Involvement of KCNQ2 subunits in [3H]dopamine release triggered by depolarization and pre-synaptic muscarinic receptor activation from rat striatal synaptosomes
Involvement of KCNQ2 subunits in [3H]dopamine release triggered by depolarization and pre-synaptic muscarinic receptor activation from rat striatal synaptosomes
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DOI：
10.1111/j.1471-4159.2007.04562.x
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发表时间：
2007-07-01
影响因子：
4.7
通讯作者：
Taglialatela, Maurizio
中科院分区：
文献类型：
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作者：
Martire, Maria;D'Amico, Monia;Taglialatela, Maurizio
KCNQ2 和 KCNQ3 亚基编码毒蕈碱调节电流 (I-KM)，这是一种亚阈值电压依赖性 K+ 电流调节神经元兴奋性。在本研究中，我们研究了 I-KM 在细胞外 K+ 浓度 ([K+](e)) 升高和毒蕈碱受体激活引起的大鼠纹状体突触体释放多巴胺 (DA) 中的参与。由 9 mmol/L [K+](e) 触发的 [H-3] 多巴胺 ([H-3]DA) 释放被 I-KM 激活剂瑞替加滨 (0.01-30 mu mol/L；E-max = 54.80 +/- 3.85%；IC50 = 0.50 +/- 0.36 mu mol/L) 抑制。 I-KM 阻滞剂四乙铵 (0.1-3 mmol/L) 和 XE-991 (0.1-30 μ mol/L) 增强 K+ 诱发的 [H-3]DA 释放，并防止瑞替加滨诱导的去极化诱发的 [H-3]DA 释放抑制。瑞替加滨诱导的 K+ 诱发的 [H-3]DA 释放抑制也被阻断性抗 KCNQ2 多克隆抗体的突触体截留所消除，这种作用被 KCNQ2 免疫肽预吸收抗体所阻止。此外，胆碱能激动剂氧化震颤素 (OXO) (1-300 μmol/L) 可增强 9 mmol/L [K+](e) 诱发的 [H-3]DA 释放（E-max = 155 +/- 9.50%；EC50 = 25 +/- 1.80 μmol/L）。 OXO (100 μ mol/L) 诱导的 [H-3]DA 释放增强被哌仑西平 (1-10 nmol/L) 竞争性抑制，并被 M-3 优先拮抗剂 4-二苯乙酰氧基 N-甲基哌啶甲硫醚 (1 μmol/L) 消除，但不受 M-1 选择性拮抗剂 MT-7 (10-100 nmol/L) 或百日咳毒素 (1.5-3 mu g/mL)，可解偶联 M-2 和 M-4 介导的反应。最后，OXO 诱导的去极化诱导的 [H-3]DA 释放增强作用与 XE-991 (10 μmol/L) 产生的增强作用不相加，不受瑞替加滨 (10 μmol/L) 的影响，并且被抗 KCNQ2 抗体的突触体捕获所消除。总的来说，这些发现表明，在大鼠纹状体神经末梢中，含有 KCNQ2 亚基的 I-KM 通道调节去极化诱导的 DA 释放，并且 I-KM 抑制参与了由突触前毒蕈碱异质受体激活触发的去极化诱导的 DA 释放的增强。
KCNQ2 and KCNQ3 subunits encode for the muscarinic-regulated current (I-KM), a sub-threshold voltage-dependent K+ current regulating neuronal excitability. In this study, we have investigated the involvement of I-KM in dopamine (DA) release from rat striatal synaptosomes evoked by elevated extracellular K+ concentrations ([K+](e)) and by muscarinic receptor activation. [H-3]dopamine ([H-3]DA) release triggered by 9 mmol/L [K+](e) was inhibited by the I-KM activator retigabine (0.01-30 mu mol/L; E-max = 54.80 +/- 3.85%; IC50 = 0.50 +/- 0.36 mu mol/L). The I-KM blockers tetraethylammonium (0.1-3 mmol/L) and XE-991 (0.1-30 mu mol/L) enhanced K+-evoked [H-3]DA release and prevented retigabine-induced inhibition of depolarization-evoked [H-3]DA release. Retigabine-induced inhibition of K+-evoked [H-3]DA release was also abolished by synaptosomal entrapment of blocking anti-KCNQ2 polyclonal antibodies, an effect prevented by antibody pre-absorption with the KCNQ2 immunizing peptide. Furthermore, the cholinergic agonist oxotremorine (OXO) (1-300 mu mol/L) potentiated 9 mmol/L [K+](e)-evoked [H-3]DA release (E-max = 155 +/- 9.50%; EC50 = 25 +/- 1.80 mu mol/L). OXO (100 mu mol/L)-induced [H-3]DA release enhancement was competitively inhibited by pirenzepine (1-10 nmol/L) and abolished by the M-3-preferring antagonist 4-diphenylacetoxy N-methylpiperidine methiodide (1 mu mol/L), but was unaffected by the M-1-selective antagonist MT-7 (10-100 nmol/L) or by Pertussis toxin (1.5-3 mu g/mL), which uncouples M-2- and M-4-mediated responses. Finally, OXO-induced potentiation of depolarization-induced [H-3]DA release was not additive to that produced by XE-991 (10 mu mol/L), was unaffected by retigabine (10 mu mol/L), and was abolished by synaptosomal entrapment of anti-KCNQ2 antibodies. Collectively, these findings indicate that, in rat striatal nerve endings, I-KM channels containing KCNQ2 subunits regulate depolarization-induced DA release and that I-KM suppression is involved in the reinforcement of depolarization-induced DA release triggered by the activation of pre-synaptic muscarinic heteroreceptors.