Proctolin affects gut functions in lepidopteran larvae
Proctolin affects gut functions in lepidopteran larvae
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DOI：
10.1111/j.1439-0418.2009.01501.x
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发表时间：
2010-12-01
影响因子：
1.9
通讯作者：
Giordana, B.
中科院分区：
文献类型：
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作者：
Fiandra, L.;Casartelli, M.;Giordana, B.
我们研究了五肽proctolin，一个良好的研究肌营养性神经递质/神经调节剂，其中可能的作用，在昆虫控制已被建议，影响鳞翅目幼虫的胃肠道功能。我们验证了在模式物种的家蚕（鳞翅目，Bombicidae），如果内脏肌肉的幼虫肠道表达受体的肽，通过监测自发收缩的后肠中存在或不存在的proctolin。蠕动收缩的频率仅在非常高的肽浓度下增加，表明proctolin可以以低亲和力有效地结合非特异性受体。通过记录标准营养指标，研究了四龄幼虫口服递增剂量的proctolin对幼虫适合度的影响。在最低试验剂量（0.18 mg/g幼虫）下观察到摄食和消化食物转化为身体物质的效率显著降低，同时相对生长率（RGR）降低。给予的肽的量似乎是关键的，因为10倍高剂量的proctolin通过刺激摄食行为消除了对RGR的负面影响，这可能是由于代偿机制的激活。在多食性害虫Spodoptera littoralis（鳞翅目，夜蛾科）中也观察到低浓度的proctolin对幼虫RGR的类似降低。
We examined if the pentapeptide proctolin, a well-investigated myotropic neutrotrasmitter/neuromodulator for which a possible role in insect control has been suggested, affected the gastrointestinal function in lepidopteran larvae. We verified in the model species Bombyx mori (Lepidoptera, Bombicidae) if the visceral muscles of the larval gut expressed receptors for the peptide, by monitoring the spontaneous contractions of the hindgut in the absence or in the presence of proctolin. The frequency of the peristaltic contractions increased only at a very high concentration of the peptide, suggesting that proctolin could effectively bind with low affinity to non-specific receptors. The outcome on larval fitness of increasing doses of proctolin orally administered to fourth instar larvae were investigated by recording the standard nutritional indices. A significant decrease of the Efficiency of Conversion of Ingested and Digested food to body substance with a concomitant reduction of the Relative Growth Rate (RGR) was observed at the lowest dose tested (0.18 mg/g larva). The amount of peptide administered appeared critical, because a 10-fold higher dose of proctolin abolished the negative effect on RGR by a stimulation of the feeding behaviour, possibly as a result of the activation of compensatory mechanisms. A similar decrease of larval RGR with a low concentration of proctolin was observed also in the polyphagous pest Spodoptera littoralis (Lepidoptera, Noctuidae).