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Cervetto C, Amaroli A, Amato S, Gatta E, Diaspro A, Maura G, Signore A, Benedicenti S, Marcoli M. Photons Induce Vesicular Exocytotic Release of Glutamate in a Power-Dependent Way. Int J Mol Sci 2023; 24:10977. [PMID: 37446155 DOI: 10.3390/ijms241310977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/20/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
Increasing evidence indicates that photobiomodulation, based on tissue irradiation with photons in the red to near-infrared spectrum, may be an effective therapeutic approach to central nervous system disorders. Although nervous system functionality has been shown to be affected by photons in animal models, as well as in preliminary evidence in healthy subjects or in patients with neuropsychiatric disorders, the mechanisms involved in the photobiomodulation effects have not yet been clarified. We previously observed that photobiomodulation could stimulate glutamate release. Here, we investigate mechanisms potentially involved in the glutamate-releasing effect of photons from adult mouse cerebrocortical nerve terminals. We report evidence of photon ability to induce an exocytotic vesicular release of glutamate from the terminals of glutamatergic neurons in a power-dependent way. It can be hypothesized that photobiomodulation, depending on the potency, can release glutamate in a potentially neurotoxic or physiological range.
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Affiliation(s)
- Chiara Cervetto
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), 56122 Pisa, Italy
| | - Andrea Amaroli
- Department of Earth, Environment and Life Sciences, University of Genova, Viale Benedetto XV 5, 16132 Genova, Italy
| | - Sarah Amato
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Elena Gatta
- DIFILAB, Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Alberto Diaspro
- DIFILAB, Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
- Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia-IIT, Via Morego 30, 16133 Genova, Italy
- Biophysics Institute, National Research Council-CNR, Via de Marini, 6, 16149 Genova, Italy
| | - Guido Maura
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Antonio Signore
- Therapeutic Dentistry Department, Institute of Dentistry, Sechenov First Moscow State Medical University, Trubetskaya Str. 8, b. 2, 119992 Moskow, Russia
| | - Stefano Benedicenti
- Department of Surgical Sciences and Integrated Diagnostics, University of Genova, Viale Benedetto XV 6, 16132 Genova, Italy
| | - Manuela Marcoli
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), 56122 Pisa, Italy
- Center of Excellence for Biomedical Research, University of Genova, 16132 Genova, Italy
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Lu CW, Wu CC, Chiu KM, Lee MY, Lin TY, Wang SJ. Inhibition of Synaptic Glutamate Exocytosis and Prevention of Glutamate Neurotoxicity by Eupatilin from Artemisia argyi in the Rat Cortex. Int J Mol Sci 2022; 23:13406. [PMID: 36362193 PMCID: PMC9657139 DOI: 10.3390/ijms232113406] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 10/28/2022] [Accepted: 11/01/2022] [Indexed: 01/03/2024] Open
Abstract
The inhibition of synaptic glutamate release to maintain glutamate homeostasis contributes to the alleviation of neuronal cell injury, and accumulating evidence suggests that natural products can repress glutamate levels and associated excitotoxicity. In this study, we investigated whether eupatilin, a constituent of Artemisia argyi, affected glutamate release in rat cortical nerve terminals (synaptosomes). Additionally, we evaluated the effect of eupatilin in an animal model of kainic acid (KA) excitotoxicity, particularly on the levels of glutamate and N-methyl-D-aspartate (NMDA) receptor subunits (GluN2A and GluN2B). We found that eupatilin decreased depolarization-evoked glutamate release from rat cortical synaptosomes and that this effect was accompanied by a reduction in cytosolic Ca2+ elevation, inhibition of P/Q-type Ca2+ channels, decreased synapsin I Ca2+-dependent phosphorylation and no detectable effect on the membrane potential. In a KA-induced glutamate excitotoxicity rat model, the administration of eupatilin before KA administration prevented neuronal cell degeneration, glutamate elevation, glutamate-generating enzyme glutaminase increase, excitatory amino acid transporter (EAAT) decrease, GluN2A protein decrease and GluN2B protein increase in the rat cortex. Taken together, the results suggest that eupatilin depresses glutamate exocytosis from cerebrocortical synaptosomes by decreasing P/Q-type Ca2+ channels and synapsin I phosphorylation and alleviates glutamate excitotoxicity caused by KA by preventing glutamatergic alterations in the rat cortex. Thus, this study suggests that eupatilin can be considered a potential therapeutic agent in the treatment of brain impairment associated with glutamate excitotoxicity.
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Affiliation(s)
- Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Chia-Chan Wu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Electrical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Department of Medical Research, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
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3
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Lu CW, Yeh KC, Chiu KM, Lee MY, Lin TY, Wang SJ. The Effect of Isosaponarin Derived from Wasabi Leaves on Glutamate Release in Rat Synaptosomes and Its Underlying Mechanism. Int J Mol Sci 2022; 23:ijms23158752. [PMID: 35955884 PMCID: PMC9368944 DOI: 10.3390/ijms23158752] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/05/2022] [Accepted: 08/05/2022] [Indexed: 11/23/2022] Open
Abstract
Excessive glutamate release is known to be involved in the pathogenesis of neurological diseases, and suppression of glutamate release from nerve terminals is considered to be a treatment strategy. In this study, we investigated whether isosaponarin, a flavone glycoside isolated from wasabi leaves, could affect glutamate release in rat cerebral cortex nerve terminals (synaptosomes). The release of glutamate was evoked by the K+ channel blocker 4-aminopyridine (4-AP) and measured by an online enzyme-coupled fluorimetric assay. Isosaponarin produced a concentration-dependent inhibition of 4-AP-evoked glutamate release with a half-maximum inhibition of release value of 22 μM. The inhibition caused by isosaponarin was prevented by eliminating extracellular Ca2+ or by using bafilomycin A1, an inhibitor of synaptic vesicle exocytosis. Isosaponarin decreased intrasynaptosomal rises in Ca2+ levels that were induced by 4-AP, without affecting the synaptosomal membrane potential. The isosaponarin-induced inhibition of glutamate release was significantly prevented in synaptosomes that were pretreated with a combination of the calcium channel blockers ω-conotoxin GVIA (N-type) and ω-agatoxin IVA (P/Q-types). The protein kinase C (PKC) pan-inhibitor GF109203X and the Ca2+-dependent PKC inhibitor Go6976 abolished the inhibition of glutamate release by isosaponarin, while the Ca2+-independent PKC inhibitor rottlerin did not show any effect. The results from immunoblotting assays also showed that isosaponarin lowered PKC, PKCα, synaptosomal-associated protein of 25 kDa (SNAP-25), and myristoylated alanine-rich C-kinase substrate (MARCKS) phosphorylation induced by 4-AP. In addition, FM1-43-labeled synaptic vesicles in synaptosomes showed that treatment with isosaponarin resulted in an attenuation of the 4-AP-induced decrease in fluorescence intensity that is consistent with glutamate release. Transmission electron microscopy of synaptosomes also provided evidence that isosaponarin altered the number of synaptic vesicles. These results indicate that isosaponarin suppresses the Ca2+-dependent PKC/SNAP-25 and MARCKS pathways in synaptosomes, causing a decrease in the number of available synaptic vesicles, which inhibits vesicular glutamate release from synaptosomes.
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Affiliation(s)
- Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Kun-Chieh Yeh
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Department of Surgery, Taoyuan Armed Forces General Hospital, Taoyuan 325208, Taiwan
- Department of Surgery, Fu Jen Catholic University Hospital, Fu Jen Catholic University, New Taipei City 24205, Taiwan
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Electrical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Department of Medical Research, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
- Correspondence: (T.-Y.L.); (S.-J.W.); Tel.: +886-2-8966-7000 (T.-Y.L.); +886-2-2905-3465 (S.-J.W.)
| | - Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
- Correspondence: (T.-Y.L.); (S.-J.W.); Tel.: +886-2-8966-7000 (T.-Y.L.); +886-2-2905-3465 (S.-J.W.)
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Chiu KM, Lin TY, Lee MY, Lu CW, Wang SJ. Lappaconitine inhibits glutamate release from rat cerebrocortical nerve terminals by suppressing Ca2+ influx and protein kinase A cascade. Neurotoxicology 2022; 91:218-227. [DOI: 10.1016/j.neuro.2022.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 05/02/2022] [Accepted: 05/20/2022] [Indexed: 10/18/2022]
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Huang SK, Lu CW, Lin TY, Wang SJ. Neuroprotective Role of the B Vitamins in the Modulation of the Central Glutamatergic Neurotransmission. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2022; 21:292-301. [PMID: 34477538 DOI: 10.2174/1871527320666210902165739] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/27/2021] [Accepted: 07/12/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Regulation of glutamate release is crucial for maintaining normal brain function, but excess glutamate release is implicated in many neuropathological conditions. Therefore, the minimum glutamate release from presynaptic nerve terminals is an important neuroprotective mechanism. OBJECTIVE In this mini-review, we analyze the three B vitamins, namely vitamin B2 (riboflavin), vitamin B6 (pyridoxine), and vitamin B12 (cyanocobalamin), that affect the 4-aminopyridine (4- AP)-evoked glutamate release from presynaptic nerve terminal in rat and discuss their neuroprotective role. METHODS In this study, the measurements include glutamate release, DiSC3(5), and Fura-2. RESULTS The riboflavin, pyridoxine, and cyanocobalamin produced significant inhibitory effects on 4-aminopyridine-evoked glutamate release from rat cerebrocortical nerve terminals (synaptosomes) in a dose-dependent relationship. These presynaptic inhibitory actions of glutamate release are attributed to inhibition of physiologic Ca2+-dependent vesicular exocytosis but not Ca2+-independent nonvesicular release. These effects also did not affect membrane excitability, while diminished cytosolic (Ca2+)c through a reduction of direct Ca2+ influx via Cav2.2 (N-type) and Cav2.1 (P/Q-type) Ca2+ channels, rather than through indirect Ca2+induced Ca2+ release from ryanodine-sensitive intracellular stores. Furthermore, their effects were attenuated by GF109203X and Ro318220, two protein kinase C (PKC) inhibitors, suggesting suppression of PKC activity. Taken together, these results suggest that riboflavin, pyridoxine, and cyanocobalamin inhibit presynaptic vesicular glutamate release from rat cerebrocortical synaptosomes, through the depression Ca2+ influx via voltage- dependent Cav2.2 (N-type) and Cav2.1 (P/Q-type) Ca2+ channels, and PKC signaling cascade. CONCLUSION Therefore, these B vitamins may reduce the strength of glutamatergic synaptic transmission and is of considerable importance as potential targets for therapeutic agents in glutamate- induced excitation-related diseases.
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Affiliation(s)
- Shu-Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, China
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, China
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, China
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan, China
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Lin TK, Hung CF, Weng JR, Hsieh TY, Wang SJ. Kaempferol 3-Rhamnoside on Glutamate Release from Rat Cerebrocortical Nerve Terminals Involves P/Q-Type Ca 2+ Channel and Ca 2+/Calmodulin-Dependent Protein Kinase II-Dependent Pathway Suppression. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27041342. [PMID: 35209129 PMCID: PMC8879690 DOI: 10.3390/molecules27041342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/12/2022] [Accepted: 02/14/2022] [Indexed: 11/22/2022]
Abstract
Excess synaptic glutamate release has pathological consequences, and the inhibition of glutamate release is crucial for neuroprotection. Kaempferol 3-rhamnoside (KR) is a flavonoid isolated from Schima superba with neuroprotective properties, and its effecton the release of glutamate from rat cerebrocortical nerve terminals was investigated. KR produced a concentration-dependent inhibition of 4-aminopyridine (4-AP)-evoked glutamate release with half-maximal inhibitory concentration value of 17 µM. The inhibition of glutamate release by KR was completely abolished by the omission of external Ca2+ or the depletion of glutamate in synaptic vesicles, and it was unaffected by blocking carrier-mediated release. In addition, KR reduced the 4-AP-evoked increase in Ca2+ concentration, while it did not affect 4-AP-evoked membrane potential depolarization. The application of selective antagonists of voltage-dependent Ca2+ channels revealed that the KR-mediated inhibition of glutamate release involved the suppression of P/Q-type Ca2+ channel activity. Furthermore, the inhibition of release was abolished by the calmodulin antagonist, W7, and Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor, KN62, but not by the protein kinase A (PKA) inhibitor, H89, or the protein kinase C (PKC) inhibitor, GF109203X. We also found that KR reduced the 4-AP-induced increase in phosphorylation of CaMKII and its substrate synapsin I. Thus, the effect of KR on evoked glutamate release is likely linked to a decrease in P/Q-type Ca2+ channel activity, as well as to the consequent reduction in the CaMKII/synapsin I pathway.
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Affiliation(s)
- Tzu-Kang Lin
- Department of Neurosurgery, Fu Jen Catholic University Hospital, Fu Jen Catholic University, New Taipei City 24205, Taiwan;
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan;
| | - Chi-Feng Hung
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan;
| | - Jing-Ru Weng
- Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan;
| | - Ting-Yang Hsieh
- P.H.D. Program in Nutrition & Food Science, Fu Jen Catholic University, New Taipei City 24205, Taiwan;
| | - Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan;
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
- Correspondence: ; Tel.: +886-2-2905-3465; Fax: +886-2-2905-2096
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Inhibition of Glutamate Release from Rat Cortical Nerve Terminals by Dehydrocorydaline, an Alkaloid from Corydalis yanhusuo. Molecules 2022; 27:molecules27030960. [PMID: 35164225 PMCID: PMC8838318 DOI: 10.3390/molecules27030960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 02/01/2023] Open
Abstract
Excessive release of glutamate induces excitotoxicity and causes neuronal damage in several neurodegenerative diseases. Natural products have emerged as potential neuroprotective agents for preventing and treating neurological disorders. Dehydrocorydaline (DHC), an active alkaloid compound isolated from Corydalis yanhusuo, possesses neuroprotective capacity. The present study investigated the effect of DHC on glutamate release using a rat brain cortical synaptosome model. Our results indicate that DHC inhibited 4-aminopyridine (4-AP)-evoked glutamate release and elevated intrasynaptosomal calcium levels. The inhibitory effect of DHC on 4-AP-evoked glutamate release was prevented in the presence of the vesicular transporter inhibitor bafilomycin A1 and the N- and P/Q-type Ca2+ channel blocker ω-conotoxin MVIIC but not the intracellular inhibitor of Ca2+ release dantrolene or the mitochondrial Na+/Ca2+ exchanger inhibitor CGP37157. Moreover, the inhibitory effect of DHC on evoked glutamate release was prevented by the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) inhibitor PD98059. Western blotting data in synaptosomes also showed that DHC significantly decreased the level of ERK1/2 phosphorylation and synaptic vesicle-associated protein synapsin I, the main presynaptic target of ERK. Together, these results suggest that DHC inhibits presynaptic glutamate release from cerebrocortical synaptosomes by suppressing presynaptic voltage-dependent Ca2+ entry and the MAPK/ERK/synapsin I signaling pathway.
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Lu CW, Huang YC, Chiu KM, Lee MY, Lin TY, Wang SJ. Enmein Decreases Synaptic Glutamate Release and Protects against Kainic Acid-Induced Brain Injury in Rats. Int J Mol Sci 2021; 22:ijms222312966. [PMID: 34884781 PMCID: PMC8657722 DOI: 10.3390/ijms222312966] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 12/15/2022] Open
Abstract
This study investigated the effects of enmein, an active constituent of Isodon japonicus Hara, on glutamate release in rat cerebrocortical nerve terminals (synaptosomes) and evaluated its neuroprotective potential in a rat model of kainic acid (KA)-induced glutamate excitotoxicity. Enmein inhibited depolarization-induced glutamate release, FM1-43 release, and Ca2+ elevation in cortical nerve terminals but had no effect on the membrane potential. Removing extracellular Ca2+ and blocking vesicular glutamate transporters, N- and P/Q-type Ca2+ channels, or protein kinase C (PKC) prevented the inhibition of glutamate release by enmein. Enmein also decreased the phosphorylation of PKC, PKC-α, and myristoylated alanine-rich C kinase substrates in synaptosomes. In the KA rat model, intraperitoneal administration of enmein 30 min before intraperitoneal injection of KA reduced neuronal cell death, glial cell activation, and glutamate elevation in the hippocampus. Furthermore, in the hippocampi of KA rats, enmein increased the expression of synaptic markers (synaptophysin and postsynaptic density protein 95) and excitatory amino acid transporters 2 and 3, which are responsible for glutamate clearance, whereas enmein decreased the expression of glial fibrillary acidic protein (GFAP) and CD11b. These results indicate that enmein not only inhibited glutamate release from cortical synaptosomes by suppressing Ca2+ influx and PKC but also increased KA-induced hippocampal neuronal death by suppressing gliosis and decreasing glutamate levels by increasing glutamate uptake.
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Affiliation(s)
- Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan; (C.-W.L.); (Y.-C.H.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Yu-Chen Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan; (C.-W.L.); (Y.-C.H.)
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
- Department of Nursing, Asia Eastern University of Science and Technology, New Taipei City 22060, Taiwan
- Department of Photonics Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan; (C.-W.L.); (Y.-C.H.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
- Correspondence: (T.-Y.L.); (S.-J.W.)
| | - Su-Jane Wang
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Correspondence: (T.-Y.L.); (S.-J.W.)
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Chang A, Hung CF, Hsieh PW, Ko HH, Wang SJ. Eupafolin Suppresses P/Q-Type Ca 2+ Channels to Inhibit Ca 2+/ Calmodulin-Dependent Protein Kinase II and Glutamate Release at Rat Cerebrocortical Nerve Terminals. Biomol Ther (Seoul) 2021; 29:630-636. [PMID: 34475273 PMCID: PMC8551735 DOI: 10.4062/biomolther.2021.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/04/2021] [Accepted: 05/28/2021] [Indexed: 12/26/2022] Open
Abstract
Eupafolin, a constituent of the aerial parts of Phyla nodiflora, has neuroprotective property. Because reducing the synaptic release of glutamate is crucial to achieving pharmacotherapeutic effects of neuroprotectants, we investigated the effect of eupafolin on glutamate release in rat cerebrocortical synaptosomes and explored the possible mechanism. We discovered that eupafolin depressed 4-aminopyridine (4-AP)-induced glutamate release, and this phenomenon was prevented in the absence of extracellular calcium. Eupafolin inhibition of glutamate release from synaptic vesicles was confirmed through measurement of the release of the fluorescent dye FM 1-43. Eupafolin decreased 4-AP-induced [Ca2+]i elevation and had no effect on synaptosomal membrane potential. The inhibition of P/Q-type Ca2+ channels reduced the decrease in glutamate release that was caused by eupafolin, and docking data revealed that eupafolin interacted with P/Q-type Ca2+ channels. Additionally, the inhibition of calcium/calmodulin-dependent protein kinase II (CaMKII) prevented the effect of eupafolin on evoked glutamate release. Eupafolin also reduced the 4-AP-induced activation of CaMK II and the subsequent phosphorylation of synapsin I, which is the main presynaptic target of CaMKII. Therefore, eupafolin suppresses P/Q-type Ca2+ channels and thereby inhibits CaMKII/synapsin I pathways and the release of glutamate from rat cerebrocortical synaptosomes.
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Affiliation(s)
- Anna Chang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,Department of Neurology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 22060, Taiwan
| | - Chi-Feng Hung
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
| | - Pei-Wen Hsieh
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan.,Graduate Institute of Natural Products, School of Traditional Chinese Medicine, and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33303, Taiwan.,Department of Anesthesiology, Chang Gung Memorial Hospital, Linkou 33305, Taiwan
| | - Horng-Huey Ko
- Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.,Drug Development and Value Creation Center, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
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Chlorogenic Acid Decreases Glutamate Release from Rat Cortical Nerve Terminals by P/Q-Type Ca 2+ Channel Suppression: A Possible Neuroprotective Mechanism. Int J Mol Sci 2021; 22:ijms222111447. [PMID: 34768876 PMCID: PMC8583876 DOI: 10.3390/ijms222111447] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 12/28/2022] Open
Abstract
The glutamatergic neurotransmitter system has received substantial attention in research on the pathophysiology and treatment of neurological disorders. The study investigated the effect of the polyphenolic compound chlorogenic acid (CGA) on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). CGA inhibited 4-aminopyridine (4-AP)-induced glutamate release from synaptosomes. This inhibition was prevented in the absence of extracellular Ca2+ and was associated with the inhibition of 4-AP-induced elevation of Ca2+ but was not attributed to changes in synaptosomal membrane potential. In line with evidence observed through molecular docking, CGA did not inhibit glutamate release in the presence of P/Q-type Ca2+ channel inhibitors; therefore, CGA-induced inhibition of glutamate release may be mediated by P/Q-type Ca2+ channels. CGA-induced inhibition of glutamate release was also diminished by the calmodulin and Ca2+/calmodilin-dependent kinase II (CaMKII) inhibitors, and CGA reduced the phosphorylation of CaMKII and its substrate, synapsin I. Furthermore, pretreatment with intraperitoneal CGA injection attenuated the glutamate increment and neuronal damage in the rat cortex that were induced by kainic acid administration. These results indicate that CGA inhibits glutamate release from cortical synaptosomes by suppressing P/Q-type Ca2+ channels and CaMKII/synapsin I pathways, thereby preventing excitotoxic damage to cortical neurons.
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Lin TY, Lu CW, Hsieh PW, Chiu KM, Lee MY, Wang SJ. Natural Product Isoliquiritigenin Activates GABA B Receptors to Decrease Voltage-Gate Ca 2+ Channels and Glutamate Release in Rat Cerebrocortical Nerve Terminals. Biomolecules 2021; 11:biom11101537. [PMID: 34680170 PMCID: PMC8534184 DOI: 10.3390/biom11101537] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 12/26/2022] Open
Abstract
Reduction in glutamate release is a key mechanism for neuroprotection and we investigated the effect of isoliquiritigenin (ISL), an active ingredient of Glycyrrhiza with neuroprotective activities, on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). ISL produced a concentration-dependent inhibition of glutamate release and reduced the intraterminal [Ca2+] increase. The inhibition of glutamate release by ISL was prevented after removing extracellular Ca2+ or blocking P/Q-type Ca2+ channels. This inhibition was mediated through the γ-aminobutyric acid type B (GABAB) receptors because ISL was unable to inhibit glutamate release in the presence of baclofen (an GABAB agonist) or CGP3548 (an GABAB antagonist) and docking data revealed that ISL interacted with GABAB receptors. Furthermore, the ISL inhibition of glutamate release was abolished through the inhibition of Gi/o-mediated responses or Gβγ subunits, but not by 8-bromoadenosine 3′,5′-cyclic monophosphate or adenylate cyclase inhibition. The ISL inhibition of glutamate release was also abolished through the inhibition of protein kinase C (PKC), and ISL decreased the phosphorylation of PKC. Thus, we inferred that ISL, through GABAB receptor activation and Gβγ-coupled inhibition of P/Q-type Ca2+ channels, suppressed the PKC phosphorylation to cause a decrease in evoked glutamate release at rat cerebrocortical nerve terminals.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; (T.-Y.L.); (C.-W.L.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; (T.-Y.L.); (C.-W.L.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Pei-Wen Hsieh
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- Graduate Institute of Natural Products, School of Traditional Chinese Medicine, and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33303, Taiwan
- Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
- Department of Nursing, Asia Eastern University of Science and Technology, New Taipei City 22060, Taiwan
- Department of Photonics Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
| | - Su-Jane Wang
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Correspondence: ; Tel.: +88-62-2905-3465; Fax: +88-62-2905-2096
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12
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Wang CC, Hsieh PW, Kuo JR, Wang SJ. Rosmarinic Acid, a Bioactive Phenolic Compound, Inhibits Glutamate Release from Rat Cerebrocortical Synaptosomes through GABA A Receptor Activation. Biomolecules 2021; 11:1029. [PMID: 34356653 PMCID: PMC8301814 DOI: 10.3390/biom11071029] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 12/15/2022] Open
Abstract
Rosmarinic acid, a major component of rosemary, is a polyphenolic compound with potential neuroprotective effects. Asreducing the synaptic release of glutamate is crucial to achieving neuroprotectant's pharmacotherapeutic effects, the effect of rosmarinic acid on glutamate release was investigated in rat cerebrocortical nerve terminals (synaptosomes). Rosmarinic acid depressed the 4-aminopyridine (4-AP)-induced glutamate release in a concentration-dependent manner. The removal of extracellular calcium and the blockade of vesicular transporters prevented the inhibition of glutamate release by rosmarinic acid. Rosmarinic acid reduced 4-AP-induced intrasynaptosomal Ca2+ elevation. The inhibition of N-, P/Q-type Ca2+ channels and the calcium/calmodulin-dependent kinase II (CaMKII) prevented rosmarinic acid from having effects on glutamate release. Rosmarinic acid also reduced the 4-AP-induced activation of CaMKII and the subsequent phosphorylation of synapsin I, the main presynaptic target of CaMKII. In addition, immunocytochemistry confirmed the presence of GABAA receptors. GABAA receptor agonist and antagonist blocked the inhibitory effect of rosmarinic acid on 4-AP-evoked glutamate release. Docking data also revealed that rosmarinic acid formed a hydrogen bond with the amino acid residues of GABAA receptor. These results suggested that rosmarinic acid activates GABAA receptors in cerebrocortical synaptosomes to decrease Ca2+ influx and CaMKII/synapsin I pathway to inhibit the evoked glutamate release.
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Affiliation(s)
- Che-Chuan Wang
- Chi Mei Medical Center, Department of Neurosurgery, Tainan 71004, Taiwan; (C.-C.W.); (J.-R.K.)
- Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
| | - Pei-Wen Hsieh
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- Graduate Institute of Natural Products, School of Traditional Chinese Medicine, and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33303, Taiwan
- Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 33303, Taiwan
| | - Jinn-Rung Kuo
- Chi Mei Medical Center, Department of Neurosurgery, Tainan 71004, Taiwan; (C.-C.W.); (J.-R.K.)
- Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
| | - Su-Jane Wang
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
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13
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Chang Y, Hung CF, Ko HH, Wang SJ. Albanin A, Derived from the Root Bark of Morus alba L., Depresses Glutamate Release in the Rat Cerebrocortical Nerve Terminals via Ca 2+/Calmodulin/Adenylate Cyclase 1 Suppression. J Med Food 2021; 24:209-217. [PMID: 33739887 DOI: 10.1089/jmf.2020.4817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Decreasing synaptic release of glutamate may counteract glutamate excitotoxicity in many neurological diseases. In this study, we investigated the effect of albanin A, a constituent in the root bark of Morus alba L., on the release of glutamate in rat cerebral cortex nerve endings (synaptosomes). We found that albanin A at 5-30μM suppressed 4-aminopyridine (4-AP)-induced release of glutamate. This phenomenon was abolished by extracellular calcium removal or by vesicular transporter inhibition, and was associated with a decrease in intrasynaptosomal Ca2+ levels. However, albanin A had no effect on the synaptosomal membrane potential. The inhibition of N- and P/Q-type Ca2+ channels, calmodulin, adenylate cyclase (AC), and protein kinase A, abolished the effect of albanin A on the glutamate release evoked by 4-AP. Moreover, the albanin A-mediated inhibition of glutamate release was prevented by the Ca2+/calmodulin-stimulated AC1 inhibitor. Western blot showed that AC1, but not AC8, was presented in the synaptosomes, and albanin A reduced 4-AP-induced increases in synaptosomal cyclic adenosine monophosphate content. In addition, albanin A pretreatment substantially attenuated neuronal damage in a rat model of kainic acid-induced glutamate excitotoxicity. Our data reveal that albanin A suppresses glutamate release by decreasing Ca2+/calmodulin/AC1 activation in synaptosomes and exerts neuroprotective effect in vivo.
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Affiliation(s)
- Yi Chang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Chi Feng Hung
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Horng Huey Ko
- Department of Fragrance and Cosmetic Science, College of Pharmacy; Kaohsiung, Taiwan.,Drug Development and Value Creation Center; Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan
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14
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Chiu KM, Lin TY, Lee MY, Lu CW, Wang MJ, Wang SJ. Typhaneoside Suppresses Glutamate Release Through Inhibition of Voltage-Dependent Calcium Entry in Rat Cerebrocortical Nerve Terminals. Chem Res Toxicol 2021; 34:1286-1295. [PMID: 33621091 DOI: 10.1021/acs.chemrestox.0c00446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the brain and is involved in many brain functions. In this study, we investigated whether typhaneoside, a flavonoid from Typhae angustifolia pollen, affects endogenous glutamate release from rat cortical synaptosomes. Using a one-line enzyme-coupled fluorometric assay, glutamate release stimulated by the K+ channel blocker 4-aminopyridine was monitored to explore the possible underlying mechanisms. The vesicular transporter inhibitor bafilomycin A1 and chelation of extracellular Ca2+ ions with EGTA suppressed the effect of typhaneoside on the induced glutamate release. Nevertheless, the typhaneoside activity has not been affected by the glutamate transporter inhibitor dl-threo-beta-benzyloxyaspartate. The synaptosomal plasma membrane potential was assayed using a membrane potential-sensitive dye DiSC3(5), and cytosolic Ca2+ concentrations ([Ca2+]C) was monitored by a Ca2+ indicator Fura-2. Results showed that typhaneoside did not alter the synaptosomal membrane potential but lowered 4-aminopyridine-induced increases in [Ca2+]C. Furthermore, the Cav2.2 (N-type) channel blocker ω-conotoxin GVIA blocked Ca2+ entry and inhibited the effect of typhaneoside on 4-aminopyridine-induced glutamate release. However, the inhibitor of intracellular Ca2+ release dantrolene and the mitochondrial Na+/Ca2+ exchanger blocker 7-chloro-5-(2-chloropheny)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one have no effect on the suppression of glutamate release mediated by typhaneoside. Moreover, inhibition of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) prevented the inhibitory effect of typhaneoside on induced glutamate release. Typhaneoside reduced 4-aminopyridine-induced phosphorylation of ERK1/2 and the major presynaptic ERK target synapsin I, which is a synaptic vesicle-associated protein. In conclusion, these findings suggest a role for typhaneoside in modulating glutamate release by suppressing voltage-dependent Ca2+ channel mediated presynaptic Ca2+ influx and the MAPK/ERK/synapsin I signaling cascade.
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Affiliation(s)
- Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan.,Department of Nursing, Oriental Institute of Technology, New Taipei City 22060, Taiwan.,Department of Photonics Engineering, Yuan Ze University, Taoyuan City 32003, Taiwan
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan.,Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 32003, Taiwan
| | - Ming-Yi Lee
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan.,Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 32003, Taiwan
| | - Ming-Jiuh Wang
- Department of Anesthesiology, National Taiwan University Hospital, Taipei City 100225, Taiwan
| | - Su-Jane Wang
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City 33303, Taiwan.,School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
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15
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Silymarin Inhibits Glutamate Release and Prevents against Kainic Acid-Induced Excitotoxic Injury in Rats. Biomedicines 2020; 8:biomedicines8110486. [PMID: 33182349 PMCID: PMC7695262 DOI: 10.3390/biomedicines8110486] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/06/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022] Open
Abstract
Silymarin, a polyphenoic flavonoid derived from the seeds of milk thistle (Silybum marianum), exhibits neuroprotective effects. In this study, we used a model of rat cerebrocortical synaptosomes to investigate whether silymarin affects the release of glutamate, an essential neurotransmitter involved in excitotoxicity. Its possible neuroprotective effect on a rat model of kainic acid (KA)-induced excitotoxicity was also investigated. In rat cortical synaptosomes, silymarin reduced glutamate release and calcium elevation evoked by the K+ channel blocker 4-aminopyridine but did not affect glutamate release caused by the Na+ channel activator veratridine or the synaptosomal membrane potential. Decreased glutamate release by silymarin was prevented by removal of extracellular calcium and blocking of N- and P/Q-type Ca2+ channel or extracellular signal-regulated kinase 1/2 (ERK1/2) but not by blocking of intracellular Ca2+ release. Immunoblotting assay results revealed that silymarin reduced 4-aminopyridine-induced phosphorylation of ERK1/2. Moreover, systemic treatment of rats with silymarin (50 or 100 mg/kg) 30 min before systemic KA (15 mg/kg) administration attenuated KA-induced seizures, glutamate concentration elevation, neuronal damage, glial activation, and heat shock protein 70 expression as well as upregulated KA-induced decrease in Akt phosphorylation in the rat hippocampus. Taken together, the present study demonstrated that silymarin depressed synaptosomal glutamate release by suppressing voltage-dependent Ca2+ entry and ERK1/2 activity and effectively prevented KA-induced in vivo excitotoxicity.
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16
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[1-(4-chloro-3-nitrobenzenesulfonyl)-1H-indol-3-yl]-methanol, an indole-3-carbinol derivative, inhibits glutamate release in rat cerebrocortical nerve terminals by suppressing the P/Q-type Ca 2+ channels and Ca 2+/calmodulin/protein kinase A pathway. Neurochem Int 2020; 140:104845. [PMID: 32911011 DOI: 10.1016/j.neuint.2020.104845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/31/2020] [Accepted: 09/04/2020] [Indexed: 11/23/2022]
Abstract
Indole-3-carbinol (I3C), found in cruciferous vegetables, has been proposed to exhibit neuroprotective effects. This study aimed to investigate the effect of the I3C derivative [1(4-chloro-3-nitrobenzenesulfonyl)-1H-indol-3-yl]-methanol (CIM), which has superior pharmacokinetic properties to I3C, on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). We observed that CIM dose-dependently inhibited glutamate release evoked by the potassium channel blocker 4-aminopyridine (4-AP). CIM-mediated inhibition of glutamate release was attributed to reduced exocytosis, as it correlated with the removal of extracellular calcium and blocking of the vesicular glutamate transporter but not the glutamate transporter. In addition, CIM decreased 4-AP-evoked intrasynaptosomal Ca2+ elevation; however, it did not alter the synaptosomal membrane potential. The inhibition of P/Q-typeCa2+ channels abolished the effect of CIM on 4-AP-evoked glutamate release, and the effect was not prevented by intracellular Ca2+ release inhibitors. Moreover, the molecular docking study showed that CIM exhibited the highest binding affinity with the P/Q-type Ca2+channels. Finally, the CIM-mediated inhibition of glutamate release was sensitive to calmodulin, adenylate cyclase (AC), and protein kinase A (PKA) inhibitors. Based on these results, we propose that CIM, through the direct suppression of P/Q-type Ca2+ channels, decreases Ca2+ influx and the activation of Ca2+/calmodulin/AC/PKA signaling, thereby inhibiting glutamate release. This finding is crucial for understanding the role of CIM in the central nervous system and for exploiting its potential in therapeutic interventions.
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17
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Ultrastructural and molecular features of excitatory and glutamatergic synapses. The auditory nerve synapses. VITAMINS AND HORMONES 2020; 114:23-51. [PMID: 32723545 DOI: 10.1016/bs.vh.2020.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glutamatergic synapses mediate fast synaptic transmission in the central nervous system. New developments highlight the importance of the synapse structural and molecular remodeling during development, aging and in neurological disorders. This chapter summarizes key structural and molecular aspects of the presynaptic and postsynaptic components of glutamatergic synapses in the brain. In addition, this chapter describes how the structure of the postsynaptic density and ionotropic glutamate content contribute to the function of auditory nerve synapses in the lower auditory brainstem.
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18
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Lu CW, Lin TY, Wang SJ, Huang SK. Asiatic acid, an active substance of Centella asiatica, presynaptically depresses glutamate release in the rat hippocampus. Eur J Pharmacol 2019; 865:172781. [PMID: 31706856 DOI: 10.1016/j.ejphar.2019.172781] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/25/2019] [Accepted: 11/04/2019] [Indexed: 12/27/2022]
Abstract
Inhibiting glutamate release can reduce neuronal excitability and is recognized as a key mechanism of anti-epileptic drugs. In this study, by using isolated nerve terminal (synaptosome) and slice preparations, we investigated the effect of asiatic acid, a triterpene isolated from Centella asiatica with antiepileptic activity, on glutamate release in the hippocampus of rats. In hippocampal synaptosomes, application of asiatic acid resulted in a concentration-dependent inhibition of 4-aminopyridine-evoked glutamate release. This inhibitory action was dependent on extracellular calcium, blocked by inhibiting the vesicular transporter, but was unaffected by inhibiting the glutamate transporter. In addition, asiatic acid decreased the 4-aminopyridine-induced increase in the intraterminal calcium and failed to alter the synaptosomal potential. Furthermore, the asiatic acid-mediated release inhibition was significantly suppressed by the N- and P/Q-type calcium channel inhibitor ω-conotoxin MVIIC or protein kinase C inhibitor GF109203X. Western blotting data in synaptosomes also revealed that asiatic acid reduced 4-aminopyridine-induced phosphorylation of protein kinase C. In hippocampal slices, asiatic acid decreased the frequencies of spontaneous excitatory postsynaptic currents without changing their amplitudes and glutamate-activated currents in CA3 pyramidal neurons. We also observed that asiatic acid significantly suppressed 4-aminopyridine-induced burst firing. These data suggest that, in rat hippocampal nerve terminals, asiatic acid attenuates the calcium influx via N- and P/Q-type calcium channels, subsequently suppressing protein kinase C activity and decreasing glutamate release.
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Affiliation(s)
- Cheng Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, 22060; Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan, 320
| | - Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, 22060; Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan, 320
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan, 24205; Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan.
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan, 22060
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19
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Su IC, Hung CF, Lin CN, Huang SK, Wang SJ. Cycloheterophyllin Inhibits the Release of Glutamate from Nerve Terminals of the Rat Hippocampus. Chem Res Toxicol 2019; 32:1591-1598. [PMID: 31264847 DOI: 10.1021/acs.chemrestox.9b00121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The effect of cycloheterophyllin, a prenylflavone isolated from Artocarpus heteophyllus, on glutamate release was studied in the rat hippocampus using synaptosome and slice preparations. In rat hippocampal synaptosomes, cycloheterophyllin inhibited 4-aminopyridine (4-AP)-evoked glutamate release and elevation of intrasynaptosomal calcium levels. The inhibitory effect of cycloheterophyllin on 4-AP-evoked glutamate release was prevented in the presence of the vesicular transporter inhibitor, the N- and P/Q-type calcium channel blocker, and the protein kinase C (PKC) inhibitor but was insensitive to the intracellular Ca2+ release inhibitors, the protein kinase A inhibitor, and the mitogen-activated/extracellular signal-regulated kinase inhibitor. Western blotting data in synaptosomes also showed that cycloheterophyllin significantly decreased the level of phosphorylation of PKC. In addition, cycloheterophyllin decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) without influencing the amplitude of sEPSCs and glutamate-activated currents in hippocampal slices, supporting a presynaptic action. Together, these results suggest that cycloheterophyllin inhibits presynaptic glutamate release by suppressing N- and P/Q-type calcium channel and PKC activity in the rat hippocampus.
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Affiliation(s)
- I Chang Su
- School of Medicine , Fu Jen Catholic University , No. 510, Chung-Cheng Road , Hsin-Chuang, New Taipei City 24205 , Taiwan.,Division of Neurosurgery, Department of Surgery , Cathay General Hospital , Taipei City , Taiwan 106
| | - Chi Feng Hung
- School of Medicine , Fu Jen Catholic University , No. 510, Chung-Cheng Road , Hsin-Chuang, New Taipei City 24205 , Taiwan
| | - Chun Nan Lin
- College of Pharmacy , Kaoshiung Medical University , Kaohsiung , Taiwan 807
| | - Shu Kuei Huang
- Department of Anesthesiology , Far-Eastern Memorial Hospital , Pan-Chiao District , New Taipei City 22060 , Taiwan
| | - Su Jane Wang
- School of Medicine , Fu Jen Catholic University , No. 510, Chung-Cheng Road , Hsin-Chuang, New Taipei City 24205 , Taiwan.,Research Center for Chinese Herbal Medicine, College of Human Ecology , Chang Gung University of Science and Technology , Taoyuan City , Taiwan 333
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20
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Chang Y, Hsieh HL, Huang SK, Wang SJ. Neurosteroid allopregnanolone inhibits glutamate release from rat cerebrocortical nerve terminals. Synapse 2018; 73:e22076. [PMID: 30362283 DOI: 10.1002/syn.22076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/17/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022]
Abstract
Allopregnanolone, an active metabolite of progesterone, has been reported to exhibit neuroprotective activity in several preclinical models. Considering that the excitotoxicity caused by excessive glutamate is implicated in many brain disorders, the effect of allopregnanolone on glutamate release in rat cerebrocortical nerve terminals and possible underlying mechanism were investigated. We observed that allopregnanolone inhibited 4-aminopyridine (4-AP)-evoked glutamate release, and this inhibition was prevented by chelating the extracellular Ca2+ ions and the vesicular transporter inhibitor. Allopregnanolone reduced the elevation of 4-AP-evoked intrasynaptosomal Ca2+ levels, but did not affect the synaptosomal membrane potential. In the presence of N-, P/Q-, and R-type channel blockers, allopregnanolone-mediated inhibition of 4-AP-evoked glutamate release was markedly reduced; however, the intracellular Ca2+ -release inhibitors did not affect the allopregnanolone effect. Furthermore, allopregnanolone-mediated inhibition of 4-AP-evoked glutamate release was completely abolished in the synaptosomes pretreated with inhibitors of Ca2+ /calmodulin, adenylate cyclase, and protein kinase A (PKA), namely calmidazolium, MDL12330A, and H89, respectively. Additionally, the allopregnanolone effect on evoked glutamate release was antagonized by the GABAA receptor antagonist SR95531. Our data are the first to suggest that allopregnanolone reduce the Ca2+ influx through N-, P/Q-, and R-type Ca2+ channels, through the activation of GABAA receptors present on cerebrocortical nerve terminals, subsequently suppressing the Ca2+ -calmodulin/PKA cascade and decreasing 4-AP-evoked glutamate release.
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Affiliation(s)
- Yi Chang
- Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.,School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Hsi Lung Hsieh
- Department of Nursing, Division of Basic Medical Sciences, Research Center for Chinese Herbal Medicine, and Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan
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21
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Wang CC, Kuo JR, Huang SK, Wang SJ. Metabotropic glutamate 7 receptor agonist AMN082 inhibits glutamate release in rat cerebral cortex nerve terminal. Eur J Pharmacol 2018; 823:11-18. [PMID: 29378190 DOI: 10.1016/j.ejphar.2018.01.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/18/2018] [Accepted: 01/23/2018] [Indexed: 12/21/2022]
Abstract
AMN082 is a selective metabotropic glutamate mGlu7 receptor agonist reported to exhibit antidepressant activity. Considering that excessive glutamate release is involved in the pathogenesis of depression, the effect of N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082) on glutamate release in rat cerebrocortical nerve terminals and the possible underlying mechanism were investigated. In this study, we observed here that AMN082 inhibited 4-aminopyridine-evoked glutamate release and this phenomenon was blocked by the metabotropic glutamate mGlu7 receptor antagonist MMPIP. Moreover, western blot analysis and immunocytochemistry confirmed the presence of presynaptic metabotropic glutamate mGlu7 receptor proteins. The effect of AMN082 on the 4-aminopyridine-evoked release of glutamate was prevented by chelating the extracellular Ca2+ ions and the vesicular transporter inhibitor; however, the effect of AMN082 was unaffected by the glutamate transporter inhibitor. AMN082 reduced the elevation of 4-aminopyridine-evoked intrasynaptosomal Ca2+ concentration, but did not alter the synaptosomal membrane potential. In the presence of the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker, the adenylate cyclase inhibitor, and the protein kinase A inhibitor, the action of AMN082 on the 4-aminopyridine-evoked glutamate release was markedly reduced. These results suggest that the activation of the metabotropic glutamate mGlu7 receptors by AMN082 reduces adenylate cyclase/protein kinase A activation, which subsequently reduces the entry of Ca2+ through voltage-dependent Ca2+ channels and decreases evoked glutamate release. Additionally, fluoxetine, a clinically effective antidepressant, completely occluded the inhibitory effect of AMN082 on glutamate release, thus indicating the existence of a common intracellular mechanism for these two compounds to inhibit glutamate release from the cerebrocortical nerve terminals.
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Affiliation(s)
- Che Chuan Wang
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan, ROC; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan, ROC
| | - Jinn Rung Kuo
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan, ROC; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan, ROC
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan, ROC
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, No. 510, Chung-Cheng Rd., Hsin-Chuang, New Taipei 24205, Taiwan, ROC; Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan, ROC.
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Lu CW, Hung CF, Jean WH, Lin TY, Huang SK, Wang SJ. Lycopene depresses glutamate release through inhibition of voltage-dependent Ca 2+ entry and protein kinase C in rat cerebrocortical nerve terminals. Can J Physiol Pharmacol 2017; 96:479-484. [PMID: 29216442 DOI: 10.1139/cjpp-2017-0520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lycopene is a natural dietary carotenoid that was reported to exhibit a neuroprotective profile. Considering that excitotoxicity and cell death induced by glutamate are involved in many brain disorders, the effect of lycopene on glutamate release in rat cerebrocortical nerve terminals and the possible mechanism involved in such effect was investigated. We observed here that lycopene inhibited 4-aminopyridine (4-AP)-evoked glutamate release and intrasynaptosomal Ca2+ concentration elevation. The inhibitory effect of lycopene on 4-AP-evoked glutamate release was markedly reduced in the presence of the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, but was insensitive to the intracellular Ca2+-release inhibitors dantrolene and CGP37157. Furthermore, in the presence of the protein kinase C inhibitors GF109203X and Go6976, the action of lycopene on evoked glutamate release was prevented. These results are the first to suggest that lycopene inhibits glutamate release from rat cortical synaptosomes by suppressing presynaptic Ca2+ entry and protein kinase C activity.
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Affiliation(s)
- Cheng-Wei Lu
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan.,b Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 320, Taiwan
| | - Chi-Feng Hung
- c School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,d Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Wei-Horng Jean
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan
| | - Tzu-Yu Lin
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan.,b Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 320, Taiwan
| | - Shu-Kuei Huang
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan
| | - Su-Jane Wang
- c School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,e Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City 33303, Taiwan
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Inhibition of glutamate release by cilnidipine in rat cerebrocortical nerve terminals (synaptosomes). Neuroreport 2017; 28:527-532. [DOI: 10.1097/wnr.0000000000000795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Chang CY, Hung CF, Huang SK, Kuo JR, Wang SJ. Amiodarone reduces depolarization-evoked glutamate release from hippocampual synaptosomes. J Pharmacol Sci 2017; 133:168-175. [PMID: 28330759 DOI: 10.1016/j.jphs.2017.02.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/26/2017] [Accepted: 02/22/2017] [Indexed: 12/31/2022] Open
Abstract
Decreased brain glutamate level has emerged as a new therapeutic approach for epilepsy. This study investigated the effect and mechanism of amiodarone, an anti-arrhythmic drug with antiepileptic activity, on glutamate release in the rat hippocampus. In a synaptosomal preparation, amiodarone reduced 4-aminopyridine-evoked Ca2+-dependent glutamate release and cytosolic Ca2+ concentration elevation. Amiodarone did not affect the 4-aminopyridine-evoked depolarization of the synaptosomal membrane potential or the Na+ channel activator veratridine-evoked glutamate release, indicating that the amiodarone-mediated inhibition of glutamate release is not caused by a decrease in synaptosomal excitability. The inhibitory effect of amiodarone on 4-aminopyridine-evoked glutamate release was markedly decreased in synaptosomes pretreated with the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, the calmodulin antagonists W7 and calmidazolium, or the protein kinase A inhibitors H89 and KT5720. However, the intracellular Ca2+-release inhibitors dantrolene and CGP37157 had no effect on the amiodarone-mediated inhibition of glutamate release. Furthermore, amiodarone reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude in hippocampal slices. Our data suggest that amiodarone reduces Ca2+ influx through N- and P/Q-type Ca2+ channels, subsequently reducing the Ca2+-calmodulin/protein kinase A cascade to inhibit the evoked glutamate release from rat hippocampal nerve terminals.
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Affiliation(s)
- Chia Yu Chang
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan
| | - Chi Feng Hung
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan; Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Jinn Rung Kuo
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan; Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan.
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Lu CW, Lin TY, Chang CY, Huang SK, Wang SJ. Ciproxifan, a histamine H3 receptor antagonist and inverse agonist, presynaptically inhibits glutamate release in rat hippocampus. Toxicol Appl Pharmacol 2017; 319:12-21. [DOI: 10.1016/j.taap.2017.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/18/2017] [Accepted: 01/25/2017] [Indexed: 01/22/2023]
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Lu CW, Lin TY, Hsie TY, Huang SK, Wang SJ. Capsaicin presynaptically inhibits glutamate release through the activation of TRPV1 and calcineurin in the hippocampus of rats. Food Funct 2017; 8:1859-1868. [DOI: 10.1039/c7fo00011a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Capsaicin is the major ingredient in hot peppers of the plantCapsicum genuswith neuroprotective effects in several preclinical models; its effect on glutamate release has been investigated in the rat hippocampus using isolated nerve terminals (synaptosomes) and brain slices.
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Affiliation(s)
- Cheng Wei Lu
- Department of Anesthesiology
- Far-Eastern Memorial Hospital
- New Taipei
- Taiwan
- Department of Mechanical Engineering
| | - Tzu Yu Lin
- Department of Anesthesiology
- Far-Eastern Memorial Hospital
- New Taipei
- Taiwan
- Department of Mechanical Engineering
| | - Ting Yang Hsie
- P.H.D. Program in Nutrition & Food Science
- Fu Jen Catholic University
- New Taipei
- Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology
- Far-Eastern Memorial Hospital
- New Taipei
- Taiwan
| | - Su Jane Wang
- School of Medicine
- Fu Jen Catholic University
- New Taipei
- Taiwan
- Research Center for Chinese Herbal Medicine
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Chang Y, Lin TY, Lu CW, Huang SK, Wang YC, Wang SJ. Xanthohumol-induced presynaptic reduction of glutamate release in the rat hippocampus. Food Funct 2016; 7:212-26. [PMID: 26667007 DOI: 10.1039/c5fo01005e] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
This study examined whether xanthohumol, a hop-derived prenylated flavonoid present in beer, affects glutamate release in the rat hippocampus. In the rat hippocampal nerve terminals (synaptosomes), xanthohumol inhibited the release of 4-aminopyridine (4-AP)-evoked glutamate and the elevation of cytosolic Ca(2+) concentration, whereas it had no effect on 4-AP-mediated depolarization. The inhibitory effect of xanthohumol on the evoked glutamate release was prevented by removing extracellular Ca(2+), using the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-CgTX MVIIC, the calmodulin antagonists W7 and calmidazolium, and the protein kinase A inhibitor H89; however, no such effect was observed when the G-protein inhibitor N-ethylmaleimide was used. In addition, immunocytochemical data demonstrated that GABAA receptors are present in the hippocampal synaptosomes and that the xanthohumol effect on evoked glutamate release was antagonized by the GABAA receptor antagonist SR95531. Furthermore, in slice preparations, xanthohumol reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude. We conclude that xanthohumol acts at GABAA receptors present in the hippocampal nerve terminals to decrease the Ca(2+) influx through N- and P/Q-type Ca(2+) channels, which subsequently suppresses the Ca(2+)-calmodulin/PKA cascade to decrease the evoked glutamate release.
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Affiliation(s)
- Yi Chang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan 24205 and Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan111
| | - Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan 22060 and Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan
| | - Cheng Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan 22060 and Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City, Taiwan 22060
| | - Ying Chou Wang
- Department of Clinical Psychology, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan 24205
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan 24205 and Graduate Institute of Basic Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City, Taiwan 24205.
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Wang HY, Lu CW, Lin TY, Kuo JR, Wang SJ. WAY208466 inhibits glutamate release at hippocampal nerve terminals. Eur J Pharmacol 2016; 781:117-27. [DOI: 10.1016/j.ejphar.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 03/09/2016] [Accepted: 04/07/2016] [Indexed: 01/09/2023]
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Hikima T, Garcia-Munoz M, Arbuthnott GW. Presynaptic D1 heteroreceptors and mGlu autoreceptors act at individual cortical release sites to modify glutamate release. Brain Res 2016; 1639:74-87. [PMID: 26944299 DOI: 10.1016/j.brainres.2016.02.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 02/11/2016] [Accepted: 02/23/2016] [Indexed: 01/04/2023]
Abstract
The aim of this work was to study release of glutamic acid (GLU) from one-axon terminal or bouton at-a-time using cortical neurons grown in vitro to study the effect of presynaptic auto- and heteroreceptor stimulation. Neurons were infected with release reporters SypHx2 or iGluSnFR at 7 or 3 days-in-vitro (DIV) respectively. At 13-15 DIV single synaptic boutons were identified from images obtained from a confocal scanning microscope before and after field electrical stimulation. We further stimulated release by raising intracellular levels of cAMP with forskolin (10µM). Forskolin-mediated effects were dependent on protein kinase A (PKA) and did not result from an increase in endocytosis, but rather from an increase in the size of the vesicle readily releasable pool. Once iGluSnFR was confirmed as more sensitive than SypHx2, it was used to study the participation of presynaptic auto- and heteroreceptors on GLU release. Although most receptor agonizts (carbamylcholine, nicotine, dopamine D2, BDNF) did not affect electrically stimulated GLU release, a significant increase was observed in the presence of metabotropic D1/D5 heteroreceptor agonist (SKF38393 10µM) that was reversed by PKA inhibitors. Interestingly, stimulation of group II metabotropic mGLU2/3 autoreceptors (LY379268 50nM) induced a decrease in GLU release that was reversed by the specific mGLU2/3 receptor antagonist (LY341495 1µM) and also by PKA inhibitors (KT5720 200nM and PKI14-22 400nM). These changes in release probability at individual release sites suggest another level of control of the distribution of transmitter substances in cortical tissue.
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Affiliation(s)
- Takuya Hikima
- Brain Mechanism for Behaviour Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
| | - Marianela Garcia-Munoz
- Brain Mechanism for Behaviour Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
| | - Gordon William Arbuthnott
- Brain Mechanism for Behaviour Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
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Hesperidin inhibits glutamate release and exerts neuroprotection against excitotoxicity induced by kainic acid in the hippocampus of rats. Neurotoxicology 2015; 50:157-69. [PMID: 26342684 DOI: 10.1016/j.neuro.2015.08.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/28/2015] [Accepted: 08/31/2015] [Indexed: 02/05/2023]
Abstract
The citrus flavonoid hesperidin exerts neuroprotective effects and could cross the blood-brain barrier. Given the involvement of glutamate neurotoxicity in the pathogenesis of neurodegenerative disorders, this study was conducted to evaluate the potential role of hesperidin in glutamate release and glutamate neurotoxicity in the hippocampus of rats. In rat hippocampal nerve terminals (synaptosomes), hesperidin inhibited the release of glutamate and elevation of cytosolic free Ca(2+) concentration evoked by 4-aminopyridine (4-AP), but did not alter 4-AP-mediated depolarization. The inhibitory effect of hesperidin on evoked glutamate release was prevented by chelating the extracellular Ca(2+) ions and blocking the activity of Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels or protein kinase C. In hippocampal slice preparations, whole-cell patch clamp experiments showed that hesperidin reduced the frequency of spontaneous excitatory postsynaptic currents without affecting their amplitude, indicating the involvement of a presynaptic mechanism. In addition, intraperitoneal (i.p.) injection of kainic acid (KA, 15 mg/kg) elevated the extracellular glutamate levels and caused considerable neuronal loss in the hippocampal CA3 area. These KA-induced alterations were attenuated by pretreatment with hesperidin (10 or 50 mg/kg, i.p.) before administering the KA. These results demonstrate that hesperidin inhibits evoked glutamate release in vitro and attenuates in vivo KA-induced neuronal death in the hippocampus. Our findings indicate that hesperidin may be a promising candidate for preventing or treating glutamate excitotoxicity related brain disorders such as neurodegenerative diseases.
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31
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Changes in VGLUT2 expression and function in pain-related supraspinal regions correlate with the pathogenesis of neuropathic pain in a mouse spared nerve injury model. Brain Res 2015; 1624:515-524. [PMID: 26300222 DOI: 10.1016/j.brainres.2015.08.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 08/11/2015] [Accepted: 08/13/2015] [Indexed: 01/05/2023]
Abstract
Vesicular glutamate transporters (VGLUTs) control the storage and release of glutamate, which plays a critical role in pain processing. The VGLUT2 isoform has been found to be densely distributed in the nociceptive pathways in supraspinal regions, and VGLUT2-deficient mice exhibit an attenuation of neuropathic pain; these results suggest a possible involvement of VGLUT2 in neuropathic pain. To further examine this, we investigated the temporal changes in VGLUT2 expression in different brain regions as well as changes in glutamate release from thalamic synaptosomes in spared nerve injury (SNI) mice. We also investigated the effects of a VGLUT inhibitor, Chicago Sky Blue 6B (CSB6B), on pain behavior, c-Fos expression, and depolarization-evoked glutamate release in SNI mice. Our results showed a significant elevation of VGLUT2 expression up to postoperative day 1 in the thalamus, periaqueductal gray, and amygdala, followed by a return to control levels. Consistent with the changes in VGLUT2 expression, SNI enhanced depolarization-induced glutamate release from thalamic synaptosomes, while CSB6B treatment produced a concentration-dependent inhibition of glutamate release. Moreover, intracerebroventricular administration of CSB6B, at a dose that did not affect motor function, attenuated mechanical allodynia and c-Fos up-regulation in pain-related brain areas during the early stages of neuropathic pain development. These results demonstrate that changes in the expression of supraspinal VGLUT2 may be a new mechanism relevant to the induction of neuropathic pain after nerve injury that acts through an aggravation of glutamate imbalance.
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Chang CY, Lin TY, Lu CW, Wang CC, Wang YC, Chou SSP, Wang SJ. Apigenin, a natural flavonoid, inhibits glutamate release in the rat hippocampus. Eur J Pharmacol 2015; 762:72-81. [PMID: 26007643 DOI: 10.1016/j.ejphar.2015.05.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/04/2015] [Accepted: 05/18/2015] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to examine the effect and mechanism of apigenin, a natural flavonoid, on glutamate release in the rat hippocampus. In rat hippocampal nerve terminals (synaptosomes), apigenin inhibited glutamate release and the elevation of the cytosolic free Ca(2+) concentration evoked by 4-aminopyridine, whereas it had no effect on 4-aminopyridine-mediated depolarization and Na(+) influx. The apigenin-mediated inhibition of evoked glutamate release was prevented by chelating the extracellular Ca(2+) ions and blocking Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel activity. Furthermore, we determined that gamma-aminobutyric acid type A (GABAA) receptors are present in the hippocampal nerve terminals because they are colocalized with the presynaptic marker synaptophysin. However, the effect of apigenin on 4-aminopyridine-evoked glutamate release from synaptosomes was unaffected by the GABAA receptor antagonists SR95531 and bicuculline. Furthermore, in slice preparations, whole-cell patch-clamp experiments showed that apigenin reduced the frequency of spontaneous excitatory postsynaptic currents without affecting their amplitude, suggesting a presynaptic mechanism. On the basis of these results, we suggested that apigenin exerts its presynaptic inhibition probably by reducing Ca(2+) entry mediated by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, thereby inhibiting glutamate release from the rat hippocampal nerve terminals.
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Affiliation(s)
- Chia Ying Chang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; Department of Chemistry, Fu Jen Catholic University, No. 510, Zhongzheng Road, Xinzhuang District, New Taipei City 24205, Taiwan
| | - Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan
| | - Cheng Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan
| | - Chia Chuan Wang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Road, Xinzhuang District, New Taipei City 24205, Taiwan
| | - Ying Chou Wang
- Department of Clinical Psychology, Fu Jen Catholic University, No. 510, Zhongzheng Road, Xinzhuang District, New Taipei City 24205, Taiwan
| | - Shang Shing Peter Chou
- Department of Chemistry, Fu Jen Catholic University, No. 510, Zhongzheng Road, Xinzhuang District, New Taipei City 24205, Taiwan
| | - Su Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Road, Xinzhuang District, New Taipei City 24205, Taiwan.
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Palmitoylethanolamide inhibits glutamate release in rat cerebrocortical nerve terminals. Int J Mol Sci 2015; 16:5555-71. [PMID: 25768340 PMCID: PMC4394492 DOI: 10.3390/ijms16035555] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/25/2015] [Accepted: 03/04/2015] [Indexed: 12/14/2022] Open
Abstract
The effect of palmitoylethanolamide (PEA), an endogenous fatty acid amide displaying neuroprotective actions, on glutamate release from rat cerebrocortical nerve terminals (synaptosomes) was investigated. PEA inhibited the Ca2+-dependent release of glutamate, which was triggered by exposing synaptosomes to the potassium channel blocker 4-aminopyridine. This release inhibition was concentration dependent, associated with a reduction in cytosolic Ca2+ concentration, and not due to a change in synaptosomal membrane potential. The glutamate release-inhibiting effect of PEA was prevented by the Cav2.1 (P/Q-type) channel blocker ω-agatoxin IVA or the protein kinase A inhibitor H89, not affected by the intracellular Ca2+ release inhibitors dantrolene and CGP37157, and partially antagonized by the cannabinoid CB1 receptor antagonist AM281. Based on these results, we suggest that PEA exerts its presynaptic inhibition, likely through a reduction in the Ca2+ influx mediated by Cav2.1 (P/Q-type) channels, thereby inhibiting the release of glutamate from rat cortical nerve terminals. This release inhibition might be linked to the activation of presynaptic cannabinoid CB1 receptors and the suppression of the protein kinase A pathway.
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Chang Y, Chang CY, Wang SJ, Huang SK. Myricetin inhibits the release of glutamate in rat cerebrocortical nerve terminals. J Med Food 2014; 18:516-23. [PMID: 25340625 DOI: 10.1089/jmf.2014.3219] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of myricetin, a naturally occurring flavonoid with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. The release of glutamate was evoked by the K(+) channel blocker 4-aminopyridine (4-AP) and measured by one-line enzyme-coupled fluorometric assay. We also used a membrane potential-sensitive dye to assay the synaptosomal plasma membrane potential, and a Ca(2+) indicator Fura-2 to monitor cytosolic Ca(2+) concentrations ([Ca(2+)]C). Results show that myricetin inhibited 4-AP-evoked glutamate release, and this effect was prevented by chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate had no effect on myricetin action. Myricetin did not alter the synaptosomal membrane potential, but decreased 4-AP-induced increases in the cytosolic free Ca(2+) concentration. Furthermore, the myricetin effect on 4-AP-evoked glutamate release was prevented by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but not by blocking intracellular Ca(2+) release. These results suggest that myricetin inhibits glutamate release from cerebrocortical synaptosomes by attenuating voltage-dependent Ca(2+) entry. This implies that the inhibition of glutamate release is an important pharmacological activity of myricetin that may play a critical role in the apparent clinical efficacy of this compound.
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Affiliation(s)
- Yi Chang
- 1 School of Medicine, Fu Jen Catholic University , New Taipei City, Taiwan
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Lin TY, Lu CW, Wang CC, Huang SK, Wang SJ. Cyclooxygenase 2 inhibitor celecoxib inhibits glutamate release by attenuating the PGE2/EP2 pathway in rat cerebral cortex endings. J Pharmacol Exp Ther 2014; 351:134-45. [PMID: 25047516 DOI: 10.1124/jpet.114.217372] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The excitotoxicity caused by excessive glutamate is a critical element in the neuropathology of acute and chronic brain disorders. Therefore, inhibition of glutamate release is a potentially valuable therapeutic strategy for treating these diseases. In this study, we investigated the effect of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor that reduces the level of prostaglandin E2 (PGE2), on endogenous glutamate release in rat cerebral cortex nerve terminals (synaptosomes). Celecoxib substantially inhibited the release of glutamate induced by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by chelating the extracellular Ca(2+) ions and by the vesicular transporter inhibitor bafilomycin A1. Celecoxib inhibited a 4-AP-induced increase in cytosolic-free Ca(2+) concentration, and the celecoxib-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC. However, celecoxib did not alter 4-AP-mediated depolarization and Na(+) influx. In addition, this glutamate release-inhibiting effect of celecoxib was mediated through the PGE2 subtype 2 receptor (EP2) because it was not observed in the presence of butaprost (an EP2 agonist) or PF04418948 [1-(4-fluorobenzoyl)-3-[[6-methoxy-2-naphthalenyl)methyl]-3-azetidinecarboxylic acid; an EP2 antagonist]. The celecoxib effect on 4-AP-induced glutamate release was prevented by the inhibition or activation of protein kinase A (PKA), and celecoxib decreased the 4-AP-induced phosphorylation of PKA. We also determined that COX-2 and the EP2 receptor are present in presynaptic terminals because they are colocalized with synaptophysin, a presynaptic marker. These results collectively indicate that celecoxib inhibits glutamate release from nerve terminals by reducing voltage-dependent Ca(2+) entry through a signaling cascade involving EP2 and PKA.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Chia-Chuan Wang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Su-Jane Wang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
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Wang CC, Kuo JR, Wang SJ. Dimebon, an antihistamine drug, inhibits glutamate release in rat cerebrocortical nerve terminals. Eur J Pharmacol 2014; 734:67-76. [PMID: 24726847 DOI: 10.1016/j.ejphar.2014.03.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/05/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022]
Abstract
The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of dimebon, an antihistamine with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. Dimebon inhibited the release of glutamate that was evoked by exposing the synaptosomes to the K(+) channel blocker 4-aminopyridine, and this effect was prevented by chelating extracellular Ca(2+) ions, and the vesicular transporter inhibitor bafilomycin A1. Dimebon inhibited depolarization-evoked increase in cytosolic free Ca(2+) concentration, and the dimebon-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC. The inhibitory action of dimebon on glutamate release was not due to its decreasing synaptosomal excitability, because dimebon did not alter the resting synaptosomal membrane potential or 4-aminopyridine-mediated depolarization. Furthemore, the dimebon effect on 4-aminopyridine-evoked glutamate release was prevented by the protein kinase C inhibitor, and dimebon substantially reduced the 4-AP-induced phosphorylation of protein kinase C. However, the dimebon-mediated inhibition of glutamate release was unaffected by the N-methyl-d-aspartate receptor agonist or antagonist. These results suggest that dimebon inhibits glutamate release from rat cortical synaptosomes by suppressing presynaptic voltage-dependent Ca(2+) entry and protein kinase C activity. This implies that the inhibition of glutamate release is an additional pharmacological activity of dimebon that may play a critical role in the apparent clinical efficacy of this compound.
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Affiliation(s)
- Che-Chuan Wang
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Jinn-Rung Kuo
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang District, New Taipei 24205, Taiwan; School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang District, New Taipei 24205, Taiwan.
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Lin TY, Huang WJ, Wu CC, Lu CW, Wang SJ. Acacetin inhibits glutamate release and prevents kainic acid-induced neurotoxicity in rats. PLoS One 2014; 9:e88644. [PMID: 24520409 PMCID: PMC3919813 DOI: 10.1371/journal.pone.0088644] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/08/2014] [Indexed: 12/28/2022] Open
Abstract
An excessive release of glutamate is considered to be a molecular mechanism associated with several neurological diseases that causes neuronal damage. Therefore, searching for compounds that reduce glutamate neurotoxicity is necessary. In this study, the possibility that the natural flavone acacetin derived from the traditional Chinese medicine Clerodendrum inerme (L.) Gaertn is a neuroprotective agent was investigated. The effect of acacetin on endogenous glutamate release in rat hippocampal nerve terminals (synaptosomes) was also investigated. The results indicated that acacetin inhibited depolarization-evoked glutamate release and cytosolic free Ca2+ concentration ([Ca2+]C) in the hippocampal nerve terminals. However, acacetin did not alter synaptosomal membrane potential. Furthermore, the inhibitory effect of acacetin on evoked glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker known as ω-conotoxin MVIIC. In a kainic acid (KA) rat model, an animal model used for excitotoxic neurodegeneration experiments, acacetin (10 or 50 mg/kg) was administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg) intraperitoneal injection, and subsequently induced the attenuation of KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. The present study demonstrates that the natural compound, acacetin, inhibits glutamate release from hippocampal synaptosomes by attenuating voltage-dependent Ca2+ entry and effectively prevents KA-induced in vivo excitotoxicity. Collectively, these data suggest that acacetin has the therapeutic potential for treating neurological diseases associated with excitotoxicity.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan
| | - Wei-Jan Huang
- Graduate Institute of Pharmacognosy, Taipei Medical University, Taipei, Taiwan
| | - Chia-Chan Wu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, New Taipei, Taiwan
- * E-mail:
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Hung KL, Wang SJ, Wang YC, Chiang TR, Wang CC. Upregulation of presynaptic proteins and protein kinases associated with enhanced glutamate release from axonal terminals (synaptosomes) of the medial prefrontal cortex in rats with neuropathic pain. Pain 2014; 155:377-387. [DOI: 10.1016/j.pain.2013.10.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 10/04/2013] [Accepted: 10/29/2013] [Indexed: 11/25/2022]
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Lu CW, Lin TY, Wang SJ. Quercetin inhibits depolarization-evoked glutamate release in nerve terminals from rat cerebral cortex. Neurotoxicology 2013; 39:1-9. [DOI: 10.1016/j.neuro.2013.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 07/05/2013] [Accepted: 07/30/2013] [Indexed: 02/08/2023]
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Lin TY, Lin YW, Lu CW, Huang SK, Wang SJ. Berberine Inhibits the Release of Glutamate in Nerve Terminals from Rat Cerebral Cortex. PLoS One 2013; 8:e67215. [PMID: 23840629 PMCID: PMC3686739 DOI: 10.1371/journal.pone.0067215] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 05/15/2013] [Indexed: 11/29/2022] Open
Abstract
Berberine, an isoquinoline plant alkaloid, protects neurons against neurotoxicity. An excessive release of glutamate is considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. In this study, we investigated whether berberine could affect endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes) and explored the possible mechanism. Berberine inhibited the release of glutamate evoked by the K+ channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by the chelating extracellular Ca2+ ions and the vesicular transporter inhibitor bafilomycin A1, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Inhibition of glutamate release by berberine was not due to it decreasing synaptosomal excitability, because berberine did not alter 4-AP-mediated depolarization. The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca2+ concentration. Involvement of the Cav2.1 (P/Q-type) channels in the berberine action was confirmed by blockade of the berberine-mediated inhibition of glutamate release by the Cav2.1 (P/Q-type) channel blocker ω-agatoxin IVA. In addition, the inhibitory effect of berberine on evoked glutamate release was prevented by the mitogen-activated/extracellular signal-regulated kinase kinase (MEK) inhibitors. Berberine decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synapsin I, the main presynaptic target of ERK; this decrease was also blocked by the MEK inhibition. Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I. Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade. This finding may provide further understanding of the mode of berberine action in the brain and highlights the therapeutic potential of this compound in the treatment of a wide range of neurological disorders.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan
| | - Yu-Wan Lin
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, New Taipei, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan
| | - Shu-Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, New Taipei, Taiwan
- * E-mail:
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Lin TY, Lu CW, Huang SK, Wang SJ. Tanshinone IIA, a constituent of Danshen, inhibits the release of glutamate in rat cerebrocortical nerve terminals. JOURNAL OF ETHNOPHARMACOLOGY 2013; 147:488-496. [PMID: 23542145 DOI: 10.1016/j.jep.2013.03.045] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 03/11/2013] [Accepted: 03/18/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Danshen is a commonly used traditional Chinese medicine and has received considerable attention due to their beneficial effects on the health, including prevention of cardiovascular disease, and cancer. Tanshinone IIA, a major active constituent of Danshen, has been reported to have a neuroprotective profile. AIM OF THE STUDY An excessive release of glutamate is considered to be related to neuropathology of several neurological diseases. In this study, we investigated whether tanshinone IIA could affect endogenous glutamate release and explored the possible mechanism. MATERIALS AND METHODS The experimental model was the isolated nerve terminals (synaptosomes) purified from the rat cerebral cortex. The release of glutamate was evoked by the K(+) channel blocker 4-aminopyridine (4-AP) and measured by one-line enzyme-coupled fluorometric assay. We also used a membrane potential-sensitive dye to assay nerve terminal excitability and depolarization, and a Ca(2+) indicator, Fura-2-acetoxymethyl ester, to monitor cytosolic Ca(2+) concentrations ([Ca(2+)]C). RESULTS Tanshinone IIA inhibited the release of glutamate evoked by 4-AP in a concentration-dependent manner. Inhibition of glutamate release by tanshinone IIA was prevented by the chelating the extracellular Ca(2+) ions, and by the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate did not have any effect on the action of tanshinone IIA. Tanshinone IIA decreased the depolarization-induced increase in [Ca(2+)]C, whereas it did not alter the resting synaptosomal membrane potential or 4-AP-mediated depolarization. Furthermore, the effect of tanshinone IIA on evoked glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, but not by the ryanodine receptor blocker dantrolene or the mitochondrial Na(+)/Ca(2+) exchanger blocker CGP37157. Mitogen-activated protein kinase (MEK) inhibition also prevented the inhibitory effect of tanshinone IIA on evoked glutamate release. CONCLUSION These results show that tanshinone IIA inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca(2+) entry and MEK signaling cascade.
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Affiliation(s)
- Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan
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Lin TY, Chung CY, Lu CW, Huang SK, Shieh JS, Wang SJ. Local anesthetics inhibit glutamate release from rat cerebral cortex synaptosomes. Synapse 2013; 67:568-79. [DOI: 10.1002/syn.21661] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/05/2012] [Accepted: 02/23/2013] [Indexed: 11/11/2022]
Affiliation(s)
| | - Chih-Yang Chung
- Department of Anesthesiology; Far-Eastern Memorial Hospital; Pan-Chiao; New Taipei City; 220; Taiwan
| | | | - Shu-Kuei Huang
- Department of Anesthesiology; Far-Eastern Memorial Hospital; Pan-Chiao; New Taipei City; 220; Taiwan
| | - Jiann-Sing Shieh
- Department of Mechanical Engineering; Yuan Ze University; Taoyuan; 320; Taiwan
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Lin TY, Lu CW, Huang SK, Wang SJ. Ferulic acid suppresses glutamate release through inhibition of voltage-dependent calcium entry in rat cerebrocortical nerve terminals. J Med Food 2013; 16:112-9. [PMID: 23342970 PMCID: PMC3576904 DOI: 10.1089/jmf.2012.2387] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 11/13/2012] [Indexed: 01/28/2023] Open
Abstract
This study investigated the effects and possible mechanism of ferulic acid, a naturally occurring phenolic compound, on endogenous glutamate release in the nerve terminals of the cerebral cortex in rats. Results show that ferulic acid inhibited the release of glutamate evoked by the K⁺ channel blocker 4-aminopyridine (4-AP). The effect of ferulic acid on the evoked glutamate release was prevented by chelating the extracellular Ca²⁺ ions, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Ferulic acid suppressed the depolarization-induced increase in a cytosolic-free Ca²⁺ concentration, but did not alter 4-AP-mediated depolarization. Furthermore, the effect of ferulic acid on evoked glutamate release was abolished by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking ryanodine receptors or mitochondrial Na⁺/Ca²⁺ exchange. These results show that ferulic acid inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca²⁺ entry.
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Affiliation(s)
- Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan
| | - Cheng Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Shu-Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
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Chang Y, Huang SK, Wang SJ. Coenzyme Q10 inhibits the release of glutamate in rat cerebrocortical nerve terminals by suppression of voltage-dependent calcium influx and mitogen-activated protein kinase signaling pathway. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:11909-11918. [PMID: 23167655 DOI: 10.1021/jf302875k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This study investigates the effects and possible mechanism of coenzyme Q10 (CoQ10) on endogenous glutamate release in the cerebral cortex nerve terminals of rats. CoQ10 inhibited the release of glutamate evoked by the K+ channel blocker 4-aminopyridine (4-AP). CoQ10 reduced the depolarization-induced increase in cytosolic [Ca2+]c but did not alter the 4-AP-mediated depolarization. The effect of CoQ10 on evoked glutamate release was abolished by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) Ca2+ channels and mitogen-activated protein kinase kinase (MEK). In addition, CoQ10 decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synaptic vesicle-associated protein synapsin I, a major presynaptic substrate for ERK. Moreover, the inhibition of glutamate release by CoQ10 was strongly attenuated in mice without synapsin I. These results suggest that CoQ10 inhibits glutamate release from cortical synaptosomes in rats through the suppression of the presynaptic voltage-dependent Ca2+ entry and ERK/synapsin I signaling pathway.
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Affiliation(s)
- Yi Chang
- School of Medicine, Fu Jen Catholic University, and Department of Anesthesiology, Far-EAstern Memorial Hospital, No. 510 Zhongzheng Road, Xinzhuang District, New Taipei City, Taiwan 24205
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Lin TY, Lu CW, Wang CC, Lu JF, Wang SJ. Hispidulin inhibits the release of glutamate in rat cerebrocortical nerve terminals. Toxicol Appl Pharmacol 2012; 263:233-43. [PMID: 22759588 DOI: 10.1016/j.taap.2012.06.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/15/2012] [Accepted: 06/22/2012] [Indexed: 11/25/2022]
Abstract
Hispidulin, a naturally occurring flavone, has been reported to have an antiepileptic profile. An excessive release of glutamate is considered to be related to neuropathology of epilepsy. We investigated whether hispidulin affected endogenous glutamate release in rat cerebral cortex nerve terminals (synaptosomes) and explored the possible mechanism. Hispidulin inhibited the release of glutamate evoked by the K⁺ channel blocker 4-aminopyridine (4-AP). The effects of hispidulin on the evoked glutamate release were prevented by the chelation of extracellular Ca²⁺ ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate did not have any effect on hispidulin action. Hispidulin reduced the depolarization-induced increase in cytosolic free Ca²⁺ concentration ([Ca²⁺](C)), but did not alter 4-AP-mediated depolarization. Furthermore, the effect of hispidulin on evoked glutamate release was abolished by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking ryanodine receptors or mitochondrial Na⁺/Ca²⁺ exchange. Mitogen-activated protein kinase kinase (MEK) inhibition also prevented the inhibitory effect of hispidulin on evoked glutamate release. Western blot analyses showed that hispidulin decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synaptic vesicle-associated protein synapsin I, a major presynaptic substrate for ERK; this decrease was also blocked by the MEK inhibitor. Moreover, the inhibition of glutamate release by hispidulin was strongly attenuated in mice without synapsin I. These results show that hispidulin inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca²⁺ entry and ERK/synapsin I signaling pathway.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei 22060, Taiwan
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Lu CW, Lin TY, Wang CC, Wang SJ. σ-1 Receptor agonist SKF10047 inhibits glutamate release in rat cerebral cortex nerve endings. J Pharmacol Exp Ther 2012; 341:532-42. [PMID: 22357973 DOI: 10.1124/jpet.111.191189] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
σ-1 Receptors are expressed in the brain, and their activation has been shown to prevent neuronal death associated with glutamate toxicity. This study investigates the possible mechanism and effect of [2S-(2α,6α,11R*]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol (SKF10047), a σ-1 receptor agonist, on endogenous glutamate release in the nerve terminals of rat cerebral cortex. Results show that SKF10047 inhibited the release of glutamate evoked by the K⁺ channel blocker 4-aminopyridine (4-AP), and the σ-1 receptor antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine (BD1047) blocked this phenomenon. The effects of SKF10047 on the evoked glutamate release were prevented by the chelating extracellular Ca²⁺ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor DL-threo-β-benzyl-oxyaspartate did not have any effect on the action of SKF10047. SKF10047 decreased the depolarization-induced increase in the cytosolic free Ca²⁺ concentration ([Ca²⁺](C)), but did not alter 4-AP-mediated depolarization. Furthermore, the effects of SKF10047 on evoked glutamate release were prevented by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking the ryanodine receptors or the mitochondrial Na⁺/Ca²⁺ exchange. In addition, conventional protein kinase C (PKC) inhibitors abolished the SKF10047 effect on 4-AP-evoked glutamate release. Western blot analyses showed that SKF10047 decreased the 4-AP-induced phosphorylation of PKC and PKCα. These results show that σ-1 receptor activation inhibits glutamate release from rat cortical nerve terminals. This effect is linked to a decrease in [Ca²⁺](C) caused by Ca²⁺ entry through presynaptic voltage-dependent Ca²⁺ channels and the suppression of the PKC signaling cascade.
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Affiliation(s)
- Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
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Sun MK, Alkon DL. Activation of protein kinase C isozymes for the treatment of dementias. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2012; 64:273-302. [PMID: 22840750 DOI: 10.1016/b978-0-12-394816-8.00008-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Memories are much more easily impaired than improved. Dementias, a lasting impairment of memory function, occur in a variety of cognitive disorders and become more clinically dominant as the population ages. Protein kinase C is one of the "cognitive kinases," and plays an essential role in both memory acquisition and maintenance. Deficits in protein kinase C (PKC) signal cascades in neurons represent one of the earliest changes in the brains of patients with Alzheimer's disease (AD) and other types of memory impairment, including those related to cerebral ischemia and ischemic stroke. Inhibition or impairment of PKC activity results in compromised learning and memory, whereas an appropriate activation of certain PKC isozymes leads to an enhancement of learning and memory and/or antidementic effects. In preclinical studies, PKC activators have been shown to increase the expression and activity of PKC isozymes, thereby restoring PKC signaling and downstream activity, including stimulation of neurotrophic activity, synaptic/structural remodeling, and synaptogenesis in the hippocampus and related cortical areas. PKC activators also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation and support anti-apoptotic processes in the brain. These observations strongly suggest that PKC pharmacology may represent an attractive area for the development of effective cognition-enhancing therapeutics for the treatment of dementias.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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48
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Tamoxifen depresses glutamate release through inhibition of voltage-dependent Ca2+ entry and protein kinase Cα in rat cerebral cortex nerve terminals. Neurochem Int 2012; 60:105-14. [DOI: 10.1016/j.neuint.2011.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/17/2011] [Accepted: 11/21/2011] [Indexed: 12/30/2022]
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Lin TY, Lu CW, Huang WJ, Wang SJ. Involvement of the cGMP pathway in the osthole-facilitated glutamate release in rat hippocampal nerve endings. Synapse 2011; 66:232-9. [PMID: 22045627 DOI: 10.1002/syn.21505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 04/03/2011] [Indexed: 11/11/2022]
Abstract
Osthole, an active constituent isolated from Cnidium monnieri (L.) Cusson, has previously been shown to have the capacity to increase depolarization-evoked glutamate release in rat hippocampal nerve terminals. As cGMP-dependent signaling cascade has been found to modulate glutamate release at the presynaptic level, the aim of this study was to further examine the role of cGMP signaling pathway in the regulation of osthole on glutamate release in hippocampal synaptosomes. Results showed that osthole dose-dependently increased intrasynaptosomal cGMP levels. The elevation of cGMP levels by osthole was prevented by the phosphodiesterase 5 inhibitor sildenafil but was insensitive to the guanylyl cyclase inhibitor ODQ. In addition, osthole-induced facilitation of 4-aminopyridine (4-AP)-evoked glutamate release was completely prevented by the cGMP-dependent protein kinase (PKG) inhibitors, KT5823, and Rp-8-Br-PET-cGMPS. Direct activation of PKG with 8-Br-cGMP or 8-pCPT-cGMP also occluded the osthole-mediated facilitation of 4-AP-evoked glutamate release. Furthermore, sildenafil exhibited a dose-dependent facilitation of 4-AP-evoked release of glutamate and occluded the effect of osthole on the 4-AP-evoked glutamate release. Collectively, our findings suggest that osthole-mediated facilitation of glutamate release involves the activation of cGMP/PKG-dependent pathway.
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Affiliation(s)
- Tzu Yu Lin
- Department of Anesthesiology, Far Eastern Memorial Hospital, New Taipei City, Taiwan 220
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Inhibitory effect of glutamate release from rat cerebrocortical nerve terminals by α2 adrenoceptor agonist dexmedetomidine. Eur J Pharmacol 2011; 670:137-47. [DOI: 10.1016/j.ejphar.2011.08.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 07/21/2011] [Accepted: 08/17/2011] [Indexed: 11/21/2022]
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