Rajakumar N, Elisevich K, Flumerfelt B A
Department of Anatomy, University of Western Ontario, London, Canada.
J Comp Neurol. 1994 Dec 8;350(2):324-36. doi: 10.1002/cne.903500214.
The output of the basal ganglia is directed through the entopeduncular nucleus (EPN) and the substantia nigra pars reticulata (SNR) and pars lateralis (SNL), which provide a gamma-aminobutyric acidergic (GABAergic) projection to various nuclei of the thalamus and brainstem. Although many neurons within the SNR and EPN have been described as modality specific, the morphological and neurochemical similarities preclude their precise identification. In the present study, the immunocytochemical localization of parvalbumin, a calcium-binding protein, is used in combination with axonal tracing to verify neuronal heterogeneity within the SNR, SNL, and EPN. The results reveal that the majority of neurons in all three centers contain parvalbumin. The parvalbumin-containing neurons are distributed in the caudal two-thirds of the EPN, the rostral part of the SNL, and the lateral two-thirds of the entire rostrocaudal extent of the SNR, the areas involved in sensorimotor function of the basal ganglia. Moreover, the nigrothalamic, nigrocollicular, and EPN-thalamic neurons possess parvalbumin immunoreactivity, whereas the EPN-habenular neurons are devoid of parvalbumin immunoreactivity. The results indicate a neurochemical heterogeneity within the GABAergic output neurons of the basal ganglia and suggest that the parvalbumin-containing neurons of the SNR, SNL, and EPN are the tonically active output neurons that form a major link in the disinhibitory neuronal circuit of the basal ganglia, especially that concerned with sensorimotor function.
基底神经节的输出通过内苍白球核（EPN）、黑质网状部（SNR）和黑质外侧部（SNL）进行，它们向丘脑和脑干的各个核团发出γ-氨基丁酸能（GABA能）投射。尽管SNR和EPN内的许多神经元已被描述为具有模态特异性，但形态学和神经化学上的相似性妨碍了对它们的精确识别。在本研究中，结合轴突追踪使用钙结合蛋白小白蛋白的免疫细胞化学定位，以验证SNR、SNL和EPN内神经元的异质性。结果显示，所有三个中枢的大多数神经元都含有小白蛋白。含小白蛋白的神经元分布在EPN尾侧的三分之二、SNL的头侧部分以及SNR整个头尾长度的外侧三分之二，这些区域参与基底神经节的感觉运动功能。此外，黑质丘脑、黑质上丘和EPN-丘脑神经元具有小白蛋白免疫反应性，而EPN-缰核神经元则缺乏小白蛋白免疫反应性。这些结果表明基底神经节GABA能输出神经元存在神经化学异质性，并提示SNR、SNL和EPN中含小白蛋白的神经元是紧张性活动的输出神经元，它们在基底神经节的去抑制性神经回路中，尤其是与感觉运动功能相关的回路中，构成了主要连接。
