On the putative physiological role of allopregnanolone on GABA(A) receptor function.
On the putative physiological role of allopregnanolone on GABA(A) receptor function.
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关于四氢孕酮对 GABA(A) 受体功能的假定生理作用。
DOI：
10.1016/s0028-3908(02)00341-6
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发表时间：
2003
影响因子：
4.7
通讯作者：
Guidotti,A
中科院分区：
文献类型：
--
作者：
Puia,G;Mienville,J-M;Matsumoto,K;Takahata,H;Watanabe,H;Costa,E;Guidotti,A
为了获得内源性脑 ALLO 对 GABAA 受体功能的生理变构调节作用的明确证据，我们研究了在施用 SKF 105111-17β-17-[双（1甲基乙基）氨基羰基]后内源性脑 ALLO 浓度降低约 80% 并持续超过 5 小时的条件下的 GABAA 受体活性。雄甾烷-3,5-二烯-3-羧酸 (SKF)，5α-还原酶 I 型和 II 型的有效抑制剂。我们使用原位膜片钳技术记录了媒介物或 SKF 治疗小鼠新皮质切片中锥体神经元的 GABA 诱发电流和自发抑制性突触后电流 (sIPSC)。在接受 SKF 治疗的小鼠切片中，外源应用的 GABA 的效力（而非功效）有所降低。当新皮质切片在体外用10μM SKF处理3小时时，ALLO也减少（25-30%），此外，GABA剂量反应曲线向右移动；然而，这种变化并不像从接受 SKF 治疗的小鼠中获得的切片中的变化那么明显，这与这些切片中 ALLO 含量的较小下降一致。此外，直接将 ALLO 应用于这些切片使 GABA 的剂量反应曲线向非 SKF 处理的曲线转变。然后，我们分析了从载体或 SKF 处理的小鼠获得的新皮质切片中的 GABA 能 sIPSC。 SKF 处理显着减少了平均衰减时间和电荷转移。 sIPSC 的衰减最好用两个指数拟合，但 SKF 组中只有快速分量减少。直接应用 ALLO (100nM) 可以使 ALLO 耗尽小鼠切片中的 sIPSC 动力学正常化。 sIPSC 的振幅或频率没有检测到变化。这些数据表明，内源性 ALLO 通过作用于可能位于 GABAA 受体（受体上的受体）上的特定识别位点，在生理上调节自发诱导的 Cl−电流，从而通过促进 GABA 门控 Cl−通道构象转变为开放状态来延长抑制电流。
To obtain definitive evidence for a physiological allosteric modulatory role for endogenous brain ALLO on GABAAreceptor function, we studied GABAAreceptor activity under conditions in which the concentration of endogenous brain ALLO was decreased by about 80% for longer than 5 h following the administration of SKF 105111- 17β-17-[bis (1methylethyl) amino carbonyl] androstane-3,5-diene-3-carboxylic acid (SKF), a potent inhibitor of 5α-reductases Type I and II. We used the in situ patch–clamp technique to record GABA-evoked currents and spontaneous inhibitory postsynaptic currents (sIPSCs) from pyramidal neurons in neocortical slices of vehicle- or SKF-treated mice. The potency, but not the efficacy, of exogenously applied GABA was decreased in slices from mice treated with SKF. When neocortical slices were treated in vitro for 3 h with 10μM SKF, ALLO was also reduced (25–30%) and in addition, the GABA dose–response curve was shifted to the right; however this shift was not as marked as the shift in the slices obtained from mice treated with SKF, in keeping with the smaller decrease of the ALLO content in these slices. Furthermore, direct application of ALLO to these slices shifted the dose–response curve of GABA back toward a non-SKF treated profile. We then analyzed GABAergic sIPSCs in neocortical slices obtained from vehicle or SKF-treated mice. Mean decay time and charge transfer were significantly reduced by SKF treatment. The decay of sIPSCs was best fitted by two exponentials, but only the fast component was decreased in the SKF group. Direct application of ALLO (100nM) normalizes the sIPSC kinetics in slices from ALLO depleted mice. No changes were detected in the amplitude or frequency of sIPSCs. These data demonstrate that endogenous ALLO physiologically regulates spontaneously induced Cl−current by acting on a specific recognition site, which is probably located on GABAAreceptors (a receptor on a receptor), thereby prolonging inhibitory currents by facilitating conformational transition of the GABA-gated Cl−channel to an open state.