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Choline uptake in cholinergic nodose cell bodies
B Palouzier-Paulignan1, M C Chamoin, J P Ternaux
1CNRS UPR 148, Marseille, France.
Neuroscience
|January 1, 1991
Summary
Researchers isolated rabbit nodose ganglion cell bodies to study choline uptake. Two distinct mechanisms, one sodium-dependent and one sodium-independent, were identified at the cell body level, differing in hemicholinium-3 sensitivity.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- Cholinergic cell bodies are present in the vagus nerve's afferent fibers.
- Understanding choline uptake in neuron cell somata is crucial for neurotransmitter synthesis.
Purpose of the Study:
- To investigate choline uptake mechanisms in isolated adult rabbit nodose ganglion neuron cell bodies.
- To characterize the properties of these uptake systems and their relation to acetylcholine synthesis.
Main Methods:
- Mechanical and enzymatic dissociation of nodose ganglia.
- Percoll gradient centrifugation for cell isolation.
- Choline acetyltransferase immunohistological staining.
- [3H]choline uptake assays under varying conditions (sodium dependence, hemicholinium-3 inhibition).
Main Results:
- Isolated 45% of living cell bodies, with 2.9% identified as cholinergic.
- Detected two [3H]choline uptake mechanisms at the cell body level.
- A high-affinity, sodium-dependent system (Km1=7 µM) related to acetylcholine synthesis (43%) and inhibited by hemicholinium-3 (IC50=50 µM).
- A low-affinity, sodium-independent system (Km2=54 µM) poorly associated with acetylcholine synthesis (12%) and less sensitive to hemicholinium-3 (IC50=2 µM).
Conclusions:
- Somatic choline uptake mechanisms share similarities with synaptic systems but exhibit distinct hemicholinium-3 sensitivities.
- The findings suggest potential roles for somatic choline transport in acetylcholine metabolism and release.