Meguro R, Ohishi H, Hoshino K, Hicks T P, Norita M
Department of Neurobiology and Anatomy, Niigata University School of Medicine, Asahimachi, Japan.
J Comp Neurol. 1999 Jul 26;410(2):243-55. doi: 10.1002/(sici)1096-9861(19990726)410:2<243::aid-cne6>3.0.co;2-i.
In adult rat cerebellar cortex, the metabotropic glutamate receptors (mGluRs) 2 and 3 (mGluR2/3) are present in somata, dendrites, and terminals of Golgi cells as well as in presumed glial processes (Ohishi et al. [1994], Neuron 13:55-66). In the present study, spatiotemporal changes in immunostaining for mGluR2/3 were examined in postnatal rat cerebellar cortex. mGluR2/3-immunoreactive Golgi cell somata appeared first in the internal granular layer at postnatal day 3 (P3) and were restricted to lobules IX and X; however, by P5, they were present in all lobules. Immunoreactive Golgi cell axons were adult-like, appearing as tortuous fibers with clusters of varicosities. They were observed first in the internal granular layer at P7 and increased in number and complexity with time. It was confirmed that mGluR2/3-immunoreactive Golgi cell axon terminals belong to the synaptic glomerulus by P10. Immunoreactive Golgi cell dendrites extending into the molecular layer became prominent after P15. By that time, the immunostaining pattern was characteristic of Golgi cells, as seen typically in adults. Many intensely immunoreactive radial processes existed at birth (P0). These traversed the molecular and external granular layers, reaching the pial surface in every cerebellar lobule. Because they showed coimmunoreactivity for glial fibrillary acidic protein, they were confirmed to be Bergmann glial fibers. After P9, they began to lose immunoreactivity at the portion corresponding to the molecular layer, while an immunostained granular pattern appeared in that layer. Immunoreactive radial processes, however, remained in the external granular layer, and finally, at P21, they disappeared together along with the external granular layer. Granular staining in the molecular layer reached background levels at this time. These spatiotemporal changes in mGluR2/3 distribution suggested that there may be distinct roles for mGluR2/3 in Golgi cells and Bergmann glial cells during the early postnatal period. mGluR2/3 in Golgi cells might be associated closely with systemic maturation, whereas mGluR2/3 in Bergmann glia might be needed for neuron-glia interactions related to granule cell development.
在成年大鼠小脑皮质中，代谢型谷氨酸受体（mGluRs）2和3（mGluR2/3）存在于高尔基细胞的胞体、树突和终末以及推测的胶质细胞突起中（大西等人[1994]，《神经元》13:55 - 66）。在本研究中，检测了新生大鼠小脑皮质中mGluR2/3免疫染色的时空变化。mGluR2/3免疫反应性高尔基细胞胞体最早在出生后第3天（P3）出现在内颗粒层，且局限于小叶IX和X；然而，到P5时，它们出现在所有小叶中。免疫反应性高尔基细胞轴突呈成年样，表现为有串珠状膨体簇的曲折纤维。它们最早在P7时在内颗粒层被观察到，并且数量和复杂性随时间增加。到P10时证实mGluR2/3免疫反应性高尔基细胞轴突终末属于突触小球。延伸至分子层的免疫反应性高尔基细胞树突在P15后变得明显。到那时，免疫染色模式具有高尔基细胞的特征，这在成年动物中通常可见。出生时（P0）存在许多强免疫反应性的放射状突起。这些突起穿过分子层和外颗粒层，在每个小脑小叶中到达软脑膜表面。因为它们对胶质纤维酸性蛋白显示出共免疫反应性，所以被确认为伯格曼胶质纤维。在P9之后，它们开始在对应于分子层的部分失去免疫反应性，而在该层出现免疫染色的颗粒状模式。然而，免疫反应性放射状突起仍留在外颗粒层，最终在P21时，它们与外颗粒层一起消失。此时分子层中的颗粒状染色达到背景水平。mGluR2/3分布的这些时空变化表明，在出生后早期，mGluR2/3在高尔基细胞和伯格曼胶质细胞中可能具有不同的作用。高尔基细胞中的mGluR2/3可能与整体成熟密切相关，而伯格曼胶质细胞中的mGluR2/3可能是颗粒细胞发育相关的神经元 - 胶质细胞相互作用所必需的。
