Morara Stefano, Wang Li-Ping, Filippov Vitaly, Dickerson Ian M, Grohovaz Fabio, Provini Luciano, Kettenmann Helmut
C. N. R., Institute of Neuroscience, Via Privata Bianco 9, 20131 Milan, Italy.
Eur J Neurosci. 2008 Dec;28(11):2213-20. doi: 10.1111/j.1460-9568.2008.06514.x.
The neuropeptide calcitonin gene-related peptide (CGRP) is transiently expressed in cerebellar climbing fibers during development while its receptor is mainly expressed in astrocytes, in particular Bergmann glial cells. Here, we analyzed the effects of CGRP on astrocytic calcium signaling. Mouse cultured astrocytes from cerebellar or cerebral cortex as well as Bergmann glial cells from acutely isolated cerebellar slices were loaded with the Ca(2+) sensor Fura-2. CGRP triggered transient increases in intracellular Ca(2+) in astrocytes in culture as well as in acute slices. Responses were observed in the concentration range of 1 nm to 1 mm, in both the cell body and its processes. The calcium transients were dependent on release from intracellular stores as they were blocked by thapsigargin but not by the absence of extracellular calcium. In addition, after CGRP application a further delayed transient increase in calcium activity could be observed. Finally, cerebellar astrocytes from neonatal mice expressed receptor component protein, a component of the CGRP receptor, as revealed by immunofluorescence and confocal microscopy. It is thus proposed that the CGRP-containing afferent fibers in the cerebellum (the climbing fibers) modulate calcium in astrocytes by releasing the neuropeptide during development and hence possibly influence the differentiation of Purkinje cells.
神经肽降钙素基因相关肽（CGRP）在发育过程中于小脑攀缘纤维中短暂表达，而其受体主要在星形胶质细胞中表达，尤其是伯格曼胶质细胞。在此，我们分析了CGRP对星形胶质细胞钙信号传导的影响。从小脑或大脑皮质培养的小鼠星形胶质细胞以及从急性分离的小脑切片中获取的伯格曼胶质细胞，均用Ca(2+)传感器Fura-2进行加载。CGRP可引发培养的星形胶质细胞以及急性切片中细胞内Ca(2+)的短暂升高。在细胞体及其突起中，均在1纳米至1毫米的浓度范围内观察到反应。钙瞬变依赖于细胞内钙库的释放，因为其被毒胡萝卜素阻断，但不受细胞外钙缺失的影响。此外，应用CGRP后，可观察到钙活性进一步延迟的短暂升高。最后，免疫荧光和共聚焦显微镜显示，新生小鼠的小脑星形胶质细胞表达受体成分蛋白，这是CGRP受体的一个成分。因此，有人提出，小脑中含CGRP的传入纤维（攀缘纤维）在发育过程中通过释放神经肽来调节星形胶质细胞中的钙，从而可能影响浦肯野细胞的分化。
