Ethanol modulates the interaction of the endogenous neurosteroid allopregnanolone with the α1β2γ2L GABAA receptor
Ethanol modulates the interaction of the endogenous neurosteroid allopregnanolone with the α1β2γ2L GABAA receptor
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DOI：
10.1124/mol.106.029942
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发表时间：
2007-02-01
影响因子：
3.6
通讯作者：
Steinbach, Joe Henry
中科院分区：
文献类型：
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作者：
Akk, Gustav;Li, Ping;Steinbach, Joe Henry
我们研究了内源性类固醇别孕酮(3-α-5-αP)、孕烯醇硫酸酯和β-雌二醇在无乙醇和有乙醇存在的情况下对α1β2伽马2L GABA(A)受体的调节作用。0.1%~1%(17~170 mM)的乙醇对3α5αP的受体调节有影响，但对孕烯醇酮硫酸盐和β-雌二醇的调节无影响。3α5αP增强通道的三种动力学效应之一，即延长最长开放时间成分(OT3)，受乙醇影响，其量效曲线的中点移至较低的类固醇浓度2个数量级，而对最大效应无明显影响。旨在影响3-α-5-αP延长OT3能力的操作也影响了乙醇存在时OT3的延长。伽马2亚单位的突变降低了3α5αP延长OT3的能力，也减少了乙醇和3α5αP之间的相互作用。竞争性类固醇拮抗剂(3α，5α)-17-苯雄酮-16-烯-3-醇(17-PA)的存在减少了乙醇和3α5αP在GABA(A)受体上的正相互作用。综上所述，这些发现表明，类固醇与经典类固醇结合部位的相互作用是乙醇存在时所见效应的基础，乙醇通过增加3α5αP对该部位的亲和力而起作用。蝌蚪行为学分析表明，在不能引起蝌蚪行为改变的浓度下，3α5αP使乙醇引起的翻正反射丧失的剂量-反应曲线向低浓度移动，这一效应可被17-PA和3α5αP联合应用所抵消。
We have examined alpha 1 beta 2 gamma 2L GABA(A) receptor modulation by the endogenous steroids allopregnanolone (3 alpha 5 alpha P), pregnenolone sulfate, and beta-estradiol in the absence and presence of ethanol. Coapplication of 0.1 to 1% (17-170 mM) ethanol influenced receptor modulation by 3 alpha 5 alpha P but not that by pregnenolone sulfate or beta-estradiol. One of the three kinetic effects evident in channel potentiation by 3 alpha 5 alpha P, prolongation of the longest-lived open time component (OT3), was affected by ethanol with the midpoint of its dose-response curve moved to lower steroid concentrations by 2 orders of magnitude without significantly affecting the maximal effect. Manipulations designed to affect the ability of 3 alpha 5 alpha P to prolong OT3 also affected OT3 prolongation in the presence of ethanol. A mutation to the gamma 2 subunit, which reduces the ability of 3 alpha 5 alpha P to prolong OT3, also reduces the interaction between ethanol and 3 alpha 5 alpha P. And the presence of the competitive steroid antagonist (3 alpha,5 alpha)-17-phenylandrost-16-en-3-ol (17-PA) diminishes the positive interaction between ethanol and 3 alpha 5 alpha P on the GABA(A) receptor. Together, the findings suggest that steroid interactions with the classic steroid binding site underlie the effect seen in the presence of ethanol, and that ethanol acts by increasing the affinity of 3 alpha 5 alpha P for the site. Tadpole behavioral assays showed that the presence of 3 alpha 5 alpha P at a concentration ineffective at causing changes in tadpole behavior shifted the ethanol dose-response curve for loss of righting reflex to lower concentrations and that this effect was neutralized by coapplication of 17-PA with 3 alpha 5 alpha P.