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Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults. Brain Res 2019; 1723:146398. [PMID: 31442412 DOI: 10.1016/j.brainres.2019.146398] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/09/2019] [Accepted: 08/19/2019] [Indexed: 01/21/2023]
Abstract
The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.
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Zou Y, Yi X, Zhang JG, Liu XF, Yang K, Kong YG, Xiao BK, Tao ZZ, Chen SM. Effect of transformer noise on the neurophysiology of SD rats. Exp Ther Med 2019; 17:3383-3390. [PMID: 30988715 PMCID: PMC6447807 DOI: 10.3892/etm.2019.7360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 01/24/2019] [Indexed: 11/24/2022] Open
Abstract
Transformer noise is a type of environmental sound that causes discomfort to individuals. The aim of the present study was to determine the effect of relatively long-term periods of transformer noise on the behavior and neurophysiology of SD rats. A total of 90 healthy SD rats with normal hearing were randomly divided into two experimental groups (65 and 60 dB group) and a control group. The experimental groups were exposed to recorded transformer noise for 8 weeks (sound level limits: 65 or 60 dB) and the control group was maintained under the same conditions without noise stimulation. Changes in physiological growth (weight tests), behavior (tail suspension and open field behavior tests) and neurophysiology (glutamate, γ-aminobutyric acid, dopamine, 5-hydroxytryptamine, the morphologies of hippocampi) following noise exposure were recorded and compared. The results revealed that rats exhibited normal physiological growth, with no significant difference between the experimental and control groups. Following noise exposure, no significant differences were observed in the results of behavioral experiments (tail suspension and open field behavior tests) between the experimental and control groups. In addition, there were no significant differences in glutamate, γ-aminobutyric acid, dopamine and 5-hydroxytryptamine levels or in the morphologies of hippocampi between groups. In conclusion, exposure to transformer noise with a sound level limit of 65 dB sound pressure level (SPL) or 60 dB SPL (spectral range, 100–800 Hz) for 8 weeks (10 h/day) had no significant impact on the behavior and neurophysiology of SD rats.
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Affiliation(s)
- You Zou
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Xing Yi
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Jian-Gong Zhang
- China Electric Power Research Institute, Wuhan, Hubei 430070, P.R. China
| | - Xing-Fa Liu
- China Electric Power Research Institute, Wuhan, Hubei 430070, P.R. China
| | - Kun Yang
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Yong-Gang Kong
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Bo-Kui Xiao
- Otolaryngology Head and Neck Surgery Institute, Medical School of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Ze-Zhang Tao
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China.,Otolaryngology Head and Neck Surgery Institute, Medical School of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Shi-Ming Chen
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China.,Otolaryngology Head and Neck Surgery Institute, Medical School of Wuhan University, Wuhan, Hubei 430060, P.R. China
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Carricondo F, Romero-Gómez B. The Cochlear Spiral Ganglion Neurons: The Auditory Portion of the VIII Nerve. Anat Rec (Hoboken) 2018; 302:463-471. [DOI: 10.1002/ar.23815] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/08/2017] [Accepted: 10/08/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Francisco Carricondo
- Laboratory of Neurobiology of Hearing, Dept. of Immunology, Ophthalmology and Otorhinolaryngology, Faculty of Medicine; Complutense University of Madrid (Spain)
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos" (IdISSC); Madrid Spain
| | - Bárbara Romero-Gómez
- Laboratory of Neurobiology of Hearing, Dept. of Immunology, Ophthalmology and Otorhinolaryngology, Faculty of Medicine; Complutense University of Madrid (Spain)
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos" (IdISSC); Madrid Spain
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Abstract
UNLABELLED The senses of hearing and balance are subject to modulation by efferent signaling, including the release of dopamine (DA). How DA influences the activity of the auditory and vestibular systems and its site of action are not well understood. Here we show that dopaminergic efferent fibers innervate the acousticolateralis epithelium of the zebrafish during development but do not directly form synapses with hair cells. However, a member of the D1-like receptor family, D1b, tightly localizes to ribbon synapses in inner ear and lateral-line hair cells. To assess modulation of hair-cell activity, we reversibly activated or inhibited D1-like receptors (D1Rs) in lateral-line hair cells. In extracellular recordings from hair cells, we observed that D1R agonist SKF-38393 increased microphonic potentials, whereas D1R antagonist SCH-23390 decreased microphonic potentials. Using ratiometric calcium imaging, we found that increased D1R activity resulted in larger calcium transients in hair cells. The increase of intracellular calcium requires Cav1.3a channels, as a Cav1 calcium channel antagonist, isradipine, blocked the increase in calcium transients elicited by the agonist SKF-38393. Collectively, our results suggest that DA is released in a paracrine fashion and acts at ribbon synapses, likely enhancing the activity of presynaptic Cav1.3a channels and thereby increasing neurotransmission. SIGNIFICANCE STATEMENT The neurotransmitter dopamine acts in a paracrine fashion (diffusion over a short distance) in several tissues and bodily organs, influencing and regulating their activity. The cellular target and mechanism of the action of dopamine in mechanosensory organs, such as the inner ear and lateral-line organ, is not clearly understood. Here we demonstrate that dopamine receptors are present in sensory hair cells at synaptic sites that are required for signaling to the brain. When nearby neurons release dopamine, activation of the dopamine receptors increases the activity of these mechanosensitive cells. The mechanism of dopamine activation requires voltage-gated calcium channels that are also present at hair-cell synapses.
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Valdés-Baizabal C, Soto E, Vega R. Dopaminergic modulation of the voltage-gated sodium current in the cochlear afferent neurons of the rat. PLoS One 2015; 10:e0120808. [PMID: 25768433 PMCID: PMC4359166 DOI: 10.1371/journal.pone.0120808] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 02/06/2015] [Indexed: 11/19/2022] Open
Abstract
The cochlear inner hair cells synapse onto type I afferent terminal dendrites, constituting the main afferent pathway for auditory information flow. This pathway receives central control input from the lateral olivocochlear efferent neurons that release various neurotransmitters, among which dopamine (DA) plays a salient role. DA receptors activation exert a protective role in the over activation of the afferent glutamatergic synapses, which occurs when an animal is exposed to intense sound stimuli or during hypoxic events. However, the mechanism of action of DA at the cellular level is still not completely understood. In this work, we studied the actions of DA and its receptor agonists and antagonists on the voltage-gated sodium current (INa) in isolated cochlear afferent neurons of the rat to define the mechanisms of dopaminergic control of the afferent input in the cochlear pathway. Experiments were performed using the voltage and current clamp techniques in the whole-cell configuration in primary cultures of cochlear spiral ganglion neurons (SGNs). Recordings of the INa showed that DA receptor activation induced a significant inhibition of the peak current amplitude, leading to a significant decrease in cell excitability. Inhibition of the INa was produced by a phosphorylation of the sodium channels as shown by the use of phosphatase inhibitor that produced an inhibition analogous to that caused by DA receptor activation. Use of specific agonists and antagonists showed that inhibitory action of DA was mediated both by activation of D1- and D2-like DA receptors. The action of the D1- and D2-like receptors was shown to be mediated by a Gαs/AC/cAMP/PKA and Gαq/PLC/PKC pathways respectively. These results showed that DA receptor activation constitutes a significant modulatory input to SGNs, effectively modulating their excitability and information flow in the auditory pathway.
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Affiliation(s)
| | - Enrique Soto
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Rosario Vega
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
- * E-mail:
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Niu X, Tahera Y, Canlon B. Environmental enrichment to sound activates dopaminergic pathways in the auditory system. Physiol Behav 2007; 92:34-9. [PMID: 17631367 DOI: 10.1016/j.physbeh.2007.05.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Environmental enrichment to sound stimulation, in the adult, can promote physiological changes and protection against trauma in the auditory peripheral and central nervous system. Sound enrichment, or sound conditioning is a method that utilizes a low-level, non-damaging acoustic stimulus as a protective agent. Pre-treating subjects to a moderate or low-level acoustic stimulus reduces the damaging effects of a subsequent traumatic stimulus. The intention of this review is to describe how environmental enrichment to sound affords protection against a subsequent trauma, and the role that the dopaminergic pathways in the cochlea and the auditory brainstem play in this protection. Dopamine is released from the lateral efferents and exerts a tonic inhibition of auditory nerve activity thus preserving auditory sensitivity and protecting against excitotoxicity. Sound conditioning up-regulated tyrosine hydroxylase in the lateral efferents under the inner hair cells and acoustic trauma reduced these levels. Thus, sound conditioning triggers an up-regulation of tyrosine hydroxylase both in the lateral efferent of cochlea and in the lateral superior olivary complex. These findings expand our understanding of the neurochemical balance and regulation between the lateral olivocochlear neurons and the lateral efferent terminals in the cochlea during sound stimulation.
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Affiliation(s)
- Xianzhi Niu
- Karolinska Institutet, Department of Physiology and Pharmacology, Stockholm, Sweden
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8
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Niu X, Canlon B. The signal transduction pathway for the dopamine D1 receptor in the guinea-pig cochlea. Neuroscience 2006; 137:981-90. [PMID: 16330149 DOI: 10.1016/j.neuroscience.2005.10.044] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 09/28/2005] [Accepted: 10/07/2005] [Indexed: 11/24/2022]
Abstract
Dopamine released from lateral efferent fibers modulates the activity of the auditory nerve, but the signaling mechanism by which this is mediated is not known. The present study investigated the signal transduction pathway for the dopamine D1 receptor in the guinea-pig cochlea. D1 receptor immunolabeling was localized to the spiral ganglia neurons and at the base of the inner hair cells. Western immunoblotting on whole cochlear preparations revealed positive bands for the D1 receptor and for dopamine and the cyclic AMP-regulated phosphoprotein. The amplitude of the compound action potential was enhanced in the presence of the D1 receptor agonist, SKF 38393, an effect that was abolished by H89, a protein kinase A inhibitor. Conversely, SKF 83566, a D1 receptor antagonist decreased the amplitude of compound action potential, while forskolin, a protein kinase A activator prevented this effect. Furthermore, it was found that the level of glutamate receptor 1 phosphorylation at the protein kinase A site (Ser845) was increased by the D1 agonist, but decreased by D1 antagonist. Our results provide evidence that the D1 receptor is localized in the spiral ganglion neurons as well as the nerve endings under the inner hair cells and they can modulate auditory nerve function. One signal transduction pathway of D1 receptor in the auditory nerve is via protein kinase A-mediated glutamate receptor 1 phosphorylation.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/analogs & derivatives
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Action Potentials/drug effects
- Action Potentials/physiology
- Animals
- Blotting, Western
- Cochlea/physiology
- Cochlear Nerve/physiology
- Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Dopamine Agonists/pharmacology
- Dopamine and cAMP-Regulated Phosphoprotein 32/metabolism
- Female
- Guinea Pigs
- Immunohistochemistry
- Isoquinolines/pharmacology
- Male
- Oxidopamine
- Perfusion
- Receptors, AMPA/metabolism
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/physiology
- Signal Transduction/physiology
- Sulfonamides/pharmacology
- Sympathectomy, Chemical
- Sympatholytics
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Affiliation(s)
- X Niu
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
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9
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Halmos G, Doleviczényi Z, Répássy G, Kittel A, Vizi ES, Lendvai B, Zelles T. D2 autoreceptor inhibition reveals oxygen-glucose deprivation-induced release of dopamine in guinea-pig cochlea. Neuroscience 2005; 132:801-9. [PMID: 15837140 DOI: 10.1016/j.neuroscience.2005.01.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2005] [Indexed: 11/29/2022]
Abstract
Dopamine (DA), released from the lateral olivocochlear (LOC) efferent terminals, the efferent arm of the short-loop feedback in the cochlea, is considered as a protective factor in the inner ear since it inhibits auditory nerve dendrite firing in ischemia- or noise-induced excitotoxicity leading to sensorineural hearing loss (SNHL). In the present study we investigated the effect of oxygen-glucose deprivation (OGD), an in vitro ischemia model, on guinea-pig cochlear [(3)H]DA release in a microvolume superfusion system. We found that OGD alone failed to induce a detectable elevation of [(3)H]DA level, but in the presence of specific D(2) receptor antagonists, sulpiride and L-741,626, it evoked a significant increase in the extracellular concentration of [(3)H]DA. D(2) negative feedback receptors are involved not exclusively in the regulation of synthesis and vesicular release of DA, but also in the activation of its reuptake. Thus, D(2) receptor antagonism interferes with the powerful reuptake of DA from the extracellular space. To explore the underlying mechanism of this DA-releasing effect we applied nomifensine and found that the effect of OGD on cochlear DA release in the presence of D(2) antagonists could be inhibited by this selective DA uptake inhibitor. This finding indicates that the OGD-evoked DA release was mainly mediated through the reverse operation of the DA transporter. The two structurally different D(2) antagonists also augmented the electrical field stimulation-evoked release of DA proving the presence of D(2) autoreceptors on dopaminergic LOC terminals. Our results confirm the presence and role of D(2) DA autoreceptors in the regulation of DA release from LOC efferents, and suggest a protective local mechanism during ischemia which involves the direct transporter-mediated release of DA. Increasing the release of the protective transmitter DA locally in the inner ear may form the basis of future new therapeutic strategies in patients suffering from SNHL.
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Affiliation(s)
- G Halmos
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, H-1083 Budapest, Hungary
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10
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Niu X, Tahera Y, Canlon B. Protection against Acoustic Trauma by Forward and Backward Sound Conditioning. Audiol Neurootol 2004; 9:265-73. [PMID: 15316199 DOI: 10.1159/000080226] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2003] [Accepted: 01/12/2004] [Indexed: 11/19/2022] Open
Abstract
The purpose of the present study was to determine if short-term sound conditioning provides protection when delivered either before (forward sound conditioning) or after (backward sound conditioning) a traumatic exposure in the guinea pig. Two different sound conditioning paradigms were studied (1 kHz, 81 dB SPL, 24 h; 6.3 kHz, 78 dB SPL, 24 h). The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) protected distortion product otoacoustic emissions (DPOAEs) against a short-duration acoustic trauma (2.7 kHz, 103 dB SPL, 5 min) compared to the group exposed to the acoustic trauma alone. The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) also protected both the auditory brainstem response (ABR) thresholds and DPOAEs against a longer-duration acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The group exposed to the acoustic trauma alone showed ABR threshold shifts between 15 and 24 dB, and DPOAE amplitude shifts between 11 and 24 dB, while the group with 1-kHz forward sound conditioning showed statistically significant protection at all ABR frequencies and at all DPOAE frequencies. The 1-kHz backward sound conditioning paradigm protected against acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The ABR thresholds were protected at 1, 2 and 4 kHz, and DPOAEs at all frequencies (except 8 kHz) when compared to the group exposed only to the acoustic trauma. The 6.3-kHz forward sound conditioning paradigm protected against acoustic trauma (5.5 kHz, 109 dB SPL, 30 min) at 6.3, 8 and 10 kHz. The 6.3-kHz backward sound conditioning paradigm showed no protection against acoustic trauma at any DPOAE frequency. Taken together, these findings are important for understanding how the auditory system can be modulated by acoustic stimulation and highlights the importance of the acoustic environment during the recovery process of the auditory system.
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Affiliation(s)
- Xianzhi Niu
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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11
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Niu X, Bogdanovic N, Canlon B. The distribution and the modulation of tyrosine hydroxylase immunoreactivity in the lateral olivocochlear system of the guinea-pig. Neuroscience 2004; 125:725-33. [PMID: 15099686 DOI: 10.1016/j.neuroscience.2004.02.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 10/26/2022]
Abstract
It was previously shown that tyrosine hydroxylase (TH) immunoreactivity in the terminals of the lateral efferents of the cochlea is decreased by acoustic trauma and that sound preconditioning counteracted this decrease [Hear Res 174 (2002) 124]. Here we identify those neurons in the lateral olivocochlear system (LOC) in the brainstem that regulates the peripheral expression of TH in the cochlea. By employing retrograde tracing techniques, dextran-labeled neurons were found predominantly in the ipsilateral LOC system including lateral superior olive (LSO), and the surrounding periolivary regions (dorsal periolivary nucleus [DPO], dorsolateral periolivary nucleus [DLPO], lateral nucleus of trapezoid body [LNTB]). Employing immunocytochemistry, it was found that a control group had 35% of the ipsilateral LOC neurons positively stained with TH. Of the total population of TH neurons, 77% were double-stained (TH and dextran) in the LOC system. Acoustic trauma decreased the number of TH positive neurons in the LSO and the surrounding DLPO, and caused a reduction of TH fiber immunolabeling in these regions. Changes were not found in the DPO or the LNTB after acoustic trauma. Sound conditioning protected against the decrease of TH immunolabeling by acoustic trauma and increased the fiber staining for TH in the LSO and DLPO, but not in the DPO or the LNTB. These results provide evidence that TH positive neurons are present in the LOC system in the guinea-pig. It is now demonstrated that protection against acoustic trauma by sound conditioning has a central component that is governed by TH in the LSO and the surrounding periolivary DLPO region.
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Affiliation(s)
- X Niu
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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12
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Vicente-Torres MA, Dávila D, Bartolomé MV, Carricondo F, Gil-Loyzaga P. Biochemical evidence for the presence of serotonin transporters in the rat cochlea. Hear Res 2003; 182:43-7. [PMID: 12948600 DOI: 10.1016/s0378-5955(03)00140-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cochlear serotonergic innervation is constituted by efferent fibers projecting both to the area below the inner and the outer hair cells. Previous detection of serotonin (5-HT) metabolites and 5-HT receptor mRNAs suggests the existence of serotonergic synaptic activity in the cochlea. The present study explores this possibility through the effect of 6-nitroquipazine (6-NQ), a 5-HT selective reuptake inhibitor, on the basal turnover of 5-HT. The concentrations of 5-HT and its metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) were quantified by high performance liquid chromatography with electrochemical detection in blood-free cochleae of rats treated with 6-NQ or saline and kept under silent conditions. Treatment with 6-NQ induced a significant increase of the cochlear concentration of 5-HT and a significant reduction of 5-HIAA concentration with respect to saline treatment. These findings could indicate that 6-NQ induced the blockade of the 5-HT selective reuptake to the cochlear serotonergic fibers. This suggests that plasma membrane 5-HT transporters are present in cochlear serotonergic fibers. Even though the role of serotonergic innervation on cochlear physiology remains unknown, the existence of cochlear serotonergic synaptic activity is strongly supported by present contributions.
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Affiliation(s)
- M Angeles Vicente-Torres
- Department of Surgery II (ORL), Faculty of Medicine, University Complutense of Madrid, Madrid, Spain
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13
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Abstract
Preconditioning to sound is a well-documented strategy to provide protections against a subsequent acoustic trauma. In the present study, preconditioning (1.0 kHz tone at 81 dB sound pressure level (SPL) for 24 h) protected ABR thresholds by 17-28 dB from an acoustic trauma (2.7 kHz, 103 dB SPL, 30 min) that resulted in a temporary threshold shift. The protection afforded by sound conditioning was shown to be blocked by the administration of 6-hydroxydopamine which disrupts tyrosine hydroxylase in the nerve terminals of the lateral efferent fibers. Furthermore, tyrosine hydroxylase immunoreactivity was up-regulated both by sound conditioning alone, and by the combined treatment of sound conditioning and acoustic trauma. In contrast, acoustic trauma alone resulted in a reduction in tyrosine hydroxylase immunoreactivity compared to unexposed controls. These findings are the first demonstration that tyrosine hydroxylase in the lateral efferents are up-regulated during sound conditioning and suggests a role for the lateral efferent system in protecting against acoustic trauma by sound conditioning.
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Affiliation(s)
- Xianzhi Niu
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
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14
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Vicente-Torres MA, Gil-Loyzaga P, Carricondo F, Bartolomé MV. Simultaneous HPLC quantification of monoamines and metabolites in the blood-free rat cochlea. J Neurosci Methods 2002; 119:31-6. [PMID: 12234632 DOI: 10.1016/s0165-0270(02)00151-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Monoamine quantification in peripheral sensory receptors, such as the cochlea, is of major interest since monoamines could play a role in neurotransmission. A three-step biochemical protocol was developed to analyze monoamine content within the cochlea. Removal of the blood by aortic perfusion was carried out with an anticoagulant solution prior to the dissection of the cochlea from the temporal bone. The cochlear monoamines and some of their metabolites were then quantified, from homogenated cochlear tissue, by a new application of high performance liquid chromatography coupled to electrochemical detection. This method demonstrated enough sensitivity to detect norepinephrine (NE), dopamine (DA), serotonin (5-HT) and some of their metabolites (3,4-dihydroxyphenylacetic acid, DOPAC; homovanillic acid, HVA; and 5-hydroxyindole-3-acetic acid, 5-HIAA). Furthermore, it enabled the demonstration of noise-induced changes in the cochlear concentrations of NE, DA, DOPAC and HVA. In addition, the aortic perfusion allowed removal of the blood-borne 5-HT from the cochlea without inducing systemic alterations or monoamine degradation, as shown by the absence of effects on NE, DA, DOPAC, HVA or 5-HIAA concentrations. The present methodology may constitute a useful strategy to analyze monoamine turnover in the cochlea and other peripheral sensory receptors.
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Affiliation(s)
- Maria Angeles Vicente-Torres
- Center for Cell Culture (CAI) and Department of Surgery II (ORL), Medicine Faculty, University Complutense of Madrid, 28040 Madrid, Spain
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15
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Vicente-Torres MA, Muñoz E, Dávila D, Gil-Loyzaga P. Changes in the cochlear dopaminergic system of the aged rat. Brain Res 2001; 917:112-7. [PMID: 11602235 DOI: 10.1016/s0006-8993(01)02931-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The levels of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) have been quantified in cochleae of male and female rats aged 3, 6, 9, 12, 19 and 24 months. Animals were exposed for 1 h, under general anesthesia, to: (1) silence (basal conditions) or (2) white noise at 90 dB SPL. Afterwards, the concentrations of DA, DOPAC and HVA were determined by HPLC with electrochemical detection in homogenates of individual cochleae. In basal conditions, the cochlear concentrations of DA, DOPAC and HVA in aged females were higher than in adult ones. The concentrations of DA and DOPAC were also higher in aged males with respect to adult ones. A decrease in DA and an increase in DOPAC and HVA concentrations, with respect to silence, were detected when adult animals were exposed to noise. Meanwhile, aged animals showed either a noise-induced increase or no modification of DA and DOPAC with respect to basal levels. Present results suggest age-related failures in DA release and metabolizing mechanisms within the cochlea, together with a compensatory DA synthesis increase. However, the possibility of an initial damage in the primary auditory neurons which could also stimulate the synthesis of DA must not be excluded. Present age-related changes could indicate that the cochlear dopaminergic innervation is affected during the aging process. Since this innervation plays an important role in both the modulation and the protection of the primary auditory neurons, its metabolic alteration could profoundly modify the auditory process.
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Affiliation(s)
- M A Vicente-Torres
- Center of Cell Culture (CAI-UCM) Faculty of Medicine, Complutense University of Madrid, 28080 Madrid, Spain
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16
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Pujol R, Puel JL. Excitotoxicity, synaptic repair, and functional recovery in the mammalian cochlea: a review of recent findings. Ann N Y Acad Sci 1999; 884:249-54. [PMID: 10842598 DOI: 10.1111/j.1749-6632.1999.tb08646.x] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Besides its fast excitatory properties, glutamate is known to have neurotoxic properties when released in large amounts or when incompletely recycled. This so-called excitotoxicity is involved in a number of acute and/or degenerative forms of neuropathology such as epilepsy, Alzheimer's, Parkinson's, stroke, and retinal ischemia. In the cochlea, excitotoxicity may occur in two pathological conditions: anoxia and noise trauma. It is characterized by a two-step mechanism: (1) An acute swelling, which primarily depends on the AMPA/kainate type of receptors, together with a disruption of the postsynaptic structures (type I afferent dendrites) resulting in a loss of function. Within the next 5 days, synaptic repair may be observed with a full or a partial (acoustic trauma) recovery of cochlear potentials. (2) The second phase of excitotoxicity, which may develop after strong and/or repetitive injury, consists of a cascade of metabolic events triggered by the entry of Ca2+, which leads to neuronal death in the spiral ganglion. Ongoing experiments in animals, tracking the molecular basis of both these processes, presages the development of new pharmacological strategies to help neurites to regrow and reconnect properly to the IHCs, and to prevent or delay neuronal death in the spiral ganglion. Human applications should follow, and a local (transtympanic) strategy against cochlear excitotoxicity may, in the near future, prove to be helpful in ischemic- or noise-induced sudden deafness, as well as in the related tinnitus.
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Affiliation(s)
- R Pujol
- INSERM, Montpellier, France.
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Vicente-Torres MA, Gil-Loyzaga P. Noise stimulation decreases the concentration of norepinephrine in the rat cochlea. Neurosci Lett 1999; 266:217-9. [PMID: 10465712 DOI: 10.1016/s0304-3940(99)00305-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study was designed to analyze, by using high performance liquid chromatography (HPLC), the effect of acoustic stimulation on the cochlear concentration of norepinephrine (NE). Independently of the rat strain (Long-Evans or Wistar strains), NE concentration decreased about 18% when animals were exposed to white noise (90 dB SPL for 1 h). The same decrease was observed in animals perfused by aortic pathway to remove the blood, indicating that this decrease corresponds exclusively to a neurophysiological process. In fact, these findings could indicate that noise stimulation is involved in the NE release from sympathetic fibers innervating the cochlea. This likely release of NE supports that sympathetic fibers play a functional role in cochleae exposed to noisy situations.
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Affiliation(s)
- M A Vicente-Torres
- Centro de Cultivos Celulares (CAI) and Departamento de Cirugia II (ORL), Facultad de Medicina, Universidad Complutense de Madrid, Spain
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18
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Gáborján A, Lendvai B, Vizi ES. Neurochemical evidence of dopamine release by lateral olivocochlear efferents and its presynaptic modulation in guinea-pig cochlea. Neuroscience 1999; 90:131-8. [PMID: 10188940 DOI: 10.1016/s0306-4522(98)00461-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this study, using an in vitro superfusion technique for the first time, we provide direct neurochemical evidence of the transmitter role of dopamine at the level of lateral olivocochlear efferent fibres of the guinea-pig cochlea. Our results revealed that nerve terminals are able to take up and release dopamine upon axonal stimulation. Since dopamine is thought to protect the afferent nerve fibres from damage due to acoustic trauma or ischaemia, enhancement of the release of dopamine, a potential therapeutic site of these injuries, was investigated. Positive modulation of dopamine release has been shown by a D1 dopamine receptor agonist, an antagonist and piribedil. Furthermore, negative feedback on the stimulation-evoked release of dopamine via D2 dopamine receptors has been excluded. Electrical stimulation of the cochlear tissue produced a significant and reproducible release of [3H]dopamine, which could be blocked by tetrodotoxin (1 microM) and cadmium (100 microM), proving that axonal activity releases dopamine and its dependence on Ca2+ influx verifies its neuronal origin. Nomifensine, a high-affinity dopamine uptake blocker, prevented the tissue from taking up [3H]dopamine from the bathing solution, also indicating the neural origin of dopamine released in response to stimulation. SKF-38393 (a selective D1 agonist) increased both the resting and electrically evoked release of dopamine. Piribedil (a D3/D2/D1 agonist), a drug under investigation, known to prevent acoustic trauma or ischaemia-induced hearing loss, had a similar and concentration-dependent increasing effect on both resting and evoked release of dopamine. The effect of both drugs on stimulation-evoked release could be prevented by SKF-83566 (a selective D1 antagonist). However, SKF-83566 alone enhanced the resting and axonal conduction-associated release of dopamine. D2 agonists and antagonists failed to modulate the release of dopamine, indicating the lack of negative feedback modulation of dopamine release. Our results suggest that the release of dopamine was subjected to modulation by a D1 receptor agonist and an antagonist. In addition, it is concluded that D2 receptors are not involved in the modulation of dopamine release. This observation may have clinical relevance in the prevention or therapy of particular types of hearing loss, because enhanced dopaminergic input into the primary auditory neuron may inhibit the (over)excitation of this neuron by glutamatergic input from inner hair cells.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/analogs & derivatives
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Axons/physiology
- Bromocriptine/pharmacology
- Cadmium Chloride/pharmacology
- Calcium Signaling
- Cochlea/drug effects
- Cochlea/innervation
- Cochlea/metabolism
- Cochlear Nucleus/drug effects
- Cochlear Nucleus/metabolism
- Dopamine/metabolism
- Dopamine Agonists/pharmacology
- Dopamine Antagonists/pharmacology
- Dopamine D2 Receptor Antagonists
- Dopamine Uptake Inhibitors/pharmacology
- Drug Interactions
- Efferent Pathways/drug effects
- Efferent Pathways/metabolism
- Feedback
- Guinea Pigs
- Male
- Models, Neurological
- Neuroprotective Agents/pharmacology
- Nomifensine/pharmacology
- Olivary Nucleus/drug effects
- Olivary Nucleus/metabolism
- Piribedil/pharmacology
- Quinpirole/pharmacology
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/physiology
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D3
- Receptors, Presynaptic/drug effects
- Sulpiride/pharmacology
- Tetrodotoxin/pharmacology
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Affiliation(s)
- A Gáborján
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences and Haynal Imre University of Health Sciences, Budapest
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19
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Gil-Loyzaga P, Vicente-Torres MA, Arce A, Cardinali DP, Esquifino A. Effect of superior cervical ganglionectomy on catecholamine concentration in rat cochlea. Brain Res 1998; 779:53-7. [PMID: 9473584 DOI: 10.1016/s0006-8993(97)01077-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Both noradrenergic and dopaminergic nerve terminals have been described in the cochlea. The present report focused on the effect of superior cervical ganglionectomy (SCGx) on monoamine concentration in adult rat cochlea. In homogenates of whole cochleas, we measured the concentrations of norepinephrine (NE), dopamine (DA) and its main metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), by HPLC coupled to electrochemical detection. Measurements were carried out 4 h, 24 h or 6 days after unilateral SCGx. Most of the NE (approximately 82%) was lost after sympathectomy on the ipsilateral side, indicating that the principal localization of cochlear NE is in peripheral sympathetic fibers. Since about 18% of NE remained detectable 6 days after SCGx, a second origin of cochlear noradrenergic fibers may exist. Cochlear concentrations of DA or its metabolites did not change after SCGx. Therefore, DA and NE are located in two different populations of fibers within the cochlea, and are presumably related to distinct functional roles.
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Affiliation(s)
- P Gil-Loyzaga
- Centro de Cultivos Celulares (CAI), Departamento de Cirugía II (ORL), Universidad Complutense de Madrid, Spain
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20
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Oestreicher E, Arnold W, Ehrenberger K, Felix D. Dopamine regulates the glutamatergic inner hair cell activity in guinea pigs. Hear Res 1997; 107:46-52. [PMID: 9165346 DOI: 10.1016/s0378-5955(97)00023-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recent immunocytochemical and biochemical studies support a possible neurotransmitter function of dopamine (DA) in the efferent olivocochlear innervation of the guinea pig cochlea. However, the physiological role of DA in cochlear neurotransmission remains unknown. In the present study microiontophoretic techniques were used for testing the action of DA as well as D1- and D2-agonists and -antagonists on spontaneous and N-methyl-D-aspartic acid (NMDA)-, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-, kainic acid- or glutamate-induced firing of afferent fibres in the dendritic region of inner hair cells. Subsynaptic spike activities of anaesthetised guinea pigs were recorded after exposing the third or fourth turn of the cochlea for electrode penetration. Application of DA alone had very little effect on the spontaneous afferent firing rate. In contrast, firing induced by NMDA or AMPA could be depressed by additional administration of DA in a dose-dependent manner. A similar reduction of the induced spike activity was seen after co-administration of D1- or D2-agonists. The action of DA on glutamate agonist-induced firing could be blocked by D1- as well as D2-antagonists. These results show that DA can depress the activated firing rate of the afferent fibres and that this action is mediated by both D1- and D2-receptor subtypes.
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Affiliation(s)
- E Oestreicher
- Division of Neurobiology, University of Berne, Switzerland
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Karadaghy AA, Lasak JM, Chomchai JS, Khan KM, Drescher MJ, Drescher DG. Quantitative analysis of dopamine receptor messages in the mouse cochlea. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1997; 44:151-6. [PMID: 9030711 DOI: 10.1016/s0169-328x(96)00261-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dopamine receptor isoforms were examined in the cochlea of the CBA(J) mouse by RT-PCR analysis and nucleotide sequencing, utilizing primers specific for known dopamine receptor isoforms. Cochlear cDNA sequences corresponding to dopamine D2(long) and D3 receptors were amplified, whereas those representing D1A, D1B, D2(short), and D4 were not detected. Utilizing quantitative competitive PCR analysis, relative levels of dopamine receptor transcripts were found to be 0.002, 0.014, 0.016, and 1.000 for D2(long) cochlea, D3 cochlea, D3 brain, and D2(long) brain, respectively. In the context of previously published findings, the current work provides key quantitative evidence necessary to establish that dopamine is a neurotransmitter in the auditory inner ear.
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Affiliation(s)
- A A Karadaghy
- Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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22
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Gil-Loyzaga P, Vicente-Torres MA, García-Bonacho M, Esquifino A. Presence of catecholamines and serotonin in the rat vestibule. Brain Res 1997; 746:265-8. [PMID: 9037505 DOI: 10.1016/s0006-8993(96)01258-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The concentrations of norepinephrine (NE), dopamine (DA) and its metabolites DOPAC and HVA, and serotonin (5-HT) and its metabolite 5-HIAA, were quantified in the rat vestibule. For this purpose, homogenates of vestibules, of albino and pigmented rats, were analyzed using HPLC with electrochemical detection. Vestibules of pigmented rats showed higher DOPAC and HVA concentrations than those of albino rats, and male pigmented rats also showed significantly more DA than male albino rats. These results could indicate that the rate of DA metabolism in vestibules was higher in pigmented than in albino rats. The vestibular concentrations of NE and 5-HT did not differ significantly between the two strains. In contrast, 5-HIAA concentration was higher in vestibules of pigmented rats than in those of albino rats, suggesting an increased 5-HT metabolism for the former strain. Differences in monoamine concentrations between the two sexes o the same strain were scarce. Only, a higher HVA concentration in vestibules of females could indicate a higher DA metabolism.
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Affiliation(s)
- P Gil-Loyzaga
- Centro de Cultivos Celulares (CA1), Facultad de Medicina, Universidad Complutense de Madrid, Spain
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Gil-Loyzaga PE. Neurotransmitters of the olivocochlear lateral efferent system: with an emphasis on dopamine. Acta Otolaryngol 1995; 115:222-6. [PMID: 7610809 DOI: 10.3109/00016489509139296] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The olivocochlear lateral efferent system (OLES) of the adult mammalian cochlea uses variety of neuroactive substances, such as acetyl choline, GABA, dopamine (DA), enkephalins, dynorphins and CGRP. These neuroactive substances have been located within the efferent, small and dense matrix, fibers and terminals of the inner spiral and tunnel bundles. However, some of these neuroactive substances have also been found outside the OLES. Acetyl choline and CGRP, for instance, appear within the olivocochlear medial efferent fibers, and DA and CGRP may also be present in the perivascular innervation. A special case is GABA innervation at the apical coil, where nerve fibers containing GABA also make synapses with OHCs bodies. All these substances of the OLES could be involved in a highly selective filter modulating the activity of primary afferent fibers. For instance, sound stimulation results in an increase of cochlear DA turnover, indicating the release of DA from OLES fibers. DA probably acts on D-2 receptors since the administration of piribedil, a D-2 agonist, results in blocking of noise effects, while D-1 receptor stimulation does not modify cochlear DA turnover induced by noise. Therefore, DA could play an important role in the modulation and noise-protection of cochlear primary afferents. During cochlear development, all the aforementioned neuroactive substances appear a long time before the onset of hearing (evidenced by the recording of cochlear compound action potential and microphonic potentials). Thus, they may act during development on the late reorganization and plasticity on the afferent and efferent fibers. Moreover, the positive neurotrophic effect observed in cultured cochlear neurons, with GABA or glutamate, add new support to that hypothesis.
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Affiliation(s)
- P E Gil-Loyzaga
- Laboratory of Sensory Neurobiology, University Cell Culture Center, Faculty of Medicine, University of Madrid, Spain
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