Yuan Hongjie, Yamada Katsuya, Inagaki Nobuya
Department of Physiology, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
Neurosci Lett. 2004 Jan 23;355(1-2):136-40. doi: 10.1016/j.neulet.2003.10.058.
In acute slice of substantia nigra pars reticulata (SNr), a small proportion (6.6%) of GABAergic neurons exhibited abrupt increases in spontaneous firing rate from baseline frequency ( approximately 40 Hz) to peak (>100 Hz) with periods ranging in minutes when GABA(A) receptors were blocked by 20 microM bicuculline. The combination of GABA(B), non-NMDA, and NMDA blockers, SCH50911 (10 microM), 6,7-dinitro-quinoxaline-2,3-dione (20 microM), and DL-2-amino-5-phosphonovalerate (50 microM), respectively, did not affect the incidence or properties of these multiminute oscillations, indicating that disinhibition induced by blockade of GABA(A) receptors is crucial in their generation. Incidence of oscillatory activity was increased to 16% by elevation of the K(+) concentration to 8 mM from basal level (6.24 mM). The SNr neurons exhibiting oscillatory activity with the addition of bicuculline had shown irregular fluctuations in basal firing rate, while the non-oscillatory neurons had shown a more regular baseline firing pattern. This is the first in vitro report of oscillations in firing rate of multiminute range in basal ganglia.
在黑质网状部（SNr）的急性脑片中，当用20微摩尔荷包牡丹碱阻断GABA(A)受体时，一小部分（6.6%）GABA能神经元的自发放电频率从基线频率（约40赫兹）突然增加到峰值（>100赫兹），持续时间为几分钟。分别联合使用GABA(B)、非NMDA和NMDA受体阻断剂SCH50911（10微摩尔）、6,7-二硝基喹喔啉-2,3-二酮（20微摩尔）和DL-2-氨基-5-磷酸戊酸（50微摩尔），并不影响这些持续数分钟振荡的发生率或特性，这表明由GABA(A)受体阻断诱导的去抑制作用对其产生至关重要。将钾离子浓度从基础水平（6.24毫摩尔）提高到8毫摩尔，振荡活动的发生率增加到16%。加入荷包牡丹碱后表现出振荡活动的SNr神经元在基础放电率上呈现不规则波动，而非振荡神经元则表现出更规则的基线放电模式。这是关于基底神经节中持续数分钟范围放电率振荡的首篇体外研究报告。
