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Shin H, Sharma R, Neupane C, Pham TL, Park SE, Lee SY, Kim HW, Bae YM, Stern JE, Park JB. Tonic NMDAR Currents of NR2A-Containing NMDARs Represent Altered Ambient Glutamate Concentration in the Supraoptic Nucleus. eNeuro 2024; 11:ENEURO.0279-23.2023. [PMID: 38176904 PMCID: PMC10863629 DOI: 10.1523/eneuro.0279-23.2023] [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: 07/26/2023] [Revised: 12/03/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024] Open
Abstract
NMDA receptors (NMDARs) modulate glutamatergic excitatory tone in the brain via two complementary modalities: a phasic excitatory postsynaptic current and a tonic extrasynaptic modality. Here, we demonstrated that the tonic NMDAR-current (I NMDA) mediated by NR2A-containing NMDARs is an efficient biosensor detecting the altered ambient glutamate level in the supraoptic nucleus (SON). I NMDA of magnocellular neurosecretory cells (MNCs) measured by nonselective NMDARs antagonist, AP5, at holding potential (V holding) -70 mV in low concentration of ECF Mg2+ ([Mg2+]o) was transiently but significantly increased 1-week post induction of a DOCA salt hypertensive model rat which was compatible with that induced by a NR2A-selective antagonist, PEAQX (I PEAQX) in both DOCA-H2O and DOCA-salt groups. In agreement, NR2B antagonist, ifenprodil, or NR2C/D antagonist, PPDA, did not affect the holding current (I holding) at V holding -70 mV. Increased ambient glutamate by exogenous glutamate (10 mM) or excitatory amino acid transporters (EAATs) antagonist (TBOA, 50 mM) abolished the I PEAQX difference between two groups, suggesting that attenuated EAATs activity increased ambient glutamate concentration, leading to the larger I PEAQX in DOCA-salt rats. In contrast, only ifenprodil but not PEAQX and PPDA uncovered I NMDA at V holding +40 mV under 1.2 mM [Mg2+]o condition. I ifenprodil was not different in DOCA-H2O and DOCA-salt groups. Finally, NR2A, NR2B, and NR2D protein expression were not different in the SON of the two groups. Taken together, NR2A-containing NMDARs efficiently detected the increased ambient glutamate concentration in the SON of DOCA-salt hypertensive rats due to attenuated EAATs activity.
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Affiliation(s)
- Hyunjin Shin
- Department of Physiology & Medical Science, College of Medicine & Brain Research Institute, Chungnam National University, Daejeon 35015, South Korea
| | - Ramesh Sharma
- Department of Physiology & Medical Science, College of Medicine & Brain Research Institute, Chungnam National University, Daejeon 35015, South Korea
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Chiranjivi Neupane
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Thuy Linh Pham
- Department of Physiology & Medical Science, College of Medicine & Brain Research Institute, Chungnam National University, Daejeon 35015, South Korea
| | - Su Eun Park
- Department of Physiology & Medical Science, College of Medicine & Brain Research Institute, Chungnam National University, Daejeon 35015, South Korea
| | - So Yeong Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyun-Woo Kim
- Department of Physiology & Medical Science, College of Medicine & Brain Research Institute, Chungnam National University, Daejeon 35015, South Korea
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Javier E Stern
- Neuroscience Institute and Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, Georgia 30302
| | - Jin Bong Park
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
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Kirchner MK, Althammer F, Donaldson KJ, Cox DN, Stern JE. Changes in neuropeptide large dense core vesicle trafficking dynamics contribute to adaptive responses to a systemic homeostatic challenge. iScience 2023; 26:108243. [PMID: 38026155 PMCID: PMC10654599 DOI: 10.1016/j.isci.2023.108243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/28/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Neuropeptides are packed into large dense core vesicles (LDCVs) that are transported from the soma out into their processes. Limited information exists regarding mechanisms regulating LDCV trafficking, particularly during challenges to bodily homeostasis. Addressing this gap, we used 2-photon imaging in an ex vivo preparation to study LDCVs trafficking dynamics in vasopressin (VP) neurons, which traffic and release neuropeptide from their dendrites and axons. We report a dynamic bidirectional trafficking of VP-LDCVs with important differences in speed and directionality between axons and dendrites. Acute, short-lasting stimuli known to alter VP firing activity and axonal/dendritic release caused modest changes in VP-LDCVs trafficking dynamics. Conversely, chronic/sustained systemic osmotic challenges upregulated VP-LDCVs trafficking dynamic, with a larger effect in dendrites. These results support differential regulation of dendritic and axonal LDCV trafficking, and that changes in trafficking dynamics constitute a novel mechanism by which peptidergic neurons can efficiently adapt to conditions of increased hormonal demand.
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Affiliation(s)
- Matthew K. Kirchner
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Ferdinand Althammer
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Institute of Human Genetics, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Kevin J. Donaldson
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
- Center for Neuromics, Georgia State University, Atlanta, GA 30303, USA
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
- Center for Neuromics, Georgia State University, Atlanta, GA 30303, USA
| | - Javier E. Stern
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
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Sharma R, Neupane C, Pham TL, Lee M, Lee S, Lee SY, Nam MH, Kim CS, Park JB. Tonic Activation of NR2D-Containing NMDARs Exacerbates Dopaminergic Neuronal Loss in MPTP-Injected Parkinsonian Mice. J Neurosci 2023; 43:7730-7744. [PMID: 37726169 PMCID: PMC10648527 DOI: 10.1523/jneurosci.1955-22.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 09/01/2023] [Accepted: 09/08/2023] [Indexed: 09/21/2023] Open
Abstract
NR2D subunit-containing NMDA receptors (NMDARs) gradually disappear during brain maturation but can be recruited by pathophysiological stimuli in the adult brain. Here, we report that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication recruited NR2D subunit-containing NMDARs that generated an Mg2+-resistant tonic NMDA current (INMDA) in dopaminergic (DA) neurons in the midbrain of mature male mice. MPTP selectively generated an Mg2+-resistant tonic INMDA in DA neurons in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA). Consistently, MPTP increased NR2D but not NR2B expression in the midbrain regions. Pharmacological or genetic NR2D interventions abolished the generation of Mg2+-resistant tonic INMDA in SNpc DA neurons, and thus attenuated subsequent DA neuronal loss and gait deficits in MPTP-treated mice. These results show that extrasynaptic NR2D recruitment generates Mg2+-resistant tonic INMDA and exacerbates DA neuronal loss, thus contributing to MPTP-induced Parkinsonism. The state-dependent NR2D recruitment could be a novel therapeutic target for mitigating cell type-specific neuronal death in neurodegenerative diseases.SIGNIFICANCE STATEMENT NR2D subunit-containing NMDA receptors (NMDARs) are widely expressed in the brain during late embryonic and early postnatal development, and then downregulated during brain maturation and preserved at low levels in a few regions of the adult brain. Certain stimuli can recruit NR2D subunits to generate tonic persistent NMDAR currents in nondepolarized neurons in the mature brain. Our results show that MPTP intoxication recruits NR2D subunits in midbrain dopaminergic (DA) neurons, which leads to tonic NMDAR current-promoting dopaminergic neuronal death and consequent abnormal gait behavior in the MPTP mouse model of Parkinson's disease (PD). This is the first study to indicate that extrasynaptic NR2D recruitment could be a target for preventing neuronal death in neurodegenerative diseases.
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Affiliation(s)
- Ramesh Sharma
- Department of Biomedicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Physiology, Chungnam National University, Daejeon 35015, Republic of Korea
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08852, Republic of Korea
| | - Chiranjivi Neupane
- Department of Biomedicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Physiology, Chungnam National University, Daejeon 35015, Republic of Korea
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08852, Republic of Korea
| | - Thuy Linh Pham
- Department of Biomedicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Physiology, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Miae Lee
- Physiology, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Sanghoon Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08852, Republic of Korea
| | - So Yeong Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08852, Republic of Korea
| | - Min-Ho Nam
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Cuk-Seong Kim
- Department of Biomedicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Physiology, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Jin Bong Park
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08852, Republic of Korea
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Xiong S, Xiao H, Sun M, Liu Y, Gao L, Xu K, Liang H, Jiang N, Lin Y, Chang L, Wu H, Zhu D, Luo C. Glutamate-releasing BEST1 channel is a new target for neuroprotection against ischemic stroke with wide time window. Acta Pharm Sin B 2023; 13:3008-3026. [PMID: 37521872 PMCID: PMC10372917 DOI: 10.1016/j.apsb.2023.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/13/2023] [Accepted: 04/03/2023] [Indexed: 08/01/2023] Open
Abstract
Many efforts have been made to understand excitotoxicity and develop neuroprotectants for the therapy of ischemic stroke. The narrow treatment time window is still to be solved. Given that the ischemic core expanded over days, treatment with an extended time window is anticipated. Bestrophin 1 (BEST1) belongs to a bestrophin family of calcium-activated chloride channels. We revealed an increase in neuronal BEST1 expression and function within the peri-infarct from 8 to 48 h after ischemic stroke in mice. Interfering the protein expression or inhibiting the channel function of BEST1 by genetic manipulation displayed neuroprotective effects and improved motor functional deficits. Using electrophysiological recordings, we demonstrated that extrasynaptic glutamate release through BEST1 channel resulted in delayed excitotoxicity. Finally, we confirmed the therapeutic efficacy of pharmacological inhibition of BEST1 during 6-72 h post-ischemia in rodents. This delayed treatment prevented the expansion of infarct volume and the exacerbation of neurological functions. Our study identifies the glutamate-releasing BEST1 channel as a potential therapeutic target against ischemic stroke with a wide time window.
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Affiliation(s)
- Shuai Xiong
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Hui Xiao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Meng Sun
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yunjie Liu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Ling Gao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Ke Xu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Haiying Liang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Nan Jiang
- Department of Medicinal Chemistry, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yuhui Lin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Lei Chang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Haiyin Wu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
| | - Dongya Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
| | - Chunxia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
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Cao SY, Yang D, Huang ZQ, Lin YH, Wu HY, Chang L, Luo CX, Xu Y, Liu Y, Zhu DY. Cerebral organoids transplantation repairs infarcted cortex and restores impaired function after stroke. NPJ Regen Med 2023; 8:27. [PMID: 37253754 DOI: 10.1038/s41536-023-00301-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 05/16/2023] [Indexed: 06/01/2023] Open
Abstract
Stroke usually causes prolonged or lifelong disability, owing to the permanent loss of infarcted tissue. Although a variety of stem cell transplantation has been explored to improve neuronal defect behavior by enhancing neuroplasticity, it remains unknown whether the infarcted tissue can be reconstructed. We here cultured human cerebral organoids derived from human pluripotent stem cells (hPSCs) and transplanted them into the junction of the infarct core and the peri-infarct zone of NOD-SCID mice subjected to stroke. Months later, we found that the grafted organoids survived well in the infarcted core, differentiated into target neurons, repaired infarcted tissue, sent axons to distant brain targets, and integrated into the host neural circuit and thereby eliminated sensorimotor defect behaviors of stroke mice, whereas transplantation of dissociated single cells from organoids failed to repair the infarcted tissue. Our study offers a new strategy for reconstructing infarcted tissue via organoids transplantation thereby reversing stroke-induced disability.
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Affiliation(s)
- Shi-Ying Cao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
- Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University, Nanjing, 210008, China
| | - Di Yang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Zhen-Quan Huang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Yu-Hui Lin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Hai-Yin Wu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Lei Chang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Chun-Xia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Yun Xu
- Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University, Nanjing, 210008, China
| | - Yan Liu
- Institution of Stem Cells and Neuroregeneration, Nanjing Medical University, Nanjing, 211166, China.
| | - Dong-Ya Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China.
- Institution of Stem Cells and Neuroregeneration, Nanjing Medical University, Nanjing, 211166, China.
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Phạm TL, Noh C, Neupane C, Sharma R, Shin HJ, Park KD, Lee CJ, Kim HW, Lee SY, Park JB. MAO-B Inhibitor, KDS2010, Alleviates Spinal Nerve Ligation-induced Neuropathic Pain in Rats Through Competitively Blocking the BDNF/TrkB/NR2B Signaling. THE JOURNAL OF PAIN 2022; 23:2092-2109. [PMID: 35940543 DOI: 10.1016/j.jpain.2022.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/05/2022] [Accepted: 07/20/2022] [Indexed: 01/04/2023]
Abstract
MAO-B inhibitors have been implicated to reverse neuropathic pain behaviors. Our previous study has demonstrated that KDS2010 (KDS), a newly developed reversible MAO-B inhibitor, could attenuate Paclitaxel (PTX)-induced tactile hypersensitivity in mice through suppressing reactive oxidant species (ROS)-decreased inhibitory GABA synaptic transmission in the spinal cord. In this study, we evaluated the analgesic effect of KDS under a new approach, in which KDS acts on dorsal horn sensory neurons to reduce excitatory transmission. Oral administration of KDS effectively enhanced mechanical thresholds in the spinal nerve ligation (SNL) induced neuropathic pain in rats. Moreover, we discovered that although treatment with KDS increased brain-derived neurotrophic factor (BDNF) levels, KDS inhibited Tropomyosin receptor kinase B (TrkB) receptor activation, suppressing increased p-NR2B-induced hyperexcitability in spinal dorsal horn sensory neurons after nerve injury. In addition, KDS showed its anti-inflammatory effects by reducing microgliosis and astrogliosis and the activation of MAPK and NF-ᴋB inflammatory pathways in these glial cells. The levels of ROS production in the spinal cords after the SNL procedure were also decreased with KDS treatment. Taken together, our results suggest that KDS may represent a promising therapeutic option for treating neuropathic pain. PERSPECTIVE: Our study provides evidence suggesting the mechanisms by which KDS, a novel MAO-B inhibitor, can be effective in pain relief. KDS, by targeting multiple mechanisms involved in BDNF/TrkB/NR2B-related excitatory transmission and neuroinflammation, may represent the next future of pain medicine.
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Affiliation(s)
- Thuỳ Linh Phạm
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Histo-Pathology, Hai Phong University of Medicine & Pharmacy, Hai Phong 042-12, Vietnam
| | - Chan Noh
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Republic of Korea
| | - Chiranjivi Neupane
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Ramesh Sharma
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyun Jin Shin
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Ki Duk Park
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Republic of Korea
| | - Hyun-Woo Kim
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea
| | - So Yeong Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin Bong Park
- Department of Medical Science, Graduate School, Chungnam National University, Daejeon 35015, Republic of Korea; Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Republic of Korea; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea.
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Miracca G, Anuncibay-Soto B, Tossell K, Yustos R, Vyssotski AL, Franks NP, Wisden W. NMDA Receptors in the Lateral Preoptic Hypothalamus Are Essential for Sustaining NREM and REM Sleep. J Neurosci 2022; 42:5389-5409. [PMID: 35649726 PMCID: PMC7613025 DOI: 10.1523/jneurosci.0350-21.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 02/06/2023] Open
Abstract
The lateral preoptic (LPO) hypothalamus is a center for NREM and REM sleep induction and NREM sleep homeostasis. Although LPO is needed for NREM sleep, we found that calcium signals were, surprisingly, highest in REM sleep. Furthermore, and equally surprising, NMDA receptors in LPO were the main drivers of excitation. Deleting the NMDA receptor GluN1 subunit from LPO abolished calcium signals in all cells and produced insomnia. Mice of both sexes had highly fragmented NREM sleep-wake patterns and could not generate conventionally classified REM sleep. The sleep phenotype produced by deleting NMDA receptors depended on where in the hypothalamus the receptors were deleted. Deleting receptors from the anterior hypothalamic area (AHA) did not influence sleep-wake states. The sleep fragmentation originated from NMDA receptors on GABA neurons in LPO. Sleep fragmentation could be transiently overcome with sleeping medication (zolpidem) or sedatives (dexmedetomidine; Dex). By contrast, fragmentation persisted under high sleep pressure produced by sleep deprivation (SD), mice had a high propensity to sleep but woke up. By analyzing changes in δ power, sleep homeostasis (also referred to as "sleep drive") remained intact after NMDA receptor ablation. We suggest NMDA glutamate receptor activation stabilizes firing of sleep-on neurons and that mechanisms of sleep maintenance differ from that of the sleep drive itself.SIGNIFICANCE STATEMENT Insomnia is a common affliction. Most insomniacs feel that they do not get enough sleep, but in fact, often have good amounts of sleep. Their sleep, however, is fragmented, and sufferers wake up feeling unrefreshed. It is unknown how sleep is maintained once initiated. We find that in mice, NMDA-type glutamate receptors in the hypothalamus are the main drivers of excitation and are required for a range of sleep properties: they are, in fact, needed for both sustained NREM sleep periods, and REM sleep generation. When NMDA receptors are selectively reduced from inhibitory preoptic (PO) neurons, mice have normal total amounts of sleep but high sleep-wake fragmentation, providing a model for studying intractable insomnia.
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Affiliation(s)
- Giulia Miracca
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Berta Anuncibay-Soto
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
- UK Dementia Research Institute, Imperial College London, London SW7 2AZ, United Kingdom
| | - Kyoko Tossell
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Raquel Yustos
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Alexei L Vyssotski
- Institute of Neuroinformatics, University of Zürich/Eidgenössische Technische Hochschule Zürich, Zürich CH-8057, Switzerland
| | - Nicholas P Franks
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
- UK Dementia Research Institute, Imperial College London, London SW7 2AZ, United Kingdom
| | - William Wisden
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
- UK Dementia Research Institute, Imperial College London, London SW7 2AZ, United Kingdom
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