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Kitcher SR, Pederson AM, Weisz CJC. Diverse identities and sites of action of cochlear neurotransmitters. Hear Res 2021; 419:108278. [PMID: 34108087 DOI: 10.1016/j.heares.2021.108278] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/30/2021] [Accepted: 05/18/2021] [Indexed: 11/18/2022]
Abstract
Accurate encoding of acoustic stimuli requires temporally precise responses to sound integrated with cellular mechanisms that encode the complexity of stimuli over varying timescales and orders of magnitude of intensity. Sound in mammals is initially encoded in the cochlea, the peripheral hearing organ, which contains functionally specialized cells (including hair cells, afferent and efferent neurons, and a multitude of supporting cells) to allow faithful acoustic perception. To accomplish the demanding physiological requirements of hearing, the cochlea has developed synaptic arrangements that operate over different timescales, with varied strengths, and with the ability to adjust function in dynamic hearing conditions. Multiple neurotransmitters interact to support the precision and complexity of hearing. Here, we review the location of release, action, and function of neurotransmitters in the mammalian cochlea with an emphasis on recent work describing the complexity of signaling.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Alia M Pederson
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Catherine J C Weisz
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States.
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Kanagawa E, Sugahara K, Hirose Y, Mikuriya T, Shimogori H, Yamashita H. Effects of substance P during the recovery of hearing function after noise-induced hearing loss. Brain Res 2014; 1582:187-96. [PMID: 25064433 DOI: 10.1016/j.brainres.2014.07.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 10/25/2022]
Abstract
Substance P (SP) is a widely distributed neurotransmitter in living tissues and is involved in various repair processes. We investigated the possibility that SP may ameliorate cochlear hair cell damage produced by noise exposure. The present study examined the effect of SP in protecting the cochlea from noise damage in guinea pigs exposed to noise after an infusion of SP into the inner ear. Changes in the hearing threshold (auditory brain response, ABR), number of synaptic ribbons, and the appearance of the outer hair cells after noise exposure were analyzed at 2 severity levels of noise-induced hearing loss. The moderate noise-induced hearing loss (110dB, 3h) group showed recovery in the ABR threshold over time, finally reaching a level slightly above pre-exposure levels, with only slight injury to the synaptic ribbons and minimal changes in the appearance of the outer hair cells. Our results indicated that in moderate hearing loss, SP exhibited a protective effect on the inner ear, both functionally and structurally. While the final magnitude of ABR threshold elevation was greater in severe noise-induced hearing loss, the synaptic ribbons and outer hair cells showed signs of severe damage.
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Affiliation(s)
- Eiju Kanagawa
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Kazuma Sugahara
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Yoshinobu Hirose
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takefumi Mikuriya
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Hiroaki Shimogori
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Hiroshi Yamashita
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan.
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Toyota H, Shimogori H, Sugahara K, Yamashita H. A novel treatment for vestibular disorder with FGLM-NH2 plus SSSR. Neurosci Lett 2012; 526:128-32. [DOI: 10.1016/j.neulet.2012.08.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/25/2012] [Accepted: 08/14/2012] [Indexed: 11/26/2022]
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Orita H, Shimogori H, Yamashita H. Unilateral intra-perilymphatic infusion of substance P enhances ipsilateral vestibulo-ocular reflex gains in the sinusoidal rotation test. Neurosci Lett 2008; 449:207-10. [PMID: 19022352 DOI: 10.1016/j.neulet.2008.11.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/25/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
Abstract
Previous studies have reported localization of substance P (SP) within the inner ear and that SP exists abundantly within vestibular endorgans. While SP's functional role in the inner ear remains unclear, SP can act as a neuromodulator in the CNS and directly influences neuronal excitability. We hypothesized that SP might influence neuronal excitability within the vestibular periphery. The present study used the sinusoidal rotation test to investigate the influence of SP after its local application in the guinea pig unilateral inner ear. A tiny hole was made adjacent to the round window in the right ears of Hartley white guinea pigs that had normal tympanic membranes and Preyer reflexes. An osmotic pump infused SP (10(-4)M, 10(-3)M, and 10(-2)M), neurokinin-1 (NK-1) receptor antagonist (10(-3)M) alone, or SP (10(-3)M)+NK-1 receptor antagonist (10(-3)M) through this hole, with rotation tests performed before, and 12h and 24h after the treatment. Results were used to calculate the vestibulo-ocular reflex (VOR) gains. After administration of 10(-3)M and 10(-2)M SP, significant increases in the VOR gains were noted at 12h after treatment, with these gains disappearing by 24h after treatment. This increase was not observed when there was simultaneous NK-1 receptor antagonist administration. There were also no changes in the VOR gains noted after administration of 10(-4)M SP or the NK-1 receptor antagonist alone. These results indicate the possibility that SP may act on vestibular endorgans as an excitatory factor via the NK-1 receptors.
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Affiliation(s)
- Hiroshi Orita
- Department of Otolaryngology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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Dulon D, Jagger DJ, Lin X, Davis RL. Neuromodulation in the Spiral Ganglion: Shaping Signals from the Organ of Corti to the CNS. J Membr Biol 2006; 209:167-75. [PMID: 16773500 DOI: 10.1007/s00232-005-0841-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Indexed: 11/25/2022]
Affiliation(s)
- D Dulon
- Laboratoire de Biologie Cellulaire et Moléculaire de l'Audition, Hôpital Pellegrin, INSERM et EA 3665 Université de Bordeaux 2, 33076, Bordeaux, France
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Sun W, Ding DL, Wang P, Sun J, Jin X, Salvi RJ. Substance P inhibits potassium and calcium currents in inner ear spiral ganglion neurons. Brain Res 2004; 1012:82-92. [PMID: 15158164 DOI: 10.1016/j.brainres.2004.03.051] [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] [Accepted: 03/26/2004] [Indexed: 10/26/2022]
Abstract
Substance P (SP), a member of the tachykinin family of neurotransmitters and neuromodulators, has been identified on spiral ganglion neurons (SGNs) in the inner ear; however, its high affinity receptor, neurokinin-1 (NK1), has not been identified and the physiological effects of SP on SGNs are not well understood. To address these issues, immunolabeling, RT-PCR, Western blots and whole-cell patch-clamp recordings were made from SGNs in P0-P5 mouse cochlear organotypic cultures. The NK1 receptor was detected on SGNs by immunocytochemistry, the protein was detected in cochlear tissues by Western blots, and the mRNA for the NK1 receptor was also found in cochlear tissues of postnatal mice (P2) by RT-PCR. Application of SP (1 to 25 microM) significantly increased the latency of SGN action potentials (APs) (mean increase 7.8 +/- 4 ms; 25 microM of SP), prolonged the duration of the action potential and made the resting potential (RP) more positive (mean 9.0 +/- 7 mV) relative to normal values (-54 +/- 6 mV). SP (1 to 25 microM) also suppressed voltage-activated potassium currents (IK+) and calcium currents (ICa2+). Puffing 25 microM of SP onto SGNs suppressed IK+ by 43 +/- 9% (n = 7) and ICa2+ by 40.6 +/- 5.6% (n = 7); both currents recovered when SP was washed out. A SP antagonist blocked the SP-induced suppression of IK+ and ICa2+. These results indicate that SP acting through NK1 receptors can have direct neuromodulatory effects on SGNs.
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Affiliation(s)
- Wei Sun
- Center for Hearing and Deafness, Hear. Res. Lab, SUNY University at Buffalo, 215 Parker Hall South Campus of UB, UB3435 Main Street, Buffalo, NY 14214, USA.
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Gong S, Ding J, Chang Q. The expression of VIP and SP in the cochlea of spontaneously hypertensive rats and its implication. Curr Med Sci 2004; 24:396-9. [PMID: 15587408 DOI: 10.1007/bf02861877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Indexed: 12/15/2022]
Abstract
To investigate the expression of vasoactive intestinal peptide (VIP) and substance P (SP) in the cochlea of spontaneously hypertensive rat (SHR), and to assess the function of VIP and SP in the cochlea following the damage of hypertension, hearing thresholds of ABR were observed and the fixative (4% paraformaldehyde) was pumped through the circulatory system. Adult Wistar rats (3 months, n=20) served as the control group and SHRs (3 months, n=20) as the hypertension group. Bullas were taken out and cochleas were irrigated in vitro with the same fixative. The number of base turn's spiral ganglions in the sections was counted. The expression of VIP and SP were detected by SABC method and the images of the sections were analyzed. The number of base turn's spiral ganglsons in the hypertension group was significantly less than in the normal group (P<0.01). VIP and SP were expressed in the spiral ganglion cytoplasma and stria vascularis of the two groups. There were no significant difference in the expression of VIP and SP in spiral ganglion cytoplasma (P>0.05) between the two groups. However, in stria vascularis the expression of VIP in the hypertension group was higher than in the normal group (P<0.05), and no significant difference in SP was found between the two groups. It was suggested that VIP not only contributed to the regulation of the cochlea microcirculation, but also made the neurotransmitter in the pathway of the auditory system. However, SP made only the neurotransmitter in the pathway of the auditory system.
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Affiliation(s)
- Shusheng Gong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Lallemend F, Lefebvre PP, Hans G, Rigo JM, Van de Water TR, Moonen G, Malgrange B. Substance P protects spiral ganglion neurons from apoptosis via PKC-Ca2+-MAPK/ERK pathways. J Neurochem 2003; 87:508-21. [PMID: 14511128 DOI: 10.1046/j.1471-4159.2003.02014.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the current study, we have investigated the ability of substance P (SP) to protect 3-day-old (P3) rat spiral ganglion neurons (SGNs) from trophic factor deprivation (TFD)-induced cell death. The presence of SP high affinity neurokinin-1 receptor (NK1) transcripts was detected in the spiral ganglion and the NK1 protein localized to SGNs both ex vivo and in vitro. Treatment with SP increased cytoplasmic Ca2+ in SGNs, further arguing for the presence of functional NK1 on these neurons. Both SP and the agonist [Sar9,Met(O2)11]-SP significantly decreased SGN cell death induced by TFD, with no effect on neurite outgrowth. The survival promoting effect of SP was blocked by the NK1 antagonist, WIN51708. Both pan-caspase inhibitor BOC-D-FMK and SP treatments markedly reduced activation of caspases and DNA fragmentation in trophic factor deprived-neurons. The neuroprotective action of SP was antagonised by specific inhibitors of second messengers, including 1.2-bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM) to chelate cytosolic Ca2+, the protein kinase C (PKC) inhibitors bisindolylmaleimide I, Gö6976 and LY333531 and the MAPK/ERK inhibitor U0126. In contrast, nifedipine, a specific inhibitor of l-type Ca2+ channel, and LY294002, a phosphatidylinositol-3-OH kinase (PI3K) inhibitor, had no effect on SP trophic support of SGNs. Moreover, activation of endogenous PKC by 4 beta-phorbol 12-myristate 13-acetate (PMA) also reduced the loss of trophic factor-deprived SGNs. Thus, NK1 expressed by SGNs transmit a survival-promoting regulatory signal during TFD-induced SGN cell death via pathways involving PKC activation, Ca2+ signalling and MAPK/ERK activation, which can be accounted for by an inhibition of caspase activation.
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Affiliation(s)
- F Lallemend
- Research Center for Cellular and Molecular Neurobiology, University of Liège, Belgium.
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Ito K, Rome C, Bouleau Y, Dulon D. Substance P mobilizes intracellular calcium and activates a nonselective cation conductance in rat spiral ganglion neurons. Eur J Neurosci 2002; 16:2095-102. [PMID: 12473077 DOI: 10.1046/j.1460-9568.2002.02292.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We demonstrate the expression of functional tachykinin receptors in rat spiral ganglion neurons (SGNs) using calcium signal measurement and whole-cell patch clamp recording. Substance P (SP; 10 microm, 1 s application) induced a transient increase in intracellular calcium. The SP dose-response study showed an EC50 of 18.8 microm and a Hill slope of 0.77. Comparison between specific agonists for the three tachykinin receptor (NKR) types showed the potency NKR3 > NKR1 > NKR2 at 10 microm. The Ca2+ response could be evoked in Ca2+-free medium and was blocked by N-ethylmaleimide and U-73122, indicating that Ca2+ was released from intracellular stores via a G-protein and phospholipase C pathway. Under whole-cell voltage clamp recording at a holding potential of -50 mV, SP (10 microm, 1 s) evoked a slowly developing transient inward current. The current reversed near to 0 mV and ionic permeability experiments revealed a cation nonselective conductance also permeable to large organic cations such as N-methyl-D-glucamine and tetraethylammonium. Neither removing extracellular calcium nor chelating intracellular calcium with 10 mm BAPTA could block the SP-evoked current. This conductance appeared coupled to G-protein activation as intracellular GDP-betaS blocked the SP-evoked current. Mutual desensitization and occlusion studies with acetylcholine and ATP showed that the SP-evoked conductance share effector channels and/or intracellular processes with the purinergic/cholinergic conductance. In SGNs, SP could have both a trophic action, via a calcium response, and a neuromodulatory role, by a depolarizing action through the activation of nonselective cation channels.
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Affiliation(s)
- Ken Ito
- Laboratoire de Biologie Cellulaire et Moléculaire de l'Audition, INSERM EMI 99-27, Université de Bordeaux 2, Hôpital Pellegrin Bat PQR, Bordeaux, France
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Abstract
In order to gain a better understanding of the neuronal and local control of inner ear blood flow, the vascular innervation to the rat cochlea and vestibular system was examined. Specimens were removed in toto beginning at the basilar artery extending to the anterior inferior cerebellar artery, labyrinthine artery, common cochlear artery, modiolar artery and anterior vestibular artery. When possible the vessels were dissected in continuity through the cribrose area. The vestibular endorgans were also removed. Specimens were examined using immunohistochemical techniques for the presence of vasoactive intestinal peptide, neuronal nitric oxide synthase, neuropeptide-Y, substance P and calcitonin gene related peptide. Results show that the vasculature to the cochlea and vestibular portion of the inner ear receive similar types of nonadrenergic innervation, that within the vestibular endorgans, only CGRP and SP were found in the neuroepithelium or in association with vessels, and that within the vestibular system, the majority of the vascular innervation appears to stop at or near the cribrose area. In the cochlea however, it extends to include the radiating arterioles. These findings suggest that cochlear blood flow is under finer control and that neuronally induced changes in blood flow may have a more global effect in the vestibular periphery.
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Affiliation(s)
- M J Lyon
- Department of Otolaryngology, SUNY Health Science Center, 750 East Adams Street, Syracuse, NY, USA.
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