ILC, respectively.