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This Article Full Text Full Text (PDF) All Versions of this Article: 100/3/1211    most recent 90459.2008v2 90459.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Aoki, K. Articles by Yoshino, M. Search for Related Content PubMed PubMed Citation Articles by Aoki, K. Articles by Yoshino, M.

Monoaminergic Modulation of the Na⁺-Activated K⁺ Channel in Kenyon Cells Isolated From the Mushroom Body of the Cricket (Gryllus bimaculatus) Brain

¹Department of Biology, Tokyo Gakugei University; and ²Tokyo Gakugei University Senior High School, Tokyo, Japan

Submitted 11 April 2008; accepted in final form 5 June 2008

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.