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.
"). 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). "
"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 ,  and other vertebrates (Xenopus laevis: ; sturgeon: ; zebrafish: ; bat: ). "
[Show abstract][Hide abstract] ABSTRACT: Glutamate is the main excitatory neurotransmitter involved in spinal cord circuits in vertebrates, but in most groups the distribution of glutamatergic spinal neurons is still unknown. Lampreys have been extensively used as a model to investigate the neuronal circuits underlying locomotion. Glutamatergic circuits have been characterized on the basis of the excitatory responses elicited in postsynaptic neurons. However, the presence of glutamatergic neurochemical markers in spinal neurons has not been investigated. In this study, we report for the first time the expression of a vesicular glutamate transporter (VGLUT) in the spinal cord of the sea lamprey. We also study the distribution of glutamate in perikarya and fibers. The largest glutamatergic neurons found were the dorsal cells and caudal giant cells. Two additional VGLUT-positive gray matter populations, one dorsomedial consisting of small cells and another one lateral consisting of small and large cells were observed. Some cerebrospinal fluid-contacting cells also expressed VGLUT. In the white matter, some edge cells and some cells associated with giant axons (Müller and Mauthner axons) and the dorsolateral funiculus expressed VGLUT. Large lateral cells and the cells associated with reticulospinal axons are in a key position to receive descending inputs involved in the control of locomotion. We also compared the distribution of glutamate immunoreactivity with that of γ-aminobutyric acid (GABA) and glycine. Colocalization of glutamate and GABA or glycine was observed in some small spinal cells. These results confirm the glutamatergic nature of various neuronal populations, and reveal new small-celled glutamatergic populations, predicting that some glutamatergic neurons would exert complex actions on postsynaptic neurons.
PLoS ONE 10/2012; 7(10):e47898. DOI:10.1371/journal.pone.0047898 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We studied the organization of Met-enkephalin-containing cells and fibers in the developing preoptic-hypophyseal system of the brown trout (Salmo trutta fario) by immunohistochemistry and determined the relationship of these cells and fibers to the galaninergic and GABAergic systems. Met-enkephalin immunoreactivity was observed in cells in the preoptic area, the hypothalamus and the pituitary of late larvae. In the hypophysis, a few Met-enkephalin-containing cells were present in all divisions of the adenohypophysis, and some immunoreactive fibers were present in the interdigitations of the neural lobe with the proximal pars distalis. Concurrently, GABAergic fibers innervated the anterior and posterior neural lobe. Galanin cells coexisted with Met-enkephalin cells in neuronal groups of the preoptic-hypophyseal system. Galaninergic and GABAergic fibers innervated the preoptic and hypothalamic areas, but GABAergic fibers containing galanin were not observed. These results indicate that Met-enkephalin, galanin and GABA may modulate neuroendocrine activities in the preoptic area, hypothalamus and pituitary during the transition from larval to juvenile period. To better know how the development of the trout preoptic-hypophyseal system takes place, we studied the patterns of cell proliferation and expression of Pax6, a conserved transcription factor involved in the hypophysis development. Pax6 expressing cells and proliferating cells were present in the Rathke's pouch, the hypothalamus and the hypophysis of early larvae. In late larvae, Pax6 expression was no longer observed in these areas, and the density of proliferating cells largely decreased throughout development, although they remained in the hypophysis of late larvae and juveniles, suggesting that Pax6 might play an important role in the early regionalization of the pituitary in the trout.
General and Comparative Endocrinology 05/2011; 173(1):148-58. DOI:10.1016/j.ygcen.2011.05.012 · 2.47 Impact Factor
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