Differential activation of two distinct mechanisms for presynaptic inhibition by a single inhibitory axon
Differential activation of two distinct mechanisms for presynaptic inhibition by a single inhibitory axon
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DOI：
10.1152/jn.1996.76.6.3807
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发表时间：
1996-12-01
影响因子：
2.5
通讯作者：
Parnas, I
中科院分区：
文献类型：
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作者：
Fischer, Y;Parnas, I
1. 在小龙虾开启器神经肌肉接头的单个释放按钮上研究了抑制性轴突刺激引起的兴奋性递质释放的突触前抑制。2．当单个抑制动作电位先于兴奋性测试动作电位 1-2 ms 时，突触前抑制达到最大（接近 30%）。这种抑制最多持续5毫秒。它被50μM印防己毒素阻断，可能主要由γ-氨基丁酸-A(GABA(A))受体介导。3．当最后一个抑制性动作电位（序列）早于兴奋性测试动作电位 10 ms 时，由一串简短的抑制性动作电位（100 Hz 下 5 个脉冲）产生的突触前抑制达到最大（类似于 60%）。这种抑制持续长达 50 毫秒。似乎在这种情况下GABA(B)受体也被激活，因为需要印防己毒素(50μM)和20H-沙氯芬(100μM)的联合作用来阻断抑制作用。4．因此，我们表明，同一个抑制释放按钮可以通过激活 GABA(A) 和 GABA(B) 受体来差异激活两种不同的突触前抑制机制。
1. Presynaptic inhibition of excitatory transmitter release evoked by inhibitory axon stimulation was studied at individual release boutons of the crayfish opener neuromuscular junction.2. Presynaptic inhibition was maximal (similar to 30%) when a single inhibitory action potential preceded the excitatory test action potential by 1-2 ms. This inhibition lasted at most 5 ms. It was blocked by 50 mu M picrotoxin, and is probably mediated mainly by gamma-aminobutyric acid-A (GABA(A)) receptors.3. Presynaptic inhibition produced by a brief train of inhibitory action potentials (5 pulses at 100 Hz) was maximal (similar to 60%) when the last inhibitory action potential (of the train) preceded the excitatory test action potential by 10 ms. This inhibition lasted up to 50 ms. It seems that in this case GABA(B) receptors were activated as well, because the combined action of picrotoxin (50 mu M) and 20H-Saclofen (100 mu M) was required to block the inhibition.4. We thus show that one and the same inhibitory release bouton can differentially activate two distinct mechanisms for presynaptic inhibition by activating GABA(A) and GABA(B) receptors.