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Mehranpour M, Azimi H, Abdollahifar MA, Moghaddam MH, Eskandari N, Vakili K, Fathi M, Peyvandi AA, Aliaghaei A. Tramadol-induced apoptosis in auditory hair cells of adult male rats. J Chem Neuroanat 2022; 126:102172. [DOI: 10.1016/j.jchemneu.2022.102172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 10/15/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
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2
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Vega R, García-Garibay O, Soto E. Opioid receptor activation modulates the calcium current in the cochlear outer hair cells of the rat. Eur J Neurosci 2022; 56:3543-3552. [PMID: 35501117 DOI: 10.1111/ejn.15682] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/10/2022] [Accepted: 04/25/2022] [Indexed: 12/01/2022]
Abstract
Previous works showed that opioid peptides are produced by olivocochlear efferent neurons, while cochlear hair cells express opioid receptors. It has been proposed that opioids protect the auditory system from damage by intense stimulation, although their use for therapeutic or illicit purposes links to hearing impairment. Therefore, it is relevant to study the effect of opioids in the auditory system to define their functional expression and mechanism of action. This study investigated the modulation of the Ca2+ currents by opioid peptides in the rat outer hair cells (OHC) using the whole-cell patch-clamp technique. The influence of agonists of the three opioid receptor subtypes (μ, δ, and κ) was studied. The κ opioid receptor agonist U-50488 inhibits the Ca2+ currents in a partially reversible form. Coincidently, norbinaltorphimine (a κ receptor antagonist) blocked the U-50488 inhibitory effect on the Ca2+ current. The δ- and the μ opioid receptor agonists did not significantly affect the Ca2+ currents. These results indicate that the κ opioid receptor activation inhibits the Ca2+ current in OHC, modulating the intracellular Ca2+ concentration when OHCs depolarize. The modulation of the auditory function by opioids constitutes a relevant mechanism with a potential role in the physiopathology of auditory disturbances.
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Affiliation(s)
- Rosario Vega
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, México
| | | | - Enrique Soto
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, México
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Ramírez T, Soto E, Vega R. Opioid modulation of cochlear auditory responses in the rat inner ear. Synapse 2019; 74:e22128. [DOI: 10.1002/syn.22128] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Teresa Ramírez
- Instituto de Fisiología Benemérita Universidad Autónoma de Puebla Puebla Mexico
| | - Enrique Soto
- Instituto de Fisiología Benemérita Universidad Autónoma de Puebla Puebla Mexico
| | - Rosario Vega
- Instituto de Fisiología Benemérita Universidad Autónoma de Puebla Puebla Mexico
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Imam MZ, Kuo A, Ghassabian S, Smith MT. Progress in understanding mechanisms of opioid-induced gastrointestinal adverse effects and respiratory depression. Neuropharmacology 2017; 131:238-255. [PMID: 29273520 DOI: 10.1016/j.neuropharm.2017.12.032] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 02/06/2023]
Abstract
Opioids evoke analgesia through activation of opioid receptors (predominantly the μ opioid receptor) in the central nervous system. Opioid receptors are abundant in multiple regions of the central nervous system and the peripheral nervous system including enteric neurons. Opioid-related adverse effects such as constipation, nausea, and vomiting pose challenges for compliance and continuation of the therapy for chronic pain management. In the post-operative setting opioid-induced depression of respiration can be fatal. These critical limitations warrant a better understanding of their underpinning cellular and molecular mechanisms to inform the design of novel opioid analgesic molecules that are devoid of these unwanted side-effects. Research efforts on opioid receptor signalling in the past decade suggest that differential signalling pathways and downstream molecules preferentially mediate distinct pharmacological effects. Additionally, interaction among opioid receptors and, between opioid receptor and non-opioid receptors to form signalling complexes shows that opioid-induced receptor signalling is potentially more complicated than previously thought. This complexity provides an opportunity to identify and probe relationships between selective signalling pathway specificity and in vivo production of opioid-related adverse effects. In this review, we focus on current knowledge of the mechanisms thought to transduce opioid-induced gastrointestinal adverse effects (constipation, nausea, vomiting) and respiratory depression.
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Affiliation(s)
- Mohammad Zafar Imam
- Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Andy Kuo
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Sussan Ghassabian
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Maree T Smith
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, Faculty of Health and Behavioural Sciences, The University of Queensland, Brisbane, QLD, Australia.
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Manohar S, Dahar K, Adler HJ, Dalian D, Salvi R. Noise-induced hearing loss: Neuropathic pain via Ntrk1 signaling. Mol Cell Neurosci 2016; 75:101-12. [PMID: 27473923 DOI: 10.1016/j.mcn.2016.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 06/30/2016] [Accepted: 07/25/2016] [Indexed: 12/18/2022] Open
Abstract
Severe noise-induced damage to the inner ear leads to auditory nerve fiber degeneration thereby reducing the neural input to the cochlear nucleus (CN). Paradoxically, this leads to a significant increase in spontaneous activity in the CN which has been linked to tinnitus, hyperacusis and ear pain. The biological mechanisms that lead to an increased spontaneous activity are largely unknown, but could arise from changes in glutamatergic or GABAergic neurotransmission or neuroinflammation. To test this hypothesis, we unilaterally exposed rats for 2h to a 126dB SPL narrow band noise centered at 12kHz. Hearing loss measured by auditory brainstem responses exceeded 55dB from 6 to 32kHz. The mRNA from the exposed CN was harvested at 14 or 28days post-exposure and qRT-PCR analysis was performed on 168 genes involved in neural inflammation, neuropathic pain and glutamatergic or GABAergic neurotransmission. Expression levels of mRNA of Slc17a6 and Gabrg3, involved in excitation and inhibition respectively, were significantly increased at 28days post-exposure, suggesting a possible role in the CN spontaneous hyperactivity associated with tinnitus and hyperacusis. In the pain and inflammatory array, noise exposure upregulated mRNA expression levels of four pain/inflammatory genes, Tlr2, Oprd1, Kcnq3 and Ntrk1 and decreased mRNA expression levels of two more genes, Ccl12 and Il1β. Pain/inflammatory gene expression changes via Ntrk1 signaling may induce sterile inflammation, neuropathic pain, microglial activation and migration of nerve fibers from the trigeminal, cuneate and vestibular nuclei into the CN. These changes could contribute to somatic tinnitus, hyperacusis and otalgia.
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Affiliation(s)
- Senthilvelan Manohar
- Center for Hearing & Deafness, State University of New York at Buffalo, Buffalo, NY 14214, United States.
| | - Kimberly Dahar
- Center for Hearing & Deafness, State University of New York at Buffalo, Buffalo, NY 14214, United States
| | - Henry J Adler
- Center for Hearing & Deafness, State University of New York at Buffalo, Buffalo, NY 14214, United States
| | - Ding Dalian
- Center for Hearing & Deafness, State University of New York at Buffalo, Buffalo, NY 14214, United States
| | - Richard Salvi
- Center for Hearing & Deafness, State University of New York at Buffalo, Buffalo, NY 14214, United States
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Wu C, Sharma K, Laster K, Hersi M, Torres C, Lukas TJ, Moore EJ. Kcnq1-5 (Kv7.1-5) potassium channel expression in the adult zebrafish. BMC PHYSIOLOGY 2014; 14:1. [PMID: 24555524 PMCID: PMC4016485 DOI: 10.1186/1472-6793-14-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 02/11/2014] [Indexed: 12/21/2022]
Abstract
BACKGROUND KCNQx genes encode slowly activating-inactivating K+ channels, are linked to physiological signal transduction pathways, and mutations in them underlie diseases such as long QT syndrome (KCNQ1), epilepsy in adults (KCNQ2/3), benign familial neonatal convulsions in children (KCNQ3), and hearing loss or tinnitus in humans (KCNQ4, but not KCNQ5). Identification of kcnqx potassium channel transcripts in zebrafish (Danio rerio) remains to be fully characterized although some genes have been mapped to the genome. Using zebrafish genome resources as the source of putative kcnq sequences, we investigated the expression of kcnq1-5 in heart, brain and ear tissues. RESULTS Overall expression of the kcnqx channel transcripts is similar to that found in mammals. We found that kcnq1 expression was highest in the heart, and also present in the ear and brain. kcnq2 was lowest in the heart, while kcnq3 was highly expressed in the brain, heart and ear. kcnq5 expression was highest in the ear. We analyzed zebrafish genomic clones containing putative kcnq4 sequences to identify transcripts and protein for this highly conserved member of the Kcnq channel family. The zebrafish appears to have two kcnq4 genes that produce distinct mRNA species in brain, ear, and heart tissues. CONCLUSIONS We conclude that the zebrafish is an attractive model for the study of the KCNQ (Kv7) superfamily of genes, and are important to processes involved in neuronal excitability, cardiac anomalies, epileptic seizures, and hearing loss or tinnitus.
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Affiliation(s)
| | | | | | | | | | | | - Ernest J Moore
- Department of Molecular Pharmacology & Biological Chemistry, Northwestern University, Chicago, IL 60611, USA.
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Tongjaroenbuangam W, Jongkamonwiwat N, Phansuwan-Pujito P, Casalotti SO, Forge A, Dodson H, Govitrapong P. Relationship of opioid receptors with GABAergic neurons in the rat inferior colliculus. Eur J Neurosci 2006; 24:1987-94. [PMID: 17040471 DOI: 10.1111/j.1460-9568.2006.05098.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The inferior colliculus is a critical structure for processing auditory information and receives ascending and descending synaptic auditory projections. In addition to GABAergic and glutamatergic innervations, other neurotransmitter systems are also reported in the inferior colliculus, including opioid peptides. In the present study, the relative distribution of each type of opioid receptor, mu (MOR), delta (DOR) and kappa (KOR) within GABAergic neurons in the inferior colliculus was examined. GABA immunoreactivity was expressed by small, medium and large neurons and distributed in the central nucleus and the pericentral nucleus of the inferior colliculus. Immunostaining for MOR, DOR and KOR receptors was found in both disc-shaped cells and stellate cells. Punctiform beta-endorphin immunolabelling was observed in the proximity of GABA-positive neurons. Co-localization of GABA and MOR receptors was observed in neurons and nerve terminals in the central nucleus, dorsal cortex and external cortex of the inferior colliculus. Quantification of the co-localization patterns determined that a higher proportion of GABA neurons was associated with MOR receptors compared with KOR or DOR receptors.
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Affiliation(s)
- W Tongjaroenbuangam
- Neuro-Behavioral Biology Center, Institute of Science and Technology for Research and Development, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
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Jongkamonwiwat N, Phansuwan-Pujito P, Casalotti SO, Forge A, Dodson H, Govitrapong P. The existence of opioid receptors in the cochlea of guinea pigs. Eur J Neurosci 2006; 23:2701-11. [PMID: 16817873 DOI: 10.1111/j.1460-9568.2006.04810.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several independent investigations have demonstrated the presence of opioid peptides in the inner ear organ of Corti and in particular in the efferent nerve fibers innervating the cochlear hair cells. However, the precise innervation pattern of opioid fibers remains to be investigated. In the present study the expression of opioid receptors and their peptides is demonstrated in young adult guinea pig cochlea. Opioid receptors are mainly expressed in hair cells of the organ of Corti and in inner and outer spiral bundles with different characteristics for each type of receptor. Co-localization studies were employed to compare the distribution of mu-, delta- and kappa-opioid receptors and their respective peptides, beta-endorphin, leu-enkephalin and dynorphin. Additionally, immunostaining of synaptophysin was used in this study to identify the presynaptic site. Immunoreactivity for enkephalin and dynorphin was found in the organ of Corti. Leu-enkephalin was co-localized with synaptophysin prominently in the inner spiral bundle (ISB). Dynorphin was co-localized with synaptophysin in both inner and outer spiral bundles. Delta-opioid receptor was most prominently co-localized with its peptide in the ISB bundle. Kappa-opioid receptor was seemingly present with dynorphin in both inner and outer spiral bundles. The co-staining of both peptides and receptors with synaptophysin in the same areas suggests that some of the opioid receptors may act as auto-receptors. The results provide further evidence that opioids may function as neurotransmitters or neuromodulators in the cochlea establishing the basis for further electrophysiological and pharmacological investigations to understand better the roles of the opioid system in auditory function.
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MESH Headings
- Animals
- Cochlea/innervation
- Cochlea/metabolism
- Dynorphins/metabolism
- Enkephalin, Leucine/metabolism
- Guinea Pigs
- Immunohistochemistry
- Male
- Microscopy, Confocal
- RNA, Messenger/analysis
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Synaptophysin/metabolism
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Affiliation(s)
- Nopporn Jongkamonwiwat
- Neuro-Behavioural Biology Center, Institute of Science and Technology for Research and Development, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
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Tongjaroenbungam W, Jongkamonwiwat N, Cunningham J, Phansuwan-Pujito P, Dodson HC, Forge A, Govitrapong P, Casalotti SO. Opioid modulation of GABA release in the rat inferior colliculus. BMC Neurosci 2004; 5:31. [PMID: 15353008 PMCID: PMC517931 DOI: 10.1186/1471-2202-5-31] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 09/07/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication. RESULTS Using a perfusion protocol we demonstrate that morphine can inhibit KCl-induced release of [3H]GABA from rat inferior colliculus slices. DAMGO ([D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin) but not DADLE ([D-Ala2, D-Leu5]-enkephalin or U69593 has the same effect as morphine indicating that micro rather than delta or kappa opioid receptors mediate this action. [3H]GABA release was diminished by 16%, and this was not altered by the protein kinase C inhibitor bisindolylmaleimide I. Immunostaining of inferior colliculus cryosections shows extensive staining for glutamic acid decarboxylase, more limited staining for micro opiate receptors and relatively few neurons co-stained for both proteins. CONCLUSION The results suggest that micro-opioid receptor ligands can modify neurotransmitter release in a sub population of GABAergic neurons of the inferior colliculus. This could have important physiological implications in the processing of hearing information and/or other functions attributed to the inferior colliculus such as audiogenic seizures and aversive behaviour.
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Affiliation(s)
| | - Nopporn Jongkamonwiwat
- Neuro-Behavioural Biology Centre, Mahidol University Salaya Nakorn Pathom 73170 Thailand
| | - Joanna Cunningham
- Department of Vision and Ophthalmology, King's College London, St. Thomas' Hospital, London, UK
| | | | - Hilary C Dodson
- UCL Centre for Auditory Research, University College London, 330 Grays Inn Road London WCIX 8EE UK
| | - Andrew Forge
- UCL Centre for Auditory Research, University College London, 330 Grays Inn Road London WCIX 8EE UK
| | - Piyarat Govitrapong
- Neuro-Behavioural Biology Centre, Mahidol University Salaya Nakorn Pathom 73170 Thailand
- Center for Neuroscience and Department of Pharmacology, Faculty of Science, Bangkok, Thailand
| | - Stefano O Casalotti
- UCL Centre for Auditory Research, University College London, 330 Grays Inn Road London WCIX 8EE UK
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