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VIP modulates neuronal nicotinic acetylcholine receptor function by a cyclic AMP-dependent mechanism
D Gurantz1, A T Harootunian, R Y Tsien
1Department of Pharmacology, University of California at San Diego, La Jolla 92093.
Summary
Vasoactive intestinal peptide (VIP) enhances acetylcholine receptor (AChR) sensitivity in chick neurons by increasing intracellular cAMP. This peptide acts as a first messenger, modulating neuronal function via a cAMP-dependent pathway.
Area of Science:
- Neuroscience
- Cellular Signaling
Background:
- Neuronal nicotinic acetylcholine receptors (AChRs) are crucial for synaptic transmission.
- Cellular processes, including second messenger signaling, regulate AChR function.
- cAMP analogs enhance ACh sensitivity in chick ciliary ganglion neurons, suggesting increased functional receptors.
Purpose of the Study:
- To identify the neuromodulator involved in cAMP-mediated regulation of neuronal AChRs.
- To investigate the role of vasoactive intestinal peptide (VIP) in modulating ACh sensitivity.
Main Methods:
- Used cAMP imaging and biochemical assays to measure intracellular cAMP levels.
- Employed whole-cell recording to assess neuronal ACh sensitivity.
- Administered VIP and calcitonin gene-related peptide (CGRP) to isolated neurons.
Main Results:
- VIP application rapidly elevated intracellular cAMP in ciliary ganglion neurons.
- VIP treatment enhanced neuronal ACh sensitivity with a short latency.
- The effect of VIP was similar to cAMP analogs and not additive.
- CGRP had no significant effect on cAMP levels or ACh sensitivity.
Conclusions:
- VIP enhances ACh sensitivity in ciliary ganglion neurons through a cAMP-dependent pathway.
- VIP likely interacts with a specific receptor to initiate this signaling cascade.
- The presence of VIP-like immunoreactivity suggests a potential in vivo role for VIP in modulating AChRs.