1
|
Zhang W, Jin Y, Zhou FM. Chronic fluoxetine treatment desensitizes serotoninergic inhibition of GABA inputs and the intrinsic excitability of dorsal raphe serotonin neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.592963. [PMID: 38766100 PMCID: PMC11100661 DOI: 10.1101/2024.05.07.592963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Dorsal raphe serotonin (5-hydroxytryptamine, 5-HT) neurons are spontaneously active and release 5-HT that is critical to normal brain function such mood and emotion. Serotonin reuptake inhibitors (SSRIs) increase the synaptic and extracellular 5-HT level and are effective in treating depression. Treatment of two weeks or longer is often required for SSRIs to exert clinical benefits. The cellular mechanism underlying this delay was not fully understood. Here we show that the GABAergic inputs inhibit the spike firing of raphe 5-HT neurons; this GABAergic regulation was reduced by 5-HT, which was prevented by G-protein-activated inwardly rectifying potassium (Girk) channel inhibitor tertiapin-Q, indicating a contribution of 5-HT activation of Girk channels in GABAergic presynaptic axon terminals. Equally important, after 14 days of treatment of fluoxetine, a widely used SSRI type antidepressant, this 5-HT inhibition of GABAergic inputs was substantially downregulated. Furthermore, the chronic fluoxetine treatment substantially downregulated the 5-HT activation of the inhibitory Girk current in 5-HT neurons. Taken together, our results suggest that chronic fluoxetine administration, by blocking 5-HT reuptake and hence increasing the extracellular 5-HT level, can downregulate the function of 5-HT1B receptors on the GABAergic afferent axon terminals synapsing onto 5-HT neurons, allowing extrinsic, behaviorally important GABA neurons to more effectively influence 5-HT neurons; simultaneously, chronic fluoxetine treatment also downregulate somatic 5-HT autoreceptor-activated Girk channel-mediated hyperpolarization and decrease in input resistance and intrinsic excitability, rendering 5-HT neurons resistant to autoinhibition and leading to increased 5-HT neuron activity, potentially contributing to the antidepressant effect of SSRIs.
Collapse
|
2
|
Boyle CA, Kola PK, Oraegbuna CS, Lei S. Leptin excites basolateral amygdala principal neurons and reduces food intake by LepRb-JAK2-PI3K-dependent depression of GIRK channels. J Cell Physiol 2024; 239:e31117. [PMID: 37683049 PMCID: PMC10920395 DOI: 10.1002/jcp.31117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/08/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023]
Abstract
Leptin is an adipocyte-derived hormone that modulates food intake, energy balance, neuroendocrine status, thermogenesis, and cognition. Whereas a high density of leptin receptors has been detected in the basolateral amygdala (BLA) neurons, the physiological functions of leptin in the BLA have not been determined yet. We found that application of leptin excited BLA principal neurons by activation of the long form leptin receptor, LepRb. The LepRb-elicited excitation of BLA neurons was mediated by depression of the G protein-activated inwardly rectifying potassium (GIRK) channels. Janus Kinase 2 (JAK2) and phosphoinositide 3-kinase (PI3K) were required for leptin-induced excitation of BLA neurons and depression of GIRK channels. Microinjection of leptin into the BLA reduced food intake via activation of LepRb, JAK2, and PI3K. Our results may provide a cellular and molecular mechanism to explain the physiological roles of leptin in vivo.
Collapse
Affiliation(s)
- Cody A. Boyle
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Phani K. Kola
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Chidiebele S. Oraegbuna
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Saobo Lei
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| |
Collapse
|
3
|
Rudy SL, Wealing JC, Banayat T, Black C, Funk GD, Revill AL. A muscarinic, GIRK channel-mediated inhibition of inspiratory-related XII nerve motor output emerges in early postnatal development in mice. J Appl Physiol (1985) 2023; 135:1041-1052. [PMID: 37767557 PMCID: PMC10911762 DOI: 10.1152/japplphysiol.00042.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 09/06/2023] [Accepted: 09/21/2023] [Indexed: 09/29/2023] Open
Abstract
In neonatal rhythmic medullary slices, muscarinic acetylcholine receptor (mAChR) activation of hypoglossal (XII) motoneurons that innervate the tongue has a net excitatory effect on XII inspiratory motor output. Conversely, during rapid eye movement sleep in adult rodents, XII motoneurons experience a loss of excitability partly due to activation of mAChRs. This may be mediated by activation of G-protein-coupled inwardly rectifying potassium (GIRK) channels. Therefore, this study was designed to evaluate whether muscarinic modulation of XII inspiratory motor output in mouse rhythmic medullary slices includes GIRK channel-mediated inhibition and, if so, when this inhibitory mechanism emerges. Local pressure injection of the mAChR agonist muscarine potentiated inspiratory bursting by 150 ± 28% in postnatal day (P)0-P5 rhythmic medullary slice preparations. In the absence of muscarine, pharmacological GIRK channel block by Tertiapin-Q did not affect inspiratory burst parameters, whereas activation with ML297 decreased inspiratory burst area. Blocking GIRK channels by local preapplication of Tertiapin-Q revealed a developmental change in muscarinic modulation of inspiratory bursting. In P0-P2 rhythmic medullary slices, Tertiapin-Q preapplication had no significant effect on muscarinic potentiation of inspiratory bursting (a negligible 6% decrease). However, preapplication of Tertiapin-Q to P3-P5 rhythmic medullary slices caused a 19% increase in muscarinic potentiation of XII inspiratory burst amplitude. Immunofluorescence experiments revealed expression of GIRK 1 and 2 subunits and M1, M2, M3, and M5 mAChRs from P0 to P5. Overall, these data support that mechanisms underlying muscarinic modulation of inspiratory burst activity change postnatally and that potent GIRK-mediated inhibition described in adults emerges early in postnatal life.NEW & NOTEWORTHY Muscarinic modulation of inspiratory bursting at hypoglossal motoneurons has a net excitatory effect in neonatal rhythmic medullary slice preparations and a net inhibitory effect in adult animals. We demonstrate that muscarinic modulation of inspiratory bursting undergoes maturational changes from postnatal days 0 to 5 that include emergence of an inhibitory component mediated by G-protein-coupled inwardly rectifying potassium channels after postnatal day 3 in neonatal mouse rhythmic medullary slice preparations.
Collapse
Affiliation(s)
- Samantha L Rudy
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Jesse C Wealing
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Tatum Banayat
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
| | - Chody Black
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Gregory D Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ann L Revill
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
| |
Collapse
|
4
|
Contreras A, Djebari S, Temprano-Carazo S, Múnera A, Gruart A, Delgado-Garcia JM, Jiménez-Díaz L, Navarro-López JD. Impairments in hippocampal oscillations accompany the loss of LTP induced by GIRK activity blockade. Neuropharmacology 2023:109668. [PMID: 37474000 DOI: 10.1016/j.neuropharm.2023.109668] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/06/2023] [Accepted: 07/13/2023] [Indexed: 07/22/2023]
Abstract
Learning and memory occurrence requires of hippocampal long-term synaptic plasticity and precise neural activity orchestrated by brain network oscillations, both processes reciprocally influencing each other. As G-protein-gated inwardly rectifying potassium (GIRK) channels rule synaptic plasticity that supports hippocampal-dependent memory, here we assessed their unknown role in hippocampal oscillatory activity in relation to synaptic plasticity induction. In alert male mice, pharmacological GIRK modulation did not alter neural oscillations before long-term potentiation (LTP) induction. However, after an LTP generating protocol, both gain- and loss-of basal GIRK activity transformed LTP into long-term depression, but only specific suppression of constitutive GIRK activity caused a disruption of network synchronization (δ, α, γ bands), even leading to long-lasting ripples and fast ripples pathological oscillations. Together, our data showed that constitutive GIRK activity plays a key role in the tuning mechanism of hippocampal oscillatory activity during long-term synaptic plasticity processes that underlies hippocampal-dependent cognitive functions.
Collapse
Affiliation(s)
- Ana Contreras
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain.
| | - Souhail Djebari
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Sara Temprano-Carazo
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Alejandro Múnera
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain; Behavioral Neurophysiology Laboratory, Universidad Nacional de Colombia, 111321, Bogotá, Colombia
| | - Agnès Gruart
- Division of Neurosciences, University Pablo de Olavide, 41013, Seville, Spain
| | | | - Lydia Jiménez-Díaz
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain.
| | - Juan D Navarro-López
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, University of Castilla-La Mancha, 13071, Ciudad Real, Spain.
| |
Collapse
|
5
|
Spatial Memory Training Counteracts Hippocampal GIRK Channel Decrease in the Transgenic APPSw,Ind J9 Alzheimer’s Disease Mouse Model. Int J Mol Sci 2022; 23:ijms232113444. [PMID: 36362230 PMCID: PMC9659077 DOI: 10.3390/ijms232113444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/21/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
G-protein-gated inwardly rectifying potassium (GIRK) channels are critical determinants of neuronal excitability. They have been proposed as potential targets to restore excitatory/inhibitory balance in acute amyloidosis models, where hyperexcitability is a hallmark. However, the role of GIRK signaling in transgenic mice models of Alzheimer’s disease (AD) is largely unknown. Here, we study whether progressive amyloid-β (Aβ) accumulation in the hippocampus during aging alters GIRK channel expression in mutant β-amyloid precursor protein (APPSw,Ind J9) transgenic AD mice. Additionally, we examine the impact of spatial memory training in a hippocampal-dependent task, on protein expression of GIRK subunits and Regulator of G-protein signaling 7 (RGS7) in the hippocampus of APPSw,Ind J9 mice. Firstly, we found a reduction in GIRK2 expression (the main neuronal GIRK channels subunit) in the hippocampus of 6-month-old APPSw,Ind J9 mice. Moreover, we found an aging effect on GIRK2 and GIRK3 subunits in both wild type (WT) and APPSw,Ind J9 mice. Finally, when 6-month-old animals were challenged to a spatial memory training, GIRK2 expression in the APPSw,Ind J9 mice were normalized to WT levels. Together, our results support the evidence that GIRK2 could account for the excitatory/inhibitory neurotransmission imbalance found in AD models, and training in a cognitive hippocampal dependent task may have therapeutic benefits of reversing this effect and lessen early AD deficits.
Collapse
|
6
|
Martín-Belmonte A, Aguado C, Alfaro-Ruiz R, Moreno-Martínez AE, de la Ossa L, Aso E, Gómez-Acero L, Shigemoto R, Fukazawa Y, Ciruela F, Luján R. Nanoscale alterations in GABAB receptors and GIRK channel organization on the hippocampus of APP/PS1 mice. Alzheimers Res Ther 2022; 14:136. [PMID: 36131327 PMCID: PMC9490896 DOI: 10.1186/s13195-022-01078-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/13/2022] [Indexed: 11/10/2022]
Abstract
Alzheimer’s disease (AD) is characterized by a reorganization of brain activity determining network hyperexcitability and loss of synaptic plasticity. Precisely, a dysfunction in metabotropic GABAB receptor signalling through G protein-gated inwardly rectifying K+ (GIRK or Kir3) channels on the hippocampus has been postulated. Thus, we determined the impact of amyloid-β (Aβ) pathology in GIRK channel density, subcellular distribution, and its association with GABAB receptors in hippocampal CA1 pyramidal neurons from the APP/PS1 mouse model using quantitative SDS-digested freeze-fracture replica labelling (SDS-FRL) and proximity ligation in situ assay (P-LISA). In wild type mice, single SDS-FRL detection revealed a similar dendritic gradient for GIRK1 and GIRK2 in CA1 pyramidal cells, with higher densities in spines, and GIRK3 showed a lower and uniform distribution. Double SDS-FRL showed a co-clustering of GIRK2 and GIRK1 in post- and presynaptic compartments, but not for GIRK2 and GIRK3. Likewise, double GABAB1 and GIRK2 SDS-FRL detection displayed a high degree of co-clustering in nanodomains (40–50 nm) mostly in spines and axon terminals. In APP/PS1 mice, the density of GIRK2 and GIRK1, but not for GIRK3, was significantly reduced along the neuronal surface of CA1 pyramidal cells and in axon terminals contacting them. Importantly, GABAB1 and GIRK2 co-clustering was not present in APP/PS1 mice. Similarly, P-LISA experiments revealed a significant reduction in GABAB1 and GIRK2 interaction on the hippocampus of this animal model. Overall, our results provide compelling evidence showing a significant reduction on the cell surface density of pre- and postsynaptic GIRK1 and GIRK2, but not GIRK3, and a decline in GABAB receptors and GIRK2 channels co-clustering in hippocampal pyramidal neurons from APP/PS1 mice, thus suggesting that a disruption in the GABAB receptor–GIRK channel membrane assembly causes dysregulation in the GABAB signalling via GIRK channels in this AD animal model.
Collapse
|
7
|
Kleschevnikov AM. Enhanced GIRK2 channel signaling in Down syndrome: A feasible role in the development of abnormal nascent neural circuits. Front Genet 2022; 13:1006068. [PMID: 36171878 PMCID: PMC9510977 DOI: 10.3389/fgene.2022.1006068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022] Open
Abstract
The most distinctive feature of Down syndrome (DS) is moderate to severe cognitive impairment. Genetic, molecular, and neuronal mechanisms of this complex DS phenotype are currently under intensive investigation. It is becoming increasingly clear that the abnormalities arise from a combination of initial changes caused by triplication of genes on human chromosome 21 (HSA21) and later compensatory adaptations affecting multiple brain systems. Consequently, relatively mild initial cognitive deficits become pronounced with age. This pattern of changes suggests that one approach to improving cognitive function in DS is to target the earliest critical changes, the prevention of which can change the ‘trajectory’ of the brain development and reduce the destructive effects of the secondary alterations. Here, we review the experimental data on the role of KCNJ6 in DS-specific brain abnormalities, focusing on a putative role of this gene in the development of abnormal neural circuits in the hippocampus of genetic mouse models of DS. It is suggested that the prevention of these early abnormalities with pharmacological or genetic means can ameliorate cognitive impairment in DS.
Collapse
|
8
|
Fernández-Dueñas V, Bonaventura J, Aso E, Luján R, Ferré S, Ciruela F. Overcoming the Challenges of Detecting GPCR Oligomerization in the Brain. Curr Neuropharmacol 2022; 20:1035-1045. [PMID: 34736381 PMCID: PMC9886828 DOI: 10.2174/1570159x19666211104145727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/14/2021] [Accepted: 10/14/2021] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors (GPCRs) constitute the largest group of membrane receptor proteins controlling brain activity. Accordingly, GPCRs are the main target of commercial drugs for most neurological and neuropsychiatric disorders. One of the mechanisms by which GPCRs regulate neuronal function is by homo- and heteromerization, with the establishment of direct protein-protein interactions between the same and different GPCRs. The occurrence of GPCR homo- and heteromers in artificial systems is generally well accepted, but more specific methods are necessary to address GPCR oligomerization in the brain. Here, we revise some of the techniques that have mostly contributed to reveal GPCR oligomers in native tissue, which include immunogold electron microscopy, proximity ligation assay (PLA), resonance energy transfer (RET) between fluorescent ligands and the Amplified Luminescent Proximity Homogeneous Assay (ALPHA). Of note, we use the archetypical GPCR oligomer, the adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromer as an example to illustrate the implementation of these techniques, which can allow visualizing GPCR oligomers in the human brain under normal and pathological conditions. Indeed, GPCR oligomerization may be involved in the pathophysiology of neurological and neuropsychiatric disorders.
Collapse
Affiliation(s)
- Víctor Fernández-Dueñas
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain;,Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain;,Address correspondence to these authors at the Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain; E-mails: ,
| | - Jordi Bonaventura
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain;,Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
| | - Ester Aso
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain;,Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
| | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Albacete, Spain
| | - Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain;,Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain;,Address correspondence to these authors at the Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain; E-mails: ,
| |
Collapse
|
9
|
Kleschevnikov A. GIRK2 Channels in Down Syndrome and Alzheimer's Disease. Curr Alzheimer Res 2022; 19:819-829. [PMID: 36567290 DOI: 10.2174/1567205020666221223122110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 11/26/2022] [Accepted: 11/29/2022] [Indexed: 12/27/2022]
Abstract
Cognitive impairment in Down syndrome (DS) results from the abnormal expression of hundreds of genes. However, the impact of KCNJ6, a gene located in the middle of the 'Down syndrome critical region' of chromosome 21, seems to stand out. KCNJ6 encodes GIRK2 (KIR3.2) subunits of G protein-gated inwardly rectifying potassium channels, which serve as effectors for GABAB, m2, 5HT1A, A1, and many other postsynaptic metabotropic receptors. GIRK2 subunits are heavily expressed in neocortex, cerebellum, and hippocampus. By controlling resting membrane potential and neuronal excitability, GIRK2 channels may thus affect both synaptic plasticity and stability of neural circuits in the brain regions important for learning and memory. Here, we discuss recent experimental data regarding the role of KCNJ6/GIRK2 in neuronal abnormalities and cognitive impairment in models of DS and Alzheimer's disease (AD). The results compellingly show that signaling through GIRK2 channels is abnormally enhanced in mouse genetic models of Down syndrome and that partial suppression of GIRK2 channels with pharmacological or genetic means can restore synaptic plasticity and improve impaired cognitive functions. On the other hand, signaling through GIRK2 channels is downregulated in AD models, such as models of early amyloidopathy. In these models, reduced GIRK2 channel signaling promotes neuronal hyperactivity, causing excitatory-inhibitory imbalance and neuronal death. Accordingly, activation of GABAB/GIRK2 signaling by GIRK channel activators or GABAB receptor agonists may reduce Aβ-induced hyperactivity and subsequent neuronal death, thereby exerting a neuroprotective effect in models of AD.
Collapse
|
10
|
Alfaro-Ruiz R, Martín-Belmonte A, Aguado C, Hernández F, Moreno-Martínez AE, Ávila J, Luján R. The Expression and Localisation of G-Protein-Coupled Inwardly Rectifying Potassium (GIRK) Channels Is Differentially Altered in the Hippocampus of Two Mouse Models of Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222011106. [PMID: 34681766 PMCID: PMC8541655 DOI: 10.3390/ijms222011106] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 12/31/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are the main targets controlling excitability and synaptic plasticity on hippocampal neurons. Consequently, dysfunction of GIRK-mediated signalling has been implicated in the pathophysiology of Alzheimer´s disease (AD). Here, we provide a quantitative description on the expression and localisation patterns of GIRK2 in two transgenic mice models of AD (P301S and APP/PS1 mice), combining histoblots and immunoelectron microscopic approaches. The histoblot technique revealed differences in the expression of GIRK2 in the two transgenic mice models. The expression of GIRK2 was significantly reduced in the hippocampus of P301S mice in a laminar-specific manner at 10 months of age but was unaltered in APP/PS1 mice at 12 months compared to age-matched wild type mice. Ultrastructural approaches using the pre-embedding immunogold technique, demonstrated that the subcellular localisation of GIRK2 was significantly reduced along the neuronal surface of CA1 pyramidal cells, but increased in its frequency at cytoplasmic sites, in both P301S and APP/PS1 mice. We also found a decrease in plasma membrane GIRK2 channels in axon terminals contacting dendritic spines of CA1 pyramidal cells in P301S and APP/PS1 mice. These data demonstrate for the first time a redistribution of GIRK channels from the plasma membrane to intracellular sites in different compartments of CA1 pyramidal cells. Altogether, the pre- and post-synaptic reduction of GIRK2 channels suggest that GIRK-mediated alteration of the excitability in pyramidal cells could contribute to the cognitive dysfunctions as described in the two AD animal models.
Collapse
Affiliation(s)
- Rocío Alfaro-Ruiz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Félix Hernández
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, ISCIII, 28049 Madrid, Spain; (F.H.); (J.Á.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, 28049 Madrid, Spain
| | - Ana Esther Moreno-Martínez
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Jesús Ávila
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, ISCIII, 28049 Madrid, Spain; (F.H.); (J.Á.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, 28049 Madrid, Spain
| | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
- Correspondence: ; Tel.: +34-967-599200 (ext. 2196)
| |
Collapse
|
11
|
Djebari S, Iborra-Lázaro G, Temprano-Carazo S, Sánchez-Rodríguez I, Nava-Mesa MO, Múnera A, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. G-Protein-Gated Inwardly Rectifying Potassium (Kir3/GIRK) Channels Govern Synaptic Plasticity That Supports Hippocampal-Dependent Cognitive Functions in Male Mice. J Neurosci 2021; 41:7086-7102. [PMID: 34261700 PMCID: PMC8372024 DOI: 10.1523/jneurosci.2849-20.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 01/17/2023] Open
Abstract
The G-protein-gated inwardly rectifying potassium (Kir3/GIRK) channel is the effector of many G-protein-coupled receptors (GPCRs). Its dysfunction has been linked to the pathophysiology of Down syndrome, Alzheimer's and Parkinson's diseases, psychiatric disorders, epilepsy, drug addiction, or alcoholism. In the hippocampus, GIRK channels decrease excitability of the cells and contribute to resting membrane potential and inhibitory neurotransmission. Here, to elucidate the role of GIRK channels activity in the maintenance of hippocampal-dependent cognitive functions, their involvement in controlling neuronal excitability at different levels of complexity was examined in C57BL/6 male mice. For that purpose, GIRK activity in the dorsal hippocampus CA3-CA1 synapse was pharmacologically modulated by two drugs: ML297, a GIRK channel opener, and Tertiapin-Q (TQ), a GIRK channel blocker. Ex vivo, using dorsal hippocampal slices, we studied the effect of pharmacological GIRK modulation on synaptic plasticity processes induced in CA1 by Schaffer collateral stimulation. In vivo, we performed acute intracerebroventricular (i.c.v.) injections of the two GIRK modulators to study their contribution to electrophysiological properties and synaptic plasticity of dorsal hippocampal CA3-CA1 synapse, and to learning and memory capabilities during hippocampal-dependent tasks. We found that pharmacological disruption of GIRK channel activity by i.c.v. injections, causing either function gain or function loss, induced learning and memory deficits by a mechanism involving neural excitability impairments and alterations in the induction and maintenance of long-term synaptic plasticity processes. These results support the contention that an accurate control of GIRK activity must take place in the hippocampus to sustain cognitive functions.SIGNIFICANCE STATEMENT Cognitive processes of learning and memory that rely on hippocampal synaptic plasticity processes are critically ruled by a finely tuned neural excitability. G-protein-gated inwardly rectifying K+ (GIRK) channels play a key role in maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Here, we demonstrate that modulation of GIRK channels activity, causing either function gain or function loss, transforms high-frequency stimulation (HFS)-induced long-term potentiation (LTP) into long-term depression (LTD), inducing deficits in hippocampal-dependent learning and memory. Together, our data show a crucial GIRK-activity-mediated mechanism that governs synaptic plasticity direction and modulates subsequent hippocampal-dependent cognitive functions.
Collapse
Affiliation(s)
- Souhail Djebari
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Guillermo Iborra-Lázaro
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Sara Temprano-Carazo
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Irene Sánchez-Rodríguez
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Mauricio O Nava-Mesa
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
- Neuroscience Research Group (NEUROS), Universidad del Rosario, Bogotá, Colombia 111711
| | - Alejandro Múnera
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
- Behavioral Neurophysiology Laboratory, Universidad Nacional de Colombia, Bogotá, Colombia 111321
| | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University, Seville, Spain 41013
| | | | - Lydia Jiménez-Díaz
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Juan D Navarro-López
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| |
Collapse
|
12
|
Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system. Pharmacol Ther 2021; 223:107808. [PMID: 33476640 DOI: 10.1016/j.pharmthera.2021.107808] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/15/2022]
Abstract
G protein-gated inwardly rectifying potassium channels (Kir3/GirK) are important for maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Coupled to numerous G protein-coupled receptors (GPCRs), they mediate the effects of many neurotransmitters, neuromodulators and hormones contributing to the general homeostasis and particular synaptic plasticity processes, learning, memory and pain signaling. A growing number of behavioral and genetic studies suggest a critical role for the appropriate functioning of the central nervous system, as well as their involvement in many neurologic and psychiatric conditions, such as neurodegenerative diseases, mood disorders, attention deficit hyperactivity disorder, schizophrenia, epilepsy, alcoholism and drug addiction. Hence, GirK channels emerge as a very promising tool to be targeted in the current scenario where these conditions already are or will become a global public health problem. This review examines recent findings on the physiology, function, dysfunction, and pharmacology of GirK channels in the central nervous system and highlights the relevance of GirK channels as a worthful potential target to improve therapies for related diseases.
Collapse
|
13
|
Mett A, Karbat I, Tsoory M, Fine S, Iwanir S, Reuveny E. Reduced activity of GIRK1-containing heterotetramers is sufficient to affect neuronal functions, including synaptic plasticity and spatial learning and memory. J Physiol 2020; 599:521-545. [PMID: 33124684 DOI: 10.1113/jp280434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/27/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS G-protein inwardly rectifying K+ (GIRK) channels consist of four homologous subunits (GIRK1-4) and are essential regulators of electrical excitability in the nervous system. GIRK2-null mice have been widely investigated for their distinct behaviour and altered depotentiation following long-term potentiation (LTP), whereas GIRK1 mice are less well characterized. Here we utilize a novel knockin mouse strain in which the GIRK1 subunit is fluorescently tagged with yellow fluorescent protein (YFP-GIRK1) and the GIRK1-null mouse line to investigate the role of GIRK1 in neuronal processes such as spatial learning and memory, locomotion and depotentiation following LTP. Neurons dissected from YFP-GIRK1 mice had significantly reduced potassium currents and this mouse line phenotypically resembled GIRK1-null mice, making it a 'functional knockdown' model of GIRK1-containing channels. YFP-GIRK1 and GIRK1-null mice had increased locomotion, reduced spatial learning and memory and blunted depotentiation following LTP. ABSTRACT GIRK channels are essential for the slow inhibition of electrical activity in the nervous system and heart rate regulation via the parasympathetic system. The implications of individual GIRK isoforms in specific physiological activities are based primarily on studies conducted with GIRK-null mouse lines. Here we utilize a novel knockin mouse line in which YFP was fused in-frame to the N-terminus of GIRK1 (YFP-GIRK1) to correlate GIRK1 spatial distribution with physiological activities. These mice, however, displayed spontaneous seizure-like activity and thus were investigated for the origin of such activity. We show that GIRK tetramers containing YFP-GIRK1 are correctly assembled and trafficked to the plasma membrane, but are functionally impaired. A battery of behavioural assays conducted on YFP-GIRK1 and GIRK1-null (GIRK1-/- ) mice revealed similar phenotypes, including impaired nociception, reduced anxiety and hyperactivity in an unfamiliar environment. However, YFP-GIRK1 mice exhibited increased home-cage locomotion while GIRK1-/- mice did not. In addition, we show that the GIRK1 subunit is essential for intact spatial learning and memory and synaptic plasticity in hippocampal brain slices. This study expands our knowledge regarding the role of GIRK1 in neuronal processes and underlines the importance of GIRK1-containing heterotetramers.
Collapse
Affiliation(s)
- Alice Mett
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Izhar Karbat
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Michael Tsoory
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Shachar Fine
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shachar Iwanir
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Reuveny
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
14
|
Sánchez-Rodríguez I, Djebari S, Temprano-Carazo S, Vega-Avelaira D, Jiménez-Herrera R, Iborra-Lázaro G, Yajeya J, Jiménez-Díaz L, Navarro-López JD. Hippocampal long-term synaptic depression and memory deficits induced in early amyloidopathy are prevented by enhancing G-protein-gated inwardly rectifying potassium channel activity. J Neurochem 2020; 153:362-376. [PMID: 31875959 PMCID: PMC7217154 DOI: 10.1111/jnc.14946] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 12/06/2019] [Accepted: 12/20/2019] [Indexed: 12/11/2022]
Abstract
Hippocampal synaptic plasticity disruption by amyloid‐β (Aβ) peptides + thought to be responsible for learning and memory impairments in Alzheimer's disease (AD) early stage. Failures in neuronal excitability maintenance seems to be an underlying mechanism. G‐protein‐gated inwardly rectifying potassium (GirK) channels control neural excitability by hyperpolarization in response to many G‐protein‐coupled receptors activation. Here, in early in vitro and in vivo amyloidosis mouse models, we study whether GirK channels take part of the hippocampal synaptic plasticity impairments generated by Aβ1–42. In vitro electrophysiological recordings from slices showed that Aβ1–42 alters synaptic plasticity by switching high‐frequency stimulation (HFS) induced long‐term potentiation (LTP) to long‐term depression (LTD), which led to in vivo hippocampal‐dependent memory deficits. Remarkably, selective pharmacological activation of GirK channels with ML297 rescued both HFS‐induced LTP and habituation memory from Aβ1–42 action. Moreover, when GirK channels were specifically blocked by Tertiapin‐Q, their activation with ML297 failed to rescue LTP from the HFS‐dependent LTD induced by Aβ1–42. On the other hand, the molecular analysis of the recorded slices by western blot showed that the expression of GIRK1/2 subunits, which form the prototypical GirK channel in the hippocampus, was not significantly regulated by Aβ1–42. However, immunohistochemical examination of our in vivo amyloidosis model showed Aβ1–42 to down‐regulate hippocampal GIRK1 subunit expression. Together, our results describe an Aβ‐mediated deleterious synaptic mechanism that modifies the induction threshold for hippocampal LTP/LTD and underlies memory alterations observed in amyloidosis models. In this scenario, GirK activation assures memory formation by preventing the transformation of HFS‐induced LTP into LTD. ![]()
Collapse
Affiliation(s)
- Irene Sánchez-Rodríguez
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Souhail Djebari
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Sara Temprano-Carazo
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - David Vega-Avelaira
- Departamento de Ciencias Biomédicas Básicas, European University of Madrid, Madrid, Spain
| | - Raquel Jiménez-Herrera
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Guillermo Iborra-Lázaro
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Javier Yajeya
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Lydia Jiménez-Díaz
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Juan D Navarro-López
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| |
Collapse
|
15
|
Martín-Belmonte A, Aguado C, Alfaro-Ruíz R, Moreno-Martínez AE, de la Ossa L, Martínez-Hernández J, Buisson A, Früh S, Bettler B, Shigemoto R, Fukazawa Y, Luján R. Reduction in the neuronal surface of post and presynaptic GABA B receptors in the hippocampus in a mouse model of Alzheimer's disease. Brain Pathol 2019; 30:554-575. [PMID: 31729777 PMCID: PMC7317930 DOI: 10.1111/bpa.12802] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/04/2019] [Indexed: 12/25/2022] Open
Abstract
The hippocampus plays key roles in learning and memory and is a main target of Alzheimer's disease (AD), which causes progressive memory impairments. Despite numerous investigations about the processes required for the normal hippocampal functions, the neurotransmitter receptors involved in the synaptic deficits by which AD disables the hippocampus are not yet characterized. By combining histoblots, western blots, immunohistochemistry and high-resolution immunoelectron microscopic methods for GABAB receptors, this study provides a quantitative description of the expression and the subcellular localization of GABAB1 in the hippocampus in a mouse model of AD at 1, 6 and 12 months of age. Western blots and histoblots showed that the total amount of protein and the laminar expression pattern of GABAB1 were similar in APP/PS1 mice and in age-matched wild-type mice. In contrast, immunoelectron microscopic techniques showed that the subcellular localization of GABAB1 subunit did not change significantly in APP/PS1 mice at 1 month of age, was significantly reduced in the stratum lacunosum-moleculare of CA1 pyramidal cells at 6 months of age and significantly reduced at the membrane surface of CA1 pyramidal cells at 12 months of age. This reduction of plasma membrane GABAB1 was paralleled by a significant increase of the subunit at the intracellular sites. We further observed a decrease of membrane-targeted GABAB receptors in axon terminals contacting CA1 pyramidal cells. Our data demonstrate compartment- and age-dependent reduction of plasma membrane-targeted GABAB receptors in the CA1 region of the hippocampus, suggesting that this decrease might be enough to alter the GABAB -mediated synaptic transmission taking place in AD.
Collapse
Affiliation(s)
- Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| | - Rocío Alfaro-Ruíz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| | - Ana Esther Moreno-Martínez
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| | - Luis de la Ossa
- Departamento de Sistemas Informáticos, Escuela Superior de Ingeniería Informática, Universidad de Castilla-La Mancha, 02071, Albacete, Spain
| | - José Martínez-Hernández
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| | - Alain Buisson
- Grenoble Institut des Neurosciences, Université Grenoble Alpes, BP 170, Grenoble, France
| | - Simon Früh
- Department of Biomedicine, Institute of Physiology, University of Basel, Basel, Switzerland
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, University of Basel, Basel, Switzerland
| | - Ryuichi Shigemoto
- Institute of Science and Technology (IST Austria), Am Campus 1, A-3400, Klosterneuburg, Austria
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Faculty of Medical Science, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, Faculty of Medical Science, University of Fukui, Fukui, Japan
| | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/ Almansa 14, 02008, Albacete, Spain
| |
Collapse
|
16
|
Morató X, Luján R, Gonçalves N, Watanabe M, Altafaj X, Carvalho AL, Fernández-Dueñas V, Cunha RA, Ciruela F. Metabotropic glutamate type 5 receptor requires contactin-associated protein 1 to control memory formation. Hum Mol Genet 2019; 27:3528-3541. [PMID: 30010864 DOI: 10.1093/hmg/ddy264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/09/2018] [Indexed: 12/31/2022] Open
Abstract
The hippocampus is a key brain region for memory formation. Metabotropic glutamate type 5 receptors (mGlu5R) are strongly expressed in CA1 pyramidal neurons and fine-tune synaptic plasticity. Accordingly, mGlu5R pharmacological manipulation may represent an attractive therapeutic strategy to manage hippocampal-related neurological disorders. Here, by means of a membrane yeast two-hybrid screening, we identified contactin-associated protein 1 (Caspr1), a type I transmembrane protein member of the neurexin family, as a new mGlu5R partner. We report that mGlu5R and Caspr1 co-distribute and co-assemble both in heterologous expression systems and in rat brain. Furthermore, downregulation of Caspr1 in rat hippocampal primary cultures decreased mGlu5R-mediated signaling. Finally, silencing Caspr1 expression in the hippocampus impaired the impact of mGlu5R on spatial memory. Our results indicate that Caspr1 plays a pivotal role controlling mGlu5R function in hippocampus-dependent memory formation. Hence, this new protein-protein interaction may represent novel target for neurological disorders affecting hippocampal glutamatergic neurotransmission.
Collapse
Affiliation(s)
- Xavier Morató
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Rafael Luján
- IDINE, Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Albacete, Spain
| | - Nélio Gonçalves
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Xavier Altafaj
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain
| | - Ana Luísa Carvalho
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Víctor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Rodrigo A Cunha
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
17
|
Sánchez-Rodríguez I, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. Role of GirK Channels in Long-Term Potentiation of Synaptic Inhibition in an In Vivo Mouse Model of Early Amyloid- β Pathology. Int J Mol Sci 2019; 20:ijms20051168. [PMID: 30866445 PMCID: PMC6429279 DOI: 10.3390/ijms20051168] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 02/26/2019] [Accepted: 03/02/2019] [Indexed: 01/01/2023] Open
Abstract
Imbalances of excitatory/inhibitory synaptic transmission occur early in the pathogenesis of Alzheimer’s disease (AD), leading to hippocampal hyperexcitability and causing synaptic, network, and cognitive dysfunctions. G-protein-gated potassium (GirK) channels play a key role in the control of neuronal excitability, contributing to inhibitory signaling. Here, we evaluate the relationship between GirK channel activity and inhibitory hippocampal functionality in vivo. In a non-transgenic mouse model of AD, field postsynaptic potentials (fPSPs) from the CA3–CA1 synapse in the dorsal hippocampus were recorded in freely moving mice. Intracerebroventricular (ICV) injections of amyloid-β (Aβ) or GirK channel modulators impaired ionotropic (GABAA-mediated fPSPs) and metabotropic (GirK-mediated fPSPs) inhibitory signaling and disrupted the potentiation of synaptic inhibition. However, the activation of GirK channels prevented Aβ-induced changes in GABAA components. Our data shows, for the first time, the presence of long-term potentiation (LTP) for both the GABAA and GirK-mediated inhibitory postsynaptic responses in vivo. In addition, our results support the importance of an accurate level of GirK-dependent signaling for dorsal hippocampal performance in early amyloid pathology models by controlling the excess of excitation that disrupts synaptic plasticity processes.
Collapse
Affiliation(s)
- Irene Sánchez-Rodríguez
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
| | - Agnès Gruart
- Division of Neurosciences, University Pablo de Olavide, 41013 Seville, Spain.
| | | | - Lydia Jiménez-Díaz
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
| | - Juan D Navarro-López
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
| |
Collapse
|
18
|
Mutual action by Gγ and Gβ for optimal activation of GIRK channels in a channel subunit-specific manner. Sci Rep 2019; 9:508. [PMID: 30679535 PMCID: PMC6346094 DOI: 10.1038/s41598-018-36833-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/29/2018] [Indexed: 01/06/2023] Open
Abstract
The tetrameric G protein-gated K+ channels (GIRKs) mediate inhibitory effects of neurotransmitters that activate Gi/o-coupled receptors. GIRKs are activated by binding of the Gβγ dimer, via contacts with Gβ. Gγ underlies membrane targeting of Gβγ, but has not been implicated in channel gating. We observed that, in Xenopus oocytes, expression of Gγ alone activated homotetrameric GIRK1* and heterotetrameric GIRK1/3 channels, without affecting the surface expression of GIRK or Gβ. Gγ and Gβ acted interdependently: the effect of Gγ required the presence of ambient Gβ and was enhanced by low doses of coexpressed Gβ, whereas excess of either Gβ or Gγ imparted suboptimal activation, possibly by sequestering the other subunit “away” from the channel. The unique distal C-terminus of GIRK1, G1-dCT, was important but insufficient for Gγ action. Notably, GIRK2 and GIRK1/2 were not activated by Gγ. Our results suggest that Gγ regulates GIRK1* and GIRK1/3 channel’s gating, aiding Gβ to trigger the channel’s opening. We hypothesize that Gγ helps to relax the inhibitory effect of a gating element (“lock”) encompassed, in part, by the G1-dCT; GIRK2 acts to occlude the effect of Gγ, either by setting in motion the same mechanism as Gγ, or by triggering an opposing gating effect.
Collapse
|
19
|
Alfaro-Ruíz R, Aguado C, Martín-Belmonte A, Moreno-Martínez AE, Luján R. Expression, Cellular and Subcellular Localisation of Kv4.2 and Kv4.3 Channels in the Rodent Hippocampus. Int J Mol Sci 2019; 20:ijms20020246. [PMID: 30634540 PMCID: PMC6359635 DOI: 10.3390/ijms20020246] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/29/2018] [Accepted: 01/03/2019] [Indexed: 12/31/2022] Open
Abstract
The Kv4 family of voltage-gated K⁺ channels underlie the fast transient (A-type) outward K⁺ current. Although A-type currents are critical to determine somato-dendritic integration in central neurons, relatively little is known about the precise subcellular localisation of the underlying channels in hippocampal circuits. Using histoblot and immunoelectron microscopic techniques, we investigated the expression, regional distribution and subcellular localisation of Kv4.2 and Kv4.3 in the adult brain, as well as the ontogeny of their expression during postnatal development. Histoblot demonstrated that Kv4.2 and Kv4.3 proteins were widely expressed in the brain, with mostly non-overlapping patterns. During development, levels of Kv4.2 and Kv4.3 increased with age but showed marked region- and developmental stage-specific differences. Immunoelectron microscopy showed that labelling for Kv4.2 and Kv4.3 was differentially present in somato-dendritic domains of hippocampal principal cells and interneurons, including the synaptic specialisation. Quantitative analyses indicated that most immunoparticles for Kv4.2 and Kv4.3 were associated with the plasma membrane in dendritic spines and shafts, and that the two channels showed very similar distribution patterns in spines of principal cells and along the surface of granule cells. Our data shed new light on the subcellular localisation of Kv4 channels and provide evidence for their non-uniform distribution over the plasma membrane of hippocampal neurons.
Collapse
Affiliation(s)
- Rocío Alfaro-Ruíz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Dept. Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Dept. Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | - Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Dept. Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | - Ana Esther Moreno-Martínez
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Dept. Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Dept. Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| |
Collapse
|
20
|
Abstract
Whilst the nociceptin/orphanin FQ (N/OFQ) receptor (NOP) has similar intracellular coupling mechanisms to opioid receptors, it has distinct modulatory effects on physiological functions such as pain. These actions range from agonistic to antagonistic interactions with classical opioids within the spinal cord and brain, respectively. Understanding the electrophysiological actions of N/OFQ has been crucial in ascertaining the mechanisms by which these agonistic and antagonistic interactions occur. These similarities and differences between N/OFQ and opioids are due to the relative location of NOP versus opioid receptors on specific neuronal elements within these CNS regions. These mechanisms result in varied cellular actions including postsynaptic modulation of ion channels and presynaptic regulation of neurotransmitter release.
Collapse
|
21
|
Luján R, Aguado C, Ciruela F, Arus XM, Martín-Belmonte A, Alfaro-Ruiz R, Martínez-Gómez J, de la Ossa L, Watanabe M, Adelman JP, Shigemoto R, Fukazawa Y. SK2 Channels Associate With mGlu 1α Receptors and Ca V2.1 Channels in Purkinje Cells. Front Cell Neurosci 2018; 12:311. [PMID: 30283304 PMCID: PMC6156379 DOI: 10.3389/fncel.2018.00311] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/28/2018] [Indexed: 11/13/2022] Open
Abstract
The small-conductance, Ca2+-activated K+ (SK) channel subtype SK2 regulates the spike rate and firing frequency, as well as Ca2+ transients in Purkinje cells (PCs). To understand the molecular basis by which SK2 channels mediate these functions, we analyzed the exact location and densities of SK2 channels along the neuronal surface of the mouse cerebellar PCs using SDS-digested freeze-fracture replica labeling (SDS-FRL) of high sensitivity combined with quantitative analyses. Immunogold particles for SK2 were observed on post- and pre-synaptic compartments showing both scattered and clustered distribution patterns. We found an axo-somato-dendritic gradient of the SK2 particle density increasing 12-fold from soma to dendritic spines. Using two different immunogold approaches, we also found that SK2 immunoparticles were frequently adjacent to, but never overlap with, the postsynaptic density of excitatory synapses in PC spines. Co-immunoprecipitation analysis demonstrated that SK2 channels form macromolecular complexes with two types of proteins that mobilize Ca2+: CaV2.1 channels and mGlu1α receptors in the cerebellum. Freeze-fracture replica double-labeling showed significant co-clustering of particles for SK2 with those for CaV2.1 channels and mGlu1α receptors. SK2 channels were also detected at presynaptic sites, mostly at the presynaptic active zone (AZ), where they are close to CaV2.1 channels, though they are not significantly co-clustered. These data demonstrate that SK2 channels located in different neuronal compartments can associate with distinct proteins mobilizing Ca2+, and suggest that the ultrastructural association of SK2 with CaV2.1 and mGlu1α provides the mechanism that ensures voltage (excitability) regulation by distinct intracellular Ca2+ transients in PCs.
Collapse
Affiliation(s)
- Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Department of Biochemistry and Microbiology, Faculty of Sciences, University of Ghent, Ghent, Belgium
| | - Xavier Morató Arus
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Rocío Alfaro-Ruiz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Jesús Martínez-Gómez
- Departamento de Sistemas Informáticos, Escuela Superior de Ingeniería Informática, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Luis de la Ossa
- Departamento de Sistemas Informáticos, Escuela Superior de Ingeniería Informática, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Masahiko Watanabe
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - John P Adelman
- Vollum Institute, Oregon Health and Science University, Portland, OR, United States
| | - Ryuichi Shigemoto
- Institute of Science and Technology (IST Austria), Klosterneuburg, Austria
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Research Center for Child Mental Development, Life Science Advancement Program, Faculty of Medical Science, University of Fukui, Fukui, Japan
| |
Collapse
|
22
|
Strand J, Stinson C, Bellinger LL, Peng Y, Kramer PR. G i protein functions in thalamic neurons to decrease orofacial nociceptive response. Brain Res 2018; 1694:63-72. [PMID: 29763576 PMCID: PMC6026072 DOI: 10.1016/j.brainres.2018.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 02/27/2018] [Accepted: 05/12/2018] [Indexed: 01/01/2023]
Abstract
Orofacial pain includes neuronal pathways that project from the trigeminal nucleus to and through the thalamus. What role the ventroposterior thalamic complex (VP) has on orofacial pain transmission is not understood. To begin to address this question an inhibitory G protein (Gi) designer receptor exclusively activated by a designer drug (DREADD) was transfected in cells of the VP using adeno-associated virus isotype 8. Virus infected cells were identified by a fluorescent tag and immunostaining. Cells were silenced after injecting the designer drug clozapine-n-oxide, which binds the designer receptor activating Gi. Facial rubbing and local field potentials (LFP) in the VP were then recorded in awake, free moving Sprague Dawley rats after formalin injection of the masseter muscle to induce nociception. Formalin injection significantly increased LFP and the nociceptive behavioral response. Activation of DREADD Gi with clozapine-n-oxide significantly reduced LFP in the VP and reduced the orofacial nociceptive response. Because DREADD silencing can result from Gi-coupled inwardly-rectifying potassium channels (GIRK), the GIRK channel blocker tertiapin-Q was injected. Injection of GIRK blocker resulted in an increase in the nociceptive response and increased LFP activity. Immunostaining of the VP for glutamate vesicular transporter (VGLUT2) and gamma-aminobutyric acid vesicular transporter (VGAT) indicated a majority of the virally transfected cells were excitatory (VGLUT2 positive) and a minority were inhibitory (VGAT positive). We conclude first, that inhibition of the excitatory neurons within the VP reduced electrical activity and the orofacial nociceptive response and that the effect on excitatory neurons overwhelmed any change resulting from inhibitor neurons. Second, inhibition of LFP and nociception was due, in part, to GIRK activation.
Collapse
Affiliation(s)
- Jennifer Strand
- Department of Psychology, University of Texas at Arlington, Arlington, TX 76019, United States
| | - Crystal Stinson
- Texas A&M University College of Dentistry, Dallas, TX 75246, United States
| | - Larry L Bellinger
- Texas A&M University College of Dentistry, Dallas, TX 75246, United States
| | - Yuan Peng
- Department of Psychology, University of Texas at Arlington, Arlington, TX 76019, United States
| | - Phillip R Kramer
- Texas A&M University College of Dentistry, Dallas, TX 75246, United States.
| |
Collapse
|
23
|
Constitutive and Synaptic Activation of GIRK Channels Differentiates Mature and Newborn Dentate Granule Cells. J Neurosci 2018; 38:6513-6526. [PMID: 29915136 DOI: 10.1523/jneurosci.0674-18.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/30/2018] [Accepted: 05/30/2018] [Indexed: 12/21/2022] Open
Abstract
Sparse neural activity in the dentate gyrus is enforced by powerful networks of inhibitory GABAergic interneurons in combination with low intrinsic excitability of the principal neurons, the dentate granule cells (GCs). Although the cellular and circuit properties that dictate synaptic inhibition are well studied, less is known about mechanisms that confer low GC intrinsic excitability. Here we demonstrate that intact G protein-mediated signaling contributes to the characteristic low resting membrane potential that differentiates mature dentate GCs from CA1 pyramidal cells and developing adult-born GCs. In mature GCs from male and female mice, intact G protein signaling robustly reduces intrinsic excitability, whereas deletion of G protein-activated inwardly rectifying potassium channel 2 (GIRK2) increases excitability and blocks the effects of G protein signaling on intrinsic properties. Similarly, pharmacological manipulation of GABAB receptors (GABABRs) or GIRK channels alters intrinsic excitability and GC spiking behavior. However, adult-born new GCs lack functional GIRK activity, with phasic and constitutive GABABR-mediated GIRK signaling appearing after several weeks of maturation. Phasic activation is interneuron specific, arising primarily from nNOS-expressing interneurons rather than parvalbumin- or somatostatin-expressing interneurons. Together, these results demonstrate that G protein signaling contributes to the intrinsic excitability that differentiates mature and developing dentate GCs and further suggest that late maturation of GIRK channel activity is poised to convert early developmental functions of GABAB receptor signaling into GABABR-mediated inhibition.SIGNIFICANCE STATEMENT The dentate gyrus exhibits sparse neural activity that is essential for the computational function of pattern separation. Sparse activity is ascribed to strong local inhibitory circuits in combination with low intrinsic excitability of the principal neurons, the granule cells. Here we show that constitutive activity of G protein-coupled inwardly rectifying potassium channels (GIRKs) underlies to the hallmark low resting membrane potential and input resistance of mature dentate neurons. Adult-born neurons initially lack functional GIRK channels, with constitutive and phasic GABAB receptor-mediated GIRK inhibition developing in tandem after several weeks of maturation. Our results reveal that GABAB/GIRK activity is an important determinant of low excitability of mature dentate granule cells that may contribute to sparse DG activity in vivo.
Collapse
|
24
|
Differential association of GABA B receptors with their effector ion channels in Purkinje cells. Brain Struct Funct 2017; 223:1565-1587. [PMID: 29177691 PMCID: PMC5869904 DOI: 10.1007/s00429-017-1568-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/10/2017] [Indexed: 11/23/2022]
Abstract
Metabotropic GABAB receptors mediate slow inhibitory effects presynaptically and postsynaptically through the modulation of different effector signalling pathways. Here, we analysed the distribution of GABAB receptors using highly sensitive SDS-digested freeze-fracture replica labelling in mouse cerebellar Purkinje cells. Immunoreactivity for GABAB1 was observed on presynaptic and, more abundantly, on postsynaptic compartments, showing both scattered and clustered distribution patterns. Quantitative analysis of immunoparticles revealed a somato-dendritic gradient, with the density of immunoparticles increasing 26-fold from somata to dendritic spines. To understand the spatial relationship of GABAB receptors with two key effector ion channels, the G protein-gated inwardly rectifying K+ (GIRK/Kir3) channel and the voltage-dependent Ca2+ channel, biochemical and immunohistochemical approaches were performed. Co-immunoprecipitation analysis demonstrated that GABAB receptors co-assembled with GIRK and CaV2.1 channels in the cerebellum. Using double-labelling immunoelectron microscopic techniques, co-clustering between GABAB1 and GIRK2 was detected in dendritic spines, whereas they were mainly segregated in the dendritic shafts. In contrast, co-clustering of GABAB1 and CaV2.1 was detected in dendritic shafts but not spines. Presynaptically, although no significant co-clustering of GABAB1 and GIRK2 or CaV2.1 channels was detected, inter-cluster distance for GABAB1 and GIRK2 was significantly smaller in the active zone than in the dendritic shafts, and that for GABAB1 and CaV2.1 was significantly smaller in the active zone than in the dendritic shafts and spines. Thus, GABAB receptors are associated with GIRK and CaV2.1 channels in different subcellular compartments. These data provide a better framework for understanding the different roles played by GABAB receptors and their effector ion channels in the cerebellar network.
Collapse
|
25
|
Sánchez-Rodríguez I, Temprano-Carazo S, Nájera A, Djebari S, Yajeya J, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. Activation of G-protein-gated inwardly rectifying potassium (Kir3/GirK) channels rescues hippocampal functions in a mouse model of early amyloid-β pathology. Sci Rep 2017; 7:14658. [PMID: 29116174 PMCID: PMC5676742 DOI: 10.1038/s41598-017-15306-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/25/2017] [Indexed: 12/15/2022] Open
Abstract
The hippocampus plays a critical role in learning and memory. Its correct performance relies on excitatory/inhibitory synaptic transmission balance. In early stages of Alzheimer’s disease (AD), neuronal hyperexcitability leads to network dysfunction observed in cortical regions such as the hippocampus. G-protein-gated potassium (GirK) channels induce neurons to hyperpolarize, contribute to the resting membrane potential and could compensate any excesses of excitation. Here, we have studied the relationship between GirK channels and hippocampal function in a mouse model of early AD pathology. Intracerebroventricular injections of amyloid-β (Aβ1-42) peptide—which have a causal role in AD pathogenesis—were performed to evaluate CA3–CA1 hippocampal synapse functionality in behaving mice. Aβ increased the excitability of the CA3–CA1 synapse, impaired long-term potentiation (LTP) and hippocampal oscillatory activity, and induced deficits in novel object recognition (NOR) tests. Injection of ML297 alone, a selective GirK activator, was also translated in LTP and NOR deficits. However, increasing GirK activity rescued all hippocampal deficits induced by Aβ due to the restoration of excitability values in the CA3–CA1 synapse. Our results show a synaptic mechanism, through GirK channel modulation, for the prevention of the hyperexcitability that causally contributes to synaptic, network, and cognitive deficits found in early AD pathogenesis.
Collapse
Affiliation(s)
- Irene Sánchez-Rodríguez
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Sara Temprano-Carazo
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Alberto Nájera
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Souhail Djebari
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Javier Yajeya
- University of Salamanca, Instituto de Neurociencias de Castilla y León, Salamanca, Spain
| | - Agnès Gruart
- Pablo de Olavide University, Division of Neurosciences, Seville, Spain
| | | | - Lydia Jiménez-Díaz
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain.
| | - Juan D Navarro-López
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain.
| |
Collapse
|
26
|
Prolonged seizure activity causes caspase dependent cleavage and dysfunction of G-protein activated inwardly rectifying potassium channels. Sci Rep 2017; 7:12313. [PMID: 28951616 PMCID: PMC5615076 DOI: 10.1038/s41598-017-12508-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 09/08/2017] [Indexed: 01/09/2023] Open
Abstract
Recurrent high-frequency epileptic seizures cause progressive hippocampal sclerosis, which is associated with caspase-3 activation and NMDA receptor-dependent excitotoxicity. However, the identity of caspase-3 substrates that contribute to seizure-induced hippocampal atrophy remains largely unknown. Here, we show that prolonged high-frequency epileptiform discharges in cultured hippocampal neurons leads to caspase-dependent cleavage of GIRK1 and GIRK2, the major subunits of neuronal G protein-activated inwardly rectifying potassium (GIRK) channels that mediate membrane hyperpolarization and synaptic inhibition in the brain. We have identified caspase-3 cleavage sites in GIRK1 (387ECLD390) and GIRK2 (349YEVD352). The YEVD motif is highly conserved in GIRK2-4, and located within their C-terminal binding sites for Gβγ proteins that mediate membrane-delimited GIRK activation. Indeed, the cleaved GIRK2 displays reduced binding to Gβγ and cannot coassemble with GIRK1. Loss of an ER export motif upon cleavage of GIRK2 abolishes surface and current expression of GIRK2 homotetramic channels. Lastly, kainate-induced status epilepticus causes GIRK1 and GIRK2 cleavage in the hippocampus in vivo. Our findings are the first to show direct cleavage of GIRK1 and GIRK2 subunits by caspase-3, and suggest the possible role of caspase-3 mediated down-regulation of GIRK channel function and expression in hippocampal neuronal injury during prolonged epileptic seizures.
Collapse
|
27
|
Morató X, Luján R, López-Cano M, Gandía J, Stagljar I, Watanabe M, Cunha RA, Fernández-Dueñas V, Ciruela F. The Parkinson's disease-associated GPR37 receptor interacts with striatal adenosine A 2A receptor controlling its cell surface expression and function in vivo. Sci Rep 2017; 7:9452. [PMID: 28842709 PMCID: PMC5573386 DOI: 10.1038/s41598-017-10147-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/04/2017] [Indexed: 11/24/2022] Open
Abstract
G protein-coupled receptor 37 (GPR37) is an orphan receptor associated to Parkinson’s disease (PD) neuropathology. Here, we identified GPR37 as an inhibitor of adenosine A2A receptor (A2AR) cell surface expression and function in vivo. In addition, we showed that GPR37 and A2AR do oligomerize in the striatum. Thus, a close proximity of GPR37 and A2AR at the postsynaptic level of striatal synapses was observed by double-labelling post-embedding immunogold detection. Indeed, the direct receptor-receptor interaction was further substantiated by proximity ligation in situ assay. Interestingly, GPR37 deletion promoted striatal A2AR cell surface expression that correlated well with an increased A2AR agonist-mediated cAMP accumulation, both in primary striatal neurons and nerve terminals. Furthermore, GPR37−/− mice showed enhanced A2AR agonist-induced catalepsy and an increased response to A2AR antagonist-mediated locomotor activity. Overall, these results revealed a key role for GPR37 controlling A2AR biology in the striatum, which may be relevant for PD management.
Collapse
Affiliation(s)
- Xavier Morató
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Rafael Luján
- IDINE, Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Albacete, Spain
| | - Marc López-Cano
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Jorge Gandía
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Igor Stagljar
- Donnelly Centre, Department of Molecular Genetics, Department of Biochemistry, University of Toronto, Toronto, M5S 3E1, Canada
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, 060-0818, Japan
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Víctor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain. .,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain. .,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
| |
Collapse
|
28
|
Marron Fernandez de Velasco E, Zhang L, N Vo B, Tipps M, Farris S, Xia Z, Anderson A, Carlblom N, Weaver CD, Dudek SM, Wickman K. GIRK2 splice variants and neuronal G protein-gated K + channels: implications for channel function and behavior. Sci Rep 2017; 7:1639. [PMID: 28487514 PMCID: PMC5431628 DOI: 10.1038/s41598-017-01820-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/03/2017] [Indexed: 11/21/2022] Open
Abstract
Many neurotransmitters directly inhibit neurons by activating G protein-gated inwardly rectifying K+ (GIRK) channels, thereby moderating the influence of excitatory input on neuronal excitability. While most neuronal GIRK channels are formed by GIRK1 and GIRK2 subunits, distinct GIRK2 isoforms generated by alternative splicing have been identified. Here, we compared the trafficking and function of two isoforms (GIRK2a and GIRK2c) expressed individually in hippocampal pyramidal neurons lacking GIRK2. GIRK2a and GIRK2c supported comparable somato-dendritic GIRK currents in Girk2−/− pyramidal neurons, although GIRK2c achieved a more uniform subcellular distribution in pyramidal neurons and supported inhibitory postsynaptic currents in distal dendrites better than GIRK2a. While over-expression of either isoform in dorsal CA1 pyramidal neurons restored contextual fear learning in a conditional Girk2−/− mouse line, GIRK2a also enhanced cue fear learning. Collectively, these data indicate that GIRK2 isoform balance within a neuron can impact the processing of afferent inhibitory input and associated behavior.
Collapse
Affiliation(s)
| | - Lei Zhang
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Baovi N Vo
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Megan Tipps
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Shannon Farris
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Zhilian Xia
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Allison Anderson
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Nicholas Carlblom
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - C David Weaver
- Vanderbilt University, Department of Pharmacology, Nashville, TN, 37235, USA
| | - Serena M Dudek
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Kevin Wickman
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA.
| |
Collapse
|
29
|
Chorlian DB, Rangaswamy M, Manz N, Meyers JL, Kang SJ, Kamarajan C, Pandey AK, Wang JC, Wetherill L, Edenberg H, Porjesz B. Genetic correlates of the development of theta event related oscillations in adolescents and young adults. Int J Psychophysiol 2017; 115:24-39. [PMID: 27847216 PMCID: PMC5456461 DOI: 10.1016/j.ijpsycho.2016.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/18/2016] [Accepted: 11/08/2016] [Indexed: 12/22/2022]
Abstract
The developmental trajectories of theta band (4-7Hz) event-related oscillations (EROs), a key neurophysiological constituent of the P3 response, were assessed in 2170 adolescents and young adults ages 12 to 25. The theta EROs occurring in the P3 response, important indicators of neurocognitive function, were elicited during the evaluation of task-relevant target stimuli in visual and auditory oddball tasks. Associations between the theta EROs and genotypic variants of 4 KCNJ6 single nucleotide polymorphisms (SNPs) were found to vary with age, sex, scalp location, and task modality. Three of the four KCNJ6 SNPs studied here were found to be significantly associated with the same theta EROs in adults in a previous family genome wide association study. Since measures of the P3 response have been found to be a useful endophenotypes for the study of a number of clinical and behavioral disorders, studies of genetic effects on its development in adolescents and young adults may illuminate neurophysiological factors contributing to the onset of these conditions.
Collapse
Affiliation(s)
- David B Chorlian
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA.
| | | | - Niklas Manz
- Department of Physics, College of Wooster, Wooster, OH, USA
| | - Jacquelyn L Meyers
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Sun J Kang
- Stratton VA Medical Center, Albany, NY, USA
| | - Chella Kamarajan
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Ashwini K Pandey
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | | | - Leah Wetherill
- Indiana University School of Medicine, Indianapolis, IN, USA
| | - Howard Edenberg
- Indiana University School of Medicine, Indianapolis, IN, USA
| | - Bernice Porjesz
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA
| |
Collapse
|
30
|
Kleschevnikov AM, Yu J, Kim J, Lysenko LV, Zeng Z, Yu YE, Mobley WC. Evidence that increased Kcnj6 gene dose is necessary for deficits in behavior and dentate gyrus synaptic plasticity in the Ts65Dn mouse model of Down syndrome. Neurobiol Dis 2017; 103:1-10. [PMID: 28342823 DOI: 10.1016/j.nbd.2017.03.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/09/2017] [Accepted: 03/21/2017] [Indexed: 11/15/2022] Open
Abstract
Down syndrome (DS), trisomy 21, is caused by increased dose of genes present on human chromosome 21 (HSA21). The gene-dose hypothesis argues that a change in the dose of individual genes or regulatory sequences on HSA21 is necessary for creating DS-related phenotypes, including cognitive impairment. We focused on a possible role for Kcnj6, the gene encoding Kir3.2 (Girk2) subunits of a G-protein-coupled inwardly-rectifying potassium channel. This gene resides on a segment of mouse Chromosome 16 that is present in one extra copy in the genome of the Ts65Dn mouse, a well-studied genetic model of DS. Kir3.2 subunit-containing potassium channels serve as effectors for a number of postsynaptic metabotropic receptors including GABAB receptors. Several studies raise the possibility that increased Kcnj6 dose contributes to synaptic and cognitive abnormalities in DS. To assess directly a role for Kcnj6 gene dose in cognitive deficits in DS, we produced Ts65Dn mice that harbor only 2 copies of Kcnj6 (Ts65Dn:Kcnj6++- mice). The reduction in Kcnj6 gene dose restored to normal the hippocampal level of Kir3.2. Long-term memory, examined in the novel object recognition test with the retention period of 24h, was improved to the level observed in the normosomic littermate control mice (2N:Kcnj6++). Significantly, both short-term and long-term potentiation (STP and LTP) was improved to control levels in the dentate gyrus (DG) of the Ts65Dn:Kcnj6++- mouse. In view of the ability of fluoxetine to suppress Kir3.2 channels, we asked if fluoxetine-treated DG slices of Ts65Dn:Kcnj6+++ mice would rescue synaptic plasticity. Fluoxetine increased STP and LTP to control levels. These results are evidence that increased Kcnj6 gene dose is necessary for synaptic and cognitive dysfunction in the Ts65Dn mouse model of DS. Strategies aimed at pharmacologically reducing channel function should be explored for enhancing cognition in DS.
Collapse
Affiliation(s)
- Alexander M Kleschevnikov
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
| | - Jessica Yu
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Jeesun Kim
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Larisa V Lysenko
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Academy of Biology and Biotechnology of Southern Federal University, 194/1 Stachki Str, Rostov-na-Donu 344090, Russian Federation
| | - Zheng Zeng
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Y Eugene Yu
- The Children's Guild Foundation Down Syndrome Research Program, Genetics Program and Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - William C Mobley
- Department of Neurosciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| |
Collapse
|
31
|
Aguado C, García-Madrona S, Gil-Minguez M, Luján R. Ontogenic Changes and Differential Localization of T-type Ca(2+) Channel Subunits Cav3.1 and Cav3.2 in Mouse Hippocampus and Cerebellum. Front Neuroanat 2016; 10:83. [PMID: 27616982 PMCID: PMC4999439 DOI: 10.3389/fnana.2016.00083] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/11/2016] [Indexed: 12/31/2022] Open
Abstract
T-type calcium (Ca(2+)) channels play a central role in regulating membrane excitability in the brain. Although the contributions of T-type current to neuron output is often proposed to reflect a differential distribution of T-type channel subtypes to somato-dendritic compartments, their precise subcellular distributions in central neurons are not fully determined. Using histoblot and high-resolution immunoelectron microscopic techniques, we have investigated the expression, regional distribution and subcellular localization of T-type Cav3.1 and Cav3.2 channel subunits in the adult brain, as well as the ontogeny of expression during postnatal development. Histoblot analysis showed that Cav3.1 and Cav3.2 proteins were widely expressed in the brain, with mostly non-overlapping patterns. Cav3.1 showed the highest expression level in the molecular layer (ml) of the cerebellum (Cb), and Cav3.2 in the hippocampus (Hp) and the ml of Cb. During development, levels of Cav3.1 and Cav3.2 increased with age, although there were marked region- and developmental stage-specific differences in their expression. At the cellular and subcellular level, immunoelectron microscopy showed that labeling for Cav3.1 was present in somato-dendritic domains of hippocampal interneurons and Purkinje cells (PCs), while Cav3.2 was present in somato-dendritic domains of CA1 pyramidal cells, hippocampal interneurons and PCs. Most of the immunoparticles for Cav3.1 and Cav3.2 were either associated with the plasma membrane or the intracellular membranes, with notable differences depending on the compartment. Thus, Cav3.1 was mainly located in the plasma membrane of interneurons, whereas Cav3.2 was mainly located in the plasma membrane of dendritic spines and had a major intracellular distribution in dendritic shafts. In PCs, Cav3.1 and Cav3.2 showed similar distribution patterns. In addition to its main postsynaptic distribution, Cav3.2 but not Cav3.1 was also detected in axon terminals establishing excitatory synapses. These results shed new light on the subcellular localization of T-type channel subunits and provide evidence for the non-uniform distribution of Cav3.1 and Cav3.2 subunits over the plasma membrane of central neurons, which may account for the functional heterogeneity of T-type mediated current.
Collapse
Affiliation(s)
- Carolina Aguado
- Synaptic Structure Laboratory, Department Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | - Sebastián García-Madrona
- Synaptic Structure Laboratory, Department Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | - Mercedes Gil-Minguez
- Synaptic Structure Laboratory, Department Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | - Rafael Luján
- Synaptic Structure Laboratory, Department Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| |
Collapse
|
32
|
Joshi K, Shen L, Michaeli A, Salter M, Thibault-Messier G, Hashmi S, Eubanks JH, Cortez MA, Snead OC. Infantile spasms in down syndrome: Rescue by knockdown of the GIRK2 channel. Ann Neurol 2016; 80:511-21. [PMID: 27462820 DOI: 10.1002/ana.24749] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 07/25/2016] [Accepted: 07/25/2016] [Indexed: 02/05/2023]
Abstract
OBJECTIVE The Ts65Dn (Ts) mouse model of Down syndrome (DS) is exquisitely sensitive to an infantile spasms phenotype induced by γ-aminobutyric acidB receptor (GABAB R) agonists. The Ts mouse contains the core genomic triplication of the DS critical region, which includes 3 copies of the Kcnj6 gene that encodes the GABAB R-coupled G protein-coupled inward rectifying potassium channel subunit 2 (GIRK2) channel. We test the hypothesis that GIRK2 is necessary for the GABAB R agonist-induced infantile spasms phenotype in Ts. METHODS We assessed the result of either genetic or pharmacological knockdown of the GIRK2 channel in Ts brain upon the GABAB R agonist-induced infantile spasms phenotype in the Ts mouse model of DS. As well, we examined GABAB R currents in hippocampal neurons prepared from GIRK2-trisomic Ts control mice and GIRK2-disomic Ts mice in which Kcnj6 had been genetically knocked down from 3 to 2 copies. RESULTS The reduction of the copy number of Kcnj6 in Ts mice rescued the GABAB R agonist-induced infantile spasms phenotype. There was an increase in GABAB R-mediated GIRK2 currents in GIRK2-trisomic Ts mouse hippocampal neurons, which were normalized in the GIRK2-disomic Ts mice. Similarly, pharmacological knockdown of the GIRK2 channel in Ts brain using the GIRK antagonist tertiapin-Q also rescued the GABAB R agonist-induced infantile spasms phenotype in Ts mutants. INTERPRETATION The GABAB R-coupled GIRK2 channel is necessary for the GABAB R agonist-induced infantile spasms phenotype in the Ts mouse and may represent a novel therapeutic target for the treatment of infantile spasms in DS. Ann Neurol 2016;80:511-521.
Collapse
Affiliation(s)
- Krutika Joshi
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Pharmacology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
| | - Lily Shen
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Avner Michaeli
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael Salter
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | | | - Sumaiya Hashmi
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - James H Eubanks
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,University Health Network, Toronto Western Research Institute, Toronto, Ontario, Canada
| | - Miguel A Cortez
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Pediatrics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - O Carter Snead
- Neuroscience and Mental Health Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Pharmacology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Pediatrics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
33
|
Brandalise F, Lujan R, Leone R, Lodola F, Cesaroni V, Romano C, Gerber U, Rossi P. Distinct expression patterns of inwardly rectifying potassium currents in developing cerebellar granule cells of the hemispheres and the vermis. Eur J Neurosci 2016; 43:1460-73. [DOI: 10.1111/ejn.13219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 02/14/2016] [Accepted: 02/23/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Federico Brandalise
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Rafael Lujan
- Instituto de Investigación en Discapacidades Neurológicas (IDINE); Department of Ciencias Médicas; Facultad de Medicina; Universidad Castilla-La Mancha; Albacete Spain
| | - Roberta Leone
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Francesco Lodola
- Molecular Cardiology; IRCCS Fondazione Salvatore Maugeri; Pavia Italy
| | - Valentina Cesaroni
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
| | - Chiara Romano
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
| | - Urs Gerber
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Paola Rossi
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
| |
Collapse
|
34
|
Nozaki K, Kubo R, Furukawa Y. Serotonin modulates the excitatory synaptic transmission in the dentate granule cells. J Neurophysiol 2016; 115:2997-3007. [PMID: 26961099 DOI: 10.1152/jn.00064.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/04/2016] [Indexed: 01/23/2023] Open
Abstract
Serotonergic fibers from the raphe nuclei project to the hippocampal formation, the activity of which is known to modulate the inhibitory interneurons in the dentate gyrus. On the other hand, serotonergic modulation of the excitatory synapses in the dentate gyrus is not well examined. In the present study, we examined the effects of 5-HT on the excitatory postsynaptic potentials (EPSPs) in the dentate granule cells evoked by the selective stimulation of the lateral perforant path (LPP), the medial perforant path (MPP), or the mossy cell fibers (MCF). 5-HT depressed the amplitude of unitary EPSPs (uEPSPs) evoked by the stimulation of LPP or MPP, whereas uEPSPs evoked by MCF stimulation were little affected. The effect was partly explained by the decrease of the resting membrane resistance following the activation of 5-HT1A receptors, which was confirmed by computer simulations. We also found that the probability of evoking uEPSP by LPP stimulation but not MPP or MCF stimulation was reduced by 5-HT and that the paired-pulse ratio of LPP-evoked EPSP but not that of MPP- or MCF-evoked ones was increased by 5-HT. These effects were blocked by 5-HT2 antagonist, suggesting that the transmitter release in the LPP-granule cell synapse is inhibited by the activation of 5-HT2 receptors. The present results suggest that 5-HT can modulate the EPSPs in the dentate granule cells by at least two distinct mechanisms.
Collapse
Affiliation(s)
- Kanako Nozaki
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan; and
| | - Reika Kubo
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi, Naka-ku, Hiroshima, Japan
| | - Yasuo Furukawa
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan; and
| |
Collapse
|
35
|
Characterization of Rebound Depolarization in Neurons of the Rat Medial Geniculate Body In Vitro. Neurosci Bull 2016; 32:16-26. [PMID: 26781877 DOI: 10.1007/s12264-015-0006-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 10/11/2015] [Indexed: 10/22/2022] Open
Abstract
Rebound depolarization (RD) is a response to the offset from hyperpolarization of the neuronal membrane potential and is an important mechanism for the synaptic processing of inhibitory signals. In the present study, we characterized RD in neurons of the rat medial geniculate body (MGB), a nucleus of the auditory thalamus, using whole-cell patch-clamp and brain slices. RD was proportional in strength to the duration and magnitude of the hyperpolarization; was effectively blocked by Ni(2+) or Mibefradil; and was depressed when the resting membrane potential was hyperpolarized by blocking hyperpolarization-activated cyclic nucleotide-gated (HCN) channels with ZD7288 or by activating G-protein-gated inwardly-rectifying K(+) (GIRK) channels with baclofen. Our results demonstrated that RD in MGB neurons, which is carried by T-type Ca(2+) channels, is critically regulated by HCN channels and likely by GIRK channels.
Collapse
|
36
|
Sodium salicylate potentiates the GABAB-GIRK pathway to suppress rebound depolarization in neurons of the rat's medial geniculate body. Hear Res 2015; 332:104-112. [PMID: 26688177 DOI: 10.1016/j.heares.2015.11.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 11/16/2015] [Accepted: 11/23/2015] [Indexed: 12/15/2022]
Abstract
Rebound depolarization (RD) is a voltage response to the offset from pre-hyperpolarization of neuronal membrane potential, which manifests a particular form of the postsynaptic membrane potential response to inhibitory presynaptic inputs. We previously demonstrated that sodium salicylate (NaSal), a tinnitus inducer, can drastically suppress the RD in neurons of rat medial geniculate body (MGB) (Su et al, 2012; PLoS ONE 7, e46969). The purpose of the present study was to investigate the underlying cellular mechanism by using whole-cell patch-clamp recordings in rat MGB slices. NaSal (1.4 mM) had no effects on the current mediated by T-type Ca(2+) channels, indicating that it does not target these channels to suppress the RD. Instead, NaSal was shown to hyperpolarize the resting membrane potential to suppress the RD. NaSal had no effects on the current mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, indicating that it does not target these channels to hyperpolarize the resting membrane potential. NaSal induced an outward leak current that could be abolished by CGP55845, a GABAB receptor blocker, or respectively by Ba(2+) and Tertiapin-Q, blockers for G-protein-gated inwardly rectifying potassium (GIRK) channels, indicating that NaSal potentiates the GABAB-GIRK pathway to hyperpolarize the resting membrane potential. Our study demonstrates that NaSal targets GABAB receptors to alter functional behaviors of MGB neurons, which may be implicated in NaSal-induced tinnitus.
Collapse
|
37
|
Yakubovich D, Berlin S, Kahanovitch U, Rubinstein M, Farhy-Tselnicker I, Styr B, Keren-Raifman T, Dessauer CW, Dascal N. A Quantitative Model of the GIRK1/2 Channel Reveals That Its Basal and Evoked Activities Are Controlled by Unequal Stoichiometry of Gα and Gβγ. PLoS Comput Biol 2015; 11:e1004598. [PMID: 26544551 PMCID: PMC4636287 DOI: 10.1371/journal.pcbi.1004598] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/13/2015] [Indexed: 12/02/2022] Open
Abstract
G protein-gated K+ channels (GIRK; Kir3), activated by Gβγ subunits derived from Gi/o proteins, regulate heartbeat and neuronal excitability and plasticity. Both neurotransmitter-evoked (Ievoked) and neurotransmitter-independent basal (Ibasal) GIRK activities are physiologically important, but mechanisms of Ibasal and its relation to Ievoked are unclear. We have previously shown for heterologously expressed neuronal GIRK1/2, and now show for native GIRK in hippocampal neurons, that Ibasal and Ievoked are interrelated: the extent of activation by neurotransmitter (activation index, Ra) is inversely related to Ibasal. To unveil the underlying mechanisms, we have developed a quantitative model of GIRK1/2 function. We characterized single-channel and macroscopic GIRK1/2 currents, and surface densities of GIRK1/2 and Gβγ expressed in Xenopus oocytes. Based on experimental results, we constructed a mathematical model of GIRK1/2 activity under steady-state conditions before and after activation by neurotransmitter. Our model accurately recapitulates Ibasal and Ievoked in Xenopus oocytes, HEK293 cells and hippocampal neurons; correctly predicts the dose-dependent activation of GIRK1/2 by coexpressed Gβγ and fully accounts for the inverse Ibasal-Ra correlation. Modeling indicates that, under all conditions and at different channel expression levels, between 3 and 4 Gβγ dimers are available for each GIRK1/2 channel. In contrast, available Gαi/o decreases from ~2 to less than one Gα per channel as GIRK1/2's density increases. The persistent Gβγ/channel (but not Gα/channel) ratio support a strong association of GIRK1/2 with Gβγ, consistent with recruitment to the cell surface of Gβγ, but not Gα, by GIRK1/2. Our analysis suggests a maximal stoichiometry of 4 Gβγ but only 2 Gαi/o per one GIRK1/2 channel. The unique, unequal association of GIRK1/2 with G protein subunits, and the cooperative nature of GIRK gating by Gβγ, underlie the complex pattern of basal and agonist-evoked activities and allow GIRK1/2 to act as a sensitive bidirectional detector of both Gβγ and Gα. Many neurotransmitters and hormones inhibit the electric activity of excitable cells (such as cardiac cells and neurons) by activating a K+ channel, GIRK (G protein-gated Inwardly Rectifying K+ channel). GIRK channels also possess constitutive “basal” activity which contributes to regulation of neuronal and cardiac excitability and certain disorders, but the mechanism of this activity and its interrelation with the neurotransmitter-evoked activity are poorly understood. In this work we show that key features of basal and neurotransmitter-evoked activities are similar in cultured hippocampal neurons and in two model systems (mammalian HEK293 cells and Xenopus oocytes). Using experimental data of the neuronal GIRK1/2 channel function upon changes in GIRK and G protein concentrations, we constructed a mathematical model that quantitatively accounts for basal and evoked activity, and for the inverse correlation between the two. Our analysis suggests a novel and unexpected mechanism of interaction of GIRK1/2 with the G protein subunits, where the tetrameric GIRK channel can assemble with 4 molecules of the Gβγ subunits but only 2 molecules of Gα. GIRK is a prototypical effector of Gβγ, and the unequal stoichiometry of interaction with G protein subunits may have general implications for G protein signaling.
Collapse
Affiliation(s)
- Daniel Yakubovich
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Shai Berlin
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Uri Kahanovitch
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Moran Rubinstein
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Isabella Farhy-Tselnicker
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Boaz Styr
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Tal Keren-Raifman
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Nathan Dascal
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
| |
Collapse
|
38
|
GIRK3 gates activation of the mesolimbic dopaminergic pathway by ethanol. Proc Natl Acad Sci U S A 2015; 112:7091-6. [PMID: 25964320 DOI: 10.1073/pnas.1416146112] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels are critical regulators of neuronal excitability and can be directly activated by ethanol. Constitutive deletion of the GIRK3 subunit has minimal phenotypic consequences, except in response to drugs of abuse. Here we investigated how the GIRK3 subunit contributes to the cellular and behavioral effects of ethanol, as well as to voluntary ethanol consumption. We found that constitutive deletion of GIRK3 in knockout (KO) mice selectively increased ethanol binge-like drinking, without affecting ethanol metabolism, sensitivity to ethanol intoxication, or continuous-access drinking. Virally mediated expression of GIRK3 in the ventral tegmental area (VTA) reversed the phenotype of GIRK3 KO mice and further decreased the intake of their wild-type counterparts. In addition, GIRK3 KO mice showed a blunted response of the mesolimbic dopaminergic (DA) pathway to ethanol, as assessed by ethanol-induced excitation of VTA neurons and DA release in the nucleus accumbens. These findings support the notion that the subunit composition of VTA GIRK channels is a critical determinant of DA neuron sensitivity to drugs of abuse. Furthermore, our study reveals the behavioral impact of this cellular effect, whereby the level of GIRK3 expression in the VTA tunes ethanol intake under binge-type conditions: the more GIRK3, the less ethanol drinking.
Collapse
|
39
|
Trimmer JS. Subcellular localization of K+ channels in mammalian brain neurons: remarkable precision in the midst of extraordinary complexity. Neuron 2015; 85:238-56. [PMID: 25611506 DOI: 10.1016/j.neuron.2014.12.042] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Potassium channels (KChs) are the most diverse ion channels, in part due to extensive combinatorial assembly of a large number of principal and auxiliary subunits into an assortment of KCh complexes. Their structural and functional diversity allows KChs to play diverse roles in neuronal function. Localization of KChs within specialized neuronal compartments defines their physiological role and also fundamentally impacts their activity, due to localized exposure to diverse cellular determinants of channel function. Recent studies in mammalian brain reveal an exquisite refinement of KCh subcellular localization. This includes axonal KChs at the initial segment, and near/within nodes of Ranvier and presynaptic terminals, dendritic KChs found at sites reflecting specific synaptic input, and KChs defining novel neuronal compartments. Painting the remarkable diversity of KChs onto the complex architecture of mammalian neurons creates an elegant picture of electrical signal processing underlying the sophisticated function of individual neuronal compartments, and ultimately neurotransmission and behavior.
Collapse
Affiliation(s)
- James S Trimmer
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616, USA; Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA.
| |
Collapse
|
40
|
de Velasco EMF, McCall N, Wickman K. GIRK Channel Plasticity and Implications for Drug Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:201-38. [DOI: 10.1016/bs.irn.2015.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
41
|
Luján R, Aguado C. Localization and Targeting of GIRK Channels in Mammalian Central Neurons. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:161-200. [PMID: 26422985 DOI: 10.1016/bs.irn.2015.05.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
G protein-gated inwardly rectifying K(+) (GIRK/K(ir)3) channels are critical to brain function. They hyperpolarize neurons in response to activation of different G protein-coupled receptors, reducing cell excitability. Molecular cloning has revealed four distinct mammalian genes (GIRK1-4), which, with the exception of GIRK4, are broadly expressed in the central nervous system (CNS) and have been implicated in a variety of neurological disorders. Although the molecular structure and composition of GIRK channels are key determinants of their biophysical properties, their cellular and subcellular localization patterns and densities on the neuronal surface are just as important to nerve function. Current data obtained with high-resolution quantitative localization techniques reveal complex, subcellular compartment-specific distribution patterns of GIRK channel subunits. Recent efforts have focused on determining the associated proteins that form macromolecular complexes with GIRK channels. Demonstration of the precise subcellular compartmentalization of GIRK channels and their associated proteins represents a crucial step in understanding the contribution of these channels to specific aspects of neuronal function under both physiological and pathological conditions. Here, we present an overview of studies aimed at determining the cellular and subcellular localization of GIRK channel subunits in mammalian brain neurons and discuss implications for neuronal physiology.
Collapse
Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain.
| | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain
| |
Collapse
|
42
|
Li MH, Suchland KL, Ingram SL. GABAergic transmission and enhanced modulation by opioids and endocannabinoids in adult rat rostral ventromedial medulla. J Physiol 2014; 593:217-30. [PMID: 25556797 DOI: 10.1113/jphysiol.2014.275701] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 10/17/2014] [Indexed: 01/24/2023] Open
Abstract
KEY POINTS Electrical stimulation of the rostral ventromedial medulla (RVM) facilitates pain behaviours in neonates but inhibits these behaviours in adults. The cellular mechanisms underlying these changes in RVM modulation of pain behaviours are not known. We optimized whole-cell patch-clamp recordings for RVM neurons in animals older than postnatal day 30 and compared the results to postnatal day 10-21 animals. Our results demonstrate that the γ-aminobutyric acid (GABA) release is lower and opioid effects are more evident in adult rats compared to early postnatal rats. A cannabinoid receptor antagonist significantly increased GABA release in mature but not in immature RVM neurons suggesting the presence of local endocannabinoid tone in mature RVM. Neurons in the rostral ventromedial medulla (RVM) play critical and complex roles in pain modulation. Recent studies have shown that electrical stimulation of the RVM produces pain facilitation in young animals (postnatal (PN) day < 21) but predominantly inhibits pain behaviours in adults. The cellular mechanisms underlying these changes in RVM modulation of pain behaviours are not known. This is in part because whole-cell patch-clamp studies in RVM to date have been in young (PN day < 18) animals because the organization and abundance of myelinated fibres in this region make the RVM a challenging area for whole-cell patch-clamp recording in adults. Several neurotransmitter systems, including GABAergic neurotransmission, undergo developmental changes that mature by PN day 21. Thus, we focused on optimizing whole-cell patch-clamp recordings for RVM neurons in animals older than PN day 30 and compared the results to animals at PN day 10-21. Our results demonstrate that the probability of GABA release is lower and that opioid and endocannabinoid effects are more evident in adult rats (mature) compared to early postnatal (immature) rats. Differences in these properties of RVM neurons may contribute to the developmental changes in descending control of pain from the RVM to the spinal cord.
Collapse
Affiliation(s)
- Ming-Hua Li
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR, 97239, USA
| | | | | |
Collapse
|
43
|
Amaral AC, Jakovcevski M, McGaughy JA, Calderwood SK, Mokler DJ, Rushmore RJ, Galler JR, Akbarian SA, Rosene DL. Prenatal protein malnutrition decreases KCNJ3 and 2DG activity in rat prefrontal cortex. Neuroscience 2014; 286:79-86. [PMID: 25446346 DOI: 10.1016/j.neuroscience.2014.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/08/2014] [Accepted: 11/04/2014] [Indexed: 10/24/2022]
Abstract
Prenatal protein malnutrition (PPM) in rats causes enduring changes in brain and behavior including increased cognitive rigidity and decreased inhibitory control. A preliminary gene microarray screen of PPM rat prefrontal cortex (PFC) identified alterations in KCNJ3 (GIRK1/Kir3.1), a gene important for regulating neuronal excitability. Follow-up with polymerase chain reaction and Western blot showed decreased KCNJ3 expression in the PFC, but not hippocampus or brainstem. To verify localization of the effect to the PFC, baseline regional brain activity was assessed with (14)C-2-deoxyglucose. Results showed decreased activation in the PFC but not hippocampus. Together these findings point to the unique vulnerability of the PFC to the nutritional insult during early brain development, with enduring effects in adulthood on KCNJ3 expression and baseline metabolic activity.
Collapse
Affiliation(s)
- A C Amaral
- Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA 02118, United States.
| | | | - J A McGaughy
- Department of Psychology, University of New Hampshire, Durham, NH 03824, United States
| | - S K Calderwood
- Department of Radiation Oncology, Beth Israel Deaconess Hospital, Harvard Medical School, Boston, MA 02215, United States
| | - D J Mokler
- Department of Biomedical Sciences, University of New England, Biddeford, ME 02120, United States
| | - R J Rushmore
- Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA 02118, United States
| | - J R Galler
- Judge Baker Children's Center and Department of Psychiatry, Harvard Medical School, Boston, MA 02120, United States
| | - S A Akbarian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - D L Rosene
- Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA 02118, United States
| |
Collapse
|
44
|
Bista P, Cerina M, Ehling P, Leist M, Pape HC, Meuth SG, Budde T. The role of two-pore-domain background K⁺ (K₂p) channels in the thalamus. Pflugers Arch 2014; 467:895-905. [PMID: 25346156 DOI: 10.1007/s00424-014-1632-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 12/15/2022]
Abstract
The thalamocortical system is characterized by two fundamentally different activity states, namely synchronized burst firing and tonic action potential generation, which mainly occur during the behavioral states of sleep and wakefulness, respectively. The switch between the two firing modes is crucially governed by the bidirectional modulation of members of the K2P channel family, namely tandem of P domains in a weakly inward rectifying K(+) (TWIK)-related acid-sensitive K(+) (TASK) and TWIK-related K(+) (TREK) channels, in thalamocortical relay (TC) neurons. Several physicochemical stimuli including neurotransmitters, protons, di- and multivalent cations as well as clinically used drugs have been shown to modulate K2P channels in these cells. With respect to modulation of these channels by G-protein-coupled receptors, PLCβ plays a unique role with both substrate breakdown and product synthesis exerting important functions. While the degradation of PIP2 leads to the closure of TREK channels, the production of DAG induces the inhibition of TASK channels. Therefore, TASK and TREK channels were found to be central elements in the control of thalamic activity modes. Since research has yet focused on identifying the muscarinic pathway underling the modulation of TASK and TREK channels in TC neurons, future studies should address other thalamic cell types and members of the K2P channel family.
Collapse
Affiliation(s)
- Pawan Bista
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, 48149, Münster, Germany
| | | | | | | | | | | | | |
Collapse
|
45
|
Nagi K, Pineyro G. Kir3 channel signaling complexes: focus on opioid receptor signaling. Front Cell Neurosci 2014; 8:186. [PMID: 25071446 PMCID: PMC4085882 DOI: 10.3389/fncel.2014.00186] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 06/18/2014] [Indexed: 12/03/2022] Open
Abstract
Opioids are among the most effective drugs to treat severe pain. They produce their analgesic actions by specifically activating opioid receptors located along the pain perception pathway where they inhibit the flow of nociceptive information. This inhibition is partly accomplished by activation of hyperpolarizing G protein-coupled inwardly-rectifying potassium (GIRK or Kir3) channels. Kir3 channels control cellular excitability in the central nervous system and in the heart and, because of their ubiquitous distribution, they mediate the effects of a large range of hormones and neurotransmitters which, upon activation of corresponding G protein-coupled receptors (GPCRs) lead to channel opening. Here we analyze GPCR signaling via these effectors in reference to precoupling and collision models. Existing knowledge on signaling bias is discussed in relation to these models as a means of developing strategies to produce novel opioid analgesics with an improved side effects profile.
Collapse
Affiliation(s)
- Karim Nagi
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada
| | - Graciela Pineyro
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada ; Département de Psychiatrie, Faculté de Médecine, Université de Montréal Montréal, QC, Canada
| |
Collapse
|
46
|
Kirizs T, Kerti-Szigeti K, Lorincz A, Nusser Z. Distinct axo-somato-dendritic distributions of three potassium channels in CA1 hippocampal pyramidal cells. Eur J Neurosci 2014; 39:1771-83. [PMID: 24606584 PMCID: PMC4150533 DOI: 10.1111/ejn.12526] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 12/21/2022]
Abstract
Potassium channels comprise the most diverse family of ion channels and play critical roles in a large variety of physiological and pathological processes. In addition to their molecular diversity, variations in their distributions and densities on the axo-somato-dendritic surface of neurons are key parameters in determining their functional impact. Despite extensive electrophysiological and anatomical investigations, the exact location and densities of most K+ channels in small subcellular compartments are still unknown. Here we aimed at providing a quantitative surface map of two delayed-rectifier (Kv1.1 and Kv2.1) and one G-protein-gated inwardly rectifying (Kir3.2) K+ channel subunits on hippocampal CA1 pyramidal cells (PCs). Freeze-fracture replica immunogold labelling was employed to determine the relative densities of these K+ channel subunits in 18 axo-somato-dendritic compartments. Significant densities of the Kv1.1 subunit were detected on axon initial segments (AISs) and axon terminals, with an approximately eight-fold lower density in the latter compartment. The Kv2.1 subunit was found in somatic, proximal dendritic and AIS plasma membranes at approximately the same densities. This subunit has a non-uniform plasma membrane distribution; Kv2.1 clusters are frequently adjacent to, but never overlap with, GABAergic synapses. A quasi-linear increase in the Kir3.2 subunit density along the dendrites of PCs was detected, showing no significant difference between apical dendritic shafts, oblique dendrites or dendritic spines at the same distance from the soma. Our results demonstrate that each subunit has a unique cell-surface distribution pattern, and predict their differential involvement in synaptic integration and output generation at distinct subcellular compartments.
Collapse
Affiliation(s)
- Tekla Kirizs
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony Street 43, Budapest, Hungary
| | | | | | | |
Collapse
|
47
|
Ballesteros-Merino C, Watanabe M, Shigemoto R, Fukazawa Y, Adelman JP, Luján R. Differential subcellular localization of SK3-containing channels in the hippocampus. Eur J Neurosci 2014; 39:883-892. [PMID: 24405447 DOI: 10.1111/ejn.12474] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 12/22/2022]
Abstract
Small-conductance, Ca(2+) -activated K(+) (SK) channels are expressed in the hippocampus where they regulate synaptic responses, plasticity, and learning and memory. To investigate the expression of SK3 (KCNN3) subunits, we determined the developmental profile and subcellular distribution of SK3 in the developing mouse hippocampus using western blots, immunohistochemistry and high-resolution immunoelectron microscopy. The results showed that SK3 expression increased during postnatal development, and that the localization of SK3 changed from being mainly associated with the endoplasmic reticulum and intracellular sites during the first postnatal week to being progressively concentrated in dendritic spines during later stages. In the adult, SK3 was localized mainly in postsynaptic compartments, both at extrasynaptic sites and along the postsynaptic density of excitatory synapses. Double labelling showed that SK3 co-localized with SK2 (KCNN2) and with N-methyl-D-aspartate receptors. Finally, quantitative analysis of SK3 density revealed two subcellular distribution patterns in different hippocampal layers, with SK3 being unevenly distributed in CA1 region of the hippocampus pyramidal cells and homogeneously distributed in dentate gyrus granule cells. Our results revealed a complex cell surface distribution of SK3-containing channels and a distinct developmental program that may influence different hippocampal functions.
Collapse
Affiliation(s)
- Carmen Ballesteros-Merino
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain
| | | | | | | | | | | |
Collapse
|
48
|
Luján R, Marron Fernandez de Velasco E, Aguado C, Wickman K. New insights into the therapeutic potential of Girk channels. Trends Neurosci 2013; 37:20-9. [PMID: 24268819 DOI: 10.1016/j.tins.2013.10.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/01/2023]
Abstract
G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.
Collapse
Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | | | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, 321 Church Street South East, Minneapolis, MN 55455, USA.
| |
Collapse
|
49
|
Fajardo-Serrano A, Wydeven N, Young D, Watanabe M, Shigemoto R, Martemyanov KA, Wickman K, Luján R. Association of Rgs7/Gβ5 complexes with Girk channels and GABAB receptors in hippocampal CA1 pyramidal neurons. Hippocampus 2013; 23:1231-45. [PMID: 23804514 DOI: 10.1002/hipo.22161] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2013] [Indexed: 12/15/2022]
Abstract
In the hippocampus, signaling through G protein-coupled receptors is modulated by Regulators of G protein signaling (Rgs) proteins, which act to stimulate the rate of GTP hydrolysis, and consequently, G protein inactivation. The R7-Rgs subfamily selectively deactivates the G(i/o)-class of Gα subunits that mediate the action of several GPCRs. Here, we used co-immunoprecipitation, electrophysiology and immunoelectron microscopy techniques to investigate the formation of macromolecular complexes and spatial relationship of Rgs7/Gβ5 complexes and its prototypical signaling partners, the GABAB receptor and Girk channel. Co-expression of recombinant GABAB receptors and Girk channels in combination with co-immunoprecipitation experiments established that the Rgs7/Gβ5 forms complexes with GABAB receptors or Girk channels. Using electrophysiological experiments, we found that GABAB -Girk current deactivation kinetics was markedly faster in cells coexpressing Rgs7/Gβ5. At the electron microscopic level, immunolabeling for Rgs7 and Gβ5 proteins was found primarily in the dendritic layers of the hippocampus and showed similar distribution patterns. Immunoreactivity was mostly localized along the extrasynaptic plasma membrane of dendritic shafts and spines of pyramidal cells and, to a lesser extent, to that of presynaptic terminals. Quantitative analysis of immunogold particles for Rgs7 and Gβ5 revealed an enrichment of the two proteins around excitatory synapses on dendritic spines, virtually identical to that of Girk2 and GABAB1 . These data support the existence of macromolecular complexes composed of GABAB receptor-G protein-Rgs7-Girk channels in which Rgs7 and Gβ5 proteins may preferentialy modulate GABAB receptor signaling through the deactivation of Girk channels on dendritic spines. In contrast, Rgs7 and Girk2 were associated but mainly segregated from GABAB1 in dendritic shafts, where Rgs7/Gβ5 signaling complexes might modulate Girk-dependent signaling via a different metabotropic receptor(s).
Collapse
Affiliation(s)
- Ana Fajardo-Serrano
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02006, Albacete, Spain
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Aguado C, Fernández-Alacid L, Cabañero MJ, Yanagawa Y, Schilling K, Watanabe M, Fritschy JM, Luján R. Differential maturation of GIRK2-expressing neurons in the mouse cerebellum. J Chem Neuroanat 2013; 47:79-89. [DOI: 10.1016/j.jchemneu.2012.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 11/22/2012] [Accepted: 11/26/2012] [Indexed: 12/22/2022]
|