Allosteric modulation of retinal GABA receptors by ascorbic acid
Ionotropic GABA receptors (GABAA and GABAC) belong to the Cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse pr...
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2011
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02706474_v31_n26_p9672_Calero http://hdl.handle.net/20.500.12110/paper_02706474_v31_n26_p9672_Calero |
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paper:paper_02706474_v31_n26_p9672_Calero2023-06-08T15:24:49Z Allosteric modulation of retinal GABA receptors by ascorbic acid 3 amino 2 (3 carboxypropyl) 6 (4 methoxyphenyl)pyridazinium bromide 4 aminobutyric acid A receptor 4 aminobutyric acid C receptor ascorbic acid bicuculline methiodide cysteine loop ligand gated ion channel receptor histidine thiol derivative allosterism animal cell article controlled study drug determination drug structure enzyme regulation evoked response goldfish human human cell neuromodulation neurotransmission nonhuman patch clamp priority journal protein expression protein function retina retina bipolar ganglion cell Xenopus laevis Ionotropic GABA receptors (GABAA and GABAC) belong to the Cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA puff-evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ρ1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereo-specific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two Cys-loop cysteines and histidine 141, all located in the ρ1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. © 2011 the authors. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02706474_v31_n26_p9672_Calero http://hdl.handle.net/20.500.12110/paper_02706474_v31_n26_p9672_Calero |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
3 amino 2 (3 carboxypropyl) 6 (4 methoxyphenyl)pyridazinium bromide 4 aminobutyric acid A receptor 4 aminobutyric acid C receptor ascorbic acid bicuculline methiodide cysteine loop ligand gated ion channel receptor histidine thiol derivative allosterism animal cell article controlled study drug determination drug structure enzyme regulation evoked response goldfish human human cell neuromodulation neurotransmission nonhuman patch clamp priority journal protein expression protein function retina retina bipolar ganglion cell Xenopus laevis |
| spellingShingle |
3 amino 2 (3 carboxypropyl) 6 (4 methoxyphenyl)pyridazinium bromide 4 aminobutyric acid A receptor 4 aminobutyric acid C receptor ascorbic acid bicuculline methiodide cysteine loop ligand gated ion channel receptor histidine thiol derivative allosterism animal cell article controlled study drug determination drug structure enzyme regulation evoked response goldfish human human cell neuromodulation neurotransmission nonhuman patch clamp priority journal protein expression protein function retina retina bipolar ganglion cell Xenopus laevis Allosteric modulation of retinal GABA receptors by ascorbic acid |
| topic_facet |
3 amino 2 (3 carboxypropyl) 6 (4 methoxyphenyl)pyridazinium bromide 4 aminobutyric acid A receptor 4 aminobutyric acid C receptor ascorbic acid bicuculline methiodide cysteine loop ligand gated ion channel receptor histidine thiol derivative allosterism animal cell article controlled study drug determination drug structure enzyme regulation evoked response goldfish human human cell neuromodulation neurotransmission nonhuman patch clamp priority journal protein expression protein function retina retina bipolar ganglion cell Xenopus laevis |
| description |
Ionotropic GABA receptors (GABAA and GABAC) belong to the Cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA puff-evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ρ1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereo-specific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two Cys-loop cysteines and histidine 141, all located in the ρ1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. © 2011 the authors. |
| title |
Allosteric modulation of retinal GABA receptors by ascorbic acid |
| title_short |
Allosteric modulation of retinal GABA receptors by ascorbic acid |
| title_full |
Allosteric modulation of retinal GABA receptors by ascorbic acid |
| title_fullStr |
Allosteric modulation of retinal GABA receptors by ascorbic acid |
| title_full_unstemmed |
Allosteric modulation of retinal GABA receptors by ascorbic acid |
| title_sort |
allosteric modulation of retinal gaba receptors by ascorbic acid |
| publishDate |
2011 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02706474_v31_n26_p9672_Calero http://hdl.handle.net/20.500.12110/paper_02706474_v31_n26_p9672_Calero |
| _version_ |
1768545186884878336 |