Lurie D I, Rubel E W
Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Seattle 98195.
J Comp Neurol. 1994 Aug 8;346(2):276-88. doi: 10.1002/cne.903460207.
Astrocytes in the central nervous system (CNS) respond to injury and disease by proliferating and extending processes. The intermediate filament protein of astrocytes, glial fibrillary acidic protein (GFAP) also increases in astrocytes. These cells are called "reactive astrocytes" and are thought to play a role in CNS repair. We have previously demonstrated rapid increases (< 6 hours) in GFAP-immunoreactive and silver-impregnated glial processes in the chick cochlear nucleus, nucleus magnocellularis (NM), following cochlea removal or activity blockade of the eighth nerve. It was not known whether these changes were the result of glial proliferation, glial hypertrophy, or both. The present study examined the time course of astrocyte proliferation in NM following cochlea removal. Postnatal chicks received unilateral cochlea removal and survived for 6, 12, 18, 24, 36, 48, and 72 hours. Bromodeoxyuridine was used to label proliferating cells. The volume and number of labeled cells in NM was calculated for both the experimental and control sides of the brains for experimental animals was well as for unoperated control animals. A subset of astrocytes continuously divide in the normal posthatch chick brainstem. The percentage of labeled nuclei increases within NM 36 hours following cochlea removal and is robust by 48 hours. This increase is due to astrocyte proliferation within, rather than migration to, NM. These results indicate that rapid increases in GFAP following reduced activity are independent of cell proliferation. The time course of astrocyte proliferation suggests that cellular degeneration within the nucleus may play a role in upregulating astrocyte proliferation.
中枢神经系统（CNS）中的星形胶质细胞通过增殖和延伸突起对损伤和疾病作出反应。星形胶质细胞的中间丝蛋白，即胶质纤维酸性蛋白（GFAP）在星形胶质细胞中也会增加。这些细胞被称为“反应性星形胶质细胞”，被认为在中枢神经系统修复中发挥作用。我们之前已经证明，在摘除耳蜗或阻断第八神经的活动后，雏鸡耳蜗核大细胞（NM）中GFAP免疫反应性和银浸染的胶质突起会迅速增加（<6小时）。尚不清楚这些变化是胶质细胞增殖、胶质细胞肥大还是两者共同作用的结果。本研究考察了摘除耳蜗后NM中星形胶质细胞增殖的时间进程。出生后的雏鸡接受单侧耳蜗摘除，并存活6、12、18、24、36、48和72小时。用溴脱氧尿苷标记增殖细胞。计算了实验动物大脑实验侧和对照侧以及未手术对照动物大脑中NM中标记细胞的体积和数量。在正常孵化后的雏鸡脑干中，一部分星形胶质细胞持续分裂。摘除耳蜗后36小时内，NM中标记细胞核的百分比增加，到48小时时显著增加。这种增加是由于NM内星形胶质细胞的增殖，而不是迁移到NM。这些结果表明，活动减少后GFAP的快速增加与细胞增殖无关。星形胶质细胞增殖的时间进程表明，核内的细胞变性可能在上调星形胶质细胞增殖中起作用。
