Abstract
The second messenger, 3′,5′-cyclic adenosine monophosphate (cAMP), is known to be modulated in taste buds following exposure to gustatory and other stimuli. Which taste cell type(s) (Type I/glial-like cells, Type II/receptor cells, or Type III/presynaptic cells) undergo taste-evoked changes of cAMP and what the functional consequences of such changes are remain unknown. Using Fura-2 imaging of isolated mouse vallate taste cells, we explored how elevating cAMP alters Ca2+ levels in identified taste cells. Stimulating taste buds with forskolin (Fsk; 1 μm) + isobutylmethylxanthine (IBMX; 100 μm), which elevates cellular cAMP, triggered Ca2+ transients in 38% of presynaptic cells (n = 128). We used transgenic GAD-GFP mice to show that cAMP-triggered Ca2+ responses occur only in the subset of presynaptic cells that lack glutamic acid decarboxylase 67 (GAD). We never observed cAMP-stimulated responses in receptor cells, glial-like cells or GAD-expressing presynaptic cells. The response to cAMP was blocked by the protein kinase A inhibitor H89 and by removing extracellular Ca2+. Thus, the response to elevated cAMP is a PKA-dependent influx of Ca2+. This Ca2+ influx was blocked by nifedipine (an inhibitor of L-type voltage-gated Ca2+ channels) but was unperturbed by ω-agatoxin IVA and ω-conotoxin GVIA (P/Q-type and N-type channel inhibitors, respectively). Single-cell RT-PCR on functionally identified presynaptic cells from GAD-GFP mice confirmed the pharmacological analyses: Cav1.2 (an L-type subunit) is expressed in cells that display cAMP-triggered Ca2+ influx, while Cav2.1 (a P/Q subunit) is expressed in all presynaptic cells, and underlies depolarization-triggered Ca2+ influx. Collectively, these data demonstrate cross-talk between cAMP and Ca2+ signalling in a subclass of taste cells that form synapses with gustatory fibres and may integrate tastant-evoked signals.
| Original language | English |
|---|---|
| Pages (from-to) | 1657-1668 |
| Number of pages | 12 |
| Journal | Journal of Physiology |
| Volume | 587 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 15 2009 |
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ASJC Scopus subject areas
- Physiology
Cite this
Interaction between the second messengers cAMP and Ca2+ in mouse presynaptic taste cells. / Roberts, Craig D.; Dvoryanchikov, Gennady; Roper, Stephen D; Chaudhari, Nirupa.
In: Journal of Physiology, Vol. 587, No. 8, 15.04.2009, p. 1657-1668.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Interaction between the second messengers cAMP and Ca2+ in mouse presynaptic taste cells
AU - Roberts, Craig D.
AU - Dvoryanchikov, Gennady
AU - Roper, Stephen D
AU - Chaudhari, Nirupa
PY - 2009/4/15
Y1 - 2009/4/15
N2 - The second messenger, 3′,5′-cyclic adenosine monophosphate (cAMP), is known to be modulated in taste buds following exposure to gustatory and other stimuli. Which taste cell type(s) (Type I/glial-like cells, Type II/receptor cells, or Type III/presynaptic cells) undergo taste-evoked changes of cAMP and what the functional consequences of such changes are remain unknown. Using Fura-2 imaging of isolated mouse vallate taste cells, we explored how elevating cAMP alters Ca2+ levels in identified taste cells. Stimulating taste buds with forskolin (Fsk; 1 μm) + isobutylmethylxanthine (IBMX; 100 μm), which elevates cellular cAMP, triggered Ca2+ transients in 38% of presynaptic cells (n = 128). We used transgenic GAD-GFP mice to show that cAMP-triggered Ca2+ responses occur only in the subset of presynaptic cells that lack glutamic acid decarboxylase 67 (GAD). We never observed cAMP-stimulated responses in receptor cells, glial-like cells or GAD-expressing presynaptic cells. The response to cAMP was blocked by the protein kinase A inhibitor H89 and by removing extracellular Ca2+. Thus, the response to elevated cAMP is a PKA-dependent influx of Ca2+. This Ca2+ influx was blocked by nifedipine (an inhibitor of L-type voltage-gated Ca2+ channels) but was unperturbed by ω-agatoxin IVA and ω-conotoxin GVIA (P/Q-type and N-type channel inhibitors, respectively). Single-cell RT-PCR on functionally identified presynaptic cells from GAD-GFP mice confirmed the pharmacological analyses: Cav1.2 (an L-type subunit) is expressed in cells that display cAMP-triggered Ca2+ influx, while Cav2.1 (a P/Q subunit) is expressed in all presynaptic cells, and underlies depolarization-triggered Ca2+ influx. Collectively, these data demonstrate cross-talk between cAMP and Ca2+ signalling in a subclass of taste cells that form synapses with gustatory fibres and may integrate tastant-evoked signals.
AB - The second messenger, 3′,5′-cyclic adenosine monophosphate (cAMP), is known to be modulated in taste buds following exposure to gustatory and other stimuli. Which taste cell type(s) (Type I/glial-like cells, Type II/receptor cells, or Type III/presynaptic cells) undergo taste-evoked changes of cAMP and what the functional consequences of such changes are remain unknown. Using Fura-2 imaging of isolated mouse vallate taste cells, we explored how elevating cAMP alters Ca2+ levels in identified taste cells. Stimulating taste buds with forskolin (Fsk; 1 μm) + isobutylmethylxanthine (IBMX; 100 μm), which elevates cellular cAMP, triggered Ca2+ transients in 38% of presynaptic cells (n = 128). We used transgenic GAD-GFP mice to show that cAMP-triggered Ca2+ responses occur only in the subset of presynaptic cells that lack glutamic acid decarboxylase 67 (GAD). We never observed cAMP-stimulated responses in receptor cells, glial-like cells or GAD-expressing presynaptic cells. The response to cAMP was blocked by the protein kinase A inhibitor H89 and by removing extracellular Ca2+. Thus, the response to elevated cAMP is a PKA-dependent influx of Ca2+. This Ca2+ influx was blocked by nifedipine (an inhibitor of L-type voltage-gated Ca2+ channels) but was unperturbed by ω-agatoxin IVA and ω-conotoxin GVIA (P/Q-type and N-type channel inhibitors, respectively). Single-cell RT-PCR on functionally identified presynaptic cells from GAD-GFP mice confirmed the pharmacological analyses: Cav1.2 (an L-type subunit) is expressed in cells that display cAMP-triggered Ca2+ influx, while Cav2.1 (a P/Q subunit) is expressed in all presynaptic cells, and underlies depolarization-triggered Ca2+ influx. Collectively, these data demonstrate cross-talk between cAMP and Ca2+ signalling in a subclass of taste cells that form synapses with gustatory fibres and may integrate tastant-evoked signals.
UR - http://www.scopus.com/inward/record.url?scp=65249138108&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=65249138108&partnerID=8YFLogxK
U2 - 10.1113/jphysiol.2009.170555
DO - 10.1113/jphysiol.2009.170555
M3 - Article
C2 - 19221121
AN - SCOPUS:65249138108
VL - 587
SP - 1657
EP - 1668
JO - Journal of Physiology
JF - Journal of Physiology
SN - 0022-3751
IS - 8
ER -