Regulation of glutamatergic and GABAergic neurotransmission in the chick nucleus laminaris: role of N-type calcium channels.

Title

Regulation of glutamatergic and GABAergic neurotransmission in the chick nucleus laminaris: role of N-type calcium channels.

Creator

Lu Y

Publisher

Neuroscience

Date

2009
2009-12

Description

Neurons in the chicken nucleus laminaris (NL), the third order auditory nucleus involved in azimuth sound localization, receive bilaterally segregated (ipsilateral vs contralateral) glutamatergic excitation from the cochlear nucleus magnocellularis and GABAergic inhibition from the ipsilateral superior olivary nucleus (SON). Here, I investigate the voltage-gated calcium channels (VGCCs) that trigger the excitatory and the inhibitory transmission in the NL. Whole-cell recordings were performed in acute brainstem slices. The excitatory transmission was predominantly mediated by N-type VGCCs, as the specific N-type blocker omega-Conotoxin-GVIA (omega-CTx-GVIA, 1-2.5 microM) inhibited excitatory postsynaptic currents (EPSCs) by approximately 90%. Blockers for P/Q- and L-type VGCCs produced no inhibition, and blockade of R-type VGCCs produced a small inhibition. In individual cells, the effect of each VGCC blocker on the EPSC elicited by activation of the ipsilateral input was the same as that on the EPSC elicited by activation of the contralateral input, and the two EPSCs had similar kinetics, suggesting physiological symmetry between the two glutamatergic inputs to single NL neurons. The inhibitory transmission in NL neurons was almost exclusively mediated by N-type VGCCs, as omega-CTx-GVIA (1 microM) produced a approximately 90% reduction of inhibitory postsynaptic currents, whereas blockers for other VGCCs produced no inhibition. In conclusion, N-type VGCCs play a dominant role in triggering both the excitatory and the inhibitory transmission in the NL, and the presynaptic VGCCs that mediate the two bilaterally segregated glutamatergic inputs to individual NL neurons are identical. These features may play a role in optimizing coincidence detection in NL neurons.

Subject

Animals; Auditory Pathways/cytology/drug effects/metabolism; Calcium Channel Blockers/pharmacology; Calcium Channels; Chick Embryo; Chickens; Cochlear Nucleus/cytology/drug effects/*metabolism; Excitatory Postsynaptic Potentials/drug effects/physiology; Functional Laterality/drug effects/physiology; gamma-Aminobutyric Acid/*metabolism; Glutamic Acid/*metabolism; N-Type/*metabolism; Neural Inhibition/physiology; Neurons/drug effects/metabolism; omega-Conotoxin GVIA/pharmacology; Organ Culture Techniques; Patch-Clamp Techniques; Rhombencephalon/cytology/*metabolism; Synaptic Transmission/drug effects/*physiology

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

1009–1019

Issue

3

Volume

164

Citation

Lu Y, “Regulation of glutamatergic and GABAergic neurotransmission in the chick nucleus laminaris: role of N-type calcium channels.,” NEOMED Bibliography Database, accessed April 20, 2021, https://neomed.omeka.net/items/show/3737.

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