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Borroto-Escuela DO, Gonzalez-Cristo E, Ochoa-Torres V, Serra-Rojas EM, Ambrogini P, Arroyo-García LE, Fuxe K. Understanding electrical and chemical transmission in the brain. Front Cell Neurosci 2024; 18:1398862. [PMID: 38988663 PMCID: PMC11233782 DOI: 10.3389/fncel.2024.1398862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 06/14/2024] [Indexed: 07/12/2024] Open
Abstract
The histochemical Falck-Hillarp method for the localization of dopamine (DA), noradrenaline (NA) and serotonin in the central nervous system (CNS) of rodents was introduced in the 1960s. It supported the existence of chemical neurotransmission in the CNS. The monoamine neurons in the lower brain stem formed monosynaptic ascending systems to the telencephalon and diencephalon and monoamine descending systems to the entire spinal cord. The monoamines were early on suggested to operate via synaptic chemical transmission in the CNS. This chemical transmission reduced the impact of electrical transmission. In 1969 and the 1970s indications were obtained that important modes of chemical monoamine communication in the CNS also took place through the extra-synaptic fluid, the extracellular fluid, and long-distance communication in the cerebrospinal fluid involving diffusion and flow of transmitters like DA, NA and serotonin. In 1986, this type of transmission was named volume transmission (VT) by Agnati and Fuxe and their colleagues, also characterized by transmitter varicosity and receptor mismatches. The short and long-distance VT pathways were characterized by volume fraction, tortuosity and clearance. Electrical transmission also exists in the mammalian CNS, but chemical transmission is in dominance. One electrical mode is represented by electrical synapses formed by gap junctions which represent low resistant passages between nerve cells. It allows for a more rapid passage of action potentials between nerve cells compared to chemical transmission. The second mode is based on the ability of synaptic currents to generate electrical fields to modulate chemical transmission. One aim is to understand how chemical transmission can be integrated with electrical transmission and how putative (aquaporin water channel, dopamine D2R and adenosine A2AR) complexes in astrocytes can significancy participate in the clearance of waste products from the glymphatic system. VT may also help accomplish the operation of the acupuncture meridians essential for Chinese medicine in view of the indicated existence of extracellular VT pathways.
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Affiliation(s)
- Dasiel O. Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
| | - Emmanuell Gonzalez-Cristo
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
| | - Verty Ochoa-Torres
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
- Faculty of Engineering and Biotechnology, University OTR and the Regional Cooperative for Comprehensive Medical Assistance (CRAMI), Montevideo, Uruguay
| | - Emilio M. Serra-Rojas
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
- Cardiology Service, Lozano Blesa University Clinical Hospital, Zaragoza, Spain
| | - Patrizia Ambrogini
- Department of Biomolecular Sciences, Università di Urbino Carlo Bo, Urbino, Italy
| | - Luis E. Arroyo-García
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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2
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Özçete ÖD, Banerjee A, Kaeser PS. Mechanisms of neuromodulatory volume transmission. Mol Psychiatry 2024:10.1038/s41380-024-02608-3. [PMID: 38789677 DOI: 10.1038/s41380-024-02608-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024]
Abstract
A wealth of neuromodulatory transmitters regulate synaptic circuits in the brain. Their mode of signaling, often called volume transmission, differs from classical synaptic transmission in important ways. In synaptic transmission, vesicles rapidly fuse in response to action potentials and release their transmitter content. The transmitters are then sensed by nearby receptors on select target cells with minimal delay. Signal transmission is restricted to synaptic contacts and typically occurs within ~1 ms. Volume transmission doesn't rely on synaptic contact sites and is the main mode of monoamines and neuropeptides, important neuromodulators in the brain. It is less precise than synaptic transmission, and the underlying molecular mechanisms and spatiotemporal scales are often not well understood. Here, we review literature on mechanisms of volume transmission and raise scientific questions that should be addressed in the years ahead. We define five domains by which volume transmission systems can differ from synaptic transmission and from one another. These domains are (1) innervation patterns and firing properties, (2) transmitter synthesis and loading into different types of vesicles, (3) architecture and distribution of release sites, (4) transmitter diffusion, degradation, and reuptake, and (5) receptor types and their positioning on target cells. We discuss these five domains for dopamine, a well-studied monoamine, and then compare the literature on dopamine with that on norepinephrine and serotonin. We include assessments of neuropeptide signaling and of central acetylcholine transmission. Through this review, we provide a molecular and cellular framework for volume transmission. This mechanistic knowledge is essential to define how neuromodulatory systems control behavior in health and disease and to understand how they are modulated by medical treatments and by drugs of abuse.
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Affiliation(s)
- Özge D Özçete
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Aditi Banerjee
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA.
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3
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Del Franco AP, Newman EA. Astrocyte β-Adrenergic Receptor Activity Regulates NMDA Receptor Signaling of Medial Prefrontal Cortex Pyramidal Neurons. J Neurosci 2024; 44:e0990232023. [PMID: 37989594 PMCID: PMC10860478 DOI: 10.1523/jneurosci.0990-23.2023] [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: 05/29/2023] [Revised: 10/23/2023] [Accepted: 11/13/2023] [Indexed: 11/23/2023] Open
Abstract
Glutamate spillover from the synapse is tightly regulated by astrocytes, limiting the activation of extrasynaptically located NMDA receptors (NMDAR). The processes of astrocytes are dynamic and can modulate synaptic physiology. Though norepinephrine (NE) and β-adrenergic receptor (β-AR) activity can modify astrocyte volume, this has yet to be confirmed outside of sensory cortical areas, nor has the effect of noradrenergic signaling on glutamate spillover and neuronal NMDAR activity been explored. We monitored changes to astrocyte process volume in response to noradrenergic agonists in the medial prefrontal cortex of male and female mice. Both NE and the β-AR agonist isoproterenol (ISO) increased process volume by ∼20%, significantly higher than changes seen when astrocytes had G-protein signaling blocked by GDPβS. We measured the effect of β-AR signaling on evoked NMDAR currents. While ISO did not affect single stimulus excitatory currents of Layer 5 pyramidal neurons, ISO reduced NMDAR currents evoked by 10 stimuli at 50 Hz, which elicits glutamate spillover, by 18%. After isolating extrasynaptic NMDARs by blocking synaptic NMDARs with the activity-dependent NMDAR blocker MK-801, ISO similarly reduced extrasynaptic NMDAR currents in response to 10 stimuli by 18%. Finally, blocking β-AR signaling in the astrocyte network by loading them with GDPβS reversed the ISO effect on 10 stimuli-evoked NMDAR currents. These results demonstrate that astrocyte β-AR activity reduces extrasynaptic NMDAR recruitment, suggesting that glutamate spillover is reduced.
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Affiliation(s)
- Armani P Del Franco
- Department of Neuroscience, University of Minnesota, Minneapolis 55455, Minnesota
| | - Eric A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis 55455, Minnesota
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4
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Gebicke-Haerter PJ. The computational power of the human brain. Front Cell Neurosci 2023; 17:1220030. [PMID: 37608987 PMCID: PMC10441807 DOI: 10.3389/fncel.2023.1220030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/05/2023] [Indexed: 08/24/2023] Open
Abstract
At the end of the 20th century, analog systems in computer science have been widely replaced by digital systems due to their higher computing power. Nevertheless, the question keeps being intriguing until now: is the brain analog or digital? Initially, the latter has been favored, considering it as a Turing machine that works like a digital computer. However, more recently, digital and analog processes have been combined to implant human behavior in robots, endowing them with artificial intelligence (AI). Therefore, we think it is timely to compare mathematical models with the biology of computation in the brain. To this end, digital and analog processes clearly identified in cellular and molecular interactions in the Central Nervous System are highlighted. But above that, we try to pinpoint reasons distinguishing in silico computation from salient features of biological computation. First, genuinely analog information processing has been observed in electrical synapses and through gap junctions, the latter both in neurons and astrocytes. Apparently opposed to that, neuronal action potentials (APs) or spikes represent clearly digital events, like the yes/no or 1/0 of a Turing machine. However, spikes are rarely uniform, but can vary in amplitude and widths, which has significant, differential effects on transmitter release at the presynaptic terminal, where notwithstanding the quantal (vesicular) release itself is digital. Conversely, at the dendritic site of the postsynaptic neuron, there are numerous analog events of computation. Moreover, synaptic transmission of information is not only neuronal, but heavily influenced by astrocytes tightly ensheathing the majority of synapses in brain (tripartite synapse). At least at this point, LTP and LTD modifying synaptic plasticity and believed to induce short and long-term memory processes including consolidation (equivalent to RAM and ROM in electronic devices) have to be discussed. The present knowledge of how the brain stores and retrieves memories includes a variety of options (e.g., neuronal network oscillations, engram cells, astrocytic syncytium). Also epigenetic features play crucial roles in memory formation and its consolidation, which necessarily guides to molecular events like gene transcription and translation. In conclusion, brain computation is not only digital or analog, or a combination of both, but encompasses features in parallel, and of higher orders of complexity.
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Affiliation(s)
- Peter J. Gebicke-Haerter
- Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine, University of Heidelberg, Mannheim, Germany
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5
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Behl T, Kaur I, Sehgal A, Singh S, Makeen HA, Albratty M, Alhazmi HA, Bhatia S, Bungau S. The Locus Coeruleus - Noradrenaline system: Looking into Alzheimer's therapeutics with rose coloured glasses. Biomed Pharmacother 2022; 151:113179. [PMID: 35676784 DOI: 10.1016/j.biopha.2022.113179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/17/2022] [Accepted: 05/22/2022] [Indexed: 11/16/2022] Open
Abstract
Owing to the challenging ethos of global healthcare system, the Alzheimer's Disease (AD) researchers are consistently striving for a suitable target for disease amelioration. Besides the neurotransmitter release by neurons, the cells release tau proteins and amyloid peptides, within the extracellular vacancies, aggregating into tangles and plaques (AD pathological hallmarks). During neuro-stimulation, release of neuromodulator noradrenaline (NA), contained in the locus coeruleus (LC), exerts a significant impact on the neurons and microglia. The production of amyloid-β (Aβ) and hyperphosphorylation of tau proteins are affected by the α2A and β adrenoreceptors, parallel to influencing their clearance. The manuscript entails a detailed understanding of the LC-NA system, as a possible avenue in AD management. The authors provide a comprehensive data on AD pathology and its link with LC neuroanatomical projections, followed by the pathogenic implications of LC-NA system in AD. The data also integrates numerous studies from online databases, evidently supporting the loss of the system integrity in AD patients, and the impact of the sympathetic system on specific AD hallmarks. Thus, the objective of this review is to compile a wide compendium of studies, for the convenience of the neuro-researchers, aiding in the establishment of a suitable therapeutic regimen for AD treatment.
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Affiliation(s)
- Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania.
| | - Ishnoor Kaur
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Sukhbir Singh
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Hafiz A Makeen
- Pharmacy Practice Research Unit, Clinical Pharmacy Department, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Mohammed Albratty
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Hassan A Alhazmi
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Substance Abuse and Toxicology Research Centre, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Saurabh Bhatia
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman; School of Health Science, University of Petroleum and Energy Studies, Dehradun, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea, Romania; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania.
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Mather M. Noradrenaline in the aging brain: Promoting cognitive reserve or accelerating Alzheimer's disease? Semin Cell Dev Biol 2021; 116:108-124. [PMID: 34099360 PMCID: PMC8292227 DOI: 10.1016/j.semcdb.2021.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Many believe that engaging in novel and mentally challenging activities promotes brain health and prevents Alzheimer's disease in later life. However, mental stimulation may also have risks as well as benefits. As neurons release neurotransmitters, they often also release amyloid peptides and tau proteins into the extracellular space. These by-products of neural activity can aggregate into the tau tangle and amyloid plaque signatures of Alzheimer's disease. Over time, more active brain regions accumulate more pathology. Thus, increasing brain activity can have a cost. But the neuromodulator noradrenaline, released during novel and mentally stimulating events, may have some protective effects-as well as some negative effects. Via its inhibitory and excitatory effects on neurons and microglia, noradrenaline sometimes prevents and sometimes accelerates the production and accumulation of amyloid-β and tau in various brain regions. Both α2A- and β-adrenergic receptors influence amyloid-β production and tau hyperphosphorylation. Adrenergic activity also influences clearance of amyloid-β and tau. Furthermore, some findings suggest that Alzheimer's disease increases noradrenergic activity, at least in its early phases. Because older brains clear the by-products of synaptic activity less effectively, increased synaptic activity in the older brain risks accelerating the accumulation of Alzheimer's pathology more than it does in the younger brain.
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Affiliation(s)
- Mara Mather
- Leonard Davis School of Gerontology, Department of Psychology, & Department of Biomedical Engineering, University of Southern California, 3715 McClintock Ave, Los Angeles, CA 90089, United States.
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7
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Fischer T, Prey J, Eschholz L, Rotermund N, Lohr C. Norepinephrine-Induced Calcium Signaling and Store-Operated Calcium Entry in Olfactory Bulb Astrocytes. Front Cell Neurosci 2021; 15:639754. [PMID: 33833669 PMCID: PMC8021869 DOI: 10.3389/fncel.2021.639754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/02/2021] [Indexed: 11/30/2022] Open
Abstract
It is well-established that astrocytes respond to norepinephrine with cytosolic calcium rises in various brain areas, such as hippocampus or neocortex. However, less is known about the effect of norepinephrine on olfactory bulb astrocytes. In the present study, we used confocal calcium imaging and immunohistochemistry in mouse brain slices of the olfactory bulb, a brain region with a dense innervation of noradrenergic fibers, to investigate the calcium signaling evoked by norepinephrine in astrocytes. Our results show that application of norepinephrine leads to a cytosolic calcium rise in astrocytes which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. In addition, store-operated calcium entry (SOCE) contributes to the late phase of the response. Antagonists of both α1- and α2-adrenergic receptors, but not β-receptors, largely reduce the adrenergic calcium response, indicating that both α-receptor subtypes mediate norepinephrine-induced calcium transients in olfactory bulb astrocytes, whereas β-receptors do not contribute to the calcium transients.
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Affiliation(s)
- Timo Fischer
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Jessica Prey
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Lena Eschholz
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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8
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Kitano T, Eguchi R, Okamatsu-Ogura Y, Yamaguchi S, Otsuguro KI. Opposing functions of α- and β-adrenoceptors in the formation of processes by cultured astrocytes. J Pharmacol Sci 2021; 145:228-240. [PMID: 33602503 DOI: 10.1016/j.jphs.2020.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/07/2020] [Accepted: 12/17/2020] [Indexed: 10/22/2022] Open
Abstract
Astrocytes are glial cells with numerous fine processes which are important for the functions of the central nervous system. The activation of β-adrenoceptors induces process formation of astrocytes via cyclic AMP (cAMP) signaling. However, the role of α-adrenoceptors in the astrocyte morphology has not been elucidated. Here, we examined it by using cultured astrocytes from neonatal rat spinal cords and cortices. Exposure of these cells to noradrenaline and the β-adrenoceptor agonist isoproterenol increased intracellular cAMP levels and induced the formation of processes. Noradrenaline-induced process formation was enhanced with the α1-adrenoceptor antagonist prazosin and α2-adrenoceptor antagonist atipamezole. Atipamezole also enhanced noradrenaline-induced cAMP elevation. Isoproterenol-induced process formation was not inhibited by the α1-adrenoceptor agonist phenylephrine but was inhibited by the α2-adrenoceptor agonist dexmedetomidine. Dexmedetomidine also inhibited process formation induced by the adenylate cyclase activator forskolin and the membrane-permeable cAMP analog dibutyryl-cAMP. Moreover, dexmedetomidine inhibited cAMP-independent process formation induced by adenosine or the Rho-associated kinase inhibitor Y27632. In the presence of propranolol, noradrenaline inhibited Y27632-induced process formation, which was abolished by prazosin or atipamezole. These results demonstrate that α-adrenoceptors inhibit both cAMP-dependent and -independent astrocytic process formation.
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Affiliation(s)
- Taisuke Kitano
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Ryota Eguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Yuko Okamatsu-Ogura
- Laboratory of Biochemistry, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Soichiro Yamaguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Ken-Ichi Otsuguro
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan.
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Horvat A, Muhič M, Smolič T, Begić E, Zorec R, Kreft M, Vardjan N. Ca 2+ as the prime trigger of aerobic glycolysis in astrocytes. Cell Calcium 2021; 95:102368. [PMID: 33621899 DOI: 10.1016/j.ceca.2021.102368] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 12/17/2022]
Abstract
Astroglial aerobic glycolysis, a process during which d-glucose is converted to l-lactate, a brain fuel and signal, is regulated by the plasmalemmal receptors, including adrenergic receptors (ARs) and purinergic receptors (PRs), modulating intracellular Ca2+ and cAMP signals. However, the extent to which the two signals regulate astroglial aerobic glycolysis is poorly understood. By using agonists to stimulate intracellular α1-/β-AR-mediated Ca2+/cAMP signals, β-AR-mediated cAMP and P2R-mediated Ca2+ signals and genetically encoded fluorescence resonance energy transfer-based glucose and lactate nanosensors in combination with real-time microscopy, we show that intracellular Ca2+, but not cAMP, initiates a robust increase in the concentration of intracellular free d-glucose ([glc]i) and l-lactate ([lac]i), both depending on extracellular d-glucose, suggesting Ca2+-triggered glucose uptake and aerobic glycolysis in astrocytes. When the glycogen shunt, a process of glycogen remodelling, was inhibited, the α1-/β-AR-mediated increases in [glc]i and [lac]i were reduced by ∼65 % and ∼30 %, respectively, indicating that at least ∼30 % of the utilization of d-glucose is linked to glycogen remodelling and aerobic glycolysis. Additional activation of β-AR/cAMP signals aided to α1-/β-AR-triggered [lac]i increase, whereas the [glc]i increase was unaltered. Taken together, an increase in intracellular Ca2+ is the prime mechanism of augmented aerobic glycolysis in astrocytes, while cAMP has only a moderate role. The results provide novel information on the signals regulating brain metabolism and open new avenues to explore whether astroglial Ca2+ signals are dysregulated and contribute to neuropathologies with impaired brain metabolism.
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Affiliation(s)
- Anemari Horvat
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Marko Muhič
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tina Smolič
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Ena Begić
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia; Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia.
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10
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Verkhratsky A, Semyanov A, Zorec R. Physiology of Astroglial Excitability. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa016. [PMID: 35330636 PMCID: PMC8788756 DOI: 10.1093/function/zqaa016] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/29/2020] [Accepted: 09/03/2020] [Indexed: 01/06/2023]
Abstract
Classic physiology divides all neural cells into excitable neurons and nonexcitable neuroglia. Neuroglial cells, chiefly responsible for homeostasis and defense of the nervous tissue, coordinate their complex homeostatic responses with neuronal activity. This coordination reflects a specific form of glial excitability mediated by complex changes in intracellular concentration of ions and second messengers organized in both space and time. Astrocytes are equipped with multiple molecular cascades, which are central for regulating homeostasis of neurotransmitters, ionostasis, synaptic connectivity, and metabolic support of the central nervous system. Astrocytes are further provisioned with multiple receptors for neurotransmitters and neurohormones, which upon activation trigger intracellular signals mediated by Ca2+, Na+, and cyclic AMP. Calcium signals have distinct organization and underlying mechanisms in different astrocytic compartments thus allowing complex spatiotemporal signaling. Signals mediated by fluctuations in cytosolic Na+ are instrumental for coordination of Na+ dependent astrocytic transporters with tissue state and homeostatic demands. Astroglial ionic excitability may also involve K+, H+, and Cl-. The cyclic AMP signalling system is, in comparison to ions, much slower in targeting astroglial effector mechanisms. This evidence review summarizes the concept of astroglial intracellular excitability.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK,Achucarro Center for Neuroscience, Ikerbasque, 48011 Bilbao, Spain,Address correspondence to A.V. (e-mail: )
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,Faculty of Biology, Moscow State University, Moscow, Russia,Sechenov First Moscow State Medical University, Moscow, Russia
| | - Robert Zorec
- Celica Biomedical, Ljubljana 1000, Slovenia,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
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11
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Albertini G, Etienne F, Roumier A. Regulation of microglia by neuromodulators: Modulations in major and minor modes. Neurosci Lett 2020; 733:135000. [DOI: 10.1016/j.neulet.2020.135000] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023]
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12
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Jiang X, Challiss J, Glynn P. β1-adrenoceptor-stimulated lactate production in cultured astrocytes is predominantly glycogen-independent. Biochem Pharmacol 2020; 177:114035. [PMID: 32413424 DOI: 10.1016/j.bcp.2020.114035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/06/2020] [Indexed: 10/24/2022]
Abstract
Noradrenaline (NA) promotes breakdown of the glucose-polymer, glycogen, and hence enhances glycolytic production of lactate in astrocytes. Here, in cultured rat cerebrocortical astrocytes, we examined the contributions of different adrenoceptor subtypes to NA-modulated glucose metabolism, and the relationship of NA-induced glycogenolysis to lactate production. Stimulation of astrocytic glucose metabolism by NA was mediated predominantly via β1-adrenoceptors and cAMP. Constitutive β 1-adrenoceptor activity - in the absence of exogenous NA - contributed to the basal rate of glycogen turnover. Although mRNAs encoding both β 1- and β 2-adrenoceptors were detected in these astrocytes, β 2-adrenoceptors contributed little to NA-induced modulation of glucose metabolism. Activation of α2- and α 1-adrenoceptors in these cells decreased cAMP and increased cytosolic Ca2+, respectively, but did not modulate NA-induced glycogenolysis: α 2-adrenoceptors because glycogenolysis was induced maximally by NA concentrations that only began to inhibit cAMP production; and α 1-adrenoceptors possibly because of desensitisation and depletion of Ca2+ stores. Under basal conditions, astrocytes converted glucose to extracellular lactate in near stoichiometric manner. When glucose-starved astrocytes were given fresh glucose-containing medium, lactate accumulation displayed a brief lag period before attaining a steady-state rate. During this lag period NA, acting at β 1-adrenoceptors, increased the rate of lactate accumulation both in the absence and presence of an inhibitor of glycogen turnover. At the steady-state, the rate of glucose incorporation into accumulated glycogen was ~ 5% of that into lactate, but NA enhanced lactate output by 20-50%: this further indicates that NA, via β 1-adrenoceptors and cAMP, can enhance astrocytic lactate production independently of its effect on glycogen turnover.
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Affiliation(s)
- Xianguo Jiang
- Department of Molecular and Cell Biology, University of Leicester, Leicester, LE1 9HN, UK
| | - John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, LE1 9HN, UK
| | - Paul Glynn
- Department of Molecular and Cell Biology, University of Leicester, Leicester, LE1 9HN, UK.
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Velebit J, Horvat A, Smolič T, Prpar Mihevc S, Rogelj B, Zorec R, Vardjan N. Astrocytes with TDP-43 inclusions exhibit reduced noradrenergic cAMP and Ca 2+ signaling and dysregulated cell metabolism. Sci Rep 2020; 10:6003. [PMID: 32265469 PMCID: PMC7138839 DOI: 10.1038/s41598-020-62864-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 03/20/2020] [Indexed: 12/12/2022] Open
Abstract
Most cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have cytoplasmic inclusions of TAR DNA-binding protein 43 (TDP-43) in neurons and non-neuronal cells, including astrocytes, which metabolically support neurons with nutrients. Neuronal metabolism largely depends on the activation of the noradrenergic system releasing noradrenaline. Activation of astroglial adrenergic receptors with noradrenaline triggers cAMP and Ca2+ signaling and augments aerobic glycolysis with production of lactate, an important neuronal energy fuel. Astrocytes with cytoplasmic TDP-43 inclusions can cause motor neuron death, however, whether astroglial metabolism and metabolic support of neurons is altered in astrocytes with TDP-43 inclusions, is unclear. We measured lipid droplet and glucose metabolisms in astrocytes expressing the inclusion-forming C-terminal fragment of TDP-43 or the wild-type TDP-43 using fluorescent dyes or genetically encoded nanosensors. Astrocytes with TDP-43 inclusions exhibited a 3-fold increase in the accumulation of lipid droplets versus astrocytes expressing wild-type TDP-43, indicating altered lipid droplet metabolism. In these cells the noradrenaline-triggered increases in intracellular cAMP and Ca2+ levels were reduced by 35% and 31%, respectively, likely due to the downregulation of β2-adrenergic receptors. Although noradrenaline triggered a similar increase in intracellular lactate levels in astrocytes with and without TDP-43 inclusions, the probability of activating aerobic glycolysis was facilitated by 1.6-fold in astrocytes with TDP-43 inclusions and lactate MCT1 transporters were downregulated. Thus, while in astrocytes with TDP-43 inclusions noradrenergic signaling is reduced, aerobic glycolysis and lipid droplet accumulation are facilitated, suggesting dysregulated astroglial metabolism and metabolic support of neurons in TDP-43-associated ALS and FTD.
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Affiliation(s)
- Jelena Velebit
- Laboratory of Cell Engineering, Celica Biomedical, 1000, Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Cell Engineering, Celica Biomedical, 1000, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Tina Smolič
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Sonja Prpar Mihevc
- Department of Biotechnology, Jožef Stefan Institute, 1000, Ljubljana, Slovenia
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, 1000, Ljubljana, Slovenia.,Biomedical Research Institute BRIS, 1000, Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Cell Engineering, Celica Biomedical, 1000, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Cell Engineering, Celica Biomedical, 1000, Ljubljana, Slovenia. .,Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia.
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14
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Tozaki-Saitoh H, Sasaki I, Yamashita T, Hosoi M, Kato TA, Tsuda M. Involvement of exchange protein directly activated by cAMP and tumor progression locus 2 in IL-1β production in microglial cells following activation of β-adrenergic receptors. J Pharmacol Sci 2020; 143:133-140. [PMID: 32253104 DOI: 10.1016/j.jphs.2020.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 10/24/2022] Open
Abstract
Endogenous noradrenaline (NA) has multiple bioactive functions and, in the central nervous system (CNS), has been implicated in modulating neuroinflammation via β-adrenergic receptors (β-ARs). Microglia, resident macrophages in the CNS, have a central role in the brain immune system and have been reported to be activated by NA. However, intracellular signaling mechanisms of the AR-mediated proinflammatory responses of microglia are not fully understood. Using a rapid and stable in vitro reporter assay system to evaluate IL-1β production in microglial BV2 cells, we found that NA and the β-AR agonist isoproterenol upregulated the IL-1β reporter activity. This effect was suppressed by β-AR antagonists. We further examined the involvement of EPAC (exchange protein directly activated by cAMP) and TPL2 (tumor progression locus 2, MAP3K8) and found that inhibitors for EPAC and TPL2 reduced AR agonist-induced IL-1β reporter activity. These inhibitors also suppressed NA-induced endogenous Il1b mRNA expression and IL-1β protein production. Our results suggest that EPAC and TPL2 are involved in β-AR-mediated IL-1β production in microglial cells, and extend our understanding of its intracellular signaling mechanism.
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Affiliation(s)
- Hidetoshi Tozaki-Saitoh
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
| | - Izumi Sasaki
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Tomohiro Yamashita
- Department of Global Healthcare, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masako Hosoi
- Department of Psychosomatic Medicine, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Takahiro A Kato
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Makoto Tsuda
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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15
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Sugama S, Takenouchi T, Hashimoto M, Ohata H, Takenaka Y, Kakinuma Y. Stress-induced microglial activation occurs through β-adrenergic receptor: noradrenaline as a key neurotransmitter in microglial activation. J Neuroinflammation 2019; 16:266. [PMID: 31847911 PMCID: PMC6916186 DOI: 10.1186/s12974-019-1632-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 11/06/2019] [Indexed: 02/06/2023] Open
Abstract
Background The involvement of microglia in neuroinflammatory responses has been extensively demonstrated. Recent animal studies have shown that exposure to either acute or chronic stress induces robust microglial activation in the brain. In the present study, we investigated the underlying mechanism of brain microglial activation by acute stress. Methods We first looked at the spatial distribution of the noradrenaline (NA)-synthesizing enzyme, DBH (dopamine β-hydroxylase), in comparison with NA receptors—β1, β2, and β3 adrenergic receptors (β1-AR, β2-AR, and β3-AR)—after which we examined the effects of the β-blocker propranolol and α-blockers prazosin and yohimbine on stress-induced microglial activation. Finally, we compared stress-induced microglial activation between wild-type (WT) mice and double-knockout (DKO) mice lacking β1-AR and β2-AR. Results The results demonstrated that (1) microglial activation occurred in most studied brain regions, including the hippocampus (HC), thalamus (TM), and hypothalamus (HT); (2) within these three brain regions, the NA-synthesizing enzyme DBH was densely stained in the neuronal fibers; (3) β1-AR and β2-AR, but not β3-AR, are detected in the whole brain, and β1-AR and β2-AR are co-localized with microglial cells, as observed by laser scanning microscopy; (4) β-blocker treatment inhibited microglial activation in terms of morphology and count through the whole brain; α-blockers did not show such effect; (5) unlike WT mice, DKO mice exhibited substantial inhibition of stress-induced microglial activation in the brain. Conclusions We demonstrate that neurons/microglia may interact with NA via β1-AR and β2-AR.
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Affiliation(s)
- Shuei Sugama
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo, 113-8602, Japan.
| | - Takato Takenouchi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Makoto Hashimoto
- Division of Sensory and Motor Systems, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-0057, Japan
| | - Hisayuki Ohata
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo, 113-8602, Japan
| | - Yasuhiro Takenaka
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo, 113-8602, Japan
| | - Yoshihiko Kakinuma
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo, 113-8602, Japan
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16
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Slezak M, Kandler S, Van Veldhoven PP, Van den Haute C, Bonin V, Holt MG. Distinct Mechanisms for Visual and Motor-Related Astrocyte Responses in Mouse Visual Cortex. Curr Biol 2019; 29:3120-3127.e5. [PMID: 31495587 PMCID: PMC6859477 DOI: 10.1016/j.cub.2019.07.078] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 06/19/2019] [Accepted: 07/26/2019] [Indexed: 02/02/2023]
Abstract
Astrocytes are a major cell type in the mammalian nervous system, are in close proximity to neurons, and show rich Ca2+ activity thought to mediate cellular outputs. Astrocytes show activity linked to sensory [1, 2] and motor [3, 4] events, reflecting local neural activity and brain-wide neuromodulatory inputs. Sensory responses are highly variable [5, 6, 7, 8, 9, 10], which may reflect interactions between distinct input types [6, 7, 9]. However, the diversity of inputs generating astrocyte activity, particularly during sensory stimulation and behavior, is not fully understood [11, 12]. Using a combination of Ca2+ imaging, a treadmill assay, and visual stimulation, we examined the properties of astrocyte activity in mouse visual cortex associated with motor or sensory events. Consistent with previous work, motor activity activated astrocytes across the cortex with little specificity, reflecting a diffuse neuromodulatory mechanism. In contrast, moving visual stimuli generated specific activity patterns that reflected the stimulus' trajectory within the visual field, precisely as one would predict if astrocytes reported local neural activity. Visual responses depended strongly on behavioral state, with astrocytes showing high amplitude Ca2+ transients during locomotion and little activity during stillness. Furthermore, the amplitudes of visual responses were highly correlated with pupil size, suggesting a role of arousal. Interestingly, while depletion of cortical noradrenaline abolished locomotor responses, visual responses were only reduced in amplitude and their spatiotemporal organization remained intact, suggesting two distinct types of inputs underlie visual responses. We conclude that cortical astrocytes integrate local sensory information and behavioral state, suggesting a role in information processing. Astrocytes of moving mice display robust retinotopic responses to visual stimuli Sensory responses are distinguishable from responses to locomotion Vision-driven responses are correlated to arousal Vision- and arousal-driven responses are differentially regulated by noradrenaline
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Affiliation(s)
- Michal Slezak
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; VIB Center for Brain and Disease Research, Herestraat 49-Box 602, 3000 Leuven, Belgium
| | - Steffen Kandler
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium
| | - Paul P Van Veldhoven
- KU Leuven, Department of Cellular and Molecular Medicine, LIPIT, Herestraat 49-Box 601, 3000 Leuven, Belgium
| | - Chris Van den Haute
- KU Leuven, Laboratory for Neurobiology and Gene Therapy and Leuven Brain Institute, RK-Herestraat 49-Box 1023, 3000 Leuven, Belgium; KU Leuven, Leuven Viral Vector Core, RK-Herestraat 49, 3000 Leuven, Belgium
| | - Vincent Bonin
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium; KU Leuven, Department of Biology and Leuven Brain Institute, Naamsestraat 59-Box 2465, 3001 Leuven, Belgium.
| | - Matthew G Holt
- VIB Center for Brain and Disease Research, Herestraat 49-Box 602, 3000 Leuven, Belgium; KU Leuven, Department of Neuroscience and Leuven Brain Institute, Herestraat 49-Box 1021, 3000 Leuven, Belgium.
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17
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Liu Y, Xing R, Liu S, Qin Y, Li K, Yu H, Li P. Effects of chitooligosaccharides supplementation with different dosages, molecular weights and degrees of deacetylation on growth performance, innate immunity and hepatopancreas morphology in Pacific white shrimp (Litopenaeus vannamei). Carbohydr Polym 2019; 226:115254. [PMID: 31582076 DOI: 10.1016/j.carbpol.2019.115254] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/26/2019] [Accepted: 08/26/2019] [Indexed: 10/26/2022]
Abstract
Three trials were conducted to comprehensively evaluate the application of chitooligosaccharides (COSs) different dosages, molecular weights (MW) and degrees of deacetylation (DD) as a feed additive for Pacific white shrimp (Litopenaeus vannamei). In trial 1, COSs (3 KDa and 85% DD) at four different dosages (0.05%, 0.1%, 0.15% and 0.2%) were added to feed to investigate the appropriate dosages. The survival ratio (SR) of the shrimps was not significantly different (P > 0.05) between the control and treatment groups. The shrimps fed with 0.1% COSs supplementation exhibited the highest wet body weight (FBW), specific growth ratio (SGR), and weight gain (WG) and the lowest feed conversion ratio (FCR). In trial 2, COSs with different MW (85% DD and 0.1% dosage) were tested. Except for the group treated with the 12 KDa COSs, all shrimps fed with COSs had remarkably higher (P < 0.05) FBW, WG, and SGR and lower FCR (P < 0.05) than the control group, and shrimps fed with the 1 KDa COSs showed most positive effects. In trial 3, COSs with different DD (MW of 1 KDa and 0.1% dosage) were further studied. The different DD were DD5, DD25, DD50, DD75, and DD95. Shrimps fed COSs-supplemented diets of DD75 or DD95 exhibited higher (P < 0.05) FBW, WG and SGR and lower FCR than the other groups. The DD95 group had the highest FBW, WG and SGR and the lowest FCR, but there were no significant differences (P > 0.05) between the DD75 and DD95 groups. Moreover, for COSs supplementation, especially for the DD75 and DD95 groups, the antioxidant parameters were significantly different from those of the other groups. Furthermore, groups fed diets with COSs supplementation had higher (P < 0.05) trypsin activity than those fed control diets. In addition, immune and antioxidant gene expression and the morphology of the hepatopancreas were affected by the DD of COSs. Therefore, the additive dosages, molecular weights and degrees of deacetylation of COSs significantly affected the growth performance of the shrimps; therefore, it is particularly important to determine the optimum parameters of COSs.
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Affiliation(s)
- Yongliang Liu
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Ronge Xing
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
| | - Song Liu
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
| | - Yukun Qin
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
| | - Kecheng Li
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
| | - Huahua Yu
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
| | - Pengcheng Li
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237, China.
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Dissociation between morphine-induced spinal gliosis and analgesic tolerance by ultra-low-dose α2-adrenergic and cannabinoid CB1-receptor antagonists. Behav Pharmacol 2019; 29:241-254. [PMID: 29481424 DOI: 10.1097/fbp.0000000000000377] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Long-term use of opioid analgesics is limited by tolerance development and undesirable adverse effects. Paradoxically, spinal administration of ultra-low-dose (ULD) G-protein-coupled receptor antagonists attenuates analgesic tolerance. Here, we determined whether systemic ULD α2-adrenergic receptor (AR) antagonists attenuate the development of morphine tolerance, whether these effects extend to the cannabinoid (CB1) receptor system, and if behavioral effects are reflected in changes in opioid-induced spinal gliosis. Male rats were treated daily with morphine (5 mg/kg) alone or in combination with ULD α2-AR (atipamezole or efaroxan; 17 ng/kg) or CB1 (rimonabant; 5 ng/kg) antagonists; control groups received ULD injections only. Thermal tail flick latencies were assessed across 7 days, before and 30 min after the injection. On day 8, spinal cords were isolated, and changes in spinal gliosis were assessed through fluorescent immunohistochemistry. Both ULD α2-AR antagonists attenuated morphine tolerance, whereas the ULD CB1 antagonist did not. In contrast, both ULD atipamezole and ULD rimonabant attenuated morphine-induced microglial reactivity and astrogliosis in deep and superficial spinal dorsal horn. So, although paradoxical effects of ULD antagonists are common to several G-protein-coupled receptor systems, these may not involve similar mechanisms. Spinal glia alone may not be the main mechanism through which tolerance is modulated.
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Morita M, Ikeshima-Kataoka H, Kreft M, Vardjan N, Zorec R, Noda M. Metabolic Plasticity of Astrocytes and Aging of the Brain. Int J Mol Sci 2019; 20:ijms20040941. [PMID: 30795555 PMCID: PMC6413111 DOI: 10.3390/ijms20040941] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/17/2019] [Accepted: 02/18/2019] [Indexed: 01/03/2023] Open
Abstract
As part of the blood-brain-barrier, astrocytes are ideally positioned between cerebral vasculature and neuronal synapses to mediate nutrient uptake from the systemic circulation. In addition, astrocytes have a robust enzymatic capacity of glycolysis, glycogenesis and lipid metabolism, managing nutrient support in the brain parenchyma for neuronal consumption. Here, we review the plasticity of astrocyte energy metabolism under physiologic and pathologic conditions, highlighting age-dependent brain dysfunctions. In astrocytes, glycolysis and glycogenesis are regulated by noradrenaline and insulin, respectively, while mitochondrial ATP production and fatty acid oxidation are influenced by the thyroid hormone. These regulations are essential for maintaining normal brain activities, and impairments of these processes may lead to neurodegeneration and cognitive decline. Metabolic plasticity is also associated with (re)activation of astrocytes, a process associated with pathologic events. It is likely that the recently described neurodegenerative and neuroprotective subpopulations of reactive astrocytes metabolize distinct energy substrates, and that this preference is supposed to explain some of their impacts on pathologic processes. Importantly, physiologic and pathologic properties of astrocytic metabolic plasticity bear translational potential in defining new potential diagnostic biomarkers and novel therapeutic targets to mitigate neurodegeneration and age-related brain dysfunctions.
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Affiliation(s)
- Mitsuhiro Morita
- Department of Biology, Graduate School of Sciences, Kobe University, 657-8501 Kobe, Japan.
| | - Hiroko Ikeshima-Kataoka
- Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
| | - Marko Kreft
- Laboratory of Cell Engineering, Celica Biomedical, 1000 Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
- Department of Biology, Biotechnical Faculty University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Nina Vardjan
- Laboratory of Cell Engineering, Celica Biomedical, 1000 Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Robert Zorec
- Laboratory of Cell Engineering, Celica Biomedical, 1000 Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Mami Noda
- Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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Verkhratsky A, Parpura V, Rodriguez-Arellano JJ, Zorec R. Astroglia in Alzheimer's Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:273-324. [PMID: 31583592 DOI: 10.1007/978-981-13-9913-8_11] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease is the most common cause of dementia. Cellular changes in the brains of the patients suffering from Alzheimer's disease occur well in advance of the clinical symptoms. At the cellular level, the most dramatic is a demise of neurones. As astroglial cells carry out homeostatic functions of the brain, it is certain that these cells are at least in part a cause of Alzheimer's disease. Historically, Alois Alzheimer himself has recognised this at the dawn of the disease description. However, the role of astroglia in this disease has been understudied. In this chapter, we summarise the various aspects of glial contribution to this disease and outline the potential of using these cells in prevention (exercise and environmental enrichment) and intervention of this devastating disease.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA.,University of Rijeka, Rijeka, Croatia
| | - Jose Julio Rodriguez-Arellano
- BioCruces Health Research Institute, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.,Department of Neuroscience, The University of the Basque Country UPV/EHU, Plaza de Cruces 12, 48903, Barakaldo, Bizkaia, Spain
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica BIOMEDICAL, Ljubljana, Slovenia
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21
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Robertson JM. The Gliocentric Brain. Int J Mol Sci 2018; 19:ijms19103033. [PMID: 30301132 PMCID: PMC6212929 DOI: 10.3390/ijms19103033] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 09/23/2018] [Accepted: 09/28/2018] [Indexed: 01/10/2023] Open
Abstract
The Neuron Doctrine, the cornerstone of research on normal and abnormal brain functions for over a century, has failed to discern the basis of complex cognitive functions. The location and mechanisms of memory storage and recall, consciousness, and learning, remain enigmatic. The purpose of this article is to critically review the Neuron Doctrine in light of empirical data over the past three decades. Similarly, the central role of the synapse and associated neural networks, as well as ancillary hypotheses, such as gamma synchrony and cortical minicolumns, are critically examined. It is concluded that each is fundamentally flawed and that, over the past three decades, the study of non-neuronal cells, particularly astrocytes, has shown that virtually all functions ascribed to neurons are largely the result of direct or indirect actions of glia continuously interacting with neurons and neural networks. Recognition of non-neural cells in higher brain functions is extremely important. The strict adherence of purely neurocentric ideas, deeply ingrained in the great majority of neuroscientists, remains a detriment to understanding normal and abnormal brain functions. By broadening brain information processing beyond neurons, progress in understanding higher level brain functions, as well as neurodegenerative and neurodevelopmental disorders, will progress beyond the impasse that has been evident for decades.
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Leanza G, Gulino R, Zorec R. Noradrenergic Hypothesis Linking Neurodegeneration-Based Cognitive Decline and Astroglia. Front Mol Neurosci 2018; 11:254. [PMID: 30100866 PMCID: PMC6072880 DOI: 10.3389/fnmol.2018.00254] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/05/2018] [Indexed: 12/31/2022] Open
Abstract
In the past, manipulation of the cholinergic system was seen as the most likely therapeutic for neurodegeneration-based cognitive decline in Alzheimer's disease (AD) (Whitehouse et al., 1982). However, targeting the noradrenergic system also seems a promising strategy, since more recent studies revealed that in post-mortem tissue from patients with AD and other neurodegenerative disorders there is a robust correlation between cognitive decline and loss of neurons from the Locus coeruleus (LC), a system with diffuse noradrenaline (NA) innervation in the central nervous system (CNS). Therefore, the hypothesis has been considered that increasing NA signaling in the CNS will prevent, or at least halt the progression of neurodegeneration and cognitive decline. A hallmark of the age- and neurodegeneration-related cognitive decline is reduced neurogenesis. We here discuss noradrenergic dysfunction in AD-related cognitive decline in humans and its potential involvement in AD pathology and disease progression. We also focus on animal models to allow the validation of the noradrenergic hypothesis of AD, including those based upon the immunotoxin-mediated ablation of LC based on saporin, a protein synthesis interfering agent, which offers selective and graded demise of LC neurons, Finally, we address how astrocytes, an abundant and functionally heterogeneous cell type of neuroglia maintaining homeostasis, may participate in the regulation of neurogenesis, a new strategy for preventing LC neuron loss.
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Affiliation(s)
- Giampiero Leanza
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
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Zorec R, Parpura V, Verkhratsky A. Preventing neurodegeneration by adrenergic astroglial excitation. FEBS J 2018; 285:3645-3656. [PMID: 29630772 DOI: 10.1111/febs.14456] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/17/2018] [Accepted: 03/28/2018] [Indexed: 01/22/2023]
Abstract
Impairment of the main noradrenergic nucleus of the human brain, the locus coeruleus (LC), which has been discovered in 1784, represents one of defining factors of neurodegenerative diseases progression. Projections of LC neurons release noradrenaline/norepinephrine (NA), which stimulates astrocytes, homeostatic neuroglial cells enriched with adrenergic receptors. There is a direct correlation between the reduction in noradrenergic innervations and cognitive decline associated with ageing and neurodegenerative diseases. It is, therefore, hypothesized that the resilience of LC neurons to degeneration influences the neural reserve that in turn determines cognitive decline. Deficits in the noradrenergic innervation of the brain might be reversed or restrained by increasing the activity of existing LC neurons, transplanting noradrenergic neurons, and/or using drugs that mimic the activity of NA on astroglia. Here, these strategies are discussed with the aim to understand how astrocytes integrate neuronal network activity in the brain information processing in health and disease.
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Affiliation(s)
- Robert Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, Civitan International Research Center and Center for Glial Biology in Medicine, Evelyn F. McKnight Brain Institute, Atomic Force Microscopy & Nanotechnology Laboratories, University of Alabama, Birmingham, AL, USA
| | - Alexei Verkhratsky
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia.,Faculty of Biology, Medicine and Health, The University of Manchester, UK.,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.,Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain
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24
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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25
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 942] [Impact Index Per Article: 157.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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26
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Astrocytic Pathological Calcium Homeostasis and Impaired Vesicle Trafficking in Neurodegeneration. Int J Mol Sci 2017; 18:ijms18020358. [PMID: 28208745 PMCID: PMC5343893 DOI: 10.3390/ijms18020358] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 02/08/2023] Open
Abstract
Although the central nervous system (CNS) consists of highly heterogeneous populations of neurones and glial cells, clustered into diverse anatomical regions with specific functions, there are some conditions, including alertness, awareness and attention that require simultaneous, coordinated and spatially homogeneous activity within a large area of the brain. During such events, the brain, representing only about two percent of body mass, but consuming one fifth of body glucose at rest, needs additional energy to be produced. How simultaneous energy procurement in a relatively extended area of the brain takes place is poorly understood. This mechanism is likely to be impaired in neurodegeneration, for example in Alzheimer’s disease, the hallmark of which is brain hypometabolism. Astrocytes, the main neural cell type producing and storing glycogen, a form of energy in the brain, also hold the key to metabolic and homeostatic support in the central nervous system and are impaired in neurodegeneration, contributing to the slow decline of excitation-energy coupling in the brain. Many mechanisms are affected, including cell-to-cell signalling. An important question is how changes in cellular signalling, a process taking place in a rather short time domain, contribute to the neurodegeneration that develops over decades. In this review we focus initially on the slow dynamics of Alzheimer’s disease, and on the activity of locus coeruleus, a brainstem nucleus involved in arousal. Subsequently, we overview much faster processes of vesicle traffic and cytosolic calcium dynamics, both of which shape the signalling landscape of astrocyte-neurone communication in health and neurodegeneration.
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Dienel GA, Cruz NF. Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism. J Neurochem 2016; 138:14-52. [DOI: 10.1111/jnc.13630] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Gerald A. Dienel
- Department of Cell Biology and Physiology; University of New Mexico; Albuquerque; New Mexico USA
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
| | - Nancy F. Cruz
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
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28
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Sherpa AD, Xiao F, Joseph N, Aoki C, Hrabetova S. Activation of β-adrenergic receptors in rat visual cortex expands astrocytic processes and reduces extracellular space volume. Synapse 2016; 70:307-16. [PMID: 27085090 DOI: 10.1002/syn.21908] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/11/2016] [Accepted: 04/13/2016] [Indexed: 12/18/2022]
Abstract
Brain extracellular space (ECS) is an interconnected channel that allows diffusion-mediated transport of signaling molecules, metabolites, and drugs. We tested the hypothesis that β-adrenergic receptor (βAR) activation impacts extracellular diffusion-mediated transport of molecules through alterations in the morphology of astrocytes. Two structural parameters of ECS-volume fraction and tortuosity-govern extracellular diffusion. Volume fraction (α) is the volume of ECS relative to the total tissue volume. Tortuosity (λ) is a measure of the hindrance that molecules experience in the ECS, compared to a free medium. The real-time iontophoretic (RTI) method revealed that treatment of acutely prepared visual cortical slices of adult female rats with a βAR agonist, DL-isoproterenol (ISO), decreases α significantly, from 0.22 ± 0.03 (mean ± SD) for controls without agonist to 0.18 ± 0.03 with ISO, without altering λ (control: 1.64 ± 0.04; ISO: 1.63 ± 0.04). Electron microscopy revealed that the ISO treatment significantly increased the cytoplasmic area of astrocytic distal endings per unit area of neuropil by 54%. These findings show that norepinephrine decreases α, in part, through an increase in astrocytic volume following βAR activation. Norepinephrine is recognized to be released within the brain during the awake state and increase neurons' signal-to-noise ratio through modulation of neurons' biophysical properties. Our findings uncover a new mechanism for noradrenergic modulation of neuronal signals. Through astrocytic activation leading to a reduction of α, noradrenergic modulation increases extracellular concentration of neurotransmitters and neuromodulators, thereby facilitating neuronal interactions, especially during wakefulness. Synapse 70:307-316, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ang Doma Sherpa
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York, 11203
- Neural and Behavioral Science Graduate Program, The School of Graduate Studies, State University of New York Downstate Medical Center, Brooklyn, New York, 11203
| | - Fanrong Xiao
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York, 11203
| | | | - Chiye Aoki
- Center for Neural Science, New York University, New York, New York, 10003
| | - Sabina Hrabetova
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York, 11203
- The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, New York, 11203
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29
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Nedelescu H, Chowdhury TG, Wable GS, Arbuthnott G, Aoki C. Cerebellar sub-divisions differ in exercise-induced plasticity of noradrenergic axons and in their association with resilience to activity-based anorexia. Brain Struct Funct 2016; 222:317-339. [PMID: 27056728 PMCID: PMC5215061 DOI: 10.1007/s00429-016-1220-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 03/24/2016] [Indexed: 11/01/2022]
Abstract
The vermis or "spinocerebellum" receives input from the spinal cord and motor cortex for controlling balance and locomotion, while the longitudinal hemisphere region or "cerebro-cerebellum" is interconnected with non-motor cortical regions, including the prefrontal cortex that underlies decision-making. Noradrenaline release in the cerebellum is known to be important for motor plasticity but less is known about plasticity of the cerebellar noradrenergic (NA) system, itself. We characterized plasticity of dopamine β-hydroxylase-immunoreactive NA fibers in the cerebellum of adolescent female rats that are evoked by voluntary wheel running, food restriction (FR) or by both, in combination. When 8 days of wheel access was combined with FR during the last 4 days, some responded with excessive exercise, choosing to run even during the hours of food access: this exacerbated weight loss beyond that due to FR alone. In the vermis, exercise, with or without FR, shortened the inter-varicosity intervals and increased varicosity density along NA fibers, while excessive exercise, due to FR, also shortened NA fibers. In contrast, the hemisphere required the FR-evoked excessive exercise to evoke shortened inter-varicosity intervals along NA fibers and this change was exhibited more strongly by rats that suppressed the FR-evoked excessive exercise, a behavior that minimized weight loss. Presuming that shortened inter-varicosity intervals translate to enhanced NA release and synthesis of norepinephrine, this enhancement in the cerebellar hemisphere may contribute towards protection of individuals from the life-threatening activity-based anorexia via relays with higher-order cortical areas that mediate the animal's decision to suppress the innate FR-evoked hyperactivity.
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Affiliation(s)
- Hermina Nedelescu
- Department of Systems Neurophysiology, Tokyo Medical and Dental University Graduate School, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. .,Center for Neural Science, New York University, New York, NY, 10003, USA. .,Brain Mechanisms for Behaviour Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan.
| | - Tara G Chowdhury
- Center for Neural Science, New York University, New York, NY, 10003, USA.,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Gauri S Wable
- Center for Neural Science, New York University, New York, NY, 10003, USA
| | - Gordon Arbuthnott
- Brain Mechanisms for Behaviour Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Chiye Aoki
- Center for Neural Science, New York University, New York, NY, 10003, USA.
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30
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Gibbs ME. Role of Glycogenolysis in Memory and Learning: Regulation by Noradrenaline, Serotonin and ATP. Front Integr Neurosci 2016; 9:70. [PMID: 26834586 PMCID: PMC4717441 DOI: 10.3389/fnint.2015.00070] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/17/2015] [Indexed: 01/06/2023] Open
Abstract
This paper reviews the role played by glycogen breakdown (glycogenolysis) and glycogen re-synthesis in memory processing in two different chick brain regions, (1) the hippocampus and (2) the avian equivalent of the mammalian cortex, the intermediate medial mesopallium (IMM). Memory processing is regulated by the neuromodulators noradrenaline and serotonin soon after training glycogen breakdown and re-synthesis. In day-old domestic chicks, memory formation is dependent on the breakdown of glycogen (glycogenolysis) at three specific times during the first 60 min after learning (around 2.5, 30, and 55 min). The chicks learn to discriminate in a single trial between beads of two colors and tastes. Inhibition of glycogen breakdown by the inhibitor of glycogen phosphorylase 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) given at specific times prior to the formation of long-term memory prevents memory forming. Noradrenergic stimulation of cultured chicken astrocytes by a selective β2-adrenergic (AR) agonist reduces glycogen levels and we believe that in vivo this triggers memory consolidation at the second stage of glycogenolysis. Serotonin acting at 5-HT2B receptors acts on the first stage, but not on the second. We have shown that noradrenaline, acting via post-synaptic α2-ARs, is also responsible for the synthesis of glycogen and our experiments suggest that there is a readily accessible labile pool of glycogen in astrocytes which is depleted within 10 min if glycogen synthesis is inhibited. Endogenous ATP promotion of memory consolidation at 2.5 and 30 min is also dependent on glycogen breakdown. ATP acts at P2Y1 receptors and the action of thrombin suggests that it causes the release of internal calcium ([Ca2+]i) in astrocytes. Glutamate and GABA, the primary neurotransmitters in the brain, cannot be synthesized in neurons de novo and neurons rely on astrocytic glutamate synthesis, requiring glycogenolysis.
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Affiliation(s)
- Marie E Gibbs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC, Australia
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31
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Fuxe K, Agnati LF, Marcoli M, Borroto-Escuela DO. Volume Transmission in Central Dopamine and Noradrenaline Neurons and Its Astroglial Targets. Neurochem Res 2015; 40:2600-14. [PMID: 25894681 DOI: 10.1007/s11064-015-1574-5] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/16/2015] [Accepted: 04/04/2015] [Indexed: 12/11/2022]
Abstract
Already in the 1960s the architecture and pharmacology of the brainstem dopamine (DA) and noradrenaline (NA) neurons with formation of vast numbers of DA and NA terminal plexa of the central nervous system (CNS) indicated that they may not only communicate via synaptic transmission. In the 1980s the theory of volume transmission (VT) was introduced as a major communication together with synaptic transmission in the CNS. VT is an extracellular and cerebrospinal fluid transmission of chemical signals like transmitters, modulators etc. moving along energy gradients making diffusion and flow of VT signals possible. VT interacts with synaptic transmission mainly through direct receptor-receptor interactions in synaptic and extrasynaptic heteroreceptor complexes and their signaling cascades. The DA and NA neurons are specialized for extrasynaptic VT at the soma-dendrtitic and terminal level. The catecholamines released target multiple DA and adrenergic subtypes on nerve cells, astroglia and microglia which are the major cell components of the trophic units building up the neural-glial networks of the CNS. DA and NA VT can modulate not only the strength of synaptic transmission but also the VT signaling of the astroglia and microglia of high relevance for neuron-glia interactions. The catecholamine VT targeting astroglia can modulate the fundamental functions of astroglia observed in neuroenergetics, in the Glymphatic system, in the central renin-angiotensin system and in the production of long-distance calcium waves. Also the astrocytic and microglial DA and adrenergic receptor subtypes mediating DA and NA VT can be significant drug targets in neurological and psychiatric disease.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, 17177, Stockholm, Sweden.
| | - Luigi F Agnati
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41100, Modena, Italy
| | - Manuela Marcoli
- Dipartimento di Farmacia, Sezione di Farmacologia e Tossicologia, Università di Genova, Viale Cembrano 4, 16148, Genoa, Italy.,Center of Excellence for Biomedical Research, Università di Genova, Viale Benedetto XV 5, 16132, Genoa, Italy
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32
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Vardjan N, Verkhratsky A, Zorec R. Pathologic Potential of Astrocytic Vesicle Traffic: New Targets to Treat Neurologic Diseases? Cell Transplant 2015; 24:599-612. [DOI: 10.3727/096368915x687750] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Vesicles are small intracellular organelles that are fundamental for constitutive housekeeping of the plasmalemma, intercellular transport, and cell-to-cell communications. In astroglial cells, traffic of vesicles is associated with cell morphology, which determines the signaling potential and metabolic support for neighboring cells, including when these cells are considered to be used for cell transplantations or for regulating neurogenesis. Moreover, vesicles are used in astrocytes for the release of vesicle-laden chemical messengers. Here we review the properties of membrane-bound vesicles that store gliotransmitters, endolysosomes that are involved in the traffic of plasma membrane receptors, and membrane transporters. These vesicles are all linked to pathological states, including amyotrophic lateral sclerosis, multiple sclerosis, neuroinflammation, trauma, edema, and states in which astrocytes contribute to developmental disorders. In multiple sclerosis, for example, fingolimod, a recently introduced drug, apparently affects vesicle traffic and gliotransmitter release from astrocytes, indicating that this process may well be used as a new pathophysiologic target for the development of new therapies.
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Affiliation(s)
- Nina Vardjan
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science, Bilbao, Spain
- Faculty of Life Sciences, The University of Manchester, Manchester, UK
| | - Robert Zorec
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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33
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Fuentes-Santamaría V, Alvarado JC, López-Muñoz DF, Melgar-Rojas P, Gabaldón-Ull MC, Juiz JM. Glia-related mechanisms in the anteroventral cochlear nucleus of the adult rat in response to unilateral conductive hearing loss. Front Neurosci 2014; 8:319. [PMID: 25352772 PMCID: PMC4195288 DOI: 10.3389/fnins.2014.00319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/19/2014] [Indexed: 11/13/2022] Open
Abstract
Conductive hearing loss causes a progressive decline in cochlear activity that may result in functional and structural modifications in auditory neurons. However, whether these activity-dependent changes are accompanied by a glial response involving microglia, astrocytes, or both has not yet been fully elucidated. Accordingly, the present study was designed to determine the involvement of glial related mechanisms in the anteroventral cochlear nucleus (AVCN) of adult rats at 1, 4, 7, and 15 d after removing middle ear ossicles. Quantitative immunohistochemistry analyses at light microscopy with specific markers of microglia or astroglia along with immunocytochemistry at the electron microscopy level were used. Also, in order to test whether trophic support by neurotrophins is modulated in glial cells by auditory activity, the expression and distribution of neurotrophin-3 (NT-3) and its colocalization with microglial or astroglial markers was investigated. Diminished cochlear activity after middle ear ossicle removal leads to a significant ipsilateral increase in the mean gray levels and stained area of microglial cells but not astrocytes in the AVCN at 1 and 4 d post-lesion as compared to the contralateral side and control animals. These results suggest that microglial cells but not astrocytes may act as dynamic modulators of synaptic transmission in the cochlear nucleus immediately following unilateral hearing loss. On the other hand, NT-3 immunostaining was localized mainly in neuronal cell bodies and axons and was upregulated at 1, 4 and 7 d post-lesion. Very few glial cells expressed this neurotrophin in both control and experimental rats, suggesting that NT-3 is primarily activated in neurons and not as much in glia after limiting auditory activity in the AVCN by conductive hearing loss.
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Affiliation(s)
- Verónica Fuentes-Santamaría
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
| | - Juan C Alvarado
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
| | - Diego F López-Muñoz
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
| | - Pedro Melgar-Rojas
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
| | - María C Gabaldón-Ull
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
| | - José M Juiz
- Facultad de Medicina, Instituto de Investigación en Discapacidades, Neurológicas (IDINE), Universidad de Castilla-La Mancha Albacete, Spain
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34
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Vardjan N, Kreft M, Zorec R. Dynamics of β-adrenergic/cAMP signaling and morphological changes in cultured astrocytes. Glia 2014; 62:566-79. [PMID: 24464905 DOI: 10.1002/glia.22626] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 11/05/2013] [Accepted: 12/20/2013] [Indexed: 11/09/2022]
Abstract
The morphology of astrocytes, likely regulated by cAMP, determines the structural association between astrocytes and the synapse, consequently modulating synaptic function. β-Adrenergic receptors (β-AR), which increase cytosolic cAMP concentration ([cAMP]i ), may affect cell morphology. However, the real-time dynamics of β-AR-mediated cAMP signaling in single live astrocytes and its effect on cell morphology have not been studied. We used the fluorescence resonance energy transfer (FRET)-based cAMP biosensor Epac1-camps to study time-dependent changes in [cAMP]i ; morphological changes in primary rat astrocytes were monitored by real-time confocal microscopy. Stimulation of β-AR by adrenaline, noradrenaline, and isoprenaline, a specific agonist of β-AR, rapidly increased [cAMP]i (∼15 s). The FRET signal response, mediated via β-AR, was faster than in the presence of forskolin (twofold) and dibutyryl-cAMP (>35-fold), which directly activate adenylyl cyclase and Epac1-camps, respectively, likely due to slow entry of these agents into the cytosol. Oscillations in [cAMP]i have not been recorded, indicating that cAMP-dependent processes operate in a slow time domain. Most Epac1-camps expressing astrocytes revealed a morphological change upon β-AR activation and attained a stellate morphology within 1 h. The morphological changes exhibited a bell-shaped dependency on [cAMP]i . The 5-10% decrease in cell cross-sectional area and the 30-50% increase in cell perimeter are likely due to withdrawal of the cytoplasm to the perinuclear region and the appearance of protrusions on the surface of astrocytes. Because astrocyte processes ensheath neurons, β-AR/cAMP-mediated morphological changes can modify the geometry of the extracellular space, affecting synaptic, neuronal, and astrocyte functions in health and disease.
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Affiliation(s)
- Nina Vardjan
- Celica Biomedical Center, Tehnološki Park 24, Ljubljana, Slovenia; Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, Slovenia
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Robertson JM. Astrocyte domains and the three-dimensional and seamless expression of consciousness and explicit memories. Med Hypotheses 2013; 81:1017-24. [DOI: 10.1016/j.mehy.2013.09.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 08/30/2013] [Accepted: 09/13/2013] [Indexed: 01/19/2023]
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36
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Zhang J, Muller JF, McDonald AJ. Noradrenergic innervation of pyramidal cells in the rat basolateral amygdala. Neuroscience 2013; 228:395-408. [PMID: 23103792 PMCID: PMC4586037 DOI: 10.1016/j.neuroscience.2012.10.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/16/2012] [Accepted: 10/16/2012] [Indexed: 11/26/2022]
Abstract
The basolateral nuclear complex of the amygdala (BLC) receives dense noradrenergic/norepinephrine (NE) inputs from the locus coeruleus that play a key role in modulating emotional memory consolidation. Knowledge of the extent of synapse formation by NE inputs to the BLC, as well as the cell types innervated, would contribute to an understanding of how NE modulates the activity of the BLC. To gain a better understanding of NE circuits in the BLC, dual-label immunohistochemistry was used at the light and electron microscopic levels in the present study to analyze NE axons and their innervation of pyramidal cells in the anterior subdivision of the basolateral amygdalar nucleus (BLa). NE axons and BLa pyramidal cells were labeled using antibodies to the norepinephrine transporter (NET) and Ca(2+)/calmodulin-dependent protein kinase (CaMK), respectively. Dual localization studies using antibodies to NET and dopamine-beta-hydroxylase (DBH) revealed that virtually all NE axons and varicosities expressed both proteins. The BLa exhibited a medium density of NET+ fibers. Ultrastructural analysis of serial section reconstructions of NET+ axons revealed that only about half of NET+ terminals formed synapses. The main postsynaptic targets were small-caliber CAMK+ dendritic shafts and spines of pyramidal cells. A smaller number of NET+ terminals formed synapses with unlabeled cell bodies and dendrites. These findings indicate that the distal dendritic domain of BLa pyramidal cells is the major target of NE terminals in the BLa, and the relatively low synaptic incidence suggests that diffusion from non-synaptic terminals may be important for noradrenergic modulation of the BLa.
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Affiliation(s)
- Jingyi Zhang
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208
| | - Jay F. Muller
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208
| | - Alexander J. McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208
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β-Arrestins in the Central Nervous System. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:267-95. [DOI: 10.1016/b978-0-12-394440-5.00011-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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38
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β2-adrenergic receptor and astrocyte glucose metabolism. J Mol Neurosci 2012; 48:456-63. [PMID: 22399228 DOI: 10.1007/s12031-012-9742-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 02/27/2012] [Indexed: 12/19/2022]
Abstract
Astrocyte glucose metabolism functions to maintain brain activity in both normal and stress conditions. Dysregulation of astrocyte glucose metabolism relates to development of neuronal disease, such as multiple sclerosis and Alzheimer's disease. In response to acute stress, beta2-adrenergic receptor is activated and initiates multiple signaling events mediated by Gs, Gi, arrestin, or other effectors depending on specific cellular contexts. In astrocytes, beta2-adrenergic receptor promotes glucose uptake through GLUT1 and accelerates glycogen degradation via coupling to Gs and second messenger cAMP-dependent pathway. Beta2-adrenergic receptor may regulate other steps in astrocyte glucose metabolism, such as lactate production or transduction. Inappropriate regulation of beta2-adrenergic receptor activity can disrupt normal glucose metabolism, and leads to accelerate neuronal disease development. It was demonstrated that the absence of beta2-adrenergic receptor in astrocytes occurred in multiple sclerosis patients, and the increased beta2-adrenergic receptor activity relates to Alzheimer's disease. A clear view of beta2-adrenergic receptor-mediated signaling pathways in regulating astrocyte glucose metabolism could help us to develop neuronal diseases treatment by targeting to the beta2-adrenergic receptor.
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39
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Effect of stimulation of β adrenoreceptors on conditioned reflex-related spike activity of neurons of the cat somatosensory cortex. NEUROPHYSIOLOGY+ 2011. [DOI: 10.1007/s11062-011-9216-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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40
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Xu B, Zhang WS, Yang JL, Lû N, Deng XM, Xu H, Zhang YQ. Evidence for suppression of spinal glial activation by dexmedetomidine in a rat model of monoarthritis. Clin Exp Pharmacol Physiol 2010; 37:e158-66. [DOI: 10.1111/j.1440-1681.2010.05426.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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41
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McNamee EN, Griffin ÉW, Ryan KM, Ryan KJ, Heffernan S, Harkin A, Connor TJ. Noradrenaline acting at β-adrenoceptors induces expression of IL-1β and its negative regulators IL-1ra and IL-1RII, and drives an overall anti-inflammatory phenotype in rat cortex. Neuropharmacology 2010; 59:37-48. [DOI: 10.1016/j.neuropharm.2010.03.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 03/23/2010] [Accepted: 03/24/2010] [Indexed: 10/19/2022]
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42
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Gibbs ME, Bowser DN. Astrocytic adrenoceptors and learning: alpha1-adrenoceptors. Neurochem Int 2010; 57:404-10. [PMID: 20380858 DOI: 10.1016/j.neuint.2010.03.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 03/15/2010] [Accepted: 03/31/2010] [Indexed: 11/26/2022]
Abstract
Noradrenergic receptors are expressed on both on astrocytes and neurons and noradrenergic activation of astrocytic beta(2)- and beta(3)-adrenoceptors are necessary for memory consolidation. In this paper, we marshal evidence for astrocytic alpha(1)-adrenoceptor involvement in memory consolidation. We examine the role of alpha(1)-adrenoceptors in hippocampal and mesopallial (cortical) memory processing using a discriminative avoidance task in the day-old chick. The selective alpha(1)-adrenoceptor agonist, methoxamine, caused the consolidation of weakly-reinforced memory at the time of transition of short-term to intermediate memory and at the time of transition of intermediate to long-term memory. The selective antagonist prazosin prevented memory consolidation at these two times. Blockade of memory by injection of an alpha(2)-adrenoceptor agonist into the LoC could be overcome by mesopallial or hippocampal injection of alpha(1)-, beta(2)- and beta(3)-adrenoceptor agonists. The results of studies where we challenged the ability of methoxamine to promote consolidation by pre-administration of astrocytic metabolic inhibitors of glycogenolysis or oxidative metabolism, suggest that the alpha(1)-adrenoceptor effect is astrocytic. This conclusion is supported by the finding that co-administration of suboptimal doses of methoxamine and thrombin have an additive effect on promoting consolidation. Thrombin causes a calcium response in cultured chick astrocytes but not in neurons. Thrombin, like methoxamine, promotes consolidation at the transition points between short-term, intermediate memory and long-term memory stages. Thrombin enhancement of memory consolidation is blocked by an alpha(1)-adrenoceptor antagonist but not by antagonists of beta(2)- or beta(3)-adrenoceptors. In summary, noradrenaline activation of alpha(1)-adrenoceptors is necessary for consolidation from both short-term and intermediate memory in both the hippocampus and the mesopallium in the chick. Evidence is presented suggesting that the memory consolidating action of alpha(1)-adrenoceptor stimulation results from receptors located on astroctyes and involves an increase in free cytosolic calcium from internal stores.
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Affiliation(s)
- Marie E Gibbs
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia.
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43
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Laureys G, Clinckers R, Gerlo S, Spooren A, Wilczak N, Kooijman R, Smolders I, Michotte Y, De Keyser J. Astrocytic beta(2)-adrenergic receptors: from physiology to pathology. Prog Neurobiol 2010; 91:189-99. [PMID: 20138112 DOI: 10.1016/j.pneurobio.2010.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 12/07/2009] [Accepted: 01/27/2010] [Indexed: 12/24/2022]
Abstract
Evidence accumulates for a key role of the beta(2)-adrenergic receptors in the many homeostatic and neuroprotective functions of astrocytes, including glycogen metabolism, regulation of immune responses, release of neurotrophic factors, and the astrogliosis that occurs in response to neuronal injury. A dysregulation of the astrocytic beta(2)-adrenergic-pathway is suspected to contribute to the physiopathology of a number of prevalent and devastating neurological conditions such as multiple sclerosis, Alzheimer's disease, human immunodeficiency virus encephalitis, stroke and hepatic encephalopathy. In this review we focus on the physiological functions of astrocytic beta(2)-adrenergic receptors, and their possible impact in disease states.
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Affiliation(s)
- Guy Laureys
- Department of Pharmaceutical Chemistry and Drug Analysis, Vrije Universiteit Brussel, Belgium
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44
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McNamee EN, Ryan KM, Kilroy D, Connor TJ. Noradrenaline induces IL-1ra and IL-1 type II receptor expression in primary glial cells and protects against IL-1beta-induced neurotoxicity. Eur J Pharmacol 2009; 626:219-28. [PMID: 19818755 DOI: 10.1016/j.ejphar.2009.09.054] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 09/18/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
Abstract
The pro-inflammatory cytokine interleukin-1beta (IL-1beta) plays a key role in initiating an immune response within the central nervous system (CNS), and is thought to be a significant contributor to the neurodegenerative process. The actions of IL-1beta can be regulated by interleukin-1 receptor antagonist (IL-1ra), which prevents IL-1beta from acting on the IL-1 type I receptor (IL-1RI). Another negative regulator of the IL-1 system is the IL-1 type II receptor (IL-1RII); a decoy receptor that serves to sequester IL-1. Consequently, pharmacological strategies that tip the balance in favour of IL-1ra and IL-1RII may be of therapeutic benefit. Evidence suggests that the neurotransmitter noradrenaline elicits anti-inflammatory actions in the CNS, and consequently may play an endogenous neuroprotective role. Here we report that noradrenaline induces production of IL-1ra and IL-1RII from primary rat mixed glial cells. In contrast, noradrenaline did not alter IL-1beta expression, or expression of IL-1RI or the IL-1 type I receptor accessory protein (IL-1RAcp); both of which are required for IL-1 signalling. Our results demonstrate that the ability of noradrenaline to induce IL-1ra and IL-1RII is mediated via beta-adrenoceptor activation and downstream activation of protein kinase A and extracellular signal-regulated kinase (ERK). In parallel with its ability to increase IL-1ra and IL-1RII, noradrenaline prevented neurotoxicity in cortical primary neurons induced by conditioned medium from IL-1beta treated mixed glial cells. These data indicate that noradrenaline negatively regulates IL-1 system in glial cells and has neuroprotective properties in situations where IL-1 contributes to pathology.
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Affiliation(s)
- Eoin N McNamee
- Neuroimmunology Research Group, Department of Physiology, School of Medicine & Trinity College Institute of Neuroscience, Trinity College, Dublin 2, Ireland
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45
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Constantinou S, Fern R. Conduction block and glial injury induced in developing central white matter by glycine, GABA, noradrenalin, or nicotine, studied in isolated neonatal rat optic nerve. Glia 2009; 57:1168-77. [DOI: 10.1002/glia.20839] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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46
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Noradrenaline reuptake inhibitors limit neuroinflammation in rat cortex following a systemic inflammatory challenge: implications for depression and neurodegeneration. Int J Neuropsychopharmacol 2009; 12:687-99. [PMID: 19046481 DOI: 10.1017/s146114570800967x] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Evidence suggests that noradrenaline has a tonic anti-inflammatory action in the central nervous system (CNS) via its ability to suppress microglial and astrocytic activation, and inhibit production of inflammatory mediators. Consequently it is suggested that noradrenaline may play an endogenous neuroprotective role in CNS disorders where inflammatory events contribute to pathology. Here we demonstrate that acute treatment of rats with the noradrenaline reuptake inhibitors (NRIs) desipramine and atomoxetine elicited anti-inflammatory actions in rat cortex following a systemic challenge with bacterial lipopolysaccharide (LPS). This was characterized by a reduction in cortical gene expression of the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha), the enzyme inducible nitric oxide synthase (iNOS), and the microglial activation markers CD11b and CD40. These anti-inflammatory actions of NRIs were associated with reduced activation of nuclear factor-kappa B (NF-kappaB); a transcription factor that is considered the major regulator of inflammation in the CNS. To determine whether NRI administration directly altered glial expression of these inflammatory markers, primary cortical glial cells were exposed in vitro to the NRIs desipramine or atomoxetine. In vitro treatment with NRIs largely failed to alter mRNA expression of IL-1beta, TNF-alpha, iNOS, CD11b and CD40, following stimulation with LPS. Similarly, LPS-induced TNF-alpha and IL-1beta protein production from glial cells was unaffected by NRI treatment. In contrast, in vitro exposure of cultured glial cells to noradrenaline suppressed IL-1beta, TNF-alpha, iNOS and CD40 expression. These results suggest that in vivo administration of NRIs limit inflammatory events in the brain, probably by increasing noradrenaline availability. Overall, this study has yielded significant insights into the ability of noradrenaline-augmentation strategies to limit neuroinflammation.
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47
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Inaba M, Maruyama T, Yoshimura Y, Hosoi H, Komatsu Y. Facilitation of low-frequency stimulation-induced long-term potentiation by endogenous noradrenaline and serotonin in developing rat visual cortex. Neurosci Res 2009; 64:191-8. [DOI: 10.1016/j.neures.2009.02.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
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48
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Vijayaraghavan S. Glial-neuronal interactions--implications for plasticity and drug addiction. AAPS JOURNAL 2009; 11:123-32. [PMID: 19238557 DOI: 10.1208/s12248-009-9085-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 01/19/2009] [Indexed: 11/30/2022]
Abstract
Among neuroscientists, astrocytes have for long played Cinderella to their neuron stepsisters. While the importance of glia in regulating brain activity was predicted by Ramon y Cajal more than a century ago (Garcia-Marin et al., Trends. Neurosci. 30:479-787, 2007), these cells, until recently, have been thought to play mainly a passive part in synaptic signaling. Results obtained over the last decade have begun to suggest otherwise. Experiments carried out in a number of labs have shown that glial cells, especially astrocytes, directly participate in synaptic signaling and potentially regulate synaptic plasticity and network excitability. The presence of signaling pathways on astrocytes that are analogous to those at presynaptic terminals suggests a role for these cells in network plasticity. Findings that the same signaling pathways can be activated by receptors for drugs of abuse present on astrocytes suggest a role for these cells in the addictive process. In this review, we summarize current understanding of astrocytic role in synaptic signaling and suggest that a complete understanding of the process of addiction requires a better understanding of the functional role of these cells.
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Affiliation(s)
- Sukumar Vijayaraghavan
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, Denver, School of Medicine, Anschutz Medical Campus, MS 8307, P18-7121, Aurora, Colorado 80045, USA.
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49
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Cellular localization and distribution of dopamine D4 receptors in the rat cerebral cortex and their relationship with the cortical dopaminergic and noradrenergic nerve terminal networks. Neuroscience 2008; 155:997-1010. [DOI: 10.1016/j.neuroscience.2008.05.060] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 05/21/2008] [Accepted: 05/26/2008] [Indexed: 01/10/2023]
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50
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Ramos BP, Colgan LA, Nou E, Arnsten AF. Beta2 adrenergic agonist, clenbuterol, enhances working memory performance in aging animals. Neurobiol Aging 2008; 29:1060-9. [PMID: 17363115 PMCID: PMC3154024 DOI: 10.1016/j.neurobiolaging.2007.02.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 01/29/2007] [Accepted: 02/05/2007] [Indexed: 11/29/2022]
Abstract
Previous studies using a mixed beta1 and beta2 adrenergic antagonist, propanolol, have indicated that beta adrenoceptors have little effect on the cognitive functioning of the prefrontal cortex. However, recent studies have suggested that endogenous stimulation of beta1 adrenoceptors impairs working memory in both rats and monkeys. Since propanolol has no effect on cognition, we hypothesized that activation of beta2 adrenoceptors might improve performance in a working memory task. We tested this hypothesis by observing the effects of the beta2 agonist, clenbuterol, on spatial working memory performance. Clenbuterol was either infused directly into the prefrontal cortex (rats) or administered systemically (monkeys). Results demonstrated that clenbuterol improved performance in many young and aged rats and monkeys who performed poorly under control conditions. Actions at beta2 adrenoceptors were confirmed by challenging the clenbuterol response with the beta2 adrenergic antagonist, ICI 118,551. The effects of clenbuterol were not universal and depended on the cognitive status of the animal: the drug moderately improved only a subset of animals with working memory impairment.
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Affiliation(s)
- Brian P. Ramos
- Yale University School of Medicine, Department of Neurobiology, SHM C-300, 333 Cedar Street, New Haven, CT 06510, USA
| | - Leslie A. Colgan
- Yale University School of Medicine, Department of Neurobiology, SHM C-300, 333 Cedar Street, New Haven, CT 06510, USA
| | - Eric Nou
- Yale University School of Medicine, Department of Neurobiology, SHM C-300, 333 Cedar Street, New Haven, CT 06510, USA
| | - Amy F.T. Arnsten
- Yale University School of Medicine, Department of Neurobiology, SHM C-300, 333 Cedar Street, New Haven, CT 06510, USA
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