Dopamine modulates sodium currents in cochlear spiral ganglion neurons.
Lateral olivocochlear (LOC) efferent neurons, putatively dopaminergic, synapse on afferent dendrites of type I spiral ganglion neurons (SGNs) in the cochlea and depress their activity. To investigate the underlying mechanisms, whole-cell patch clamp recordings were obtained from mouse SGNs. Dopamine (DA), and D1-like (D1, D5) and D2-like (D2, D3 and D4) receptor agonists, reduced AP amplitude and induced a slow transient depolarization. Under voltage clamp, D1-like and D2-like agonists induced a dose-dependent inward current that was reversibly blocked by their receptor antagonists. The inward current was blocked by tetrodotoxin (TTX), implicating Na+ channels. The reduction of AP amplitude and voltage-gated Na+ current by DA and DA agonists provides a mechanism for suppressing spike activity in type I afferent neurons.
Hearing Research Lab, SUNY University at Buffalo, NY 14214, USA.
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Sun
R J
RJ
Salvi
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D001971:Bromocriptine / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D019257:Quinpirole / Q000494:pharmacology; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013136:Spiral Ganglion / Q000166:cytology* / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D001971:Bromocriptine; D013779:Tetrodotoxin; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D012964:Sodium; D004298:Dopamine