title: Connectivity and ultrastructure of dopaminergic innervation of the inner ear and auditory efferent system of a vocal fish.
abstract: Dopamine (DA) is a conserved modulator of vertebrate neural circuitry, yet our knowledge of its role in peripheral auditory processing is limited to mammals. The present study combines immunohistochemistry, neural tract tracing, and electron microscopy to investigate the origin and synaptic characteristics of DA fibers innervating the inner ear and the hindbrain auditory efferent nucleus in the plainfin midshipman, a vocal fish that relies upon the detection of mate calls for reproductive success. We identify a DA cell group in the diencephalon as a common source for innervation of both the hindbrain auditory efferent nucleus and saccule, the main hearing endorgan of the inner ear. We show that DA terminals in the saccule contain vesicles but transmitter release appears paracrine in nature, due to the apparent lack of synaptic contacts. In contrast, in the hindbrain, DA terminals form traditional synaptic contacts with auditory efferent neuronal cell bodies and dendrites, as well as unlabeled axon terminals, which, in turn, form inhibitory-like synapses on auditory efferent somata. Our results suggest a distinct functional role for brain-derived DA in the direct and indirect modulation of the peripheral auditory system of a vocal nonmammalian vertebrate.
authors.affiliation: Program in Behavioral and Cognitive Neuroscience, The Graduate Center, City University of New York, New York, New York, 10016.|Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, 11210.
authors.forename: Jonathan T
authors.identifier: http://orcid.org/0000-0001-9785-8211
authors.initials: JT
authors.lastname: Perelmuter
authors.affiliation: Program in Behavioral and Cognitive Neuroscience, The Graduate Center, City University of New York, New York, New York, 10016.|Program in Ecology, Evolutionary Biology and Behavior, The Graduate Center, City University of New York, New York, New York, 10016.|Program in Neuroscience, The Graduate Center, City University of New York, New York, New York, 10016.|Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, 11210.|Aquatic Research and Environmental Assessment Center, Brooklyn College, Brooklyn NY, New York, 11210.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Forlano
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001306:Auditory Pathways / Q000502:physiology* / Q000648:ultrastructure*; D002795:Choline O-Acetyltransferase / Q000378:metabolism / Q000648:ultrastructure; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000502:physiology* / Q000648:ultrastructure*; D007758:Ear, Inner / Q000166:cytology* / Q000648:ultrastructure; D005399:Fishes / Q000033:anatomy & histology; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000596:Amino Acids; C098463:dolaisoleucine; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase; D002795:Choline O-Acetyltransferase
keywords: RRID: 22806; RRID: AB_2201528; RRID: AB_90650; auditory efferents; dopamine; electron microscopy; hearing; immunohistochemistry; teleost