Role of a9 nicotinic ACh receptor subunits in the development and function of cochlear efferent innervation

VETTER, D.E; LIBERMAN MC; MANN J; BARHANIN J; BROWN MC; SAFFIOTE-KOLMAN J; HEINEMANN S; ELGOYHEN AB

NEURON

CELL PRESS

Lugar: United States; Año: 1999 vol. 23 p. 93 - 103

0896-6273

Cochlear outer hair cells (OHCs) express á9 nACh receptors and are contacted by descending, predominately cholinergic, efferent fibers originating in the CNS. Mice carrying a null mutation for the nACh á9 gene were produced to investigate its role(s) in auditory processing and development of hair cell innervation. In á9 knockout mice, most OHCs were innervated by one large terminal instead of multiple smaller terminals as in wild types, suggesting a role for the nACh á9 subunit in development of mature synaptic connections. á9 knockout mice also failed to show suppression of cochlear responses (compound action potentials, distortion product otoacoustic emissions) during efferent fiber activation, demonstrating the key role á9 receptors play in mediating the only known effects of the olivocochlear system.