Hösli L, Hösli E, Redle S, Rojas J, Schramek H
Department of Physiology, University of Basel, Switzerland.
Neurosci Lett. 1990 Sep 18;117(3):307-12. doi: 10.1016/0304-3940(90)90682-y.
The action of gamma-aminobutyric acid A (GABAA) and B (GABAB)-agonists has been studied on the membrane potential of astrocytes in explant cultures of rat spinal cord by means of intracellular microelectrode recordings. The GABAB-agonists (-)-baclofen and CGP 27 492 (3-aminopropyl phosphonous acid; 10(-6) to 10(-4) M) caused a hyperpolarization of the majority of astrocytes studied. On approximately 25% of the cells, the compounds had no effect. The hyperpolarization by baclofen (10(-4) M) was reversibly antagonized by the GABAB-antagonist 5-hydroxysaclofen (10(-4) M). GABA and the GABAA-agonist muscimol (10(-4) and 10(-3) M) depolarized approximately two thirds of the glial cells tested, whereas the remaining third remained unaffected. The GABAA-antagonist bicuculline (10(-4) and 10(-3) M) only reduced the depolarization by GABA (10(-4) M) but did not completely block it. On half of the cells tested, the depolarization by GABA was not affected by bicuculline, suggesting that the glial GABAA-receptor is different from the neuronal GABAA-receptor. Our electrophysiological investigations together with recent autoradiographic binding studies strongly suggest the existence of GABAB-receptors on astrocytes whereas there is less evidence for GABAA-sites on these cells.
通过细胞内微电极记录法，研究了γ-氨基丁酸A（GABAA）和B（GABAB）激动剂对大鼠脊髓外植体培养物中星形胶质细胞膜电位的作用。GABAB激动剂（-）-巴氯芬和CGP 27492（3-氨基丙基膦酸；10^-6至10^-4 M）使所研究的大多数星形胶质细胞发生超极化。在大约25%的细胞上，这些化合物没有作用。巴氯芬（10^-4 M）引起的超极化可被GABAB拮抗剂5-羟基巴氯芬（10^-4 M）可逆性拮抗。γ-氨基丁酸（GABA）和GABAA激动剂蝇蕈醇（10^-4和10^-3 M）使大约三分之二受试神经胶质细胞发生去极化，而其余三分之一未受影响。GABAA拮抗剂荷包牡丹碱（10^-4和10^-3 M）仅减少了GABA（10^-4 M）引起的去极化，但并未完全阻断。在一半受试细胞上，GABA引起的去极化不受荷包牡丹碱影响，这表明神经胶质细胞的GABAA受体不同于神经元的GABAA受体。我们的电生理研究以及最近的放射自显影结合研究有力地表明星形胶质细胞上存在GABAB受体，而这些细胞上存在GABAA位点的证据较少。
