Shirasaka Y, Wasterlain C G
Epilepsy Research Laboratory, Veterans Affairs Medical Center, Sepulveda, CA 91343-2099, USA.
Eur J Pharmacol. 1995 Aug 25;282(1-3):11-7. doi: 10.1016/0014-2999(95)00244-f.
We examined the effect of urethane (1000 mg/kg, followed by 50 mg/kg per h, i.v.), an anesthetic commonly used by physiologists, on evoked potentials recorded in dentate gyrus in adult Wistar rats by stimulating the ipsilateral perforant path, via chronically implanted electrodes. Urethane decreased paired-pulse inhibition. Under urethane, with paired-pulse stimulation, the ratio of the second population spike amplitude to the first increased by 11.1-20.7% at 25-60 ms interstimulus interval (n = 18, P < 0.05). At 25 ms, the proportion was 3.6 +/- 1.6 while awake, and 14.7 +/- 3.5 under urethane. Urethane depressed granule cell excitability and strength of synaptic responses. Under urethane, the ratio of the population spike amplitude obtained at 250 microA stimulation to the maximal response in the same input/output response examination decreased by 20%, and the ratio of the excitatory postsynaptic response slopes fell by 10%. These results indicate that urethane affects neurotransmission in the hippocampus, and suggest that its effect may be exerted in part on excitatory neurotransmission.
我们通过慢性植入电极刺激成年Wistar大鼠同侧穿通通路，研究了生理学家常用的麻醉剂乌拉坦（1000 mg/kg静脉注射，随后每小时50 mg/kg静脉注射）对齿状回记录的诱发电位的影响。乌拉坦降低了双脉冲抑制。在乌拉坦作用下，采用双脉冲刺激时，在25 - 60毫秒的刺激间隔下，第二个群体峰电位幅度与第一个的比值增加了11.1 - 20.7%（n = 18，P < 0.05）。在25毫秒时，清醒时该比例为3.6 ± 1.6，在乌拉坦作用下为14.7 ± 3.5。乌拉坦降低了颗粒细胞的兴奋性和突触反应强度。在乌拉坦作用下，在相同的输入/输出反应检测中，250微安刺激时获得的群体峰电位幅度与最大反应的比值降低了20%，兴奋性突触后反应斜率的比值下降了10%。这些结果表明乌拉坦影响海马体中的神经传递，并提示其作用可能部分通过兴奋性神经传递发挥。
