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Cobalt-permeable non-NMDA receptors in developing chick brainstem auditory nuclei
N Zhou1, D A Taylor, T N Parks
1Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City 84132, USA.
Neuroreport
|November 27, 1995
Summary
Calcium-permeable non-NMDA receptors are transiently expressed in the chick brain stem auditory nuclei during development. Kainate-induced cobalt uptake indicates these receptors play a role in neuronal maturation.
Area of Science:
- Neuroscience
- Developmental Biology
- Auditory System Research
Background:
- Glutamate receptors are key mediators of synaptic transmission in the central nervous system.
- Non-NMDA glutamate receptors, including AMPA and kainate subtypes, are involved in fast excitatory neurotransmission.
- Understanding the developmental expression and function of specific glutamate receptor subtypes is crucial for deciphering neuronal circuit formation.
Purpose of the Study:
- To investigate the role of non-NMDA glutamate receptors in the developing chick brain stem auditory nuclei.
- To characterize the developmental expression pattern of calcium-permeable non-NMDA receptors.
- To determine the functional significance of these receptors during neuronal maturation and synapse establishment.
Main Methods:
- Utilized cobalt accumulation as a measure of ion flux through activated glutamate receptors.
- Administered kainate, a non-NMDA receptor agonist, to chick embryos at various developmental stages.
- Employed specific antagonists (CNQX, GYKI 53655) to block AMPA/kainate receptors and NMDA receptors.
- Examined cobalt uptake in specific auditory nuclei: angularis (NL) and magnocellularis (NM).
Main Results:
- Kainate evoked significant, concentration-dependent cobalt accumulation in NL and NM.
- Cobalt uptake was completely blocked by AMPA/kainate receptor antagonists (CNQX, GYKI 53655) but not by NMDA receptor antagonists.
- Kainate-induced cobalt uptake was observed from embryonic day (E)9 to E21, peaking at E15.
- Developmental expression showed distinct patterns: uptake was high in NL before E13, declined in NM after E15, and ceased in NL by E21.
Conclusions:
- Calcium-permeable non-NMDA receptors are transiently expressed in chick brain stem auditory nuclei during critical periods of neuronal development.
- These receptors appear to play a significant role in establishing neuronal number, morphology, and synaptic connectivity.
- The developmental regulation of non-NMDA receptor expression suggests a specific functional contribution to auditory circuit maturation.