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Zinc-enriched GABAergic terminals in mouse spinal cord.
1Department of Anatomy and Cell Biology, Göteborg University, Gothenburg, Sweden.
Brain Research
|November 27, 2001
Summary
This study reveals that most zinc-enriched terminals in the mouse spinal cord are GABAergic, with some excitatory glutamatergic and inhibitory glycinergic terminals also identified. These findings advance our understanding of neurotransmission and spinal cord circuitry.
Area of Science:
- Neuroscience
- Neurochemistry
- Spinal Cord Research
Background:
- Zinc ions are known to modulate glutamate and GABA receptors in the brain.
- Previously, all identified zinc-enriched neuronal pathways were glutamatergic.
- Zinc-enriched terminals with specific morphological features have been observed in the spinal cord.
Purpose of the Study:
- To investigate the colocalization of zinc ions, zinc transporter-3 (ZnT3), and glutamic acid decarboxylase (GAD) in spinal cord terminals.
- To characterize the identity and distribution of zinc-enriched terminals in the mouse spinal cord.
Main Methods:
- Confocal analysis of ZnT3 and GAD immunofluorescence at the light microscopic level.
- Zinc selenium autometallography and GAD immunocytochemistry at the electron microscopic level.
- Morphological classification of synaptic terminals based on vesicle shape and synapse symmetry.
Main Results:
- Colocalization of zinc ions and GAD was observed in synaptic vesicles of zinc-enriched terminals throughout the mouse spinal cord.
- Zinc-enriched/GABAergic terminals were most abundant in laminae I and III of the dorsal horn and radiated from the white matter.
- A subset of zinc-enriched terminals lacked GAD, and some GAD-positive terminals lacked zinc; these were morphologically classified as likely glutamatergic or glycinergic.
Conclusions:
- The majority of zinc-enriched terminals in the spinal cord are GABAergic.
- Zinc-enriched terminals with excitatory morphology are likely glutamatergic.
- Some zinc-enriched terminals with inhibitory morphology are likely glycinergic, not GABAergic.