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Bazzurro V, Gatta E, Angeli E, Cupello A, Lange S, Jennische E, Robello M, Diaspro A. Mapping the effect of the antisecretory factor on GABA A receptor α 1 and α 6 subunits in cerebellar granule cells in vitro. IBRO Neurosci Rep 2024; 17:188-195. [PMID: 39234147 PMCID: PMC11372602 DOI: 10.1016/j.ibneur.2024.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Revised: 07/22/2024] [Accepted: 08/03/2024] [Indexed: 09/06/2024] Open
Abstract
The Antisecretory Factor (AF) is a protein that can reduce intestinal hypersecretion and various inflammation disorders in vivo. Discovered in many mammalian tissues and plasma, its mechanism of action remains unknown. Interestingly, its induction has been found to counteract vertigo in patients with Méniere's disease. This suggests an inherent ability to control body balance and posture, an activity that may play a role in cerebellar function. Therefore, it may be worthwhile to investigate whether this activity can inhibit neuronal cells involved in cerebellar circuitries and its potential action on enteric nervous system ganglia, which could explain its antisecretory effect in the intestine. Previously, we studied the role of AF on GABAA receptors in cerebellar granule cells, taking advantage of electrophysiology and evaluating the effects of the administration of AF-16, an AF peptide. Treatment with AF-16 increased GABAA receptor responses, especially those containing the α6 subunit. Here, we performed immunofluorescence experiments by staining α1 and α6 subunits before and after incubation with AF-16, analyzed super-resolved images comparing pre- and post-treatment maps and critically examined these experimental results with our previous electrophysiological data to shed light on the mechanisms of action of AF protein on GABAA receptor subpopulations, specifically the "fast" receptors of αn β2/3 γ2 composition that contain either the α1 or the α6 subunit. The results indicate that the α6 subunit is redistributed, with a decrease in neurites and an increase in soma. Conversely, the α1 subunit shows opposite results, with an increase in neurites and a decrease in soma.
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Affiliation(s)
| | - Elena Gatta
- DIFILAB, Department of Physics, University of Genoa, Italy
| | - Elena Angeli
- DIFILAB, Department of Physics, University of Genoa, Italy
| | - Aroldo Cupello
- DIFILAB, Department of Physics, University of Genoa, Italy
| | - Stefan Lange
- Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, Sweden
- Region Västra Götaland, Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Eva Jennische
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Mauro Robello
- DIFILAB, Department of Physics, University of Genoa, Italy
| | - Alberto Diaspro
- DIFILAB, Department of Physics, University of Genoa, Italy
- Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy
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Meera P, Uusi-Oukari M, Wallner M, Lipshutz GS. Guanidinoacetate (GAA) is a potent GABA A receptor GABA mimetic: Implications for neurological disease pathology. J Neurochem 2023; 165:445-454. [PMID: 36726215 DOI: 10.1111/jnc.15774] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/24/2023] [Accepted: 01/28/2023] [Indexed: 02/03/2023]
Abstract
Impairment of excretion and enzymatic processing of nitrogen, for example, because of liver or kidney failure, or with urea cycle and creatine synthesis enzyme defects, surprisingly leads to primarily neurologic symptoms, yet the exact mechanisms remain largely mysterious. In guanidinoacetate N-methyltransferase (GAMT) deficiency, the guanidino compound guanidinoacetate (GAA) increases dramatically, including in the cerebrospinal fluid (CSF), and has been implicated in mediating the neurological symptoms in GAMT-deficient patients. GAA is synthesized by arginine-glycine amidinotransferase (AGAT), a promiscuous enzyme that not only transfers the amidino group from arginine to glycine, but also to primary amines in, for example, GABA and taurine to generate γ-guanidinobutyric acid (γ-GBA) and guanidinoethanesulfonic acid (GES), respectively. We show that GAA, γ-GBA, and GES share structural similarities with GABA, evoke GABAA receptor (GABAA R) mediated currents (whereas creatine [methylated GAA] and arginine failed to evoke discernible currents) in cerebellar granule cells in mouse brain slices and displace the high-affinity GABA-site radioligand [3 H]muscimol in total brain homogenate GABAA Rs. While γ-GBA and GES are GABA agonists and displace [3 H]muscimol (EC50 /IC50 between 10 and 40 μM), GAA stands out as particularly potent in both activating GABAA Rs (EC50 ~6 μM) and also displacing the GABAA R ligand [3 H]muscimol (IC50 ~3 μM) at pathophysiologically relevant concentrations. These findings stress the role of substantially elevated GAA as a primary neurotoxic agent in GAMT deficiency and we discuss the potential role of GAA in arginase (and creatine transporter) deficiency which show a much more modest increase in GAA concentrations yet share the unique hyperexcitability neuropathology with GAMT deficiency. We conclude that orthosteric activation of GABAA Rs by GAA, and potentially other GABAA R mimetic guanidino compounds (GCs) like γ-GBA and GES, interferes with normal inhibitory GABAergic neurotransmission which could mediate, and contribute to, neurotoxicity.
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Affiliation(s)
- Pratap Meera
- Department of Neurobiology, University of California, Los Angeles, California, USA
| | - Mikko Uusi-Oukari
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Martin Wallner
- Departments of Surgery, University of California, Los Angeles, California, USA
| | - Gerald S Lipshutz
- Departments of Surgery, University of California, Los Angeles, California, USA.,Molecular & Medical Pharmacology, University of California, Los Angeles, California, USA.,Intellectual and Developmental Disabilities Research Center, University of California, Los Angeles, California, USA.,Semel Institute for Neuroscience, University of California, Los Angeles, California, USA
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Bazzurro V, Gatta E, Angeli E, Cupello A, Lange S, Jennische E, Robello M, Diaspro A. Involvement of GABA A receptors containing α 6 subtypes in antisecretory factor activity on rat cerebellar granule cells studied by two-photon uncaging. Eur J Neurosci 2022; 56:4505-4513. [PMID: 35848658 PMCID: PMC9541628 DOI: 10.1111/ejn.15775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/11/2022] [Accepted: 07/07/2022] [Indexed: 11/28/2022]
Abstract
The antisecretory factor (AF) is an endogenous protein that counteracts intestinal hypersecretion and various inflammation conditions in vivo. It has been detected in many mammalian tissues and plasma, but its mechanisms of action are largely unknown. To study the pharmacological action of the AF on different GABAA receptor populations in cerebellar granule cells, we took advantage of the two‐photon uncaging method as this technique allows to stimulate the cell locally in well‐identified plasma membrane parts. We compared the electrophysiological response evoked by releasing a caged GABA compound on the soma, the axon initial segment and neurites before and after administering AF‐16, a 16 amino acids long peptide obtained from the amino‐terminal end of the AF protein. After the treatment with AF‐16, we observed peak current increases of varying magnitude depending on the neuronal region. Thus, studying the effects of furosemide and AF‐16 on the electrophysiological behaviour of cerebellar granules, we suggest that GABAA receptors, containing the α6 subunit, may be specifically involved in the increase of the peak current by AF, and different receptor subtype distribution may be responsible for differences in this increase on the cell.
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Affiliation(s)
- Virginia Bazzurro
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy.,Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Elena Gatta
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy
| | - Elena Angeli
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy
| | - Aroldo Cupello
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy
| | - Stefan Lange
- Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.,Region Västra Götaland, Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Eva Jennische
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mauro Robello
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy
| | - Alberto Diaspro
- DIFILAB, Department of Physics, University of Genoa, Genoa, Italy.,Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy
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Synthesis and pharmacological evaluation of functionalized isoindolinones on GABA-activated chloride currents in rat cerebellum granule cells in culture. Bioorg Med Chem Lett 2016; 26:5284-5289. [DOI: 10.1016/j.bmcl.2016.09.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/14/2016] [Accepted: 09/15/2016] [Indexed: 01/17/2023]
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Anticonvulsive Activity in Audiogenic DBA/2 Mice of 1,4-Benzodiazepines and 1,5-Benzodiazepines with Different Activities at Cerebellar Granule Cell GABAA Receptors. J Mol Neurosci 2016; 60:539-547. [DOI: 10.1007/s12031-016-0838-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
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Nikas P, Gatta E, Cupello A, Di Braccio M, Grossi G, Pellistri F, Robello M. Study of the Interaction of 1,4- and 1,5-Benzodiazepines with GABAA Receptors of Rat Cerebellum Granule Cells in Culture. J Mol Neurosci 2015; 56:768-772. [DOI: 10.1007/s12031-015-0495-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
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Cupello A, Di Braccio M, Gatta E, Grossi G, Nikas P, Pellistri F, Robello M. GABA A Receptors of Cerebellar Granule Cells in Culture: Interaction with Benzodiazepines. Neurochem Res 2013; 38:2453-2462. [PMID: 24122079 DOI: 10.1007/s11064-013-1171-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/17/2013] [Accepted: 10/01/2013] [Indexed: 11/24/2022]
Abstract
GABAA receptor mediated inhibition plays an important role in modulating the input/output dynamics of cerebellum. A characteristic of cerebellar GABAA receptors is the presence in cerebellar granule cells of subunits such as α6 and δ which give insensitivity to classical benzodiazepines. In fact, cerebellar GABAA receptors have generally been considered a poor model for testing drugs which potentially are active at the benzodiazepine site. In this overview we show how rat cerebellar granule cells in culture may be a useful model for studying new benzodiazepine site agonists. This is based on the pharmacological separation of diazepam-sensitive α1 β2/3 γ2 receptors from those which are diazepam-insensitive and contain the α6 subunit. This is achieved by utilizing furosemide/Zn2+ which block α6 containing and incomplete receptors.
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Affiliation(s)
- Aroldo Cupello
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146, Genoa, Italy,
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Modulation of native GABAA receptor activity by triazolo 1,5-benzodiazepines. Neuroscience 2013; 243:158-64. [DOI: 10.1016/j.neuroscience.2013.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/16/2013] [Accepted: 04/07/2013] [Indexed: 11/21/2022]
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Thellung S, Gatta E, Pellistri F, Corsaro A, Villa V, Vassalli M, Robello M, Florio T. Excitotoxicity through NMDA receptors mediates cerebellar granule neuron apoptosis induced by prion protein 90-231 fragment. Neurotox Res 2012; 23:301-14. [PMID: 22855343 DOI: 10.1007/s12640-012-9340-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/13/2012] [Accepted: 07/18/2012] [Indexed: 10/28/2022]
Abstract
Prion diseases recognize, as a unique molecular trait, the misfolding of CNS-enriched prion protein (PrP(C)) into an aberrant isoform (PrP(Sc)). In this work, we characterize the in vitro toxicity of amino-terminally truncated recombinant PrP fragment (amino acids 90-231, PrP90-231), on rat cerebellar granule neurons (CGN), focusing on glutamatergic receptor activation and Ca(2+) homeostasis impairment. This recombinant fragment assumes a toxic conformation (PrP90-231(TOX)) after controlled thermal denaturation (1 h at 53 °C) acquiring structural characteristics identified in PrP(Sc) (enrichment in β-structures, increased hydrophobicity, partial resistance to proteinase K, and aggregation in amyloid fibrils). By annexin-V binding assay, and evaluation of the percentage of fragmented and condensed nuclei, we show that treatment with PrP90-231(TOX), used in pre-fibrillar aggregation state, induces CGN apoptosis. This effect was associated with a delayed, but sustained elevation of [Ca(2+)]i. Both CGN apoptosis and [Ca(2+)]i increase were not observed using PrP90-231 in PrP(C)-like conformation. PrP90-231(TOX) effects were significantly reduced in the presence of ionotropic glutamate receptor antagonists. In particular, CGN apoptosis and [Ca(2+)]i increase were largely reduced, although not fully abolished, by pre-treatment with the NMDA antagonists APV and memantine, while the AMPA antagonist CNQX produced a lower, although still significant, effect. In conclusion, we report that CGN apoptosis induced by PrP90-231(TOX) correlates with a sustained elevation of [Ca(2+)]i mediated by the activation of NMDA and AMPA receptors.
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Affiliation(s)
- Stefano Thellung
- Department of Internal Medicine, Section of Pharmacology and Centre of Excellence for Biomedical Research (CEBR) School of Medicine, University of Genova, Viale Benedetto XV, 2, 16132, Genoa, Italy
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Hengen KB, Gomez TM, Stang KM, Johnson SM, Behan M. Changes in ventral respiratory column GABAaR ε- and δ-subunits during hibernation mediate resistance to depression by EtOH and pentobarbital. Am J Physiol Regul Integr Comp Physiol 2010; 300:R272-83. [PMID: 21084677 DOI: 10.1152/ajpregu.00607.2010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
During hibernation in the 13-lined ground squirrel, Ictidomys tridecemlineatus, the cerebral cortex is electrically silent, yet the brainstem continues to regulate cardiorespiratory function. Previous work showed that neurons in slices through the medullary ventral respiratory column (VRC) but not the cortex are insensitive to high doses of pentobarbital during hibernation, leading to the hypothesis that GABA(A) receptors (GABA(A)R) in the VRC undergo a seasonal modification in subunit composition. To test whether alteration of GABA(A)R subunits are responsible for hibernation-associated pentobarbital insensitivity, we examined an array of subunits using RT-PCR and Western blots and identified changes in ε- and δ-subunits in the medulla but not the cortex. Using immunohistochemistry, we confirmed that during hibernation, the expression of ε-subunit-containing GABA(A)Rs nearly doubles in the VRC. We also identified a population of δ-subunit-containing GABA(A)Rs adjacent to the VRC that were differentially expressed during hibernation. As δ-subunit-containing GABA(A)Rs are particularly sensitive to ethanol (EtOH), multichannel electrodes were inserted in slices of medulla and cortex from hibernating squirrels and EtOH was applied. EtOH, which normally inhibits neuronal activity, excited VRC but not cortical neurons during hibernation. This excitation was prevented by bicuculline pretreatment, indicating the involvement of GABA(A)Rs. We propose that neuronal activity in the VRC during hibernation is unaffected by pentobarbital due to upregulation of ε-subunit-containing GABA(A)Rs on VRC neurons. Synaptic input from adjacent inhibitory interneurons that express δ-subunit-containing GABA(A)Rs is responsible for the excitatory effects of EtOH on VRC neurons during hibernation.
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Affiliation(s)
- K B Hengen
- Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin, USA
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Gatta E, Cupello A, Di Braccio M, Grossi G, Ferruzzi R, Roma G, Robello M. New 1,5-benzodiazepine compounds: activity at native GABA(A) receptors. Neuroscience 2010; 166:917-23. [PMID: 20096335 DOI: 10.1016/j.neuroscience.2010.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/21/2009] [Accepted: 01/07/2010] [Indexed: 11/26/2022]
Abstract
Various new 1,5-benzodiazepine compounds were synthesized and tested for their biological activity in terms of effects on GABA(A) receptors of rat cerebellar granules in culture. Their effects were compared to those of a 1,4-benzodiazepine agonist, flunitrazepam and the already known 1,5-benzodiazepine antiepileptic clobazam. The effects were evaluated for the two different GABA(A) receptor populations present in these neurons, one mediating phasic inhibition and the other one mediating tonic inhibition. Many such compounds display a profile of inverse agonist to both GABA(A) receptor populations. One of them presents a profile of full agonist at the component mediating phasic inhibition. Interestingly, substitution of just one oxygen atom in that compound with sulphur in a specific position of a morpholine ring resulted in a remarkable change of activity from full agonist to a probable inverse agonist. This indicates such a position as a proton accepting one for the ligand within the benzodiazepine binding pocket of the relevant GABA(A) receptors. In addition, that position appears to be critical for the pharmacological activity.
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Affiliation(s)
- E Gatta
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Italy
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