Cyclic AMP mediates serotonin-induced synaptic enhancement of lateral giant interneuron of the crayfish
Cyclic AMP mediates serotonin-induced synaptic enhancement of lateral giant interneuron of the crayfish
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DOI：
10.1152/jn.00502.2005
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发表时间：
2005-10-01
影响因子：
2.5
通讯作者：
Sprayberry, J
中科院分区：
文献类型：
--
作者：
Araki, M;Nagayama, T;Sprayberry, J
侧巨人介导的逃避行为的小龙虾习惯于重复的感官刺激。最近的研究表明，生物胺5-羟色胺和章鱼胺调节适应后LG反应的恢复和/或再抑制的时间过程。然而，很少有人知道血清素和章鱼胺如何影响LG习惯化以及它们可能激活的第二信使级联。为了研究生物胺对LG习惯化的影响，在重复感觉刺激之前灌流5-羟色胺和章鱼胺。5-羟色胺和章鱼胺增加了适应LG反应所需的刺激数量。通过混合应用cAMP类似物[8-（4-氯苯硫基）- cAMP（CPT-cAMP）]和磷酸二酯酶抑制剂[3-异丁基-1-甲基黄嘌呤（IBMX）]而不是cGMP类似物（8-溴鸟苷3 '，5'-环一磷酸）来模拟其作用。灌注腺苷酸环化酶抑制剂（SQ 22536）取消了5-羟色胺的影响，但不是章鱼胺。为了研究每种生物胺在介导LG逃逸的神经回路中的作用部位，研究了药物对直接和间接诱发的LG突触后电位的影响。5-羟色胺，章鱼胺，CPT-cAMP和IBMX的混合物增加了直接和间接的突触输入。同时应用SQ 22536消除了5-羟色胺对两种输入的影响，但没有阻断章鱼胺的作用。直接注射cAMP类似物（腺苷-3 '，5'-环硫代磷酸的Sp-异构体）到LG增加了直接和间接的输入LG。这些结果表明，血清素介导的cAMP水平在LG中的增加，但章鱼胺的作用独立于cAMP和cGMP。
The lateral giant (LG)mediated escape behavior of the crayfish habituates readily on repetitive sensory stimulation. Recent studies suggested that the biogenic amines serotonin and octopamine modulate the time course of recovery and/or re-depression of the LG response after habituation. However, little is known of how serotonin and octopamine effect LG habituation and what second-messenger cascades they may activate. To investigate the effect of biogenic amines on LG habituation, serotonin and octopamine were superfused before presenting repetitive sensory stimulation. Serotonin and octopamine increased the number of stimuli needed to habituate the LG response. Their effects were mimicked by mixed application of a cAMP analogue [8-(4-chlorophenylthio)- cAMP (CPT-cAMP)] and a phosphodiesterase inhibitor [3-isobutyl-1-methylxanthine ( IBMX)] but not by a cGMP analogue ( 8- bromoguanosine 3',5'-cyclic monophosphate). Perfusion of the adenylate cyclase inhibitor (SQ22536) abolished the effect of serotonin but not that of octopamine. To investigate the site of action of each biogenic amines in the neural circuit meditating LG escape, the effect of drugs on directly and indirectly elicited postsynaptic potentials in LG was investigated. Serotonin, octopamine, and a mixture of CPT-cAMP and IBMX increased both the direct and indirect synaptic inputs. Simultaneous application of SQ22536 abolished the effect of serotonin on both inputs but did not block the effect of octopamine. Direct injection of the cAMP analogue (Sp-isomer of adenosine-3',5'-cyclic monophosphorothioate) into LG increased both the direct and indirect inputs to LG. These results indicate that serotonin mediates an increase in cAMP levels in LG, but octopamine acts independently of cAMP and cGMP.