Kimelberg H K, Cai Z, Rastogi P, Charniga C J, Goderie S, Dave V, Jalonen T O
Division of Neurosurgery, Albany Medical College, New York 12208, USA.
J Neurochem. 1997 Mar;68(3):1088-98. doi: 10.1046/j.1471-4159.1997.68031088.x.
Glial fibrillary acid protein (GFAP)-positive astrocytes isolated from the cerebral cortices of 3-10-day-old rats frequently showed increased intracellular Ca2+ concentration responses to L-glutamate and glutamate analogues. However, few of the acutely isolated cells responded to ATP, and no such cells responded to serotonin [5-hydroxytryptamine (5-HT)]. The same cell that failed to respond to ATP or 5-HT often responded to glutamate. Culturing acutely isolated cells in media containing horse serum decreased Ca2+ responses to glutamate but increased the responses to ATP and induced responses to 5-HT. In primary cultures prepared from the cerebral cortices of 1-day-old rats and cultured in horse serum, fewer of the cells responded to glutamate, but almost all cells responded to ATP and 5-HT. The lack of or limited response to, 5-HT or ATP in the acutely isolated cells seems unlikely to be due to selective damage to the respective receptors because acutely isolated GFAP-negative cells showed responses to ATP, several different proteases and mechanical dissociation yielded cells that also responded to glutamate but not to ATP, and exposure of primary cultures to papain did not abolish Ca2+ responses to several transmitters. The responses of the acutely isolated cells to glutamate but limited or lack of responses to ATP and 5-HT also correspond to what has been seen so far for astrocytes in situ. Thus, the present studies provide direct evidence that some of the receptors seen in primary astrocyte cultures may reflect a response to culture conditions and that, in the context of the relevant information so far available, acutely isolated astrocytes seem to reflect better the in vivo state.
从3至10日龄大鼠大脑皮层分离出的胶质纤维酸性蛋白（GFAP）阳性星形胶质细胞，对L-谷氨酸和谷氨酸类似物的细胞内钙离子浓度反应常常增强。然而，急性分离的细胞中很少有细胞对ATP有反应，且没有细胞对血清素[5-羟色胺（5-HT）]有反应。对ATP或5-HT无反应的同一细胞常常对谷氨酸有反应。在含有马血清的培养基中培养急性分离的细胞，会降低对谷氨酸的钙离子反应，但会增强对ATP的反应并诱导对5-HT的反应。在从1日龄大鼠大脑皮层制备并在马血清中培养的原代培养物中，对谷氨酸有反应的细胞较少，但几乎所有细胞都对ATP和5-HT有反应。急性分离的细胞对5-HT或ATP缺乏或反应有限，似乎不太可能是由于各自受体的选择性损伤，因为急性分离的GFAP阴性细胞对ATP有反应，几种不同的蛋白酶和机械解离产生的细胞对谷氨酸也有反应，但对ATP无反应，并且将原代培养物暴露于木瓜蛋白酶并不会消除对几种递质的钙离子反应。急性分离的细胞对谷氨酸的反应以及对ATP和5-HT反应的有限或缺乏，也与迄今为止在原位星形胶质细胞中观察到的情况相符。因此，本研究提供了直接证据，表明原代星形胶质细胞培养物中所见的一些受体可能反映了对培养条件的反应，并且，就目前可得的相关信息而言，急性分离的星形胶质细胞似乎能更好地反映体内状态。
