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In vivo Calcium Imaging of Mouse Geniculate Ganglion Neuron Responses to Taste Stimuli
Published on: February 11, 2021
Interaction between the second messengers cAMP and Ca2+ in mouse presynaptic taste cells
Craig D Roberts1, Gennady Dvoryanchikov, Stephen D Roper
1Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
The Journal of Physiology
|February 18, 2009
Summary
Elevated cyclic adenosine monophosphate (cAMP) triggers calcium (Ca2+) influx in specific presynaptic taste cells via protein kinase A and L-type channels. This reveals cross-talk between cAMP and Ca2+ signaling in taste bud function.
Area of Science:
- Neuroscience
- Cell Biology
- Sensory Biology
Background:
- Cyclic adenosine monophosphate (cAMP) is a key second messenger in taste buds, but its specific cellular targets and functional roles remain unclear.
- Understanding how different taste cell types respond to cAMP is crucial for deciphering taste signal transduction pathways.
Purpose of the Study:
- To identify which taste cell types exhibit cAMP-modulated calcium (Ca2+) signaling.
- To elucidate the molecular mechanisms and functional consequences of cAMP-induced Ca2+ changes in taste cells.
Main Methods:
- Utilized Fura-2 imaging in isolated mouse vallate taste cells to measure intracellular Ca2+ levels.
- Employed forskolin (Fsk) and isobutylmethylxanthine (IBMX) to elevate intracellular cAMP levels.
- Used transgenic GAD-GFP mice, protein kinase A (PKA) inhibitors, and specific Ca2+ channel blockers for mechanistic studies.
- Performed single-cell RT-PCR to confirm gene expression of Ca2+ channel subunits.
Main Results:
- Elevating cAMP triggered Ca2+ transients in 38% of presynaptic taste cells (Type III), specifically those lacking glutamic acid decarboxylase 67 (GAD).
- These cAMP-induced Ca2+ responses were dependent on PKA and involved the influx of extracellular Ca2+ through L-type voltage-gated Ca2+ channels (Ca(v)1.2).
- Receptor cells (Type II) and GAD-expressing presynaptic cells did not show cAMP-stimulated Ca2+ responses.
Conclusions:
- A specific subclass of presynaptic taste cells integrates cAMP signaling pathways.
- This cross-talk between cAMP and Ca2+ signaling, mediated by PKA and L-type Ca2+ channels, likely plays a role in modulating taste perception.
- These findings provide new insights into the complex signaling networks within taste buds.
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