Adaptation in pheromone-sensitive trichoid sensilla of the hawkmoth Manduca sexta
Adaptation in pheromone-sensitive trichoid sensilla of the hawkmoth Manduca sexta
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DOI：
10.1242/jeb.00302
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发表时间：
2003-05-01
影响因子：
2.8
通讯作者：
Stengl, M
中科院分区：
文献类型：
--
作者：
Dolzer, J;Fischer, K;Stengl, M
在雄性天蛾长毛状感器的细胞外尖端记录中，我们研究了适应和非适应状态下对两种不同持续时间的家蚕刺激的剂量-反应关系。在每个触角感器中，Bombykal反应细胞可以与非Bombykal反应细胞区分开来，因为Bombykal反应细胞总是产生初始幅度较大的动作电位。记录在远端鞭毛环内的定义位置的bombykal细胞可以分辨至少4个log（10）单位的信息素浓度，但显然不能编码所有测试的刺激持续时间。在不同的适应状态下，检测了幅度调制感觉电位和频率调制动作电位反应的参数。证据是存在的几种机制的适应，影响不同的步骤的转导级联。适应信息素刺激后，感觉电位上升到一个较低的幅度和下降速度比非适应反应。此外，适应性动作电位反应的频率降低。只有上升的感觉电位的时间是不同的影响，通过适应信息素刺激的不同持续时间。上升的时间不会增加后短，但只有在长，适应刺激。短适应刺激和长适应刺激都使感觉电位振幅的剂量-反应曲线以及其上升相的初始斜率向更高的刺激浓度移动大约一个log（10）单位。动作电位反应的剂量-反应曲线的偏移大于感觉电位反应的偏移，表明在动作电位产生的水平上存在额外的适应机制。此外，在短和长适应刺激后感觉电位的更快下降表明嗅觉受体神经元的静息电位稳定。
In extracellular tip recordings from long trichoid sensilla of male Manduca sexta moths, we studied dose-response relationships in response to bombykal stimuli of two different durations in the adapted and the non-adapted state. Bombykal-responsive cells could be distinguished from non-bombykal-sensitive cells in each trichoid sensillum because the bombykal-responsive cell always generated the action potentials of larger initial amplitude. The bombykal cell, which was recorded at a defined location within a distal flagellar annulus, can resolve at least four log(10)-units of pheromone concentrations but is apparently unable to encode all stimulus durations tested. Parameters of the amplitude-modulated sensillar potential and the frequency-modulated action potential responses were examined in different states of adaptation. Evidence is presented for the existence of several mechanisms of adaptation, which affect distinct steps of the transduction cascade. After adapting pheromone stimuli, the sensillar potential rises to a lower amplitude and declines faster compared with the non-adapted response. In addition, the frequency of the adapted action potential response is reduced. Only the time of rise of the sensillar potential is differentially affected by adapting pheromone stimuli of different duration. The time of rise does not increase after short, but only after long, adapting stimuli. Both short and long adapting stimuli shift the dose-response curves of the sensillar potential amplitude, as well as the initial slope of its rising phase, to higher stimulus concentrations by approximately one log(10)-unit. The shift in the dose-response curve of the action potential response is larger than for the sensillar potential response, suggesting that an additional adaptation mechanism acts at the level of action potential generation. Furthermore, a faster decline of the sensillar potential after short and long adapting stimuli suggests that the resting potential of the olfactory receptor neuron is stabilized.