1
|
Khlaifia A, Honoré E, Artinian J, Laplante I, Lacaille JC. mTORC1 function in hippocampal parvalbumin interneurons: regulation of firing and long-term potentiation of intrinsic excitability but not long-term contextual fear memory and context discrimination. Mol Brain 2022; 15:56. [PMID: 35715811 PMCID: PMC9204956 DOI: 10.1186/s13041-022-00941-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/07/2022] [Indexed: 02/03/2023] Open
Abstract
Hippocampal CA1 parvalbumin-expressing interneurons (PV INs) play a central role in controlling principal cell activity and orchestrating network oscillations. PV INs receive excitatory inputs from CA3 Schaffer collaterals and local CA1 pyramidal cells, and they provide perisomatic inhibition. Schaffer collateral excitatory synapses onto PV INs express Hebbian and anti-Hebbian types of long-term potentiation (LTP), as well as elicit LTP of intrinsic excitability (LTPIE). LTPIE requires the activation of type 5 metabotropic glutamate receptors (mGluR5) and is mediated by downregulation of potassium channels Kv1.1. It is sensitive to rapamycin and thus may involve activation of the mammalian target of rapamycin complex 1 (mTORC1). LTPIE facilitates PV INs recruitment in CA1 and maintains an excitatory-inhibitory balance. Impaired CA1 PV INs activity or LTP affects network oscillations and memory. However, whether LTPIE in PV INs plays a role in hippocampus-dependent memory remains unknown. Here, we used conditional deletion of the obligatory component of mTORC1, the Regulatory-Associated Protein of mTOR (Raptor), to directly manipulate mTORC1 in PV INs. We found that homozygous, but not heterozygous, conditional knock-out of Rptor resulted in a decrease in CA1 PV INs of mTORC1 signaling via its downstream effector S6 phosphorylation assessed by immunofluorescence. In whole-cell recordings from hippocampal slices, repetitive firing of CA1 PV INs was impaired in mice with either homozygous or heterozygous conditional knock-out of Rptor. High frequency stimulation of Schaffer collateral inputs that induce LTPIE in PV INs of control mice failed to do so in mice with either heterozygous or homozygous conditional knock-out of Rptor in PV INs. At the behavioral level, mice with homozygous or heterozygous conditional knock-out of Rptor showed similar long-term contextual fear memory or contextual fear memory discrimination relative to control mice. Thus, mTORC1 activity in CA1 PV INs regulates repetitive firing and LTPIE but not consolidation of long-term contextual fear memory and context discrimination. Our results indicate that mTORC1 plays cell-specific roles in synaptic plasticity of hippocampal inhibitory interneurons that are differentially involved in hippocampus-dependent learning and memory.
Collapse
Affiliation(s)
- Abdessattar Khlaifia
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group On Neural Signaling and Circuitry (GRSNC), Université de Montréal, P.O. Box 6128, Station Downtown, QC, H3C 3J7, Montreal, Canada.,Department of Psychology, University of Toronto Scarborough, ON, M1C1A4, Toronto, Canada
| | - Eve Honoré
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group On Neural Signaling and Circuitry (GRSNC), Université de Montréal, P.O. Box 6128, Station Downtown, QC, H3C 3J7, Montreal, Canada
| | - Julien Artinian
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group On Neural Signaling and Circuitry (GRSNC), Université de Montréal, P.O. Box 6128, Station Downtown, QC, H3C 3J7, Montreal, Canada.,NeuroService, Neurocentre Magendie , Bordeaux, France
| | - Isabel Laplante
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group On Neural Signaling and Circuitry (GRSNC), Université de Montréal, P.O. Box 6128, Station Downtown, QC, H3C 3J7, Montreal, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group On Neural Signaling and Circuitry (GRSNC), Université de Montréal, P.O. Box 6128, Station Downtown, QC, H3C 3J7, Montreal, Canada.
| |
Collapse
|
2
|
Haji N, Riebe I, Aguilar-Valles A, Artinian J, Laplante I, Lacaille JC. Tsc1 haploinsufficiency in Nkx2.1 cells upregulates hippocampal interneuron mTORC1 activity, impairs pyramidal cell synaptic inhibition, and alters contextual fear discrimination and spatial working memory in mice. Mol Autism 2020; 11:29. [PMID: 32375878 PMCID: PMC7201610 DOI: 10.1186/s13229-020-00340-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/24/2020] [Indexed: 12/23/2022] Open
Abstract
Background Mutations in TSC1 or TSC2 genes cause tuberous sclerosis complex (TSC), a disorder associated with epilepsy, autism, and intellectual disability. TSC1 and TSC2 are repressors of the mechanistic target of rapamycin complex 1 (mTORC1), a key regulator of protein synthesis. Dysregulation of mTORC1 in TSC mouse models leads to impairments in excitation-inhibition balance, synaptic plasticity, and hippocampus-dependent learning and memory deficits. However, synaptic inhibition arises from multiple types of inhibitory interneurons and how changes in specific interneurons contribute to TSC remains largely unknown. In the present work, we determined the effect of conditional Tsc1 haploinsufficiency in a specific subgroup of inhibitory cells on hippocampal function in mice. Methods We investigated the consequences of conditional heterozygous knockout of Tsc1 in MGE-derived inhibitory cells by crossing Nkx2.1Cre/wt;Tsc1f/f mice. We examined the changes in mTORC1 activity and synaptic transmission in hippocampal cells, as well as hippocampus-related cognitive tasks. Results We detected selective increases in phosphorylation of ribosomal protein S6 in interneurons, indicating cell-specific-upregulated mTORC1 signaling. At the behavioral level, Nkx2.1Cre/wt;Tsc1f/wt mice exhibited intact contextual fear memory, but impaired contextual fear discrimination. They displayed intact spatial learning and reference memory but impairment in spatial working memory. Whole-cell recordings in hippocampal slices of Nkx2.1Cre/wt;Tsc1f/wt mice showed intact basic membrane properties, as well as miniature excitatory and inhibitory synaptic transmission, in pyramidal and Nkx2.1-expressing inhibitory cells. Using optogenetic activation of Nkx2.1 interneurons in slices of Nkx2.1Cre/wt;Tsc1f/wt mice, we found a decrease in synaptic inhibition of pyramidal cells. Chronic, but not acute treatment, with the mTORC1 inhibitor rapamycin reversed the impairment in synaptic inhibition. Conclusions Our results indicate that Tsc1 haploinsufficiency in MGE-derived inhibitory cells upregulates mTORC1 activity in these interneurons, reduces their synaptic inhibition of pyramidal cells, and alters contextual fear discrimination and spatial working memory. Thus, selective dysregulation of mTORC1 function in Nkx2.1-expressing inhibitory cells appears sufficient to impair synaptic inhibition and contributes to cognitive deficits in the Tsc1 mouse model of TSC.
Collapse
Affiliation(s)
- Nabila Haji
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Ilse Riebe
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Argel Aguilar-Valles
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada.,Department of Biochemistry and Goodman Cancer Centre, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada
| | - Julien Artinian
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Isabel Laplante
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada.
| |
Collapse
|
3
|
Sasaki-Hamada S, Narusawa K, Nakamura R, Ishibashi H, Oka JI. Effects of centrally administered glucagon-like peptide-2 on blood pressure and barosensitive neurons in spontaneously hypertensive rats. Neuropeptides 2018; 69:66-75. [PMID: 29703428 DOI: 10.1016/j.npep.2018.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 02/25/2018] [Accepted: 04/15/2018] [Indexed: 02/07/2023]
Abstract
The central administration of glucagon-like peptide-2 (GLP-2) decreases blood pressure in rats. In the present study, we investigated the hypotensive effects of GLP-2 using spontaneously hypertensive rats (SHRs), an animal model of hypertension. The central administration of GLP-2 (0.6 μg) decreased mean arterial pressure (MAP) in SHRs (-24.1 ± 4.5%; P < 0.05), but not in normotensive Wistar-Kyoto (WKY) rats (-10.6 ± 7.4%; P > 0.05), whereas GLP-2 (6 μg) decreased MAP in WKY rats (-23.5 ± 4.2%; P < 0.05) and SHRs (-46.7 ± 11.6%; P < 0.01) under anesthesia with urethane and α-chloralose. Histological analyses revealed that the central administration of GLP-2 (6 μg) induced Fos immunoreactivity (Fos-IR) in the hypothalamic and medullary areas in WKY rats and SHRs. However, the distribution of Fos-IR in GABAergic neurons in the rostral ventrolateral medulla (RVLM) differed between WKY rats and SHRs. GLP-2 directly modulated the excitability of RVLM neurons in brainstem slices from SHRs, but not WKY rats. These results suggest that neuronal activity through the activation of GLP-2 receptors in the RVLM contributes to lowering blood pressure in SHRs.
Collapse
Affiliation(s)
- Sachie Sasaki-Hamada
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; Department of Physiology, School of Allied Health Sciences, Kitasato University, Sagamihara 252-0373, Japan
| | - Koji Narusawa
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Ryuji Nakamura
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hitoshi Ishibashi
- Department of Physiology, School of Allied Health Sciences, Kitasato University, Sagamihara 252-0373, Japan
| | - Jun-Ichiro Oka
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| |
Collapse
|
4
|
Yang K, Ma R, Wang Q, Jiang P, Li YQ. Optoactivation of parvalbumin neurons in the spinal dorsal horn evokes GABA release that is regulated by presynaptic GABAB receptors. Neurosci Lett 2015; 594:55-9. [PMID: 25817363 DOI: 10.1016/j.neulet.2015.03.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/13/2015] [Accepted: 03/24/2015] [Indexed: 01/22/2023]
Abstract
Among heterogeneous neural cells in the spinal dorsal horn, parvalbumin (PV)-positive neurons are one subtype of GABA (γ-aminobutyric acid)-containing interneurons. Using an optogenetic approach, we expressed blue light-sensitive cation channel channelrhodopsin-2 (ChR2) via a viral vector on PV neurons in the spinal dorsal horn. Combined with in vitro whole-cell recordings, we activated ChR2 expressed on PV neurons by blue light and recorded GABAA receptor-mediated light-evoked inhibitory postsynaptic currents (L-IPSCs). The L-IPSCs were action potential-dependent and abolished by the GABAA receptor antagonist picrotoxin, indicating a synchronic GABA release from presynaptic terminals. Activation of GABAB receptors (the metabotropic receptors of GABA) on presynaptic terminals by a putative agonist, baclofen, depressed the amplitude of L-IPSCs. This depression was largely occluded by pretreatment with the highly selective Cav2.1 (P/Q-type) Ca(2+) channel blocker ω-agatoxin IVA. N-type Ca(2+) channel blocker ω-conotoxin GVIA showed less effects on either L-IPSCs or baclofen depression. We conclude that optoactivation of PV-ChR2 neurons in the spinal dorsal horn induces GABA release from presynaptic terminals, which is modulated by presynaptic GABAB receptors that are coupled to P/Q-type Ca(2+) channels. Importantly, our studies provide a simple and reliable optogenetic approach to study dorsal horn neural circuits.
Collapse
Affiliation(s)
- Kun Yang
- School of Medicine and Affiliated Hospital, Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Rui Ma
- School of Medicine and Affiliated Hospital, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Qian Wang
- School of Medicine and Affiliated Hospital, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ping Jiang
- School of Medicine and Affiliated Hospital, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Yun-Qing Li
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China
| |
Collapse
|
5
|
Babateen O, Jin Z, Bhandage A, Korol SV, Westermark B, Forsberg Nilsson K, Uhrbom L, Smits A, Birnir B. Etomidate, propofol and diazepam potentiate GABA-evoked GABAA currents in a cell line derived from human glioblastoma. Eur J Pharmacol 2014; 748:101-7. [PMID: 25510230 DOI: 10.1016/j.ejphar.2014.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/01/2014] [Accepted: 12/04/2014] [Indexed: 12/15/2022]
Abstract
GABAA receptors are pentameric chloride ion channels that are opened by GABA. We have screened a cell line derived from human glioblastoma, U3047MG, for expression of GABAA receptor subunit isoforms and formation of functional ion channels. We identified GABAA receptors subunit α2, α3, α5, β1, β2, β3, δ, γ3, π, and θ mRNAs in the U3047MG cell line. Whole-cell GABA-activated currents were recorded and the half-maximal concentration (EC₅₀) for the GABA-activated current was 36 μM. The currents were activated by THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and enhanced by the benzodiazepine diazepam (1 μM) and the general anesthetics etomidate and propofol (50 μM). In line with the expressed GABAA receptors containing at least the α3β3θ subunits, the receptors were highly sensitive to etomidate (EC₅₀=55 nM). Immunocytochemistry identified expression of the α3 and β3 subunit proteins. Our results show that the GABAA receptors in the glial cell line are functional and are modulated by classical GABAA receptor drugs. We propose that the U3047MG cell line may be used as a model system to study GABAA receptors function and pharmacology in glial cells.
Collapse
Affiliation(s)
- Omar Babateen
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Zhe Jin
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - AmolK Bhandage
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Sergiy V Korol
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Bengt Westermark
- Department of Immunology, Genetic and Pathology, and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Karin Forsberg Nilsson
- Department of Immunology, Genetic and Pathology, and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lene Uhrbom
- Department of Immunology, Genetic and Pathology, and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Anja Smits
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Bryndis Birnir
- Department of Neuroscience, Uppsala University, Uppsala, Sweden.
| |
Collapse
|