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Analysis of neurotransmitter distribution in brain development of benthic and pelagic octopod cephalopods

Authors

  • Tim Wollesen,

    1. Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria
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  • Charuay Sukhsangchan,

    1. Department of Marine Science, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand
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  • Pedro Seixas,

    1. Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, La Curuña, Spain
    2. Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, La Curuña, Spain
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  • Jaruwat Nabhitabhata,

    1. Center for Biodiversity of Peninsular Thailand, Department of Biology, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand
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  • Andreas Wanninger

    Corresponding author
    1. Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria
    • University of Vienna, Faculty of Life Sciences, Department of Integrative Zoology, Althanstr. 14, 1090 Vienna, Austria
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Abstract

The database on neurotransmitter distribution during central nervous system development of cephalopod mollusks is still scarce. We describe the ontogeny of serotonergic (5-HT-ir) and FMRFamide-like immunoreactive (Fa-lir) neurons in the central nervous system of the benthic Octopus vulgaris and Fa-lir distribution in the pelagic Argonauta hians. Comparing our data to previous studies, we aim at revealing shared immunochemical domains among coleoid cephalopods, i.e., all cephalopods except nautiluses. During development of O. vulgaris, 5-HT-ir and Fa-lir elements occur relatively late, namely during stage XII, when the brain neuropils are already highly differentiated. In stage XII-XX individuals, Fa-lir cell somata are located in the middle and posterior subesophageal mass and in the optic, posterior basal, and superior buccal lobes. 5-HT is predominately expressed in cell somata of the superior buccal, anterior basal, and optic lobes, as well as in the subesophageal mass. The overall population of Fa-lir neurons is larger than the one expressing 5-HT. Fa-lir elements are distributed throughout homologous brain areas of A. hians and O. vulgaris. We identified neuronal subsets with similar cell number and immunochemical phenotype in coleoids. These are located in corresponding brain regions of developmental stages and adults of O. vulgaris, A. hians, and the decapod squid Idiosepius notoides. O. vulgaris and I. notoides exhibit numerous 5-HT-ir cell somata in the superior buccal lobes but none or very few in the inferior buccal lobes. The latter have previously been homologized to the gastropod buccal ganglia, which also lack 5-HT-ir cell somata in euthyneuran gastropods. Among coleoids, 5-HT-ir neuronal subsets, which are located ventrally to the lateral anterior basal lobes and in the anterior middle subesophageal mass, are candidates for homologous subsets. Contrary to I. notoides, octopods exhibit Fa-lir cell somata ventrally to the brachial lobes and 5-HT-ir cell somata close to the stellate ganglia. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.

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