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Tsentsevitsky AN, Khuzakhmetova VF, Bukharaeva EA, Petrov AM. The Mechanism of α2 adrenoreceptor-dependent Modulation of Neurotransmitter Release at the Neuromuscular Junctions. Neurochem Res 2024; 49:453-465. [PMID: 37897557 DOI: 10.1007/s11064-023-04052-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/26/2023] [Accepted: 10/17/2023] [Indexed: 10/30/2023]
Abstract
α2-Adrenoreceptors (ARs) are main Gi-protein coupled autoreceptors in sympathetic nerve terminals and targets for dexmedetomidine (DEX), a widely used sedative. We hypothesize that α2-ARs are also potent regulators of neuromuscular transmission via G protein-gated inwardly rectifying potassium (GIRK) channels. Using extracellular microelectrode recording of postsynaptic potentials, we found DEX-induced inhibition of spontaneous and evoked neurotransmitter release as well as desynchronization of evoked exocytotic events in the mouse diaphragm neuromuscular junction. These effects were suppressed by SKF-86,466, a selective α2-AR antagonist. An activator of GIRK channels ML297 had the same effects on neurotransmitter release as DEX. By contrast, inhibition of GIRK channels with tertiapin-Q prevented the action of DEX on evoked neurotransmitter release, but not on spontaneous exocytosis. The synaptic vesicle exocytosis is strongly dependent on Ca2+ influx through voltage-gated Ca2+ channels (VGCCs), which can be negatively regulated via α2-AR - GIRK channel axis. Indeed, inhibition of P/Q-, L-, N- or R-type VGCCs prevented the inhibitory action of DEX on evoked neurotransmitter release; antagonists of P/Q- and N-type channels also suppressed the DEX-mediated desynchronization of evoked exocytotic events. Furthermore, inhibition of P/Q-, L- or N-type VGCCs precluded the frequency decrease of spontaneous exocytosis upon DEX application. Thus, α2-ARs acting via GIRK channels and VGCCs (mainly, P/Q- and N-types) exert inhibitory effect on the neuromuscular communication by attenuating and desynchronizing evoked exocytosis. In addition, α2-ARs can suppress spontaneous exocytosis through GIRK channel-independent, but VGCC-dependent pathway.
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Affiliation(s)
- Andrei N Tsentsevitsky
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Venera F Khuzakhmetova
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Ellya A Bukharaeva
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Alexey M Petrov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia.
- Kazan State Medical University, 49 Butlerova St, Kazan, 420012, RT, Russia.
- Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia.
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Mazzaro A, Vita V, Ronfini M, Casola I, Klein A, Dobrowolny G, Sorarù G, Musarò A, Mongillo M, Zaglia T. Sympathetic neuropathology is revealed in muscles affected by amyotrophic lateral sclerosis. Front Physiol 2023; 14:1165811. [PMID: 37250128 PMCID: PMC10213213 DOI: 10.3389/fphys.2023.1165811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/14/2023] [Indexed: 05/31/2023] Open
Abstract
Rationale: The anatomical substrate of skeletal muscle autonomic innervation has remained underappreciated since it was described many decades ago. As such, the structural and functional features of muscle sympathetic innervation are largely undetermined in both physiology and pathology, mainly due to methodological limitations in the histopathological analysis of small neuronal fibers in tissue samples. Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease which mainly targets motor neurons, and despite autonomic symptoms occurring in a significant fraction of patients, peripheral sympathetic neurons (SNs) are generally considered unaffected and, as such, poorly studied. Purpose: In this research, we compared sympathetic innervation of normal and ALS muscles, through structural analysis of the sympathetic network in human and murine tissue samples. Methods and Results: We first refined tissue processing to circumvent methodological limitations interfering with the detection of muscle sympathetic innervation. The optimized "Neuro Detection Protocol" (NDP) was validated in human muscle biopsies, demonstrating that SNs innervate, at high density, both blood vessels and skeletal myofibers, independent of the fiber metabolic type. Subsequently, NDP was exploited to analyze sympathetic innervation in muscles of SOD1G93A mice, a preclinical ALS model. Our data show that ALS murine muscles display SN denervation, which has already initiated at the early disease stage and worsened during aging. SN degeneration was also observed in muscles of MLC/SOD1G93A mice, with muscle specific expression of the SOD1G93A mutant gene. Notably, similar alterations in SNs were observed in muscle biopsies from an ALS patient, carrying the SOD1G93A mutation. Conclusion: We set up a protocol for the analysis of murine and, more importantly, human muscle sympathetic innervation. Our results indicate that SNs are additional cell types compromised in ALS and suggest that dysfunctional SOD1G93A muscles affect their sympathetic innervation.
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Affiliation(s)
- Antonio Mazzaro
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, Padua, Italy
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Veronica Vita
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, Padua, Italy
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Marco Ronfini
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Irene Casola
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Arianna Klein
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Gabriella Dobrowolny
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Gianni Sorarù
- Department of Neuroscience, Azienda Ospedaliera di Padova, Padua, Italy
| | - Antonio Musarò
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
- Scuola Superiore di Studi Avanzati Sapienza (SSAS), Sapienza University of Rome, Rome, Italy
| | - Marco Mongillo
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- CNR Institute of Neuroscience, Padua, Italy
- CIR-MYO Myology Center, University of Padua, Padua, Italy
| | - Tania Zaglia
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- CIR-MYO Myology Center, University of Padua, Padua, Italy
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Delbono O, Wang Z, Messi ML. Brainstem noradrenergic neurons: Identifying a hub at the intersection of cognition, motility, and skeletal muscle regulation. Acta Physiol (Oxf) 2022; 236:e13887. [PMID: 36073023 PMCID: PMC9588743 DOI: 10.1111/apha.13887] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/31/2022] [Accepted: 09/05/2022] [Indexed: 01/29/2023]
Abstract
Brainstem noradrenergic neuron clusters form a node integrating efferents projecting to distinct areas such as those regulating cognition and skeletal muscle structure and function, and receive dissimilar afferents through established circuits to coordinate organismal responses to internal and environmental challenges. Genetic lineage tracing shows the remarkable heterogeneity of brainstem noradrenergic neurons, which may explain their varied functions. They project to the locus coeruleus, the primary source of noradrenaline in the brain, which supports learning and cognition. They also project to pre-ganglionic neurons, which lie within the spinal cord and form synapses onto post-ganglionic neurons. The synapse between descending brainstem noradrenergic neurons and pre-ganglionic spinal neurons, and these in turn with post-ganglionic noradrenergic neurons located at the paravertebral sympathetic ganglia, support an anatomical hierarchy that regulates skeletal muscle innervation, neuromuscular transmission, and muscle trophism. Whether any noradrenergic neuron subpopulation is more susceptible to damaged protein deposit and death with ageing and neurodegeneration is a relevant question that answer will help us to detect neurodegeneration at an early stage, establish prognosis, and anticipate disease progression. Loss of muscle mass and strength with ageing, termed sarcopenia, may predict impaired cognition with ageing and neurodegeneration and establish an early time to start interventions aimed at reducing central noradrenergic neurons hyperactivity. Complex multidisciplinary approaches, including genetic tracing, specific circuit labelling, optogenetics and chemogenetics, electrophysiology, and single-cell transcriptomics and proteomics, are required to test this hypothesis pre-clinical.
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Affiliation(s)
- Osvaldo Delbono
- Department of Internal MedicineSection on Gerontology and Geriatric Medicine. Wake Forest University School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Zhong‐Min Wang
- Department of Internal MedicineSection on Gerontology and Geriatric Medicine. Wake Forest University School of MedicineWinston‐SalemNorth CarolinaUSA
| | - María Laura Messi
- Department of Internal MedicineSection on Gerontology and Geriatric Medicine. Wake Forest University School of MedicineWinston‐SalemNorth CarolinaUSA
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