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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] [What about the content of this article? (0)] [Affiliation(s)] [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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