Monoaminergic modulation of the Na+-activated K+ channel in Kenyon cells isolated from the mushroom body of the cricket (Gryllus bimaculatus) brain
Monoaminergic modulation of the Na+-activated K+ channel in Kenyon cells isolated from the mushroom body of the cricket (Gryllus bimaculatus) brain
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DOI：
10.1152/jn.90459.2008
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发表时间：
2008-09-01
影响因子：
2.5
通讯作者：
Yoshino, Masami
中科院分区：
文献类型：
--
作者：
Aoki, Kozue;Kosakai, Kumiko;Yoshino, Masami
近年来的研究表明，章鱼胺（OA）和多巴胺（DA）分别在昆虫嗅觉学习的奖惩信号中起着重要的调节作用。然而，它们的靶分子和信号机制尚不完全清楚。在本研究中，我们首次发现OA和DA以相反的方式调节从蟋蟀（Gryllus bimaculatus）蘑菇体分离的Kenyon细胞中Na+激活的K+ (K-Na)通道。膜片钳记录显示，在高K+的情况下，膜片移液器中K- na通道的单通道电导约为122 pS。该通道被胞内Na+激活，而Li+激活较少。K+通道阻滞剂TEA和奎尼丁降低了该通道的开放概率（Po）。OA和DA分别提高和降低了K-Na通道电流的Po值。应用膜透性类似物8- br - cyclicamp和8-Br-cGMP也分别观察到K-Na通道Po的增加和减少。此外，还发现特异性蛋白激酶A （PKA）抑制剂H-89和特异性蛋白激酶G （PKG）抑制剂KT5823分别能减弱camp诱导的Po升高和cgmp诱导的Po降低。这些结果表明，K-Na通道是OA和DA的靶分子，cAMP/PKA和cGMP/PKG信号通路也参与K-Na通道的调节。
Recent studies have suggested that octopamine (OA) and dopamine (DA) play important roles in mediating the reward and punishment signals, respectively, in olfactory learning in insect. However, their target molecules and the signaling mechanisms are not fully understood. In this study, we showed for the first time that OA and DA modulate the Na+ -activated K+ (K-Na) channels in an opposite way in Kenyon cells isolated from the mushroom body of the cricket, Gryllus bimaculatus. Patch-clamp recordings showed that the single-channel conductance of the K-Na channel was about 122 pS with high K+ in the patch pipettes. The channel was found to be activated by intracellular Na+ but less activated by Li+. K+ channel blockers TEA and quinidine reduced the open probability (Po) of this channel. Bath application of OA and DA respectively increased and decreased the Po of K-Na channel currents. An increase and a decrease in Po of K-Na channels were also observed by applying the membrane-permeable analogs 8-Br-cyclic-AMP and 8-Br-cGMP, respectively. Furthermore, it was revealed that cAMP-induced increase and cGMP-induced decrease in Po were attenuated by the specific protein kinase A (PKA) inhibitor H-89 and protein kinase G (PKG) inhibitor KT5823, respectively. These results indicate that the K-Na channel is a target molecule for OA and DA and that cAMP/PKA and cGMP/PKG signaling pathways are also involved in the modulation of K-Na channels.