Control mechanism of midbrain dopaminergic neurons by the limbic system.

用顺行追踪结合免疫组织化学方法观察了杏仁核内酪氨酸羟化酶（TH）免疫反应阳性神经元与杏仁核内TH免疫反应阳性神经元之间的突触结构，发现生物素标记的右旋糖酐（BDA）注入杏仁中央核后，在红后区（RRF）有大量的BDA标记纤维和轴突终末分布。在黑质腹侧被盖区（VTA）有少量标记纤维，但在黑质腹侧被盖区（SNc）的外侧部也有标记纤维。TH样免疫反应（THir）神经元分布于RRA、SNc和VTA。这些标记的轴突和神经元在RRF中有很好的重叠分布。在RRF内，BDA标记的轴突与TH阳性神经元的树突和胞体形成对称性的突触接触，BDA注射到边缘下皮层后，在腹侧被盖区和黑质近中端分布有大量的BDA标记纤维和轴突终末，TH阳性神经元包埋在BDA标记的轴突丛中。在VTA内，BDA标记的轴突与TH阳性神经元的树突形成不对称的突触接触，提示RRF和VTA内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.