Phylogeny of a serotonin-immunoreactive neuron in the primary olfactory center of the insect brain
Phylogeny of a serotonin-immunoreactive neuron in the primary olfactory center of the insect brain
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DOI：
10.1002/cne.21076
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发表时间：
2006-10-20
影响因子：
2.5
通讯作者：
Hildebrand, John G.
中科院分区：
文献类型：
--
作者：
Dacks, Andrew M.;Christensen, Thomas A.;Hildebrand, John G.
5-羟色胺（5-hydroxytryptamine，5-HT）是昆虫体内的一种神经递质、神经调质和神经激素。在天蛾Manduca sexta中，每对触角叶（AL;昆虫大脑中的主要嗅觉中心）都有一个5 HT免疫反应（5 HT-ir）神经元投射到前脑。穿过后正中线支配对侧神经AL;这被称为对侧投射的、胡萝卜素免疫反应性中脑（CSD）神经元。这些神经元被认为是嗅觉敏感性的离心调节器。要检查的系统发育分布的5 HT-IR神经元显然是同源的CSD神经元，我们成像5 HT样免疫反应在40种昆虫的大脑中属于38个家庭在9个订单。CSD神经元在鳞翅目、毛翅目、双翅目、鞘翅目、脉翅目等昆虫中均有发现，但在膜翅目昆虫中未发现。在paraneopteran和polyneopteran物种（昆虫进行不完全变态）检查，AL 5 HT神经元支配同侧AL和项目的protocerebrum。我们的研究结果表明，CSD神经元的特征形态起源于全变态昆虫（那些经历完全变态），并失去了在Hytera。在双翅目的一个亚群中，CSD神经元在对侧AL内分支，并通过触角投射回同侧AL。连合AL的5 HT神经元的进化进行了讨论的背景下观察到的鳞翅目AL的5 HT的生理作用。
Serotonin (5-hydroxytryptamine; 5HT) functions in insects as a neurotransmitter, neuromodulator, and neurohormone. In the sphinx moth Manduca sexta, each of the paired antennal lobes (ALs; the primary olfactory centers in the insect brain) has one 5HT-immunoreactive (5HT-ir) neuron that projects into the protocerebrum., crosses the posterior midline, and innervates the contralateral. AL; this is referred to as the contralaterally projecting, serotonin-immunoreactive deutocerebral (CSD) neuron. These neurons are thought to function as centrifugal modulators of olfactory sensitivity. To examine the phylogenetic distribution of 5HT-ir neurons apparently homologous to the CSD neuron, we imaged 5HT-like immunoreactivity in the brains of 40 species of insects belonging to 38 families in nine orders. CSD neurons were found in other Lepidoptera, Trichoptera, Diptera, Coleoptera, and Neuroptera but not in the Hymenoptera. In the paraneopteran and polyneopteran species (insects that undergo incomplete metamorphosis) examined, AL 5HT neurons innervate the ispsilateral AL and project to the protocerebrum. Our findings suggest that the characteristic morphology of the CSD neurons originated in the holometabolous insects (those that undergo complete metamorphosis) and were lost in the Hymenoptera. In a subset of the Diptera, the CSD neurons branch within the contralateral AL and project back to the ipsilateral AL via the antennal. commissure. The evolution of AL 5HT neurons is discussed in the context of the physiological actions of 5HT observed in the lepidopteran AL.