Yung K K, Smith A D, Levey A I, Bolam J P
MRC Anatomical Neuropharmacology Unit, Mansfield Road, Oxford OX1 3TH, UK.
Eur J Neurosci. 1996 May;8(5):861-9. doi: 10.1111/j.1460-9568.1996.tb01573.x.
The flow of cortical information through the basal ganglia occurs through the so-called 'direct pathway' and 'indirect pathways'. The object of the present work was to attempt to determine whether spiny neurons in the neostriatum that give rise to the direct pathway (i.e. the striatonigral/entopeduncular pathway) and those giving rise to the indirect pathways (i.e. striatopallidal pathway) are synaptically interconnected. The approach was to carry out double immunocytochemistry at the electron microscopic level using antibodies against peptides or dopamine receptor subtypes that are selectively associated with the neurons that give rise to the direct (substance P or D1 receptors) and indirect pathways (enkephalin or D2 receptors). Sections of perfuse-fixed rat neostriatum were immunostained to reveal both substance P immunoreactivity and D2 receptor immunoreactivity or enkephalin and D1 receptor immunoreactivity, respectively. Double peroxidase methods were employed using different chromogens that were distinguishable at both the light and electron microscopic levels. In the electron microscope substance P-immunoreactive terminals were seen in synaptic contact with dendritic structures that displayed immunoreactivity for D2 receptor. Similarly, enkephalin-immunoreactive terminals were seen in synaptic contact with D1-immunoreactive dendritic structures. Thus, axon collaterals of neurons giving rise to the direct pathway form synaptic contacts with neurons that give rise to the indirect pathway and axon collaterals of neurons giving rise to the indirect pathway form synaptic contact with neurons that give rise to the direct pathway. These results indicate that the two pathways of information flow through the basal ganglia are synaptically linked at the level of the neostriatum.
spiny neurons, direct pathway,indirect pathways, rat neostriatum
皮质信息通过基底神经节的流动经由所谓的“直接通路”和“间接通路”。本研究的目的是试图确定新纹状体中产生直接通路（即纹状体黑质/脚内核通路）的棘状神经元与产生间接通路（即纹状体苍白球通路）的棘状神经元之间是否存在突触连接。研究方法是在电子显微镜水平上进行双重免疫细胞化学，使用针对与产生直接通路（P物质或D1受体）和间接通路（脑啡肽或D2受体）的神经元选择性相关的肽或多巴胺受体亚型的抗体。对灌注固定的大鼠新纹状体切片进行免疫染色，分别显示P物质免疫反应性和D2受体免疫反应性或脑啡肽和D1受体免疫反应性。采用双重过氧化物酶方法，使用在光镜和电镜水平上均可区分的不同显色剂。在电子显微镜下，可见P物质免疫反应性终末与显示D2受体免疫反应性的树突结构形成突触联系。同样，可见脑啡肽免疫反应性终末与D1免疫反应性树突结构形成突触联系。因此，产生直接通路的神经元的轴突侧支与产生间接通路的神经元形成突触联系，而产生间接通路的神经元的轴突侧支与产生直接通路的神经元形成突触联系。这些结果表明，通过基底神经节的两条信息流途径在新纹状体水平上存在突触连接。
棘状神经元；直接通路；间接通路；大鼠新纹状体
