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Expression of GABAergic receptors in mouse taste receptor cells.

Starostik MR, Rebello MR, Cotter KA, Kulik A, Medler KF - PLoS ONE (2010)

Bottom Line: Taste receptor cells (TRCs) in the circumvallate papillae express multiple subunits of the GABA(A) and GABA(B) receptors as well as multiple GATs.Both GABA(A)-and GABA(B)- immunoreactivity were detected in the peripheral taste receptor cells.Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, New York, United States of America.

ABSTRACT

Background: Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD) for gamma-aminobutyric acid (GABA) is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABA(A) and GABA(C)) or metabotropic receptors (GABA(B)) while it is terminated by the re-uptake of GABA through transporters (GATs).

Methodology/principal findings: Using reverse transcriptase-PCR (RT-PCR) analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs) in the circumvallate papillae express multiple subunits of the GABA(A) and GABA(B) receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABA(A)-and GABA(B)- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP) in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds.

Conclusions/significance: The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.

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RT-PCR analysis of the GABAAβ subunits.cDNA from circumvallate TRCs (C), non-gustatory lingual epithelium (E), and brain tissue (B) were subjected to PCR analysis using gene specific primers for the GABAAβ subunits 1–3. PCR products were separated by agarose gel electrophoresis. Bands were observed for all subunits in the control brain tissue at the appropriate sizes (β1–665 bp, β2–514 bp, β3–415 bp), but only GABAAβ3 was amplified in the TRCs and non-gustatory epithelium. Results were repeated at least three times and representative data are shown.
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pone-0013639-g002: RT-PCR analysis of the GABAAβ subunits.cDNA from circumvallate TRCs (C), non-gustatory lingual epithelium (E), and brain tissue (B) were subjected to PCR analysis using gene specific primers for the GABAAβ subunits 1–3. PCR products were separated by agarose gel electrophoresis. Bands were observed for all subunits in the control brain tissue at the appropriate sizes (β1–665 bp, β2–514 bp, β3–415 bp), but only GABAAβ3 was amplified in the TRCs and non-gustatory epithelium. Results were repeated at least three times and representative data are shown.

Mentions: We also identified the GABAAβ subunits expressed in mouse taste cells (Figure 2). We were unable to amplify any PCR products for β1 or β2 but detected transcript for the β3 isoform from circumvallate mouse TRCs and non-gustatory epithelium. PCR products of the appropriate size were amplified the brain control sample for β1 (665 bp), β2 (514 bp) and β3 (415 bp).


Expression of GABAergic receptors in mouse taste receptor cells.

Starostik MR, Rebello MR, Cotter KA, Kulik A, Medler KF - PLoS ONE (2010)

RT-PCR analysis of the GABAAβ subunits.cDNA from circumvallate TRCs (C), non-gustatory lingual epithelium (E), and brain tissue (B) were subjected to PCR analysis using gene specific primers for the GABAAβ subunits 1–3. PCR products were separated by agarose gel electrophoresis. Bands were observed for all subunits in the control brain tissue at the appropriate sizes (β1–665 bp, β2–514 bp, β3–415 bp), but only GABAAβ3 was amplified in the TRCs and non-gustatory epithelium. Results were repeated at least three times and representative data are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2964312&req=5

pone-0013639-g002: RT-PCR analysis of the GABAAβ subunits.cDNA from circumvallate TRCs (C), non-gustatory lingual epithelium (E), and brain tissue (B) were subjected to PCR analysis using gene specific primers for the GABAAβ subunits 1–3. PCR products were separated by agarose gel electrophoresis. Bands were observed for all subunits in the control brain tissue at the appropriate sizes (β1–665 bp, β2–514 bp, β3–415 bp), but only GABAAβ3 was amplified in the TRCs and non-gustatory epithelium. Results were repeated at least three times and representative data are shown.
Mentions: We also identified the GABAAβ subunits expressed in mouse taste cells (Figure 2). We were unable to amplify any PCR products for β1 or β2 but detected transcript for the β3 isoform from circumvallate mouse TRCs and non-gustatory epithelium. PCR products of the appropriate size were amplified the brain control sample for β1 (665 bp), β2 (514 bp) and β3 (415 bp).

Bottom Line: Taste receptor cells (TRCs) in the circumvallate papillae express multiple subunits of the GABA(A) and GABA(B) receptors as well as multiple GATs.Both GABA(A)-and GABA(B)- immunoreactivity were detected in the peripheral taste receptor cells.Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, New York, United States of America.

ABSTRACT

Background: Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD) for gamma-aminobutyric acid (GABA) is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABA(A) and GABA(C)) or metabotropic receptors (GABA(B)) while it is terminated by the re-uptake of GABA through transporters (GATs).

Methodology/principal findings: Using reverse transcriptase-PCR (RT-PCR) analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs) in the circumvallate papillae express multiple subunits of the GABA(A) and GABA(B) receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABA(A)-and GABA(B)- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP) in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds.

Conclusions/significance: The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.

Show MeSH