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  • Society for Neuroscience  (3)
  • 2005-2009  (3)
  • Linguistics  (3)
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  • Society for Neuroscience  (3)
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  • 2005-2009  (3)
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  • 1
    Online Resource
    Online Resource
    Primary Afferent Synapses on Developing and Adult Renshaw Cells
    Society for Neuroscience ; 2006
    In:  The Journal of Neuroscience Vol. 26, No. 51 ( 2006-12-20), p. 13297-13310
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 26, No. 51 ( 2006-12-20), p. 13297-13310
    Abstract: The mechanisms that diversify adult interneurons from a few pools of embryonic neurons are unknown. Renshaw cells, Ia inhibitory interneurons (IaINs), and possibly other types of mammalian spinal interneurons have common embryonic origins within the V1 group. However, in contrast to IaINs and other V1-derived interneurons, adult Renshaw cells receive motor axon synapses and lack proprioceptive inputs. Here, we investigated how this specific pattern of connectivity emerges during the development of Renshaw cells. Tract tracing and immunocytochemical markers [parvalbumin and vesicular glutamate transporter 1 (VGLUT1)] showed that most embryonic (embryonic day 18) Renshaw cells lack dorsal root inputs, but more than half received dorsal root synapses by postnatal day 0 (P0) and this input spread to all Renshaw cells by P10–P15. Electrophysiological recordings in neonates indicated that this input is functional and evokes Renshaw cell firing. VGLUT1-IR bouton density on Renshaw cells increased until P15 but thereafter decreased because of limited synapse proliferation coupled with the enlargement of Renshaw cell dendrites. In parallel, Renshaw cell postsynaptic densities apposed to VGLUT1-IR synapses became smaller in adult compared with P15. In contrast, vesicular acetylcholine transporter-IR motor axon synapses contact embryonic Renshaw cells and proliferate postnatally matching Renshaw cell growth. Like other V1 neurons, Renshaw cells are thus competent to receive sensory synapses. However, after P15, these sensory inputs appear deselected through arrested proliferation and synapse weakening. Thus, Renshaw cells shift from integrating sensory and motor inputs in neonates to predominantly motor inputs in adult. Similar synaptic weight shifts on interneurons may be involved in the maturation of motor reflexes and locomotor circuitry.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.2945-06.2006
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2006
    detail.hit.zdb_id: 1475274-8
    detail.hit.zdb_id: 604637-X
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Differential Postnatal Maturation of GABA A , Glycine Receptor, and Mixed Synaptic Currents in Renshaw Cells and Ventral Spinal Interneurons
    Society for Neuroscience ; 2005
    In:  The Journal of Neuroscience Vol. 25, No. 8 ( 2005-02-23), p. 2010-2023
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 25, No. 8 ( 2005-02-23), p. 2010-2023
    Abstract: Renshaw cells (RCs) receive excitatory inputs from motoneurons to which then they inhibit. The gain of this spinal recurrent inhibitory circuit is modulated by inhibitory synapses on RCs. Inhibitory synapses on RCs mature postnatally, developing unusually large postsynaptic gephyrin clusters that colocalize glycine and GABA A receptors. We hypothesized that these features potentiate inhibitory currents in RCs. Thus, we analyzed glycinergic and GABAergic “inhibitory” miniature postsynaptic currents (mPSCs) in neonatal [postnatal day 1 (P1) to P5] and mature (P9-P15) RCs and compared them to other ventral interneurons (non-RCs). Recorded neurons were Neurobiotin filled and identified as RCs or non-RCs using post hoc immunohistochemical criteria. Glycinergic, GABAergic, and mixed glycine/GABA mPSCs matured differently in RCs and non-RCs. In RCs, glycinergic and GABA A mPSC peak amplitudes increased 230 and 45%, respectively, from P1-P5 to P9-P15, whereas in non-RCs, glycinergic peak amplitudes changed little and GABA A amplitudes decreased. GABA A mPSCs were slower in RCs (P1-P5, τ = 58 ms; P9-P15, τ = 43 ms) compared with non-RCs (P1-P5, τ = 27 ms; P9-P15, τ = 14 ms). Thus, fast glycinergic currents dominated “mixed” mPSC peak amplitudes in mature RCs, and GABA A currents dominated their long decays. In non-RCs, GABAergic and mixed events had shorter durations, and their frequencies decreased with development. Functional maturation of inhibitory synapses on RCs correlates well with increased glycine receptor recruitment to large gephyrin patches, colocalization with α3/α5-containing GABA A receptors, and maintenance of GABA/glycine corelease. As a result, charge transfer in GABA, glycine, or mixed mPSCs was larger in mature RCs than in non-RCs, suggesting RCs receive potent inhibitory synapses.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.2383-04.2005
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2005
    detail.hit.zdb_id: 1475274-8
    detail.hit.zdb_id: 604637-X
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Regulation of Gephyrin Cluster Size and Inhibitory Synaptic Currents on Renshaw Cells by Motor Axon Excitatory Inputs
    Society for Neuroscience ; 2005
    In:  The Journal of Neuroscience Vol. 25, No. 2 ( 2005-01-12), p. 417-429
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 25, No. 2 ( 2005-01-12), p. 417-429
    Abstract: Renshaw cells receive a high density of inhibitory synapses characterized by large postsynaptic gephyrin clusters and mixed glycinergic/GABAergic inhibitory currents with large peak amplitudes and long decays. These properties appear adapted to increase inhibitory efficacy over Renshaw cells and mature postnatally by mechanisms that are unknown. We tested the hypothesis that heterosynaptic influences from excitatory motor axon inputs modulate the development of inhibitory synapses on Renshaw cells. Thus, tetanus (TeNT) and botulinum neurotoxin A (BoNT-A) were injected intramuscularly at postnatal day 5 (P5) to, respectively, elevate or reduce motor axon firing activity for ∼2 weeks. After TeNT injections, the average gephyrin cluster areas on Renshaw cells increased by 18.4% at P15 and 28.4% at P20 and decreased after BoNT-A injections by 17.7% at P15 and 19.9% at P20. The average size differences resulted from changes in the proportions of small and large gephyrin clusters. Whole-cell recordings in P9-P15 Renshaw cells after P5 TeNT injections showed increases in the peak amplitude of glycinergic miniature postsynaptic currents (mPSCs) and the fast component of mixed (glycinergic/GABAergic) mPSCs compared with controls (60.9% and 78.9%, respectively). GABAergic mPSCs increased in peak amplitude to a smaller extent (45.8%). However, because of the comparatively longer decays of synaptic GABAergic currents, total current transfer changes after TeNT were similar for synaptic glycine and GABA A receptors (56 vs 48.9% increases, respectively). We concluded that motor axon excitatory synaptic activity modulates the development of inhibitory synapse properties on Renshaw cells, influencing recruitment of postsynaptic gephyrin and glycine receptors and, to lesser extent, GABA A receptors.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.3725-04.2005
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2005
    detail.hit.zdb_id: 1475274-8
    detail.hit.zdb_id: 604637-X
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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