Molecular and functional characterization of the nicotinic cholinergic receptor at the efferent synapse of zebrafish lateral line.

AGUSTIN CARPANETO; CAROLINA WEDEMEYER; PAOLA PLAZAS; ANA BELÉN ELGOYHEN

Congreso; 2nd FALAN Congress; 2016

Zebrafish (z) lateral line (LL) is a mechanosensory system that detects water movements and pressure changes. It consists of hair cells innervated by afferent neurons that transmit information to the CNS and by efferent neurons that contact directly to hair cells. LL hair cells share structural, functional and molecular characteristics with those in vertebrate inner ear. Efferent stimulation to the LL and the inner ear leads to similar effects suggesting the existence of similar synaptic mechanisms. It is known that the alpha9 alpha10 (a9 a10) nicotinic receptor (nAChR) mediates efferent transmission in the cochlea, however this information is lacking for zLL. To characterize the nAChR at the efferent synapse in zLL, we are cloning za9 and za10 subunits and performing a functional characterization of recombinant nAChRs . Zebrafish has two a9 genes, located in chromosomes 1 (a9-1) and 14 (a9-14) and two a10 genes in chromosomes 15 (a10-15) and 21 (a10-21). We have cloned za9-1, za10-15 and za10-21, expressed them in X. laevis oocytes and performed electrophysiological recordings under two-electrode voltage-clamp. Whereas za9-1 forms functional homomeric nAChRs, zα10-X are only functional when co-expressed with zα9-1. za9-1 nAChRs exhibit high Ca2+ permeability, large desensitization rates and an EC50 of 14.89 uM. To study the native nAChR and describe the effect of efferent activation on hair-cell activity, we are setting up procedures to perform whole cell patch clamp in zebrafish LL hair cells.Supported by HFSP