Bernays E A, Chapman R F, Hartmann T
Department of Entomology, University of Arizona, P O Box 210088, Tucson, AZ 85721-0088, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 Oct;188(9):715-23. doi: 10.1007/s00359-002-0345-3. Epub 2002 Sep 14.
Adult males of Estigmene acraea use pyrrolizidine alkaloids to produce pheromones and all stages probably use pyrrolizidine alkaloids for defense. The alkaloids are obtained from plants by the caterpillars. We demonstrate that a contact chemoreceptor neuron in the lateral galeal sensillum exhibits a dose-dependent response to seneciphylline N-oxide, a widely occurring pyrrolizidine alkaloid, down to concentrations of 10(-9) x mol l(-1), and even at 10(-12) x mol l(-1) the response is greater than to salt alone. At concentrations of 10(-6) mol x l(-1) and above the instantaneous firing rate is very high, and at 10(-4) mol x l(-1) initially exceeds 500 spikes s(-1). The firing rate declines in the 200 ms following stimulus onset but then is sustained with an instantaneous firing rate in excess of 100 spikes s(-1) for at least the next 800 ms. At lower concentrations a delay occurs before firing is initiated, and then the pattern of firing is irregular. The cell is equally sensitive to some but not all of several other pyrrolizidine alkaloids tested as free bases and their N-oxides. It also responds to ouabain, which may also serve as a defensive compound, and to asparagine and fructose but with much higher thresholds than to the pyrrolizidine alkaloids.
黄斑污灯蛾的成年雄性利用吡咯里西啶生物碱来产生信息素，并且所有阶段可能都利用吡咯里西啶生物碱进行防御。这些生物碱由毛虫从植物中获取。我们证明，外侧盔形感器中的一个接触化学感受器神经元对千里光碱氮氧化物（一种广泛存在的吡咯里西啶生物碱）呈现剂量依赖性反应，低至10^(-9) x mol l^(-1) 的浓度，甚至在10^(-12) x mol l^(-1) 时，其反应也大于仅对盐的反应。在10^(-6) mol x l^(-1) 及以上的浓度下，瞬时放电频率非常高，在10^(-4) mol x l^(-1) 时最初超过500个脉冲 s^(-1)。在刺激开始后的200毫秒内放电频率下降，但随后持续，瞬时放电频率超过100个脉冲 s^(-1) 至少持续接下来的800毫秒。在较低浓度下，在开始放电之前会有延迟，然后放电模式不规则。该细胞对所测试的几种其他作为游离碱及其氮氧化物的吡咯里西啶生物碱中的一些（但不是全部）同样敏感。它也对哇巴因（其也可能作为一种防御性化合物）以及天冬酰胺和果糖有反应，但阈值比吡咯里西啶生物碱高得多。
