The locus coeruleus complex of the bottlenose dolphin (Tursiops truncatus) as revealed by tyrosine hydroxylase immunohistochemistry

Authors

  • Paul R. Manger,

    1. Department of Psychiatry, University of California, Los Angeles, Neurobiology Research, Sepulveda VAMC, North Hills, CA, USA,
    2. Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Parktown, Johannesburg, Republic of South Africa and
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  • Sam H. Ridgway,

    1. Navy Marine Mammal Program, SSC SD, San Diego, CA, USA
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  • Jerome M. Siegel

    1. Department of Psychiatry, University of California, Los Angeles, Neurobiology Research, Sepulveda VAMC, North Hills, CA, USA,
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: Paul Manger, School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, Republic of South Africa. Tel.: +27 11 7172497; fax: +27 11 7172422; e-mail: mangerpr@anatomy.wits.ac.za

Summary

Using tyrosine hydroxylase immunohistochemistry we examined the structure of the pontine, or rostral rhombencephalic, catecholaminergic cells groups, which may be collectively termed the locus coeruleus complex (LC), in the bottlenose dolphin. The present study is the first to describe the LC in a cetacean species and, at 1.3 kg, represents the largest non-human brain to date in which the LC has been investigated. We identified four catecholaminergic cell groups in the dorsal pontine tegementum and peri-aqueductal gray matter: A6 dorsal (locus coeruleus), A6 ventral (locus coeruleus alpha), A7 (subcoeruleus), and A5 (fifth arcuate nucleus). No patterns of cellular distribution, nuclear subdivision, or cellular morphology indicate specialization of the LC, which might have been anticipated because of the large absolute brain size and unihemispheric sleep phenomenology of cetaceans.

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