Functional Evidence of Rapid Evolution of Amniot á9á10 nAChRs

MOGLIE M; LIPOVSEK M; KATZ E; ELGOYHEN AB

Congreso; XXVII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2011

The á9á10 nicotinic acetylcholine receptor (nAChR) mediates efferent inhibition of vertebrate hair cells. They were the last nAChR subunits to be identified, due to the fact that they present distinct pharmacological and biophysical properties that set them apart from the rest of the nicotinic subunits. Previous work has shown profound differences in calcium permeability and channel gating properties between rat and chick á9á10 receptors. Here, we show that this interspecies variability is even more profound when performing a comparison with the Xenopus tropicalis (frog) á9á10 receptor. Desensitization, modulation by extracellular calcium and current-voltage relationships of frog differ significantly from those of amniote á9á10 receptors and closely resemble those of á7 (or á8) neuronal nAChRs. Moreover, in order to evaluate whether these differences in biophysical properties correlate with differences in pharmacology, we are performing a detailed pharmacological profiling of chick and frog á9á10. We conclude that a process of rapid functional evolution shaped the peculiar properties of amniot á9á10 nAChRs, setting them apart from other members of the nicotinic receptors family.