Dopaminergic Signaling in the Cochlea: Receptor Expression Patterns and Deletion Phenotypes

• DOI: 10.1523/jneurosci.4720-11.2012
• Publication Date: 2012-01-05T11:12:46Z
• Authors: Stéphane F. Maison; Xiao-Ping Liu; Ruth Anne Eatock; David R. Sibley; David K. Grandy; M. Charles Liberman
• Keywords: Expression (computer science)

Pharmacological studies suggest that dopamine release from lateral olivocochlear efferent neurons suppresses spontaneous and sound-evoked activity in cochlear nerve fibers helps control noise-induced excitotoxicity; however, the literature on expression localization of receptors is contradictory. To better characterize dopaminergic signaling, we studied receptor using immunohistochemistry or reverse transcriptase PCR assessed histopathology, responses function mice with targeted deletion each five subtypes. In normal ears, D1, D2, D5 were detected microdissected immature (postnatal days 10–13) spiral ganglion cells outer hair but not inner cells. D4 was only. whole cochlea samples adults, transcripts for D4, present, whereas D3 mRNA never detected. D1 D2 immunolabeling localized to fibers, near first nodes Ranvier (D2) bundle region (D1 D2) where presynaptic terminals are found. No other labeling consistent. Cochlear D3, knock-outs. knock-outs showed slight, significant enhancement suppression, respectively, responses, both neural output [auditory brainstem response (ABR) wave 1] cell [distortion product otoacoustic emissions (DPOAEs)]. Vulnerability acoustic injury significantly increased lines: could be tested, no differences seen mutants, consistent a lack expression. The vulnerability DPOAEs, suggesting role area. knock-outs, noise only ABRs, signaling minimizing damage.