Distribution of glycine immunoreactivity in the brain of the Siberian sturgeon (Acipenser baeri): Comparison with γ-aminobutyric acid

Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
The Journal of Comparative Neurology (Impact Factor: 3.23). 04/2011; 519(6):1115-42. DOI: 10.1002/cne.22556
Source: PubMed


Glycine and γ-aminobutyric acid (GABA) are the main inhibitory neurotransmitters in the central nervous system (CNS) of vertebrates. Studies on the distribution of glycinergic neurons and fibers have been carried out mainly in rodents and lampreys. With the aim of discovering more about the early evolution of this system in vertebrates, we analyzed the distribution of glycine-immunoreactive (Gly-ir) neurons and fibers in the CNS of a basal ray-finned fish, the Siberian sturgeon (Chondrostei, Acipenseriformes), by use of immunohistochemical techniques. We also compared the distribution of glycine and GABA by the use of double-immunofluorescence techniques and confocal microscopy. Our results revealed the presence of Gly-ir cells in different regions of the CNS, such as olfactory bulbs, preoptic area, hypothalamus, thalamus, pretectum, optic tectum, tegmentum and rostral spinal cord, although most of the Gly-ir cells and the most intensely immunoreactive cells were located in the rhombencephalon, mainly in the octavolateral area and reticular formation. In addition, coronet cells of the basal hypothalamus and saccus vasculosus were Gly-ir. Glycinergic fibers coursed along most brain regions and were more abundant in the thalamus, hypothalamus, optic tectum, tegmentum, isthmic region, and basal rhombencephalon. The Mauthner cell perikaryon was richly innervated by Gly-ir boutons, as reported for teleosts. With regard to the colocalization of glycine and GABA, double-immunoreactive cells were located mainly in the rhombencephalon. The results enable us to conclude that the distribution of glycine in the sturgeon brain is more similar to that observed in lampreys than that observed in mammals.

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    • "). By using anti-glycine antibody, the developmental expression of glycine immunoreactivity was studied in the brain of lamprey (Villar-Cervi~ no et al., 2008a,b), sturgeon fish (Adrio et al., 2011), zebrafish (Moly and Hatta, 2011; Barreiro-Iglesias et al., 2013), salamander (Landwehr and Dicke, 2005), guinea pig (Ostapoff et al.,1997), and in the spinal cord of frog (Dale et al., 1986; Roberts et al., 1988), chick (Berki et al., 1995), lamprey (Villar-Cervi~ no et al., 2008a), and mouse (Allain et al., 2006). GlyT2 expression was studied in the central nervous system of mouse by using anti-GlyT2 antibody (Jursky and Nelson, 1996), and in situ hybridization was used to study glyt2 mRNA expression in the CNS of Xenopus (Wester et al., 2008), zebrafish (Higashijima et al., 2004; Cui et al., 2005; Barreiro-Iglesias et al., 2013), and rat (Zafra et al., 1995b; Luque et al., 1995; Tanaka and Ezure, 2004). "
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    ABSTRACT: Glycine is a major inhibitory neurotransmitter in the central nervous system of vertebrates. Here, we report the initial development of glycine-immunoreactive (Gly-ir) neurons and fibers in zebrafish. The earliest Gly-ir cells were found in the hindbrain and rostral spinal cord by 20 hours post-fertilization (hpf). Gly-ir cells in rhombomeres 5 and 6 that also expressed glycine transporter 2 (glyt2) mRNA were highly stereotyped; they were bilaterally located and their axons ran across the midline and gradually turned caudally, joining the medial longitudinal fascicles in the spinal cord by 24 hpf. Gly-ir neurons in rhombomere 5 were uniquely identified, since there was one per hemisegment, whereas the number of Gly-ir neurons in rhombomere 6 were variable from one to three per hemisegment. Labeling of these neurons by single-cell electroporation and tracing them until the larval stage revealed that they became MiD2cm and MiD3cm respectively. The retrograde labeling of reticulo-spinal neurons in Tg(glyt2:gfp) larva, which express GFP in Gly-ir cells, and a genetic mosaic analysis with glyt2:GFP DNA construct also supported this notion. Gly-ir cells were also distributed widely in the anterior brain by 27 hpf, whereas glyt2 was hardly expressed. Double staining with anti-glycine and anti-GABA antibodies demonstrated distinct distributions of Gly-ir and GABA-ir cells, as well as the presence of doubly immunoreactive cells in the brain and placodes. These results provide evidence of identifiable glycinergic (Gly-ir/glyt2-positive) neurons in vertebrate embryos, and they can be used in further studies of the neurons' development and function at the single-cell level. © 2013 Wiley Periodicals, Inc. Develop Neurobiol, 2013.
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    • "It was tested in sections of retina and cerebellum from various mammals and other vertebrates as well as in dot blot immunoassays against a variety of amino acid-carrier protein conjugates, including the standard 20 amino acids found in proteins; the nonprotein amino acids D-serine, D-alanine and D-aspartate; GABA; and the glycine containing peptide glutathione, which did not yield significant reactivity. This antibody has been used in a number of studies of glycinergic neurons of the retina, brain and spinal cord of the sea lamprey [31], [53] and other vertebrates (Xenopus laevis: [102]; sturgeon: [103]; zebrafish: [104]; bat: [105]). "
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