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Sheng W, Weng S, Li F, Zhang Y, He Q, Sheng W, Fu Y, Yan H, Liu K. Immunohistological Localization of Mel1a Melatonin Receptor in Pigeon Retina. Nat Sci Sleep 2021; 13:113-121. [PMID: 33574722 PMCID: PMC7872906 DOI: 10.2147/nss.s290757] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/18/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Melatonin (N-acetyl-5-methoxytryptamine), a significant indoleamine neuromodulator implicated in circadian rhythms and sleep patterns, regulates diverse rhythmic functions via activating its high-affinity G-protein-coupled receptors. However, the detailed cellular expression of the Mel1a receptor in the retina is still a research gap. METHODS The expression of the Mel1a receptor in pigeon retina was assessed using Western blot analysis and immunofluorescent staining. The cellular localization of the Mel1a receptor was studied using double immunofluorescent staining and laser-scanning confocal microscopy. RESULTS Our data suggested that the Mel1a receptor was extensively expressed in the outer segment of Rho4D2-labeled rod and L/M-opsin-labeled red/green cone and in the somata of the CB-labeled horizontal cell, TH-labeled dopaminergic amacrine cell, ChAT-labeled cholinergic amacrine cell, PV-labeled AII amacrine cell, Brn3a-labeled conventional ganglion cell, melanopsin-containing ganglion cell and CRALBP-labeled Müller glial cell. In addition, the Mel1a receptor was diffusely distributed throughout the full thickness of the inner plexiform layer. However, the outer segment of S-opsin-labeled blue cone, the somata of ChX-10-labeled bipolar cell and outer plexiform layer seemed to lack immunoreactivity of the Mel1a receptor. CONCLUSION The finding that multiple types of retinal cells express the Mel1a receptor provides a new neurobiological basis for the participation of melatonin in the regulation of retinal functions through activating the Mel1a receptor.
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Affiliation(s)
- Wenlong Sheng
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
| | - Shijun Weng
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, People's Republic of China
| | - Fei Li
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
| | - Yun Zhang
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
| | - Qiuxia He
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
| | - Wenxiang Sheng
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
| | - Ying Fu
- Shandong Science and Technology Exchange Center, Jinan, People's Republic of China
| | - Haiyue Yan
- Shandong Institute of Scientific and Technical Information, Jinan, People's Republic of China
| | - Kechun Liu
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, People's Republic of China
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2
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Sheng W, Jin M, Pan G, Weng S, Sik A, Han L, Liu K. Cellular localization of melatonin receptor Mel1b in pigeon retina. Neuropeptides 2019; 78:101974. [PMID: 31645269 DOI: 10.1016/j.npep.2019.101974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/10/2019] [Accepted: 09/22/2019] [Indexed: 12/15/2022]
Abstract
Melatonin, an important neuromodulator involved in circadian rhythms, modulates a series of physiological processes via activating its specific receptors, namely Mel1a (MT1), Mel1b (MT2) and Mel1c receptors. In this work, the localization of Mel1b receptor was studied in pigeon retina using double immunohistochemistry staining and confocal scanning microscopy. Our results showed that Mel1b receptor widely existed in the outer segment of photoreceptors and in the somata of dopaminergic amacrine cells, cholinergic amacrine cells, glycinergic AII amacrine cells, conventional ganglion cells and intrinsically photosensitive retinal ganglion cells, while horizontal cells, bipolar cells and Müller glial cells seemed to lack immunoreactivity of Mel1b receptor. That multiple types of retinal cells expressing Mel1b receptor suggests melatonin may directly modulate the activities of retina via activating Mel1b receptor.
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Affiliation(s)
- Wenlong Sheng
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
| | - Meng Jin
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Ge Pan
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Shijun Weng
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Attila Sik
- Institute of Transdisciplinary Discoveries, University of Pecs, Pecs, Hungary; Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Pecs, Hungary; Medical School, University of Birmingham, Birmingham, UK
| | - Liwen Han
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Kechun Liu
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
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3
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Klosen P, Lapmanee S, Schuster C, Guardiola B, Hicks D, Pevet P, Felder-Schmittbuhl MP. MT1 and MT2 melatonin receptors are expressed in nonoverlapping neuronal populations. J Pineal Res 2019; 67:e12575. [PMID: 30937953 DOI: 10.1111/jpi.12575] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/07/2019] [Accepted: 03/25/2019] [Indexed: 12/15/2022]
Abstract
Melatonin (MLT) exerts its physiological effects principally through two high-affinity membrane receptors MT1 and MT2. Understanding the exact mechanism of MLT action necessitates the use of highly selective agonists/antagonists to stimulate/inhibit a given MLT receptor. The respective distribution of MT1 and MT2 within the CNS and elsewhere is controversial, and here we used a "knock-in" strategy replacing MT1 or MT2 coding sequences with a LacZ reporter. The data show striking differences in the distribution of MT1 and MT2 receptors in the mouse brain: whereas the MT1 subtype was expressed in very few structures (notably including the suprachiasmatic nucleus and pars tuberalis), MT2 subtype receptors were identified within numerous brain regions including the olfactory bulb, forebrain, hippocampus, amygdala and superior colliculus. Co-expression of the two subtypes was observed in very few structures, and even within these areas they were rarely present in the same individual cell. In conclusion, the expression and distribution of MT2 receptors are much more widespread than previously thought, and there is virtually no correspondence between MT1 and MT2 cellular expression. The precise phenotyping of cells/neurons containing MT1 or MT2 receptor subtypes opens new perspectives for the characterization of links between MLT brain targets, MLT actions and specific MLT receptor subtypes.
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Affiliation(s)
- Paul Klosen
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | - Sarawut Lapmanee
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | | | | | - David Hicks
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | - Paul Pevet
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
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4
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An insight into the scientific background and future perspectives for the potential uses of melatonin. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.ejbas.2015.05.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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5
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Xu Z, Wu Y, Zhang Y, Zhang H, Shi L. Melatonin activates BK Ca channels in cerebral artery myocytes via both direct and MT receptor/PKC-mediated pathway. Eur J Pharmacol 2018; 842:177-188. [PMID: 30391348 DOI: 10.1016/j.ejphar.2018.10.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 10/17/2018] [Accepted: 10/24/2018] [Indexed: 11/28/2022]
Abstract
The pineal hormone melatonin is a neuroendocrine hormone with high membrane permeability that is involved in regulation of circadian rhythm of several biological functions. Large-conductance Ca2+-activated K+ (BKCa) channels are abundantly expressed in vascular smooth muscle cells and play an important role in vascular tone regulation. We investigated the mechanisms through which myocyte BKCa channels mediate effects of melatonin on cerebral arteries (CAs). Arterial contractility measurements showed that melatonin alone did not change vascular tone in CAs; however, it induced concentration-dependent vasodilation of phenylephrine-induced contraction in CAs. In the presence of the potent endothelial oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester, melatonin-elicited relaxation was significantly inhibited by iberiotoxin (BKCa channel blocker). Melatonin significantly increased BKCa currents but not voltage-gated K+ (KV) currents in whole-cell recordings. Melatonin decreased the amplitude of Ca2+ sparks and spontaneous transient outward currents (STOCs), however, a significant increase in open probability of BKCa channels was observed in both inside-out and cell-attached patch-clamp recordings. This melatonin-induced enhancement of BKCa channel activity was significantly suppressed by luzindole (melatonin MT1/MT2 receptor inhibitor), U73122 (phospholipase C (PLC) inhibitor), and Ro31-8220 (protein kinase C (PKC) inhibitor). Melatonin had no significant effects on sarcoplasmic reticulum release of Ca2+. These findings indicate that melatonin-induced vasorelaxation of CAs is partially attributable to direct (passing through the cell membrane) and indirect (via melatonin MT1/MT2 receptors-PLC-PKC pathway) activation of BKCa channels on CA myocytes.
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Affiliation(s)
- Zhaoxia Xu
- Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China
| | - Ying Wu
- Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China
| | - Yanyan Zhang
- Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China
| | - Huirong Zhang
- Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China
| | - Lijun Shi
- Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China.
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Wu HJ, Li XY, Qian WJ, Li Q, Wang SY, Ji M, Ma YY, Gao F, Sun XH, Wang X, Miao Y, Yang XL, Wang Z. Dopamine D1 receptor-mediated upregulation of BKCa
currents modifies Müller cell gliosis in a rat chronic ocular hypertension model. Glia 2018; 66:1507-1519. [PMID: 29508439 DOI: 10.1002/glia.23321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Hang-Jing Wu
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Xue-Yan Li
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Wen-Jing Qian
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Qian Li
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Shu-Yue Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Min Ji
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Yuan-Yuan Ma
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Feng Gao
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Xing-Huai Sun
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Xin Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Yanying Miao
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Xiong-Li Yang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Zhongfeng Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
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Yu LM, Di WC, Dong X, Li Z, Zhang Y, Xue XD, Xu YL, Zhang J, Xiao X, Han JS, Liu Y, Yang Y, Wang HS. Melatonin protects diabetic heart against ischemia-reperfusion injury, role of membrane receptor-dependent cGMP-PKG activation. Biochim Biophys Acta Mol Basis Dis 2017; 1864:563-578. [PMID: 29196237 DOI: 10.1016/j.bbadis.2017.11.023] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/18/2017] [Accepted: 11/27/2017] [Indexed: 12/17/2022]
Abstract
It has been demonstrated that the anti-oxidative and cardioprotective effects of melatonin are, at least in part, mediated by its membrane receptors. However, the direct downstream signaling remains unknown. We previously found that melatonin ameliorated myocardial ischemia-reperfusion (MI/R) injury in diabetic animals, although the underlying mechanisms are also incompletely understood. This study was designed to determine the role of melatonin membrane receptors in melatonin's cardioprotective actions against diabetic MI/R injury with a focus on cGMP and its downstream effector PKG. Streptozotocin-induced diabetic Sprague-Dawley rats and high-glucose medium-incubated H9c2 cardiomyoblasts were utilized to determine the effects of melatonin against MI/R injury. Melatonin treatment preserved cardiac function and reduced oxidative damage and apoptosis. Additionally, melatonin increased intracellular cGMP level, PKGIα expression, p-VASP/VASP ratio and further modulated myocardial Nrf-2-HO-1 and MAPK signaling. However, these effects were blunted by KT5823 (a selective inhibitor of PKG) or PKGIα siRNA except that intracellular cGMP level did not changed significantly. Additionally, our in vitro study showed that luzindole (a nonselective melatonin membrane receptor antagonist) or 4P-PDOT (a selective MT2 receptor antagonist) not only blocked the cytoprotective effect of melatonin, but also attenuated the stimulatory effect of melatonin on cGMP-PKGIα signaling and its modulatory effect on Nrf-2-HO-1 and MAPK signaling. This study showed that melatonin ameliorated diabetic MI/R injury by modulating Nrf-2-HO-1 and MAPK signaling, thus reducing myocardial apoptosis and oxidative stress and preserving cardiac function. Importantly, melatonin membrane receptors (especially MT2 receptor)-dependent cGMP-PKGIα signaling played a critical role in this process.
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Affiliation(s)
- Li-Ming Yu
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Wen-Cheng Di
- Department of Cardiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu 210008, China
| | - Xue Dong
- Department of Pharmacy, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China; Department of Neurosurgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Zhi Li
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Yong Zhang
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Xiao-Dong Xue
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Yin-Li Xu
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Jian Zhang
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Xiong Xiao
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China; Department of Cardiovascular Surgery, Xijing Hospital, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi 710032, China
| | - Jin-Song Han
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Yu Liu
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Yang Yang
- Faculty of Life Science, Northwest University, 229 Taibai North Road, Xi'an, Shaanxi 710069, China; Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an, Shaanxi 710032, China.
| | - Hui-Shan Wang
- Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command, 83 Wenhua Road, Shenyang, Liaoning 110016, China.
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8
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Cui P, Li XY, Zhao Y, Li Q, Gao F, Li LZ, Yin N, Sun XH, Wang Z. Activation of dopamine D1 receptors enhances the temporal summation and excitability of rat retinal ganglion cells. Neuroscience 2017; 355:71-83. [DOI: 10.1016/j.neuroscience.2017.04.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/24/2017] [Accepted: 04/30/2017] [Indexed: 01/11/2023]
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9
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Melatonin receptors: distribution in mammalian brain and their respective putative functions. Brain Struct Funct 2017; 222:2921-2939. [DOI: 10.1007/s00429-017-1439-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/28/2017] [Indexed: 12/15/2022]
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10
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Cannabinoid CB1 and CB2 receptors differentially modulate L- and T-type Ca 2+ channels in rat retinal ganglion cells. Neuropharmacology 2017; 124:143-156. [PMID: 28431968 DOI: 10.1016/j.neuropharm.2017.04.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/15/2017] [Accepted: 04/17/2017] [Indexed: 01/09/2023]
Abstract
Endocannabinoid signaling system is involved in regulating multiple neuronal functions in the central nervous system by activating G-protein coupled cannabinoid CB1 and CB2 receptors (CB1Rs and CB2Rs). Growing evidence has shown that CB1Rs and CB2Rs are extensively expressed in retinal ganglion cells (RGCs). Here, modulation of L- and T-types Ca2+ channels by activating CB1Rs and CB2Rs in RGCs was investigated. Triple immunofluorescent staining showed that L-type subunit CaV1.2 was co-localized with T-type subunits (CaV3.1, CaV3.2 and CaV3.3) in rat RGCs. In acutely isolated rat RGCs, the CB1R agonist WIN55212-2 suppressed both peak and steady-state Ca2+ currents in a dose-dependent manner, with IC50 being 9.6 μM and 8.4 μM, respectively. It was further shown that activation of CB1Rs by WIN55212-2 or ACEA, another CB1R agonist, significantly suppressed both L- and T-type Ca2+ currents, and shifted inactivation curve of T-type one toward hyperpolarization direction. While the effect on L-type Ca2+ channels was mediated by intracellular cAMP/protein kinase A (PKA), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and calcium/calmodulin-dependent protein kinase II (CaMKII) signaling pathways, only CaMKII signaling pathway was involved in the effect on T-type Ca2+ channels. Furthermore, CB65 and HU308, two specific CB2R agonists, significantly suppressed T-type Ca2+ channels, which was mediated by intracellular cAMP/PKA and CaMKII signaling pathways, but had no effect on L-type channels. These results imply that endogenous cannabinoids may modulate the excitability and the output of RGCs by differentially suppressing the activity of L- and T-type Ca2+ channels through activation of CB1Rs and CB2Rs. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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11
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Li Q, Cui P, Miao Y, Gao F, Li XY, Qian WJ, Jiang SX, Wu N, Sun XH, Wang Z. Activation of group I metabotropic glutamate receptors regulates the excitability of rat retinal ganglion cells by suppressing Kir and I h. Brain Struct Funct 2016; 222:813-830. [PMID: 27306787 DOI: 10.1007/s00429-016-1248-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/05/2016] [Indexed: 10/21/2022]
Abstract
Group I metabotropic glutamate receptor (mGluR I) activation exerts a slow postsynaptic excitatory effect in the CNS. Here, the issues of whether and how this receptor is involved in regulating retinal ganglion cell (RGC) excitability were investigated in retinal slices using patch-clamp techniques. Under physiological conditions, RGCs displayed spontaneous firing. Extracellular application of LY367385 (10 µM)/MPEP (10 µM), selective mGluR1 and mGluR5 antagonists, respectively, significantly reduced the firing frequency, suggesting that glutamate endogenously released from bipolar cells constantly modulates RGC firing. DHPG (10 µM), an mGluR I agonist, significantly increased the firing and caused depolarization of the cells, which were reversed by LY367385, but not by MPEP, suggesting the involvement of the mGluR1 subtype. Intracellular Ca2+-dependent PI-PLC/PKC and calcium/calmodulin-dependent protein kinase II (CaMKII) signaling pathways mediated the DHPG-induced effects. In the presence of cocktail synaptic blockers (CNQX, D-AP5, bicuculline, and strychnine), which terminated the spontaneous firing in both ON and OFF RGCs, DHPG still induced depolarization and triggered the cells to fire. The DHPG-induced depolarization could not be blocked by TTX. In contrast, Ba2+, an inwardly rectifying potassium channel (Kir) blocker, and Cs+ and ZD7288, hyperpolarization-activated cation channel (I h) blockers, mimicked the effect of DHPG. Furthermore, in the presence of Ba2+/ZD7288, DHPG did not show further effects. Moreover, Kir and I h currents could be recorded in RGCs, and extracellular application of DHPG indeed suppressed these currents. Our results suggest that activation of mGluR I regulates the excitability of rat RGCs by inhibiting Kir and I h.
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Affiliation(s)
- Qian Li
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Peng Cui
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Yanying Miao
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Feng Gao
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Eye & ENT Hospital, Fudan University, Shanghai, 200031, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Xue-Yan Li
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Wen-Jing Qian
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Shu-Xia Jiang
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Institute of Neurobiology, Fudan University, Shanghai, 200032, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Na Wu
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China.,Eye & ENT Hospital, Fudan University, Shanghai, 200031, China.,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China.,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Xing-Huai Sun
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China. .,Eye & ENT Hospital, Fudan University, Shanghai, 200031, China. .,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China. .,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
| | - Zhongfeng Wang
- Institutes of Brain Science, Fudan University, 138 Yixueyuan Rd, Shanghai, 200032, China. .,Eye & ENT Hospital, Fudan University, Shanghai, 200031, China. .,Institute of Neurobiology, Fudan University, Shanghai, 200032, China. .,State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200032, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China. .,Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
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12
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Yang W, Li Q, Wang SY, Gao F, Qian WJ, Li F, Ji M, Sun XH, Miao Y, Wang Z. Cannabinoid receptor agonists modulate calcium channels in rat retinal müller cells. Neuroscience 2016; 313:213-24. [DOI: 10.1016/j.neuroscience.2015.11.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/10/2015] [Accepted: 11/17/2015] [Indexed: 10/22/2022]
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13
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Yin S, Wang ZF, Duan JG, Ji L, Lu XJ. Extraction (DSX) from Erigeron breviscapus modulates outward potassium currents in rat retinal ganglion cells. Int J Ophthalmol 2015; 8:1101-6. [PMID: 26682155 DOI: 10.3980/j.issn.2222-3959.2015.06.04] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 04/15/2015] [Indexed: 02/02/2023] Open
Abstract
AIM To investigate the effect of DSX, an active component extracted from Erigeron breviscapus, on the voltage-gated outward K(+) channel currents in rat retinal ganglion cells (RGCs) by using electrophysiological method, and to explore the possible mechanisms of DSX on optic nerve protection. METHODS Outward K(+) currents were recorded by using whole-cell patch-clamp techniques on acutely isolated rat RGCs. Outward K(+) currents were induced by a series of depolarizing voltage pulses from a holding potential of -70 mV to +20 mV in an increment of 10 mV. RESULTS Extracellular application of DSX voltage-dependently suppressed both the steady-state and peak current amplitudes of outward K(+) currents in rat RGCs. Furthermore, DSX reversibly and dose-dependently inhibited the amplitudes of outward K(+) currents of the cells. At +20 mV membrane potential DSX at the concentrations of 0.02 g/L and 0.05 g/L showed no significant effects on the currents. In contrast, DSX at higher concentrations (0.1 g/L, 0.2 g/L and 0.5 g/L) significantly suppressed the current amplitudes. CONCLUSION These results suggest that DSX reversibly and dose-dependently suppress outward K(+) channel currents in rat RGCs, which may be one of the possible mechanisms underlying Erigeron breviscapus prevents vision loss and RGC damage caused by glaucoma.
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Affiliation(s)
- Shuo Yin
- Key Laboratory for Visual Function and Ophthalmopathy, Chengdu University of Traditional Chinese Medicine, Chengdu 610032, Sichuan Province, China
| | - Zhong-Feng Wang
- Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Jun-Guo Duan
- Key Laboratory for Visual Function and Ophthalmopathy, Chengdu University of Traditional Chinese Medicine, Chengdu 610032, Sichuan Province, China
| | - Lu Ji
- Key Laboratory for Visual Function and Ophthalmopathy, Chengdu University of Traditional Chinese Medicine, Chengdu 610032, Sichuan Province, China
| | - Xue-Jing Lu
- Key Laboratory for Visual Function and Ophthalmopathy, Chengdu University of Traditional Chinese Medicine, Chengdu 610032, Sichuan Province, China
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Pack W, Hill DD, Wong KY. Melatonin modulates M4-type ganglion-cell photoreceptors. Neuroscience 2015; 303:178-88. [PMID: 26141846 PMCID: PMC4532552 DOI: 10.1016/j.neuroscience.2015.06.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/30/2015] [Accepted: 06/23/2015] [Indexed: 11/21/2022]
Abstract
In the retina, melatonin is secreted at night by rod/cone photoreceptors and serves as a dark-adaptive signal. Melatonin receptors have been found in many retinal neurons including melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), suggesting it could modulate the physiology of these inner retinal photoreceptors. Here, we investigated whether melatonin modulates the alpha-like M4-type ipRGCs, which are believed to mediate image-forming vision as well as non-image-forming photoresponses. Applying melatonin during daytime (when endogenous melatonin secretion is low) caused whole-cell-recorded M4 cells' rod/cone-driven depolarizing photoresponses to become broader and larger, whereas the associated elevation in spike rate was reduced. Melanopsin-based light responses were not affected significantly. Nighttime application of the melatonin receptor antagonist luzindole also altered M4 cells' rod/cone-driven light responses but in the opposite ways: the duration and amplitude of the graded depolarization were reduced, whereas the accompanying spiking increase was enhanced. These luzindole-induced changes confirmed that M4 cells are modulated by endogenous melatonin. Melatonin could induce the above effects by acting directly on M4 cells because immunohistochemistry detected MT1 receptors in these cells, although it could also act presynaptically. Interestingly, the daytime and nighttime recordings showed significant differences in resting membrane potential, spontaneous spike rate and rod/cone-driven light responses, suggesting that M4 cells are under circadian control. This is the first report of a circadian variation in ipRGCs' resting properties and synaptic input, and of melatoninergic modulation of ipRGCs.
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Affiliation(s)
- W Pack
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - D D Hill
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - K Y Wong
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States; Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, MI 48105, United States.
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15
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GluA2 trafficking is involved in apoptosis of retinal ganglion cells induced by activation of EphB/EphrinB reverse signaling in a rat chronic ocular hypertension model. J Neurosci 2015; 35:5409-21. [PMID: 25834064 DOI: 10.1523/jneurosci.4376-14.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
EphB1, expressed in Müller cells, and ephrinB2, expressed in both Müller cells and retinal ganglion cells (RGCs), constitute an EphB/ephrinB reverse signaling in RGCs. Whether and how this reverse signaling is involved in RGC apoptosis in a rat chronic ocular hypertension (COH) model was investigated. In the COH model, both EphB1 and ephrinB2 were significantly increased and the reverse signaling was activated, which was accompanied by increased protein levels of phosphorylated (p) src, GluA2, and p-GluA2. Intravitreal injection of EphB2-Fc, an activator of ephrinB2, induced an increase in TUNEL-positive signals in normal retinae. A coimmunoprecipitation assay demonstrated direct interactions among ephrinB2, p-src, and GluA2. Moreover, in COH rats the expression of GluA2 proteins on the surface of retinal cells was decreased. Such GluA2 endocytosis could be prevented by preoperational intravitreal injection of 4-amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo [3,4-d] pyrimidine (PP2), an inhibitor of src family tyrosine kinases, and possibly involved the protein interacting with C kinase 1 and phosphorylation of GluA2. In normal rats, intravitreal injection of EphB2-Fc caused changes in these protein levels similar to those observed in COH rats, which all could be avoided by preinjection of PP2. Patch-clamp experiments further showed that the current-voltage relationship of AMPA receptor-mediated EPSCs of RGCs exhibited stronger inward rectification in EphB2-Fc-injected rats. Furthermore, preinjection of PP2 or N-[3-[[4-[(3-aminopropyl)amino]butyl]amino]propyl]-1-naphthaleneacetamide trihydrochloride) (Naspm), a Ca(2+)-permeable GluA2-lacking AMPA receptor inhibitor, remarkably inhibited RGC apoptosis in either EphB2-Fc-injected or COH rats. Together, elevated GluA2 trafficking induced by activated EphB2/ephrinB2 reverse signaling likely contributes to RGC apoptosis in COH rats.
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16
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Tosches MA, Bucher D, Vopalensky P, Arendt D. Melatonin signaling controls circadian swimming behavior in marine zooplankton. Cell 2015; 159:46-57. [PMID: 25259919 PMCID: PMC4182423 DOI: 10.1016/j.cell.2014.07.042] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/07/2014] [Accepted: 07/25/2014] [Indexed: 12/29/2022]
Abstract
Melatonin, the "hormone of darkness," is a key regulator of vertebrate circadian physiology and behavior. Despite its ubiquitous presence in Metazoa, the function of melatonin signaling outside vertebrates is poorly understood. Here, we investigate the effect of melatonin signaling on circadian swimming behavior in a zooplankton model, the marine annelid Platynereis dumerilii. We find that melatonin is produced in brain photoreceptors with a vertebrate-type opsin-based phototransduction cascade and a light-entrained clock. Melatonin released at night induces rhythmic burst firing of cholinergic neurons that innervate locomotor-ciliated cells. This establishes a nocturnal behavioral state by modulating the length and the frequency of ciliary arrests. Based on our findings, we propose that melatonin signaling plays a role in the circadian control of ciliary swimming to adjust the vertical position of zooplankton in response to ambient light.
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Affiliation(s)
- Maria Antonietta Tosches
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
| | - Daniel Bucher
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany
| | - Pavel Vopalensky
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Detlev Arendt
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany.
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17
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Zhang Y, Li H, Pu Y, Gong S, Liu C, Jiang X, Tao J. Melatonin-mediated inhibition of Purkinje neuron P-type Ca²⁺ channels in vitro induces neuronal hyperexcitability through the phosphatidylinositol 3-kinase-dependent protein kinase C delta pathway. J Pineal Res 2015; 58:321-34. [PMID: 25707622 DOI: 10.1111/jpi.12218] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/20/2015] [Indexed: 12/18/2022]
Abstract
Although melatonin receptors are widely expressed in the mammalian central nervous system and peripheral tissues, there are limited data regarding the functions of melatonin in cerebellar Purkinje cells. Here, we identified a novel functional role of melatonin in modulating P-type Ca(2+) channels and action-potential firing in rat Purkinje neurons. Melatonin at 0.1 μm reversibly decreased peak currents (I(Ba)) by 32.9%. This effect was melatonin receptor 1 (MT(R1)) dependent and was associated with a hyperpolarizing shift in the voltage dependence of inactivation. Pertussis toxin pretreatment, intracellular application of QEHA peptide, and a selective antibody raised against the Gβ subunit prevented the inhibitory effects of melatonin. Pretreatment with phosphatidylinositol 3-kinase (PI3K) inhibitors abolished the melatonin-induced decrease in I(Ba). Surprisingly, melatonin responses were not regulated by Akt, a common downstream target of PI3K. Melatonin treatment significantly increased protein kinase C (PKC) activity 2.1-fold. Antagonists of PKC, but not of protein kinase A, abolished the melatonin-induced decrease in I(Ba). Melatonin application increased the membrane abundance of PKCδ, and PKCδ inhibition (either pharmacologically or genetically) abolished the melatonin-induced IBa response. Functionally, melatonin increased spontaneous action-potential firing by 53.0%; knockdown of MT(R1) and blockade of P-type channels abolished this effect. Thus, our results suggest that melatonin inhibits P-type channels through MT(R1) activation, which is coupled sequentially to the βγ subunits of G(i/o)-protein and to downstream PI3K-dependent PKCδ signaling. This likely contributes to its physiological functions, including spontaneous firing of cerebellar Purkinje neurons.
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Affiliation(s)
- Yuan Zhang
- Department of Neurobiology, Medical College of Soochow University, Suzhou, China; Department of Geriatrics and Institute of Neuroscience, The Second Affiliated Hospital of Soochow University, Suzhou, China
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18
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Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells. PLoS One 2015; 10:e0117967. [PMID: 25714375 PMCID: PMC4340921 DOI: 10.1371/journal.pone.0117967] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 12/15/2014] [Indexed: 12/15/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.
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19
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Wang XH, Wu Y, Yang XF, Miao Y, Zhang CQ, Dong LD, Yang XL, Wang Z. Cannabinoid CB1 receptor signaling dichotomously modulates inhibitory and excitatory synaptic transmission in rat inner retina. Brain Struct Funct 2014; 221:301-16. [DOI: 10.1007/s00429-014-0908-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/26/2014] [Indexed: 12/01/2022]
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20
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Paroni R, Terraneo L, Bonomini F, Finati E, Virgili E, Bianciardi P, Favero G, Fraschini F, Reiter RJ, Rezzani R, Samaja M. Antitumour activity of melatonin in a mouse model of human prostate cancer: relationship with hypoxia signalling. J Pineal Res 2014; 57:43-52. [PMID: 24786921 DOI: 10.1111/jpi.12142] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 04/25/2014] [Indexed: 01/08/2023]
Abstract
Melatonin is known to exert antitumour activity in several types of human cancers, but the underlying mechanisms as well as the efficacy of different doses of melatonin are not well defined. Here, we test the hypothesis whether melatonin in the nanomolar range is effective in exerting antitumour activity in vivo and examine the correlation with the hypoxia signalling mechanism, which may be a major molecular mechanism by which melatonin antagonizes cancer. To test this hypothesis, LNCaP human prostate cancer cells were xenografted into seven-wk-old Foxn1nu/nu male mice that were treated with melatonin (18 i.p. injections of 1 mg/kg in 41 days). Saline-treated mice served as control. We found that the melatonin levels in plasma and xenografted tissue were 4× and 60× higher, respectively, than in control samples. Melatonin tended to restore the redox imbalance by increasing expression of Nrf2. As part of the phenotypic response to these perturbations, xenograft microvessel density was less in melatonin-treated animals, indicative of lower angiogenesis, and the xenograft growth rate was slower (P < 0.0001). These changes were accompanied by a reduced expression of Ki67, elevated expression of HIF-1α and increased phosphorylation of Akt in melatonin than saline-treated mice. We conclude that the beneficial effect of melatonin in reducing cancer growth in vivo was evident at melatonin plasma levels as low as 4 nm and was associated with decreased angiogenesis. Higher HIF-1α expression in xenograft tissue indicates that the antitumour effect cannot be due to a postulated antihypoxic effect, but may stem from lower angiogenesis potential.
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Affiliation(s)
- Rita Paroni
- Department of Health Science, University of Milan, Milano, Italy
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21
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Corthell JT, Olcese J, Trombley PQ. Melatonin in the mammalian olfactory bulb. Neuroscience 2013; 261:74-84. [PMID: 24365461 DOI: 10.1016/j.neuroscience.2013.12.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 12/15/2013] [Indexed: 11/26/2022]
Abstract
Melatonin is a neurohormone associated with circadian rhythms. A diurnal rhythm in olfactory sensitivity has been previously reported and melatonin receptor mRNAs have been observed in the olfactory bulb, but the effects of melatonin in the olfactory bulb have not been explored. First, we corroborated data from a previous study that identified melatonin receptor messenger RNAs in the olfactory bulb. We then investigated whether melatonin treatment would affect cells in the olfactory bulbs of rats. Using a combination of polymerase chain reaction (PCR), quantitative PCR (qPCR), cell culture, and electrophysiology, we discovered that melatonin receptors and melatonin synthesis enzymes were present in the olfactory bulb and we observed changes in connexin43 protein, GluR1 mRNA, GluR2 mRNA, Per1 mRNA, Cry2 mRNA, and K(+) currents in response to 2-iodomelatonin. Via qPCR, we observed that messenger RNAs encoding melatonin receptors and melatonin biosynthesis enzymes fluctuated in the olfactory bulb across 24h. Together, these data show that melatonin receptors are present in the olfactory bulb and likely affect olfactory function. Additionally, these data suggest that melatonin may be locally synthesized in the olfactory bulb.
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Affiliation(s)
- J T Corthell
- Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL 32306, United States.
| | - J Olcese
- Florida State University, Department of Biomedical Sciences, Program in Neuroscience, Tallahassee, FL 32306, United States
| | - P Q Trombley
- Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL 32306, United States
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22
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Zhang CQ, Wu HJ, Wang SY, Yin S, Lu XJ, Miao Y, Wang XH, Yang XL, Wang Z. Suppression of outward K⁺ currents by WIN55212-2 in rat retinal ganglion cells is independent of CB1/CB2 receptors. Neuroscience 2013; 253:183-93. [PMID: 24013008 DOI: 10.1016/j.neuroscience.2013.08.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 08/25/2013] [Accepted: 08/26/2013] [Indexed: 10/26/2022]
Abstract
Cannabinoid CB1 receptor (CB1R) signaling system is extensively distributed in the vertebrate retina. Activation of CB1Rs regulates a variety of functions of retinal neurons through modulating different ion channels. In the present work we studied effects of this receptor signaling on K(+) channels in retinal ganglion cells by patch-clamp techniques. The CB1R agonist WIN55212-2 (WIN) suppressed outward K(+) currents in acutely isolated rat retinal ganglion cells in a dose-dependent manner, with an IC50 of 4.7 μM. We further showed that WIN mainly suppressed the tetraethylammonium (TEA)-sensitive K(+) current component. While CB1Rs were expressed in rat retinal ganglion cells, the WIN effect on K(+) currents was not blocked by either AM251/SR141716, specific CB1R antagonists, or AM630, a selective CB2R antagonist. Consistently, cAMP-protein kinase A (PKA) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathways were unlikely involved in the WIN-induced suppression of the K(+) currents because both PKA inhibitors H-89/Rp-cAMP and MAPK/ERK1/2 inhibitor U0126 failed to block the WIN effects. WIN-induced suppression of the K(+) currents was not observed when WIN was intracellularly applied. Furthermore, an endogenous ligand of the cannabinoid receptor anandamide, the specific CB1R agonist ACEA and the selective CB2R agonist CB65 also suppressed the K(+) currents, and the effects were not blocked by AM251/SR141716 or AM630 respectively. All these results suggest that the WIN-induced suppression of the outward K(+) currents in rat retinal ganglion cells, thereby regulating the cell excitability, were not through CB1R/CB2R signaling pathways.
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Affiliation(s)
- C-Q Zhang
- Institutes of Brain Science, Institute of Neurobiology and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
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23
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Huang H, Wang Z, Weng SJ, Sun XH, Yang XL. Neuromodulatory role of melatonin in retinal information processing. Prog Retin Eye Res 2013; 32:64-87. [PMID: 22986412 DOI: 10.1016/j.preteyeres.2012.07.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 12/15/2022]
Affiliation(s)
- Hai Huang
- Institute of Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, PR China
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24
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Role of melatonin and its receptors in the vertebrate retina. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 300:211-42. [PMID: 23273863 DOI: 10.1016/b978-0-12-405210-9.00006-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Melatonin is a chemical signal of darkness that is produced by retinal photoreceptors and pinealocytes. In the retina, melatonin diffuses from the photoreceptors to bind to specific receptors on a variety of inner retinal neurons to modify their activity. Potential target cells for melatonin in the inner retina are amacrine cells, bipolar cells, horizontal cells, and ganglion cells. Melatonin inhibits the release of dopamine from amacrine cells and increases the light sensitivity of horizontal cells. Melatonin receptor subtypes show differential, cell-specific patterns of expression that are likely to underlie differential functional modulation of specific retinal pathways. Melatonin potentiates rod signals to ON-type bipolar cells, via activation of the melatonin MT2 (Mel1b) receptor, suggesting that melatonin modulates the function of specific retinal circuits based on the differential distribution of its receptors. The selective and differential expression of melatonin receptor subtypes in cone circuits suggest a conserved function for melatonin in enhancing transmission from rods to second-order neurons and thus promote dark adaptation.
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25
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Group I mGluR-mediated inhibition of Kir channels contributes to retinal Müller cell gliosis in a rat chronic ocular hypertension model. J Neurosci 2012; 32:12744-55. [PMID: 22972998 DOI: 10.1523/jneurosci.1291-12.2012] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Müller cell gliosis, which is characterized by upregulated expression of glial fibrillary acidic protein (GFAP), is a universal response in many retinal pathological conditions. Whether down-regulation of inward rectifying K+ (Kir) channels, which commonly accompanies the enhanced GFAP expression, could contribute to Müller cell gliosis is poorly understood. We investigated changes of Kir currents, GFAP and Kir4.1 protein expression in Müller cells in a rat chronic ocular hypertension (COH) model, and explored the mechanisms underlying Müller cell gliosis. We show that Kir currents and Kir4.1 protein expression in Müller cells were reduced significantly, while GFAP expression was increased in COH rats, and these changes were eliminated by MPEP, a group I metabotropic glutamate receptors (mGluR I) subtype mGluR5 antagonist. In normal isolated Müller cells, the mGluR I agonist (S)-3,5-dihydroxyphenylglycine (DHPG) suppressed the Kir currents and the suppression was blocked by MPEP. The DHPG effect was mediated by the intracellular Ca2+ -dependent PLC/IP3-ryanodine/PKC signaling pathway, but the cAMP-PKA pathway was not involved. Moreover, intravitreal injection of DHPG in normal rats induced changes in Müller cells, similar to those observed in COH rats. The DHPG-induced increase of GFAP expression in Müller cells was obstructed by Ba2+, suggesting the involvement of Kir channels. We conclude that overactivation of mGluR5 by excessive extracellular glutamate in COH rats could contribute to Müller cell gliosis by suppressing Kir channels.
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Involvement of calpain/p35-p25/Cdk5/NMDAR signaling pathway in glutamate-induced neurotoxicity in cultured rat retinal neurons. PLoS One 2012; 7:e42318. [PMID: 22870316 PMCID: PMC3411656 DOI: 10.1371/journal.pone.0042318] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 07/03/2012] [Indexed: 11/19/2022] Open
Abstract
We investigated possible involvement of a calpain/p35-p25/cyclin-dependent kinase 5 (Cdk5) signaling pathway in modifying NMDA receptors (NMDARs) in glutamate-induced injury of cultured rat retinal neurons. Glutamate treatment decreased cell viability and induced cell apoptosis, which was accompanied by an increase in Cdk5 and p-Cdk5T15 protein levels. The Cdk5 inhibitor roscovitine rescued the cell viability and inhibited the cell apoptosis. In addition, the protein levels of both calpain 2 and calpain-specific alpha-spectrin breakdown products (SBDPs), which are both Ca2+-dependent, were elevated in glutamate-induced cell injury. The protein levels of Cdk5, p-Cdk5T15, calpain 2 and SBDPs tended to decline with glutamate treatments of more than 9 h. Furthermore, the elevation of SBDPs was attenuated by either D-APV, a NMDAR antagonist, or CNQX, a non-NMDAR antagonist, but was hardly changed by the inhibitors of intracellular calcium stores dantrolene and xestospongin. Moreover, the Cdk5 co-activator p35 was significantly up-regulated, whereas its cleaved product p25 expression showed a transient increase. Glutamate treatment for less than 9 h also considerably enhanced the ratio of the Cdk5-phosphorylated NMDAR subunit NR2A at Ser1232 site (p-NR2AS1232) and NR2A (p-NR2AS1232/NR2A), and caused a translocation of p-NR2AS1232 from the cytosol to the plasma membrane. The enhanced p-NR2AS1232 was inhibited by roscovitine, but augmented by over-expression of Cdk5. Calcium imaging experiments further showed that intracellular Ca2+ concentrations ([Ca2+]i) of retinal cells were steadily increased following glutamate treatments of 2 h, 6 h and 9 h. All these results suggest that the activation of the calpain/p35-p25/Cdk5 signaling pathway may contribute to glutamate neurotoxicity in the retina by up-regulating p-NR2AS1232 expression.
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Luo C, Gangadharan V, Bali KK, Xie RG, Agarwal N, Kurejova M, Tappe-Theodor A, Tegeder I, Feil S, Lewin G, Polgar E, Todd AJ, Schlossmann J, Hofmann F, Liu DL, Hu SJ, Feil R, Kuner T, Kuner R. Presynaptically localized cyclic GMP-dependent protein kinase 1 is a key determinant of spinal synaptic potentiation and pain hypersensitivity. PLoS Biol 2012; 10:e1001283. [PMID: 22427743 PMCID: PMC3302842 DOI: 10.1371/journal.pbio.1001283] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 01/30/2012] [Indexed: 12/23/2022] Open
Abstract
Electrophysiological and behavioral experiments in mice reveal that a cGMP-dependent kinase amplifies neurotransmitter release from peripheral pain sensors, potentiates spinal synapses, and leads to exaggerated pain. Synaptic long-term potentiation (LTP) at spinal neurons directly communicating pain-specific inputs from the periphery to the brain has been proposed to serve as a trigger for pain hypersensitivity in pathological states. Previous studies have functionally implicated the NMDA receptor-NO pathway and the downstream second messenger, cGMP, in these processes. Because cGMP can broadly influence diverse ion-channels, kinases, and phosphodiesterases, pre- as well as post-synaptically, the precise identity of cGMP targets mediating spinal LTP, their mechanisms of action, and their locus in the spinal circuitry are still unclear. Here, we found that Protein Kinase G1 (PKG-I) localized presynaptically in nociceptor terminals plays an essential role in the expression of spinal LTP. Using the Cre-lox P system, we generated nociceptor-specific knockout mice lacking PKG-I specifically in presynaptic terminals of nociceptors in the spinal cord, but not in post-synaptic neurons or elsewhere (SNS-PKG-I−/− mice). Patch clamp recordings showed that activity-induced LTP at identified synapses between nociceptors and spinal neurons projecting to the periaqueductal grey (PAG) was completely abolished in SNS-PKG-I−/− mice, although basal synaptic transmission was not affected. Analyses of synaptic failure rates and paired-pulse ratios indicated a role for presynaptic PKG-I in regulating the probability of neurotransmitter release. Inositol 1,4,5-triphosphate receptor 1 and myosin light chain kinase were recruited as key phosphorylation targets of presynaptic PKG-I in nociceptive neurons. Finally, behavioural analyses in vivo showed marked defects in SNS-PKG-I−/− mice in several models of activity-induced nociceptive hypersensitivity, and pharmacological studies identified a clear contribution of PKG-I expressed in spinal terminals of nociceptors. Our results thus indicate that presynaptic mechanisms involving an increase in release probability from nociceptors are operational in the expression of synaptic LTP on spinal-PAG projection neurons and that PKG-I localized in presynaptic nociceptor terminals plays an essential role in this process to regulate pain sensitivity. Pain is an important physiological function that protects our body from harm. Pain-sensing neurons, called nociceptors, transduce harmful stimuli into electrical signals and transmit this information to the brain via the spinal cord. When nociceptors are persistently activated, such as after injury, the connections they make with neurons in the spinal cord are altered in a process called synaptic long-term potentiation (LTP). In this study, we examine the molecular and cellular mechanisms of LTP at synapses from nociceptors onto spinal neurons. We use multiple experimental approaches in mice, from genetic to behavioural, to show that this form of LTP involves presynaptic events that unfold in nociceptors when they are repetitively activated. In particular, an enzyme activated by the second messenger cGMP, referred to as Protein Kinase G-I, phosphorylates presynaptic proteins and increases the release of neurotransmitters from nociceptor endings in the spinal cord. When we genetically silence Protein Kinase G-I or block its activation in nociceptors, inflammatory pain is markedly reduced at the behavioural level. These results clarify basic mechanisms of pathological pain and pave the way for new therapeutic approaches.
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Affiliation(s)
- Ceng Luo
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
- Institute of Neuroscience, Fourth Military Medical University, Xi'an, China
- * E-mail: (CL); (RK)
| | - Vijayan Gangadharan
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
- Molecular Medicine Partnership Unit of the European Molecular Biology Laboratory and the University of Heidelberg Medical Faculty, Heidelberg, Germany
| | - Kiran Kumar Bali
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
| | - Rou-Gang Xie
- Institute of Neuroscience, Fourth Military Medical University, Xi'an, China
| | - Nitin Agarwal
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
| | - Martina Kurejova
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
| | | | - Irmgard Tegeder
- Pharmazentrum Frankfurt, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Germany
| | - Susanne Feil
- Interfakultäres Institut für Biochemie, Universität Tübingen, Tübingen, Germany
| | - Gary Lewin
- Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Erika Polgar
- Spinal Cord Group, West Medical Building, University of Glasgow, Glasgow, United Kingdom
| | - Andrew J. Todd
- Spinal Cord Group, West Medical Building, University of Glasgow, Glasgow, United Kingdom
| | - Jens Schlossmann
- FOR 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, Munich, Germany
| | - Franz Hofmann
- FOR 923, Institut für Pharmakologie und Toxikologie, Technische Universität München, Munich, Germany
| | - Da-Lu Liu
- Institute of Neuroscience, Fourth Military Medical University, Xi'an, China
| | - San-Jue Hu
- Institute of Neuroscience, Fourth Military Medical University, Xi'an, China
| | - Robert Feil
- Interfakultäres Institut für Biochemie, Universität Tübingen, Tübingen, Germany
| | - Thomas Kuner
- Institute for Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Rohini Kuner
- Pharmacology Institute, University of Heidelberg, Heidelberg, Germany
- Molecular Medicine Partnership Unit of the European Molecular Biology Laboratory and the University of Heidelberg Medical Faculty, Heidelberg, Germany
- * E-mail: (CL); (RK)
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RGS2 and RGS4 modulate melatonin-induced potentiation of glycine currents in rat retinal ganglion cells. Brain Res 2011; 1411:1-8. [DOI: 10.1016/j.brainres.2011.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/08/2011] [Accepted: 07/05/2011] [Indexed: 11/18/2022]
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