Activation of nicotinic receptors by the neurotransmitter GABA

BRAVO M; DIONISIO L; BOUZAT, C

Salta

Congreso; XXXIX Annual Meeting of Argentinean biophysical Society, Worshop CeBEM and 3rd Latin American Protein Society Meeting; 2010

SAB, CeBEM and Latin American Protein society

>Cys-loop receptors are pentameric neurotransmitter-activated ion channels that mediate fast synaptic transmission throughout the nervous system. They include excitatory receptors, such as nicotinic (AChR) and serotonin-type 3 receptors (5-HT3), and inhibitory receptors activated by GABA or glycine. Given the homology between members of this family, we evaluated if GABAergic agonists activate nicotinic receptors. Single-channel currents from muscle AChRs are activated by GABA at concentrations higher than 10 nM. Channel activity is low compared to that observed in the presence of ACh and appears as isolated events at all GABA concentrations. ACh- and GABA-activation is affected in a similar way by mutations of key residues at the principal face of the binding site (αG153S, αG153E, αY190F). However, a mutation at the complementary face (eG57Q) enhances activation by GABA but does not affect ACh-activation. Macroscopic currents elicited by application of GABA to outside-out patches are