Isoflurane Bidirectionally Modulates the Paired-Pulse Responses in the Rat Hippocampal CA1 Field In Vivo
Isoflurane Bidirectionally Modulates the Paired-Pulse Responses in the Rat Hippocampal CA1 Field In Vivo
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DOI：
10.1213/01.ane.0000281433.73260.8d
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发表时间：
2007-10
影响因子：
5.7
通讯作者：
K. Tachibana;K. Takita;Toshikazu Hashimoto;M. Matsumoto;M. Yoshioka;Y. Morimoto
中科院分区：
文献类型：
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作者：
K. Tachibana;K. Takita;Toshikazu Hashimoto;M. Matsumoto;M. Yoshioka;Y. Morimoto
背景：我们在体内完整的神经元间回路下，研究了异氟醚对海马区突触传递和双脉冲可塑性的影响。方法：采用大鼠慢性埋植电极模型，通过刺激Schaffer侧支，测定大鼠海马CA1区兴奋性突触后电位(EPSP)和群体峰电位(PSA)。用0.25~1.5的肺泡麻醉剂最低浓度(MAC)异氟醚机械通气。在没有异氟醚的情况下，获得了一个控制值。结果：异氟醚抑制EPSP反应，增强突触效应。PSA只有在高浓度时才被抑制，这可能反映了EPSP减少和突触效能增强的良好平衡结合。低浓度异氟醚(0.25和0.5MAC)可增加双脉冲易化作用(PPF)，高浓度异氟醚(1.5MAC)可延长双脉冲抑制。结论：异氟醚可影响CA1区突触的多个部位：1)突触前谷氨酸能传递的抑制，表现为EPSP的抑制和PPF的增加；2)锥体神经元的抑制，表现为高浓度时PPF的延长和PSA的抑制；3)中间神经元的抑制，表现为突触效应增强。在不同的浓度下，这些抑制效应的程度似乎不同，突触特性的总体方向可能取决于体内这些抑制效应之间的平衡。
BACKGROUND:We studied the effects of isoflurane on hippocampal synaptic transmission and paired-pulse plasticity, under in vivo intact interneuron circuitry. METHODS:Using rats chronically implanted with electrodes, excitatory postsynaptic potential (EPSP) and population spike amplitude (PSA) were measured in the hippocampal CA1 field by stimulating Schaffer collaterals. The lungs of the rats were mechanically ventilated with 0.25–1.5 minimum alveolar anesthetic concentration (MAC) isoflurane. A control value was obtained in the absence of isoflurane. RESULTS:Isoflurane depressed EPSP responses and enhanced synaptic efficacy. PSA was not depressed except under high concentrations, presumably reflecting a well-balanced combination with the decreased EPSP and enhanced synaptic efficacy. Low concentrations of isoflurane (0.25 and 0.5 MAC) increased paired-pulse facilitation (PPF), whereas a high concentration of isoflurane (1.5 MAC) prolonged the paired-pulse depression. CONCLUSIONS:Isoflurane appeared to affect multiple sites of CA1 synapses: 1) the depression of presynaptic glutamatergic transmission as shown by depressed EPSP and increased PPF; 2) the depression of pyramidal neurons as shown by prolonged PPF and depressed PSA under high concentration; and 3) the depression of interneurons as shown by the greater synaptic efficacy. The degree of each of these inhibitory effects seemed to vary at different concentrations, and the overall direction of the synaptic properties may depend on the balances between these inhibitory effects in vivo.