Voltage-clamp analysis of taurine-induced suppression of excitatory postsynaptic potentials in frog spinal motoneurons

Yasunami, T.; Kuno, Miyuki; Matsuura, Shinya

doi:10.1152/jn.1988.60.4.1405

Cited by 8 publications

(2 citation statements)

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“…An inhibitory neurotransmitter or neuromodulatory role for taurine has been shown in the spinal cord [22,62] and in other CNS regions [63][64][65][66]. The high levels of taurine detected from the embryonic period until the early postnatal development imply that it serves other functions aside from simple neurotransmission, which is consistent with its well-established function in the brain as a trophic factor, an osmoregulator and a membrane stabilizer [20,21,67].…”

Section: Discussionmentioning

confidence: 55%

Levels of Amino Acid Neurotransmitters during Neurogenesis and in Histotypic Cultures of Mouse Spinal Cord

Miranda-Contreras

Benítez-Díaz²,

Peña-Contreras³

et al. 2002

Dev Neurosci

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The development of spinal cord interneurons and the formation of interneuronal synaptic connections has received little attention; the most comprehensively studied developing circuit has been the connection between motoneurons and the muscle they innervate. All motoneurons are cholinergic whereas spinal interneurons are mostly glutamatergic, glycinergic or GABAergic neurons. In this study, we show quantitative data, obtained by high-pressure liquid chromatography (HPLC), on the levels of amino acid neurotransmitters during mouse spinal cord neurogenesis, from embryonic day (E) 12 until postnatal day (P) 30. At E12, high levels of glutamate, glycine and taurine were already detected but between E16 and P3, significant increments in their contents were observed, indicating the occurrence of maximum synaptogenesis during this period. Important reductions in their contents were also observed in two stages: between E12–E16 and P3–P7. These results suggest that the apoptotic death of interneurons and motoneurons in the developing brain or the synapse refinement of neural circuitry during maturation reduced the number of synapses, thereby decreasing the levels of neurotransmitters. The contents of these neurotransmitters were also analyzed in primary cultures of mouse spinal cord prepared from embryos between E13 and E19. As deduced from light microscopy, ultrastructural studies, as well as results from HPLC analysis, the cultures derived from E15–E16 embryos showed the highest degree of histotypic features and neurotransmitter contents comparable with those obtained in situ. Although glycine, GABA and taurine levels reached about 80–90% of normal in situ values, the contents of aspartate and glutamate were lower by about 40%, which could be mainly due to deafferentation of both sensory and supraspinal afferent axon terminals. These results indicate that intrinsic synaptic circuits can be maintained in histotypic spinal cord cultures prepared from E15–E16 mouse embryos. Histotypic cultures of the spinal cord will serve as a good model for studies on the pathophysiology of amino-acid-based neurotransmission and repair strategies in many CNS disorders.

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Section: Discussionmentioning

confidence: 55%

Levels of Amino Acid Neurotransmitters during Neurogenesis and in Histotypic Cultures of Mouse Spinal Cord

Miranda-Contreras

Benítez-Díaz²,

Peña-Contreras³

et al. 2002

Dev Neurosci

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“…A release of taurine car be evoked by depolarizing stimuli (Collins and Topiwala,19 74), and high-affinity uptake systems have been identified (Smith et al, 1992;Uchida et al, 1992;Amara and Arriza, 19\33), Direct application of taurine to spinal neurons induces a hyperpolarizing response (Curtis and Watkins, 1965;Curtis and Johnston, 1974;Sonnhof et d . , 1975;Kurachi and Aihara, 1985;Yasunami et al, 1988;Baev et al, 19921, which can be antagonized by strychnine, suggesting an action on glycine receptors (Sonnhof et al, 1975;Kurachi and Aihara, 1985;Baev et al, 19921, but y-aminobutyric acid (GABA) receptors may also be involved (Nicoll et al, 1976;Baev et al, 1992).…”

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confidence: 99%

Extrasynaptic localization of taurine‐like immunoreactivity in the lamprey spinal cord

Shupliakov

Brodin

Srinivasan

et al. 1994

J of Comparative Neurology

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Taurine is an endogenous amino acid that can occur in nerve terminals in the central nervous system and that can produce inhibitory neuronal responses. It is unclear, however, whether this amino acid can function as a synaptic transmitter. To examine the distribution of taurine at high anatomical resolution in a vertebrate, light and electron microscopic immunocytochemical postembedding techniques were applied to the lamprey spinal cord (Ichtyomyzon unicuspis and Lampetra fluviatilis), which contains many large, unmyelinated axons. The most intense immunolabeling occurred in a population of liquor-contacting cells (tanycytes), located around the central canal, which extended processes to the dorsal, lateral, and ventral margins of the spinal cord. In addition, a proportion of the taurine-immunoreactive cells contained gamma-aminobutyric acid (GABA)-like immunoreactivity. A moderate level of taurine immunoreactivity was also present in ependymal cells, located around the central canal, as well as in astrocytes throughout all regions of the spinal cord. At the ultrastructural level, the taurine immunoreactivity showed an even distribution in the cytoplasm of the labeled cells. In contrast to the glial labeling, neuronal cell bodies and axons exhibited very low levels of taurine labeling, which were similar to the level of background labeling. The synaptic vesicle clusters within the axons did not show any clear accumulation of taurine immunoreactivity. These results suggest that taurine may have metabolic roles in the lamprey spinal cord, and, as in other systems, it may take part in osmoregulation. However, the lack of immunolabeling in presynaptic elements is not consistent with a role of taurine as a synaptic transmitter.

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A quantitative light and electron microscopic analysis of taurine‐like immunoreactivity in the dorsal horn of the rat spinal cord

Lee

Renno

Beitz

1992

J of Comparative Neurology

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Taurine has been proposed as an inhibitory neurotransmitter or neuromodulator in the vertebrate central nervous system. Within the spinal cord, taurine has been shown to have a direct inhibitory effect on spinal neurons and to have a selective antinociceptive effect on chemically induced nociception. Although sufficient data exists to suggest that taurine plays a neurotransmitter or neuromodulatory role in the spinal cord, it is not known whether this amino acid is present in axon terminals nor if this amino acid has a unique pattern of distribution within spinal tissue. To address these questions a monoclonal antibody against taurine was employed to localize taurine-like immunoreactivity in the dorsal horn of the rat spinal cord by using both light and electron microscopic techniques. Taurine-like immunoreactivity was most dense and most prominent in laminae I and II of the dorsal horn. A moderate amount of immunoreactivity was also present in laminae VIII and IX and X while the remaining laminae were only lightly stained. In laminae I and II taurine-like immunostaining was evident within neuronal cell bodies, dendrites, myelinated and unmyelinated axons, axon terminals, and astrocytes and their processes. Cell counts of these two laminae indicated that approximately 30% of neuronal perikarya at the C2 level, 52% of neuronal perikarya at the T6 level, and 18% of neuronal perikarya at the L2 level of the cord exhibited taurine-like immunoreactivity. With preembedding diaminobenzidine staining, approximately 20% of the axons examined in laminae I and II were found to be immunoreactive for taurine. Using postembedding immunogold staining in combination with quantitative procedures, the highest densities of gold particles were found in axon terminals containing pleomorphic vesicles and forming symmetrical synapses (36.8 particles/micron2), in a subpopulation of myelinated axons (34.2 particles/micron2), in a subpopulation of neuronal dendrites (32.6 particles/micron2), and in capillary endothelial cells (39.8 particles/micron2). Moderate labeling occurred in astrocytes (20.9 particles/micron2) and neuronal perikarya (18.7 particles/micron2). The localization of taurine to presumptive inhibitory axon terminals provides anatomical support for the hypothesis that taurine may serve an inhibitory neurotransmitter role in the superficial dorsal horn of the spinal cord. On the other hand, its localization to astrocytes and endothelial cells within both the dorsal ventral horns implies that it serves other nonneuronal functions as well.

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Voltage-clamp analysis of taurine-induced suppression of excitatory postsynaptic potentials in frog spinal motoneurons

Cited by 8 publications

References 0 publications

Levels of Amino Acid Neurotransmitters during Neurogenesis and in Histotypic Cultures of Mouse Spinal Cord

Levels of Amino Acid Neurotransmitters during Neurogenesis and in Histotypic Cultures of Mouse Spinal Cord

Extrasynaptic localization of taurine‐like immunoreactivity in the lamprey spinal cord

A quantitative light and electron microscopic analysis of taurine‐like immunoreactivity in the dorsal horn of the rat spinal cord

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