Connectivity and ultrastructure of dopaminergic innervation of the inner ear and auditory efferent system of a vocal fish. Issue 9 (26th March 2017)

• Record Type: Journal Article
• Authors: Perelmuter, Jonathan T.; Forlano, Paul M.
• Is Part Of: Journal of comparative neurology. Volume 525:Issue 9(2017)
• Page Start: 2090
• Page End: 2108
• Publication Date: 2017-03-26
• Subjects: auditory efferents -- dopamine -- electron microscopy -- hearing -- immunohistochemistry -- RRID: AB_90650 -- RRID: AB_2201528 -- RRID: 22806 -- teleost; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.24177
• Languages: English
• ISSNs: 0021-9967

Abstract

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. Abstract : Using immuno‐TEM, the authors demonstrate, in a vocal fish, diencephalic dopaminergic neurons project to both the inner ear, where transmitter release appears paracrine, and the hindbrain auditory efferent nucleus, where synapses are diverse. The results suggest complex direct and indirect modulation of the peripheral auditory system in a nonmammalian vertebrate.