Bolam J P, Somogyi P, Takagi H, Fodor I, Smith A D
J Neurocytol. 1983 Apr;12(2):325-44. doi: 10.1007/BF01148468.
An antiserum, to substance P has been used to study the neostriatum of rats which has received intracerebral injections of colchicine. Both cell bodies and nerve fibres were found to display immunoreactivity. Some of the fibres were swollen and could be traced back to their parent cell body. Examination in the electron microscope of structures that had first been identified in the light microscope showed that there are two different types of substance P-immunoreactive cell body. The first kind (type I) of immunoreactive cell body was of medium size and had a smooth surfaced nucleus. It displayed the ultrastructural features typical of medium-size spiny neurons. Identified axons of type I neurons gave rise to immunoreactive axon collaterals within the neostriatum: boutons along these collaterals were found to form symmetrical synaptic contacts. The second kind (type II) of immunoreactive cell body was also of medium-size and had a round or oval shape, but the nucleus was deeply indented and was surrounded by a thin rim of cytoplasm. Synaptic input to this neuron was sparse and consisted of small boutons that made symmetrical contacts with the perikaryon and proximal dendrites. Many immunoreactive dot-like structures could be seen in the light microscope: upon examination in the electron microscope these were found to be boutons. All fifty-six synaptic boutons that were studied made symmetrical synaptic contacts. These boutons were indistinguishable from the boutons of axon collaterals of identified type I immunoreactive neurons. The most common postsynaptic structures were dendrites, including some dendritic spines, although synapses between immunoreactive boutons and several perikarya, and an axon initial segment were observed. The morphological features of the immunoreactive boutons in the neostriatum were very similar to one type of substance P-immunoreactive bouton in the substantia nigra and to a bouton type in the substantia nigra which is labelled following the anterograde transport of horseradish peroxidase from the striatum. It is suggested that there are two kinds of substance P-containing neurons in the striatum and that one of these is likely to belong to the medium-spiny class. The latter type of neuron is probably the source of the striatonigral substance P-containing projection and of the immunoreactive boutons within the striatum. The finding of substance P-immunoreactive synaptic boutons within the neostriatum provides a morphological basis for the view that substance P might serve as a neurotransmitter in the neostriatum.
一种抗P物质血清已被用于研究接受脑室内注射秋水仙碱的大鼠新纹状体。发现细胞体和神经纤维均显示免疫反应性。一些纤维肿胀，可以追溯到它们的母细胞体。对最初在光学显微镜下鉴定的结构进行电子显微镜检查发现，有两种不同类型的P物质免疫反应性细胞体。第一种（I型）免疫反应性细胞体中等大小，核表面光滑。它表现出中等大小棘状神经元的典型超微结构特征。已鉴定的I型神经元轴突在新纹状体内产生免疫反应性轴突侧支：沿这些侧支的终扣被发现形成对称的突触联系。第二种（II型）免疫反应性细胞体也中等大小，呈圆形或椭圆形，但核深深凹陷，被一薄层细胞质包围。该神经元的突触输入稀少，由与胞体和近端树突形成对称联系的小终扣组成。在光学显微镜下可见许多免疫反应性点状结构：在电子显微镜下检查发现这些是终扣。所研究的所有56个突触终扣都形成对称的突触联系。这些终扣与已鉴定的I型免疫反应性神经元的轴突侧支终扣无法区分。最常见的突触后结构是树突，包括一些树突棘，尽管也观察到免疫反应性终扣与几个胞体之间以及与一个轴突起始段之间的突触。新纹状体内免疫反应性终扣的形态特征与黑质中一种P物质免疫反应性终扣以及在将辣根过氧化物酶从纹状体进行顺行运输后标记的黑质中的一种终扣类型非常相似。有人提出，纹状体中有两种含P物质的神经元，其中一种可能属于中等棘状神经元类。后一种类型的神经元可能是含P物质的纹状体黑质投射以及纹状体内免疫反应性终扣的来源。在新纹状体内发现含P物质的免疫反应性突触终扣为P物质可能作为新纹状体内神经递质的观点提供了形态学基础。
