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Fulop DB, Humli V, Szepesy J, Ott V, Reglodi D, Gaszner B, Nemeth A, Szirmai A, Tamas L, Hashimoto H, Zelles T, Tamas A. Hearing impairment and associated morphological changes in pituitary adenylate cyclase activating polypeptide (PACAP)-deficient mice. Sci Rep 2019; 9:14598. [PMID: 31601840 PMCID: PMC6787024 DOI: 10.1038/s41598-019-50775-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 09/17/2019] [Indexed: 12/18/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a regulatory and cytoprotective neuropeptide, its deficiency implies accelerated aging in mice. It is present in the auditory system having antiapoptotic effects. Expression of Ca2+-binding proteins and its PAC1 receptor differs in the inner ear of PACAP-deficient (KO) and wild-type (WT) mice. Our aim was to elucidate the functional role of PACAP in the auditory system. Auditory brainstem response (ABR) tests found higher hearing thresholds in KO mice at click and low frequency burst stimuli. Hearing impairment at higher frequencies showed as reduced ABR wave amplitudes and latencies in KO animals. Increase in neuronal activity, demonstrated by c-Fos immunolabeling, was lower in KO mice after noise exposure in the ventral and dorsal cochlear nuclei. Noise induced neuronal activation was similar in further relay nuclei of the auditory pathway of WT and KO mice. Based on the similar inflammatory and angiogenic protein profile data from cochlear duct lysates, neither inflammation nor disturbed angiogenesis, as potential pathological components in sensorineural hearing losses, seem to be involved in the pathomechanism of the presented functional and morphological changes in PACAP KO mice. The hearing impairment is probably concomitant with the markedly accelerated aging processes in these animals.
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Affiliation(s)
- Daniel Balazs Fulop
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary
| | - Viktoria Humli
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Judit Szepesy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Virag Ott
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary
| | - Dora Reglodi
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary
| | - Balazs Gaszner
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary
| | - Adrienn Nemeth
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary.,Department of Otorhinolaryngology, University of Pecs Medical School, Pecs, Hungary
| | - Agnes Szirmai
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Budapest, Hungary
| | - Laszlo Tamas
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Budapest, Hungary
| | - Hitoshi Hashimoto
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan.,Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Suita, Osaka, Japan.,Division of Bioscience, Institute for Datability Science, Osaka University, Suita, Osaka, Japan
| | - Tibor Zelles
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary. .,Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
| | - Andrea Tamas
- Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, University of Pecs Medical School, Pecs, Hungary.
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Zhang J, Zhang X. Electrical stimulation of the dorsal cochlear nucleus induces hearing in rats. Brain Res 2009; 1311:37-50. [PMID: 19941837 DOI: 10.1016/j.brainres.2009.11.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 11/11/2009] [Accepted: 11/12/2009] [Indexed: 10/20/2022]
Abstract
Auditory brainstem implants (ABIs) restore hearing by electrical stimulation of the cochlear nucleus (CN). Depending on the physiological condition, duration of the pre-existing deafness, extent of damage to the CN, and the number of channels accessible to the tonotopic frequency gradients of the CN, ABIs improve speech understanding to varying degrees. Although the ventral cochlear nucleus, a mainstream auditory structure, has been considered a logic target for ABI stimulation, it is not yet clear how the dorsal cochlear nucleus (DCN) contributes to patients' hearing during ABI stimulation. To better understand the mechanisms underlying ABIs, we tested if electrical stimulation of the rat DCN induces hearing using a novel electrical prepulse inhibition (ePPI) of startle reflex behavior model. Our results showed that bipolar electrical stimulation of all channels in the DCN induced behavioral manifestation of hearing and that electrical stimulation of certain channels in the DCN induced robust neural activity in auditory cortex channels that responded to acoustic stimulation and demonstrated well-defined frequency tuning curves. This suggests that the DCN plays an important role in electrical hearing and should be further pursued in designing new ABIs. The novel ePPI behavioral paradigm may potentially be developed into an efficient method for testing hearing in animals with an implantable prosthesis.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, 5E-UHC, Wayne State University School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA.
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Cervera-Paz FJ, Saldaña E, Manrique M. A Model for Auditory Brain Stem Implants: Bilateral Surgical Deafferentation of the Cochlear Nuclei in the Macaque Monkey. Ear Hear 2007; 28:424-33. [PMID: 17485991 DOI: 10.1097/aud.0b013e31804793d9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Patients with extensive bilateral lesions of the auditory nerve have a profound and irreversible sensorineural hearing loss (SNHL), which can only be overcome with individually-fitted auditory brain stem implants that directly stimulate the cochlear nuclei. Despite the enormous potential of this increasingly applied treatment, the auditory performance of many implanted patients is limited, and the variability between cases hinders a complete understanding of the role played by the multiple parameters related to the efficacy of the implant. OBJECTIVES To mimic the condition of patients who have bilateral lesions of the auditory nerve, we developed an experimental model of bilateral deafferentation of the cochlear nuclei by surgical transection of the cochlear nerves of adult primates. MATERIALS AND METHODS We performed bilateral transection of the cochlear nerves of six adult, healthy, male captive-bred macaques (Macaca fascicularis). Before surgery, brain stem auditory evoked potentials were recorded. The histological material obtained from these animals was compared with similarly processed sections from seven macaques with intact cochlear nerves. The surgical technique, similar to that used in human neuro-otology, combined a labyrinthectomy and a neurectomy of the cochlear nerves, and caused deafness. We analyzed immunocytochemically the expression in cochlear nerve fibers of neurofilaments (SMI-32), and cytosolic calcium binding proteins calretinin, parvalbumin and calbindin, and also applied a histochemical reaction for acetylcholinesterase. RESULTS None of the primates had any major complications due to the surgical procedure. The lesions produced massive anterograde degeneration of the cochlear nerves, evidenced by marked gliosis and by loss of both type I fibers (which in this species are immunoreactive for calretinin, parvalbumin and neurofilaments) and type II fibers (which are acetylcholinesterase positive). The model of surgical transection described herein causes extensive damage to the cochlear nerves while leaving the cochlea intact, thus mimicking the condition of patients with profound SNHL due to bilateral cochlear nerve degeneration. CONCLUSIONS The phylogenetic proximity of primates to humans, and the paramount advantage of close anatomical and physiological similarities, allowed us to use the same surgical technique applied to human patients, and to perform a thorough evaluation of the consequences of neurectomy. Thus, bilateral surgical deafferentation of the macaque cochlear nuclei may constitute an advantageous model for study of auditory brain stem implants.
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Izzo AD, Suh E, Pathria J, Walsh JT, Whitlon DS, Richter CP. Selectivity of neural stimulation in the auditory system: a comparison of optic and electric stimuli. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:021008. [PMID: 17477715 DOI: 10.1117/1.2714296] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Pulsed, mid-infrared lasers were recently investigated as a method to stimulate neural activity. There are significant benefits of optically stimulating nerves over electrically stimulating, in particular the application of more spatially confined neural stimulation. We report results from experiments in which the gerbil auditory system was stimulated by optical radiation, acoustic tones, or electric current. Immunohistochemical staining for the protein c-FOS revealed the spread of excitation. We demonstrate a spatially selective activation of neurons using a laser; only neurons in the direct optical path are stimulated. This pattern of c-FOS labeling is in contrast to that after electrical stimulation. Electrical stimulation leads to a large, more spatially extended population of labeled, activated neurons. In the auditory system, optical stimulation of nerves could have a significant impact on the performance of cochlear implants, which can be limited by the electric current spread.
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Affiliation(s)
- Agnella D Izzo
- Northwestern University, Biomedical Engineering, 2145 Sheridan Road, Tech E310, Evanston, Illinois 60208, USA
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