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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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Althammer F, Roy RK, Kirchner MK, Lira EC, Schimmer S, Charlet A, Grinevich V, Stern JE. Impaired oxytocin signaling in the central amygdala in rats with chronic heart failure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568271. [PMID: 38045233 PMCID: PMC10690294 DOI: 10.1101/2023.11.22.568271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Aims Heart failure (HF) patients often suffer from cognitive decline, depression, and mood impairments, but the molecular signals and brain circuits underlying these effects remain elusive. The hypothalamic neuropeptide oxytocin (OT) is critically involved in the regulation of mood, and OTergic signaling in the central amygdala (CeA) is a key mechanism controlling emotional responses including anxiety-like behaviors. Based on this, we used in this study a well-established ischemic rat HF model and aimed to study alterations in the hypothalamus-to-CeA OTergic circuit. Methods and Results To study potential HF-induced changes in the hypothalamus-to-CeA OTertic circuit, we combined patch-clamp electrophysiology, immunohistochemical analysis, RNAScope assessment of OTR mRNA, brain region-specific stereotaxic injections of viral vectors and retrograde tracing, optogenetic stimulation and OT biosensors in the ischemic HF model. We found that most of OTergic innervation of the central amygdala (CeA) originated from the hypothalamic supraoptic nucleus (SON). While no differences in the numbers of SON→CeA OTertic neurons (or their OT content) was observed between sham and HF rats, we did observe a blunted content and release of OT from axonal terminals within the CeA. Moreover, we report downregulation of neuronal and astrocytic OT receptors, and impaired OTR-driven GABAergic synaptic activity within the CeA microcircuit of rats with HF. Conclusions Our study provides first evidence that HF rats display various perturbations in the hypothalamus-to-amygdala OTergic circuit, and lays the foundation for future translational studies targeting either the OT system or GABAergic amygdala GABA microcircuit to ameliorate depression or mood impairments in rats or patients with chronic HF.
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Affiliation(s)
- Ferdinand Althammer
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA, USA
- Institute of Human Genetics, Heidelberg University, Heidelberg
| | - Ranjan K. Roy
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
| | - Matthew K. Kirchner
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
| | - Elba Campos Lira
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
| | - Stephanie Schimmer
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Heidelberg University, Mannheim, Germany
| | - Alexandre Charlet
- Centre National de la Recherche Scientifique and University of Strasbourg, Institute of Cellular and Integrative Neuroscience, Strasbourg, France
| | - Valery Grinevich
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Heidelberg University, Mannheim, Germany
| | - Javier E. Stern
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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Chapp AD, Collins AR, Driscoll KM, Behnke JE, Shan Z, Zhang L, Chen QH. Ethanol Metabolite, Acetate, Increases Excitability of the Central Nucleus of Amygdala Neurons through Activation of NMDA Receptors. ACS Chem Neurosci 2023; 14:1278-1290. [PMID: 36957993 PMCID: PMC11163875 DOI: 10.1021/acschemneuro.2c00784] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
The central nucleus of the amygdala (CeA) is a key brain region involved in emotional and stressor responses due to its many projections to autonomic regulatory centers. It is also a primary site of action from ethanol consumption. However, the influence of active metabolites of ethanol such as acetate on the CeA neural circuitry has yet to be elucidated. Here, we investigated the effect of acetate on CeA neurons with the axon projecting to the rostral ventrolateral medulla (CeA-RVLM), as well as quantified cytosolic calcium responses in primary neuronal cultures. Whole-cell patch-clamp recordings in brain slices containing autonomic CeA-RVLM neurons revealed a dose-dependent increase in neuronal excitability in response to acetate. N-Methyl-d-aspartate receptor (NMDAR) antagonists suppressed the acetate-induced increase in CeA-RVLM neuronal excitability and memantine suppressed the direct activation of NMDAR-dependent inward currents by acetate in brain slices. We observed that acetate increased cytosolic Ca2+ in a time-dependent manner in primary neuronal cell cultures. The acetate enhancement of calcium signaling was abolished by memantine. Computational modeling of acetic acid at NMDAR/NR1 glutamatergic and glycinergic sites suggests potential active site interactions. These findings suggest that within the CeA, acetate is excitatory at least partially through activation of NMDAR, which may underlie the impact of ethanol consumption on autonomic circuitry.
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Affiliation(s)
- Andrew D Chapp
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC, 1400 Townsend Drive, Houghton, Michigan 49931, United States
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931, United States
- Department of Neuroscience, University of Minnesota, Twin Cities, 321 Church Street SE, Minneapolis, Minnesota 55455, United States
| | - Andréa R Collins
- Department of Psychiatry, University of California, San Francisco, Fresno, California 93701, United States
| | - Kyle M Driscoll
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Jessica E Behnke
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC, 1400 Townsend Drive, Houghton, Michigan 49931, United States
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC, 1400 Townsend Drive, Houghton, Michigan 49931, United States
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Li Zhang
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20852, United States
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC, 1400 Townsend Drive, Houghton, Michigan 49931, United States
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931, United States
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Zhang H, Sheng ZF, Wang J, Zheng PR, Kang XL, Chang HM, Yeh ETH, Li DP. Signaling pathways involved in NMDA-induced suppression of M-channels in corticotropin-releasing hormone neurons in central amygdala. J Neurochem 2022; 161:478-491. [PMID: 35583089 DOI: 10.1111/jnc.15647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/02/2022] [Accepted: 05/11/2022] [Indexed: 11/27/2022]
Abstract
Glutamate N-methyl-D-aspartate (NMDA) receptors (NMDARs) and Kv7/M channels are importantly involved in regulating neuronal activity involved in various physiological and pathological functions. Corticotropin-releasing hormone (CRH)-expressing neurons in the central nucleus of the amygdala (CeA) critically mediate autonomic response during stress. However, the interaction between NMDA receptors and Kv7/M channels in the CRHCeA neurons remains unclear. In this study, we identified rat CRHCeA neurons through the expression of an AAV viral vector-mediated enhanced green fluorescent protein (eGFP) driven by the rat CRH promoter. M-currents carried by Kv7/M channels were recorded using the whole-cell patch-clamp approach in eGFP-tagged CRHCeA neurons in brain slices. Acute exposure to NMDA significantly reduced M-currents recorded from the CRHCeA neurons. NMDA-induced suppression of M-currents was eliminated by chelating intracellular Ca2+ , supplying phosphatidylinositol 4,5-bisphosphate (PIP2) intracellularly, or blocking phosphoinositide3-kinase (PI3K). In contrast, inhibiting protein kinase C (PKC) or calmodulin did not alter NMDA-induced suppression of M-currents. Sustained exposure of NMDA decreased Kv7.3 membrane protein levels and suppressed M-currents, while the Kv7.2 expression levels remained unaltered. Pre-treatment of brain slices with PKC inhibitors alleviated the decreases in Kv7.3 and reduction of M-currents in CRHCeA neurons induced by NMDA. PKC inhibitors did not alter Kv7.2 and Kv7.3 membrane protein levels and M-currents in CRHCeA neurons. These data suggest that transient activation of NMDARs suppresses M-currents through the Ca2+ -dependent PI3K-PIP2 signaling pathway. In contrast, sustained activation of NMDARs reduces Kv7.3 protein expression and suppresses M-currents through a PKC-dependent pathway.
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Affiliation(s)
- Hua Zhang
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
| | - Zhao-Fu Sheng
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
| | - Jingxiong Wang
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
| | - Pei Ru Zheng
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
| | - Xun Lei Kang
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
| | - Hui-Ming Chang
- Departments of Pharmacology and Toxicology and Internal Medicine, The University of Arkansas for Medical Sciences
| | - Edward T H Yeh
- Departments of Pharmacology and Toxicology and Internal Medicine, The University of Arkansas for Medical Sciences
| | - De-Pei Li
- Center for Precision Medicine, Department of Medicine, School of Medicine University of Missouri, Columbia MO 65212
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Khan-Mohammadi-Khorrami MK, Asle-Rousta M, Rahnema M, Amini R. Neuroprotective effect of alpha-pinene is mediated by suppression of the TNF-α/NF-κB pathway in Alzheimer's disease rat model. J Biochem Mol Toxicol 2022; 36:e23006. [PMID: 35174932 DOI: 10.1002/jbt.23006] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 12/19/2021] [Accepted: 01/19/2022] [Indexed: 01/04/2023]
Abstract
Monoterpene alpha-pinene possesses antioxidant, cardioprotective, and neuroprotective properties. We evaluated the effect of alpha-pinene on oxidative/nitrosative stress, neuroinflammation, and molecular and behavioral changes induced by beta-amyloid (Aβ)1-42 in rats and investigated the possible mechanisms of these outcomes. Male Wistar rats received alpha-pinene (50 mg/kg intraperitoneally) for 14 consecutive days after intrahippocampal injection of Aβ1-42 . Alpha-pinene decreased malondialdehyde and nitric oxide levels, increased glutathione content, and enhanced catalase activity in Aβ-injected rats. Also, messenger RNA expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, nuclear factor κB, and N-methyl- d-aspartate receptor subunits 2A and 2B reduced in the hippocampus of these animals. Besides this, alpha-pinene repressed the Aβ1-42 -induced reduction of nicotinic acetylcholine receptor α7 subunit and brain-derived neurotrophic factor expression. Treatment with alpha-pinene caused Aβ-receiving rats to spend more time in the target quadrant in the Morris water maze test and led to an increase in percentages of open arm entrance and time spent in the open arm in the elevated plus-maze test. We concluded that alpha-pinene strengthens the antioxidant system and prevents neuroinflammation in the hippocampus of rats receiving Aβ. It improves spatial learning and memory and reduces anxiety-like behavior in these animals. Consequently, alpha-pinene alleviates Aβ-induced oxidative/nitrosative stress, neuroinflammation, and behavioral deficits. It is probably a suitable candidate for the treatment of neurodegenerative diseases.
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Affiliation(s)
| | | | - Mehdi Rahnema
- Department of Physiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
| | - Rahim Amini
- Department of Biology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
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Yu H, Miao W, Ji E, Huang S, Jin S, Zhu X, Liu MZ, Sun YG, Xu F, Yu X. Social touch-like tactile stimulation activates a tachykinin 1-oxytocin pathway to promote social interactions. Neuron 2022; 110:1051-1067.e7. [PMID: 35045339 DOI: 10.1016/j.neuron.2021.12.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 08/29/2021] [Accepted: 12/15/2021] [Indexed: 12/21/2022]
Abstract
It is well known that affective and pleasant touch promotes individual well-being and facilitates affiliative social communication, although the neural circuit that mediates this process is largely unknown. Here, we show that social-touch-like tactile stimulation (ST) enhances firing of oxytocin neurons in the mouse paraventricular hypothalamus (PVH) and promotes social interactions and positively reinforcing place preference. These results link pleasant somatosensory stimulation to increased social interactions and positive affective valence. We further show that tachykinin 1 (Tac1+) neurons in the lateral and ventrolateral periaqueductal gray (l/vlPAG) send monosynaptic excitatory projections to PVH oxytocin neurons. Functionally, activation of PVH-projecting Tac1+ neurons increases firing of oxytocin neurons, promotes social interactions, and increases preference for the social touch context, whereas reducing activity of Tac1+ neurons abolishes ST-induced oxytocin neuronal firing. Together, these results identify a dipeptidergic pathway from l/vlPAG Tac1+ neurons to PVH oxytocin neurons, through which pleasant sensory experience promotes social behavior.
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Affiliation(s)
- Hang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wanying Miao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - En Ji
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shajin Huang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Sen Jin
- Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Xutao Zhu
- Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Ming-Zhe Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan-Gang Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fuqiang Xu
- University of Chinese Academy of Sciences, Beijing 100049, China; Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Xiang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Sciences, Peking-Tsinghua Center for Life Sciences, and Peking University McGovern Institute, Peking University, Beijing 100871, China; Autism Research Center of Peking University Health Science Center, Beijing 100191, China; Chinese Institute for Brain Research, Beijing 102206, China.
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7
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Mohammadi N, Asle-Rousta M, Rahnema M, Amini R. Morin attenuates memory deficits in a rat model of Alzheimer's disease by ameliorating oxidative stress and neuroinflammation. Eur J Pharmacol 2021; 910:174506. [PMID: 34534533 DOI: 10.1016/j.ejphar.2021.174506] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 07/25/2021] [Accepted: 09/13/2021] [Indexed: 01/21/2023]
Abstract
This study aimed to investigate the effect of flavonoid morin on oxidative/nitrosative stress, neuroinflammation, and histological, molecular, and behavioral changes caused by amyloid-beta (Aβ)1-42 in male Wistar rats (Alzheimer's disease model). Rats received morin (20 mg/kg, oral gavage) for 14 consecutive days after intrahippocampal injection of Aβ1-42. Morin decreased the levels of malondialdehyde and nitric oxide, increased glutathione content, and enhanced catalase activity in the hippocampus of animals receiving Aβ1-42. It also reduced the expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, nuclear factor-kappa B, and N-methyl-D-aspartate receptor subunits 2A and 2B and increased the expression of brain-derived neurotrophic factor and α7 nicotinic acetylcholine receptor in the hippocampus of Aβ1-42-injected rats. Besides, morin modified neuronal loss and histological changes in the CA1 region of the hippocampus. Morin allowed Aβ1-42-infused rats to swim more time in the target quadrant in the Morris water maze test. It is concluded that morin may be suitable for the prevention and treatment of Alzheimer's disease by strengthening the antioxidant system, inhibiting neuroinflammation, preventing neuronal death, and enhancing memory function.
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Affiliation(s)
- Negin Mohammadi
- Department of Physiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
| | | | - Mehdi Rahnema
- Department of Physiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
| | - Rahim Amini
- Department of Biology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
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8
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Pittman QJ. Vasopressin and central control of the cardiovascular system: A 40-year retrospective. J Neuroendocrinol 2021; 33:e13011. [PMID: 34235812 DOI: 10.1111/jne.13011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 06/25/2021] [Indexed: 01/24/2023]
Abstract
In the 40 years since vasopressin (AVP) was reported to have a central action with respect to raising blood pressure, the finding has been repeatedly replicated using a variety of complimentary approaches. The role of AVP as a central neurotransmitter involved in control of the cardiovascular system is now textbook material. However, it is evident that brain AVP plays, at best, a minor role in regulation of normal blood pressure. However, it appears to be an important player in a several cardiovascular-associated pathologies, ranging from hypertension to neural changes associated with heart failure. There are many interventions that have been shown to affect neural function, many of which are associated with alterations in behaviour. Possible alterations in neuronal AVP actions relevant to cardiovascular control in the setting of chronic inflammatory disease, early-life stress and inflammation are suggested areas for future research.
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Affiliation(s)
- Quentin J Pittman
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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9
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Aikins AO, Nguyen DH, Paundralingga O, Farmer GE, Shimoura CG, Brock C, Cunningham JT. Cardiovascular Neuroendocrinology: Emerging Role for Neurohypophyseal Hormones in Pathophysiology. Endocrinology 2021; 162:6247962. [PMID: 33891015 PMCID: PMC8234498 DOI: 10.1210/endocr/bqab082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Indexed: 11/19/2022]
Abstract
Arginine vasopressin (AVP) and oxytocin (OXY) are released by magnocellular neurosecretory cells that project to the posterior pituitary. While AVP and OXY currently receive more attention for their contributions to affiliative behavior, this mini-review discusses their roles in cardiovascular function broadly defined to include indirect effects that influence cardiovascular function. The traditional view is that neither AVP nor OXY contributes to basal cardiovascular function, although some recent studies suggest that this position might be re-evaluated. More evidence indicates that adaptations and neuroplasticity of AVP and OXY neurons contribute to cardiovascular pathophysiology.
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Affiliation(s)
- Ato O Aikins
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Dianna H Nguyen
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
- Texas College of Osteopathic Medicine, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Obed Paundralingga
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - George E Farmer
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Caroline Gusson Shimoura
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - Courtney Brock
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, Graduate School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX 76107, USA
- Correspondence: J. Thomas Cunningham Department of Physiology & Anatomy CBH 338 UNT Health Science Center 3500 Camp Bowie Blvd Fort Worth, TX 76107, USA.
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10
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Ferreira-Neto HC, Antunes VR, Stern JE. Purinergic P2 and glutamate NMDA receptor coupling contributes to osmotically driven excitability in hypothalamic magnocellular neurosecretory neurons. J Physiol 2021; 599:3531-3547. [PMID: 34053068 DOI: 10.1113/jp281411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 05/28/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Purinergic and glutamatergic signalling pathways play a key role in regulating the activity of hypothalamic magnocellular neurosecretory neurons (MNNs). However, the precise cellular mechanisms by which ATP and glutamate act in concert to regulate osmotically driven MNN neuronal excitability remains unknown. Here, we report that ATP acts on purinergic P2 receptors in MNNs to potentiate in a Ca2+ -dependent manner extrasynaptic NMDAR function. The P2-NMDAR coupling is engaged in response to an acute hyperosmotic stimulation, contributing to osmotically driven firing activity in MNNs. These results help us to better understand the precise mechanisms contributing to the osmotic regulation of firing activity and hormone release from MNNs. ABSTRACT The firing activity of hypothalamic magnocellular neurosecretory neurons (MNNs) located in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) is coordinated by the combined, fine-tuned action of intrinsic membrane properties, synaptic and extrasynaptic signalling. Among these, purinergic and glutamatergic signalling pathways have been shown to play a key role regulating the activity of MNNs. However, the precise cellular mechanisms by which ATP and glutamate act in concert to regulate osmotically driven MNN neuronal excitability remains unknown. Whole-cell patch-clamp recordings obtained from MNNs showed that ATP (100 μM) induced an increase in firing rate, an effect that was blocked by either 4-[[4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]2-pyridinyl]azo]1,3-benzenedisulfonic acid tetrasodium salt (PPADS) (10 μM) or kynurenic acid (1 mm). While ATP did not affect the frequency or magnitude of glutamatergic excitatory postsynaptic currents (EPSCs), it induced an inward shift in the holding current that was prevented by PPADS or kynurenic acid treatment, suggesting that ATP enhances a tonic extrasynaptic glutamatergic excitatory current. We observed that ATP-potentiated glutamatergic receptor-mediated currents were evoked by focal application of L-glu (1 mm) and NMDA (50 μM), but not AMPA (50 μM). ATP potentiation of NMDA-evoked currents was blocked by PPADS (10 μM) and by chelation of intracellular Ca2+ with BAPTA (10 mm). Finally, we report that a hyperosmotic stimulus (mannitol 1%, +55 mOsm/kgH2 O) potentiated NMDA-evoked currents and increased MNN firing activity, effects that were blocked by PPADS. Taken together, our data support a functional excitatory coupling between P2 and extrasynaptic NMDA receptors in MNNs, which is engaged in response to an acute hyperosmotic stimulus.
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Affiliation(s)
- H C Ferreira-Neto
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA
| | - V R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - J E Stern
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA
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11
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Tofighi N, Asle-Rousta M, Rahnema M, Amini R. Protective effect of alpha-linoleic acid on Aβ-induced oxidative stress, neuroinflammation, and memory impairment by alteration of α7 nAChR and NMDAR gene expression in the hippocampus of rats. Neurotoxicology 2021; 85:245-253. [PMID: 34111468 DOI: 10.1016/j.neuro.2021.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/23/2021] [Accepted: 06/04/2021] [Indexed: 01/06/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects many older people around the world. Numerous studies are underway to evaluate the protective effects of natural products in AD. Alpha-linoleic acid (ALA) is an essential unsaturated fatty acid that exhibits neuroprotective outcomes in rat models of ischemic stroke and Parkinson's disease. This research aimed to investigate the effect of ALA on oxidative stress, neuroinflammation, neuronal death, and memory deficit induced by amyloid-beta (Aβ) peptide. After intrahippocampal injection of Aβ1-42, rats received ALA (150 μg/kg, subcutaneously) for 14 consecutive days. ALA decreased the levels of malondialdehyde and nitric oxide, enhanced glutathione content, and increased the activity of catalase in the hippocampus of the rat model of AD. It also reduced the expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, nuclear factor-kappa B, and N-methyl-d-aspartate receptor subunits NR2A and NR2B mRNAs in the hippocampus, prevented the neuronal loss in the CA1 region, and enhanced the expression of α7 nicotinic acetylcholine receptor. In addition, ALA allowed Aβ1-42-injected rats to spend less time and distance to reach the hidden platform in the Morris water maze test and to swim longer in the target quadrant. We concluded that ALA reduces the biochemical, molecular, histological, and behavioral changes caused by Aβ1-42 and it may be an effective option for treating AD.
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Affiliation(s)
- Nahaleh Tofighi
- Department of Physiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
| | | | - Mehdi Rahnema
- Department of Physiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
| | - Rahim Amini
- Department of Biology, Zanjan Branch, Islamic Azad University, Zanjan, Iran
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12
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Martinez D, Rogers RC, Hasser EM, Hermann GE, Kline DD. Loss of excitatory amino acid transporter restraint following chronic intermittent hypoxia contributes to synaptic alterations in nucleus tractus solitarii. J Neurophysiol 2020; 123:2122-2135. [PMID: 32347148 PMCID: PMC7311725 DOI: 10.1152/jn.00766.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Peripheral viscerosensory afferent signals are transmitted to the nucleus tractus solitarii (nTS) via release of glutamate. Following release, glutamate is removed from the extrasynaptic and synaptic cleft via excitatory amino acid transporters (EAATs), thus limiting glutamate receptor activation or over activation, and maintaining its working range. We have shown that EAAT block with the antagonist threo-β-benzyloxyaspartic acid (TBOA) depolarized nTS neurons and increased spontaneous excitatory postsynaptic current (sEPSC) frequency yet reduced the amplitude of afferent (TS)-evoked EPSCs (TS-EPSCs). Interestingly, chronic intermittent hypoxia (CIH), a model of obstructive sleep apnea (OSA), produces similar synaptic responses as EAAT block. We hypothesized EAAT expression or function are downregulated after CIH, and this reduction in glutamate removal contributes to the observed neurophysiological responses. To test this hypothesis, we used brain slice electrophysiology and imaging of glutamate release and TS-afferent Ca2+ to compare nTS properties of rats exposed to 10 days of normoxia (Norm; 21%O2) or CIH. Results show that EAAT blockade with (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]-amino]phenyl]methoxy]-l-aspartic acid (TFB-TBOA) in Norm caused neuronal depolarization, generation of an inward current, and increased spontaneous synaptic activity. The latter augmentation was eliminated by inclusion of tetrodotoxin in the perfusate. TS stimulation during TFB-TBOA also elevated extracellular glutamate and decreased presynaptic Ca2+ and TS-EPSC amplitude. In CIH, the effects of EAAT block are eliminated or attenuated. CIH reduced EAAT expression in nTS, which may contribute to the attenuated function seen in this condition. Therefore, CIH reduces EAAT influence on synaptic and neuronal activity, which may lead to the physiological consequences seen in OSA and CIH.NEW & NOTEWORTHY Removal of excitatory amino acid transporter (EAAT) restraint increases spontaneous synaptic activity yet decreases afferent [tractus solitarius (TS)]-driven excitatory postsynaptic current (EPSC) amplitude. In the chronic intermittent hypoxia model of obstructive sleep apnea, this restraint is lost due to reduction in EAAT expression and function. Thus EAATs are important in controlling elevated glutamatergic signaling, and loss of such control results in maladaptive synaptic signaling.
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Affiliation(s)
- Diana Martinez
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | | | - Eileen M. Hasser
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri,2Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | | | - David D. Kline
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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13
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Brown CH, Ludwig M, Tasker JG, Stern JE. Somato-dendritic vasopressin and oxytocin secretion in endocrine and autonomic regulation. J Neuroendocrinol 2020; 32:e12856. [PMID: 32406599 PMCID: PMC9134751 DOI: 10.1111/jne.12856] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/29/2020] [Accepted: 04/11/2020] [Indexed: 12/29/2022]
Abstract
Somato-dendritic secretion was first demonstrated over 30 years ago. However, although its existence has become widely accepted, the function of somato-dendritic secretion is still not completely understood. Hypothalamic magnocellular neurosecretory cells were among the first neuronal phenotypes in which somato-dendritic secretion was demonstrated and are among the neurones for which the functions of somato-dendritic secretion are best characterised. These neurones secrete the neuropeptides, vasopressin and oxytocin, in an orthograde manner from their axons in the posterior pituitary gland into the blood circulation to regulate body fluid balance and reproductive physiology. Retrograde somato-dendritic secretion of vasopressin and oxytocin modulates the activity of the neurones from which they are secreted, as well as the activity of neighbouring populations of neurones, to provide intra- and inter-population signals that coordinate the endocrine and autonomic responses for the control of peripheral physiology. Somato-dendritic vasopressin and oxytocin have also been proposed to act as hormone-like signals in the brain. There is some evidence that somato-dendritic secretion from magnocellular neurosecretory cells modulates the activity of neurones beyond their local environment where there are no vasopressin- or oxytocin-containing axons but, to date, there is no conclusive evidence for, or against, hormone-like signalling throughout the brain, although it is difficult to imagine that the levels of vasopressin found throughout the brain could be underpinned by release from relatively sparse axon terminal fields. The generation of data to resolve this issue remains a priority for the field.
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Affiliation(s)
- Colin H. Brown
- Department of Physiology, Brain Health Research Centre, Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
| | - Mike Ludwig
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
- Department of Immunology, Centre for Neuroendocrinology, University of Pretoria, Pretoria, South Africa
| | - Jeffrey G. Tasker
- Department of Cell and Molecular Biology, Brain Institute, Tulane University, New Orleans, LA, USA
| | - Javier E. Stern
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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14
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Japundžić-Žigon N, Lozić M, Šarenac O, Murphy D. Vasopressin & Oxytocin in Control of the Cardiovascular System: An Updated Review. Curr Neuropharmacol 2020; 18:14-33. [PMID: 31544693 PMCID: PMC7327933 DOI: 10.2174/1570159x17666190717150501] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/03/2019] [Accepted: 07/06/2019] [Indexed: 01/19/2023] Open
Abstract
Since the discovery of vasopressin (VP) and oxytocin (OT) in 1953, considerable knowledge has been gathered about their roles in cardiovascular homeostasis. Unraveling VP vasoconstrictor properties and V1a receptors in blood vessels generated powerful hemostatic drugs and drugs effective in the treatment of certain forms of circulatory collapse (shock). Recognition of the key role of VP in water balance via renal V2 receptors gave birth to aquaretic drugs found to be useful in advanced stages of congestive heart failure. There are still unexplored actions of VP and OT on the cardiovascular system, both at the periphery and in the brain that may open new venues in treatment of cardiovascular diseases. After a brief overview on VP, OT and their peripheral action on the cardiovascular system, this review focuses on newly discovered hypothalamic mechanisms involved in neurogenic control of the circulation in stress and disease.
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Affiliation(s)
| | - Maja Lozić
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Olivera Šarenac
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - David Murphy
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
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15
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Martinez D, Rogers RC, Hermann GE, Hasser EM, Kline DD. Astrocytic glutamate transporters reduce the neuronal and physiological influence of metabotropic glutamate receptors in nucleus tractus solitarii. Am J Physiol Regul Integr Comp Physiol 2020; 318:R545-R564. [PMID: 31967862 PMCID: PMC7099463 DOI: 10.1152/ajpregu.00319.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Astrocytic excitatory amino acid transporters (EAATs) are critical to restraining synaptic and neuronal activity in the nucleus tractus solitarii (nTS). Relief of nTS EAAT restraint generates two opposing effects, an increase in neuronal excitability that reduces blood pressure and breathing and an attenuation in afferent [tractus solitarius (TS)]-driven excitatory postsynaptic current (EPSC) amplitude. Although the former is due, in part, to activation of ionotropic glutamate receptors, there remains a substantial contribution from another unidentified glutamate receptor. In addition, the mechanism(s) by which EAAT inhibition reduced TS-EPSC amplitude is unknown. Metabotropic glutamate receptors (mGluRs) differentially modulate nTS excitability. Activation of group I mGluRs on nTS neuron somas leads to depolarization, whereas group II/III mGluRs on sensory afferents decrease TS-EPSC amplitude. Thus we hypothesize that EAATs control postsynaptic excitability and TS-EPSC amplitude via restraint of mGluR activation. To test this hypothesis, we used in vivo recording, brain slice electrophysiology, and imaging of glutamate release and TS-afferent Ca2+. Results show that EAAT blockade in the nTS with (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-l-aspartic acid (TFB-TBOA) induced group I mGluR-mediated depressor, bradycardic, and apneic responses that were accompanied by neuronal depolarization, elevated discharge, and increased spontaneous synaptic activity. Conversely, upon TS stimulation TFB-TBOA elevated extracellular glutamate to decrease presynaptic Ca2+ and TS-EPSC amplitude via activation of group II/III mGluRs. Together, these data suggest an important role of EAATs in restraining mGluR activation and overall cardiorespiratory function.
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Affiliation(s)
- Diana Martinez
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | | | | | - Eileen M. Hasser
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri,2Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - David D. Kline
- 1Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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16
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Ferreira-Neto HC, Stern JE. Functional coupling between NMDA receptors and SK channels in rat hypothalamic magnocellular neurons: altered mechanisms during heart failure. J Physiol 2019; 599:507-520. [PMID: 31667845 DOI: 10.1113/jp278910] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Glutamatergic NMDA receptors (NMDARs) and small conductance Ca2+ -activated K+ (SK) channels are critical synaptic and intrinsic mechanisms, respectively, that regulate the activity of hypothalamic magnocellular neurosecretory neurons (MNNs). In this work, we investigated whether NMDARs and SK channels in MNNs are functionally coupled, and whether an altered coupling may contribute to exacerbated neuronal activity in this condition. We report that NMDARs and SK channels form a functional Ca2+ -dependent negative feedback loop that restrains the excitatory effect on membrane potential and firing activity evoked by NMDAR activation. The negative feedback loop between NMDARs and SK channels was blunted or absent in MNNs of heart failure (HF) rats. These results help us better understand how synaptic and intrinsic mechanisms regulate hypothalamic neuronal activity, as well as how changes in the interaction among these disparate mechanisms contribute to altered neuronal activity during prevalent neurogenic cardiovascular diseases. ABSTRACT Glutamatergic NMDA receptors (NMDARs) and small conductance Ca2+ -activated K+ (SK) channels are critical synaptic and intrinsic mechanisms, respectively, that regulate the activity of hypothalamic magnocellular neurosecretory neurons (MNNs), both under physiological and pathological states, such as lactation and heart failure (HF). However, whether NMDARs and SK channels in MNNs are functionally coupled, and whether changes in this coupling contribute to exacerbated neuronal activity during HF is at present unknown. In the present study, we addressed these questions using patch-clamp electrophysiology and confocal Ca2+ imaging in a rat model of ischaemic HF. We found that in MNNs of sham rats, blockade of SK channels with apamin (200 nM) significantly increased the magnitude of an NMDAR-evoked current (INMDA ). We also observed that blockade of SK channels potentiated NMDAR-evoked firing, and abolished spike frequency adaptation in MNNs from sham, but not HF rats. Importantly, a larger INMDA -ΔCa2+ response was observed under basal conditions in HF compared to sham rats. Finally, we found that dialysing recorded cells with the Ca2+ chelator BAPTA (10 mM) increased the magnitude of INMDA in MNNs from both sham and HF rats, and occluded the effects of apamin in the former. Together our studies demonstrate that in MNNs, NMDARs and SK channels are functionally coupled, forming a local negative feedback loop that restrains the excitatory effect evoked by NMDAR activation. Moreover, our studies also support a blunted NMDAR-SK channel coupling in MNNs of HF rats, establishing it as a pathophysiological mechanism contributing to exacerbated hypothalamic neuronal activity during this prevalent neurogenic cardiovascular disease.
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Affiliation(s)
| | - Javier E Stern
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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17
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Pitra S, Worker CJ, Feng Y, Stern JE. Exacerbated effects of prorenin on hypothalamic magnocellular neuronal activity and vasopressin plasma levels during salt-sensitive hypertension. Am J Physiol Heart Circ Physiol 2019; 317:H496-H504. [PMID: 31274353 DOI: 10.1152/ajpheart.00063.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulating evidence supports that the brain renin-angiotensin system (RAS), including prorenin (PR) and its receptor (PRR), two newly discovered RAS players, contribute to sympathoexcitation in salt-sensitive hypertension. Still, whether PR also contributed to elevated circulating levels of neurohormones such as vasopressin (VP) during salt-sensitive hypertension, and if so, what are the precise underlying mechanisms, remains to be determined. To address these questions, we obtained patch-clamp recordings from hypothalamic magnocellular neurosecretory neurons (MNNs) that synthesize the neurohormones oxytocin and VP in acute hypothalamic slices obtained from sham and deoxycorticosterone acetate (DOCA)-salt-treated hypertensive rats. We found that focal application of PR markedly increased membrane excitability and firing responses in MNNs of DOCA-salt, compared with sham rats. This effect included a shorter latency to spike initiation and increased numbers of spikes in response to depolarizing stimuli and was mediated by a more robust inhibition of A-type K+ channels in DOCA-salt compared with sham rats. On the other hand, the afterhyperpolarizing potential mediated by the activation of Ca2+-dependent K+ channel was not affected by PR. mRNA expression of PRR, VP, and the Kv4.3 K+ channel subunit in the supraoptic nucleus of DOCA-salt hypertensive rats was increased compared with sham rats. Finally, we report a significant decrease of plasma VP levels in neuron-selective PRR knockdown mice treated with DOCA-salt, compared with wild-type DOCA-salt-treated mice. Together, these results support that activation of PRR contributes to increased excitability and firing discharge of MNNs and increased plasma levels of VP in DOCA-salt hypertension.NEW & NOTEWORTHY Our studies support that prorenin (PR) and its receptor (PRR) within the hypothalamus contribute to elevated plasma vasopressin levels in deoxycorticosterone acetate-salt hypertension, in part because of an exacerbated effect of PR on magnocellular neurosecretory neuron excitability; Moreover, our study implicates A-type K+ channels as key underlying molecular targets mediating these effects. Thus, PR/PRR stands as a novel therapeutic target for the treatment of neurohumoral activation in salt-sensitive hypertension.
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Affiliation(s)
- Soledad Pitra
- Department of Physiology, Medical College of Georgia, Augusta University, Georgia
| | - Caleb J Worker
- Department of Pharmacology, Physiology, and Cell Biology, University of Nevada, Reno, Nevada
| | - Yumei Feng
- Department of Pharmacology, Physiology, and Cell Biology, University of Nevada, Reno, Nevada
| | - Javier E Stern
- Department of Physiology, Medical College of Georgia, Augusta University, Georgia
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18
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Pál B. Involvement of extrasynaptic glutamate in physiological and pathophysiological changes of neuronal excitability. Cell Mol Life Sci 2018; 75:2917-2949. [PMID: 29766217 PMCID: PMC11105518 DOI: 10.1007/s00018-018-2837-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/27/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
Glutamate is the most abundant neurotransmitter of the central nervous system, as the majority of neurons use glutamate as neurotransmitter. It is also well known that this neurotransmitter is not restricted to synaptic clefts, but found in the extrasynaptic regions as ambient glutamate. Extrasynaptic glutamate originates from spillover of synaptic release, as well as from astrocytes and microglia. Its concentration is magnitudes lower than in the synaptic cleft, but receptors responding to it have higher affinity for it. Extrasynaptic glutamate receptors can be found in neuronal somatodendritic location, on astroglia, oligodendrocytes or microglia. Activation of them leads to changes of neuronal excitability with different amplitude and kinetics. Extrasynaptic glutamate is taken up by neurons and astrocytes mostly via EAAT transporters, and astrocytes, in turn metabolize it to glutamine. Extrasynaptic glutamate is involved in several physiological phenomena of the central nervous system. It regulates neuronal excitability and synaptic strength by involving astroglia; contributing to learning and memory formation, neurosecretory and neuromodulatory mechanisms, as well as sleep homeostasis.The extrasynaptic glutamatergic system is affected in several brain pathologies related to excitotoxicity, neurodegeneration or neuroinflammation. Being present in dementias, neurodegenerative and neuropsychiatric diseases or tumor invasion in a seemingly uniform way, the system possibly provides a common component of their pathogenesis. Although parts of the system are extensively discussed by several recent reviews, in this review I attempt to summarize physiological actions of the extrasynaptic glutamate on neuronal excitability and provide a brief insight to its pathology for basic understanding of the topic.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.
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19
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Potassium channels-mediated electrophysiologic responses are inhibited by cytosolic phospholipase A2α ablation. Neuroreport 2018; 29:59-64. [PMID: 29112675 DOI: 10.1097/wnr.0000000000000933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cytosolic phospholipase A2α (cPLA2α) is implicated in the progression of excitotoxic neuronal injury and cerebral ischemia. Previous work suggests that cPLA2α increases aberrant electrophysiologic events through attenuating K channel functions. Nevertheless, which K channels are affected by cPLA2α needs to be determined. Here we examined K channels-mediated electrophysiologic responses in hippocampal CA1 pyramidal neurons from wild-type and cPLA2α mice using simultaneous patch-clamp recording and confocal Ca imaging. After the exposure to the blockers of Ca-sensitive and A-type K channels, all CA1 neurons developed spike broadening and increased dendritic Ca transients. These effects were occluded in CA1 neurons from cPLA2α mice. Therefore, cPLA2α modulates the functions of Ca-sensitive and A-type K channels in neurotoxicity.
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20
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Mei YY, Wu DC, Zhou N. Astrocytic Regulation of Glutamate Transmission in Schizophrenia. Front Psychiatry 2018; 9:544. [PMID: 30459650 PMCID: PMC6232167 DOI: 10.3389/fpsyt.2018.00544] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/12/2018] [Indexed: 01/19/2023] Open
Abstract
According to the glutamate hypothesis of schizophrenia, the abnormality of glutamate transmission induced by hypofunction of NMDA receptors (NMDARs) is causally associated with the positive and negative symptoms of schizophrenia. However, the underlying mechanisms responsible for the changes in glutamate transmission in schizophrenia are not fully understood. Astrocytes, the major regulatory glia in the brain, modulate not only glutamate metabolism but also glutamate transmission. Here we review the recent progress in understanding the role of astrocytes in schizophrenia. We focus on the astrocytic mechanisms of (i) glutamate synthesis via the glutamate-glutamine cycle, (ii) glutamate clearance by excitatory amino acid transporters (EAATs), (iii) D-serine release to activate NMDARs, and (iv) glutamatergic target engagement biomarkers. Abnormality in these processes is highly correlated with schizophrenia phenotypes. These findings will shed light upon further investigation of pathogenesis as well as improvement of biomarkers and therapies for schizophrenia.
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Affiliation(s)
- Yu-Ying Mei
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
| | - Dong Chuan Wu
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
| | - Ning Zhou
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
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21
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Zhang M, Stern JE. Altered NMDA receptor-evoked intracellular Ca 2+ dynamics in magnocellular neurosecretory neurons of hypertensive rats. J Physiol 2017; 595:7399-7411. [PMID: 29034474 DOI: 10.1113/jp275169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/03/2017] [Indexed: 01/03/2023] Open
Abstract
KEY POINTS NMDA receptor (NMDAR)-mediated Ca2+ signalling plays a critical role in modulating hypothalamic neurosecretory function. However, whether an altered NMDAR-evoked changes in Ca2+ (NMDAR-ΔCa2+ ) signalling in magnocellular neurosecretory cells (MNCs) may contribute to neurohumoral activation during disease states is unknown. We show that activation of NMDARs evoked similar inward currents in MNCs of sham and renovascular hypertensive (RVH) rats. Despite this, a prolonged and larger NMDAR-ΔCa2+ response was observed in the latter. The exacerbated NMDAR-ΔCa2+ responses in MNCs of RVH rats affected both somatic and dendritic compartments. Inhibition of the endoplasmic reticulum sarcoendoplasmic reticulum calcium trasport ATPase (SERCA) pump prolonged NMDAR-ΔCa2+ responses in sham rats, but not in RVH rats. Our study supports an altered spatiotemporal dynamic of NMDAR-ΔCa2+ signalling in MNCs from RVH rats, partly due to blunted endoplasmic reticulum Ca2+ buffering capacity. ABSTRACT A growing body of evidence supports an elevated NMDA receptor (NMDAR)-mediated glutamate excitatory function in the supraoptic nucleus and paraventricular nucleus of hypertensive rats that contributes to neurohumoral activation in this disease. However, the precise mechanisms underlying altered NMDAR signalling in hypertension remain to be elucidated. In this study, we performed simultaneous electrophysiology and fast confocal Ca2+ imaging to determine whether altered NMDAR-mediated changes in intracellular Ca2+ levels (NMDAR-ΔCa2+ ) occurred in hypothalamic magnocellular neurosecretory cells (MNCs) in renovascular hypertensive (RVH) rats. We found that despite evoking a similar excitatory inward current, activation of NMDARs resulted in a larger and prolonged ΔCa2+ in MNCs from RVH rats. Changes in NMDAR-ΔCa2+ dynamics were observed both in somatic and dendritic compartments. Inhibition of the sarcoendoplasmic reticulum calcium trasport ATPase (SERCA) pump activity with thapsigargin prolonged NMDAR-ΔCa2+ responses in MNCs of sham rats, but this effect was occluded in RVH rats, thus equalizing the magnitude and time course of the NMDA-ΔCa2+ responses between the two experimental groups. Taken together, our results support (1) an exacerbated NMDAR-ΔCa2+ response in somatodendritic compartments of MNCs of RVH rats, and (2) that a blunted ER Ca2+ buffering capacity contributes to the altered NMDAR-ΔCa2+ dynamics in this condition. Thus, altered spatiotemporal dynamics of the NMDAR-ΔCa2+ response stands as an underlying mechanism contributing to neurohumoral activation in neurogenic hypertension.
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Affiliation(s)
- Meng Zhang
- Department of Physiology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
| | - Javier E Stern
- Department of Physiology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
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22
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Ferreira‐Neto HC, Biancardi VC, Stern JE. A reduction in SK channels contributes to increased activity of hypothalamic magnocellular neurons during heart failure. J Physiol 2017; 595:6429-6442. [PMID: 28714070 PMCID: PMC5638886 DOI: 10.1113/jp274730] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/03/2017] [Indexed: 01/18/2023] Open
Abstract
KEY POINTS Small conductance Ca2+ -activated K+ (SK) channels play an important role in regulating the excitability of magnocellular neurosecretory cells (MNCs). Although an increased SK channel function contributes to adaptive physiological responses, it remains unknown whether changes in SK channel function/expression contribute to exacerbated MNC activity under disease conditions. We show that the input-output function of MNCs in heart failure (HF) rats is enhanced. Moreover, the SK channel blocker apamin enhanced the input-output function in sham, although not in HF rats. We found that both the after-hyperpolarizing potential magnitude and the underlying apamin-sensitive IAHP are blunted in MNCs from HF rats. The magnitude of spike-induced increases in intracellular Ca2+ levels was not affected in MNCs of HF rats. We found a diminished expression of SK2/SK3 channel subunit mRNA expression in the supraoptic nucleus of HF rats. Our studies suggest that a reduction in SK channel expression, but not changes in Ca2+ -mediated activation of SK channels, contributes to exacerbated MNC activity in HF rats. ABSTRACT Small conductance Ca2+ -activated K+ channels (SK) play an important role in regulating the activity of magnocellular neurosecretory cells (MNCs) and hormone release from the posterior pituitary. Moreover, enhanced SK activity contributes to the adaptive responses of MNCs to physiological challenge, such as lactation. Nevertheless, whether changes in SK function/expression contribute to exacerbated MNC activity during diseases such as heart failure (HF) remains unknown. In the present study, we used a combination of patch clamp electrophysiology, confocal Ca2+ imaging and molecular biology in a rat model of ischaemic HF. We found that the input-output function of MNCs was enhanced in HF compared to sham rats. Moreover, although the SK blocker apamin (200 nm) strengthened the input-output function in sham rats, it failed to have an effect in HF rats. The magnitude of the after-hyperpolarizing potential (AHP) following a train of spikes and the underlying apamin-sensitive IAHP were blunted in MNCs from HF rats. However, spike-induced increases in intracellular Ca2+ were not affected in the MNCs of HF rats. Real-time PCR measurements of SK channel subunits mRNA in supraoptic nucleus punches revealed a diminished expression of SK2/SK3 subunits in HF compared to sham rats. Together, our studies demonstrate that MNCs from HF rats exhibit increased membrane excitability and an enhanced input-output function, and also that a reduction in SK channel-mediated, apamin-sensitive AHP is a critical contributing mechanism. Moreover, our results suggest that the reduced AHP is related to a down-regulation of SK2/SK3 channel subunit expression but not the result of a blunted activity-dependent intracellular Ca2+ increase following a burst of action potentials.
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Kline DD. Tuning excitability of the hypothalamus via glutamate and potassium channel coupling. J Physiol 2017; 595:4583-4584. [PMID: 28548235 DOI: 10.1113/jp274446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- David D Kline
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, USA
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