INVESTIGADORES
PLAZAS Paola Viviana
congresos y reuniones científicas
Título:
Effects of neramexane, an open channel blocker of NMDA receptors, on the 910 nicotinic receptor.
Autor/es:
PLAZAS PV; SAVINO J; GOMEZ-CASATI ME; PARSONS CG; ELGOYHEN AB
Reunión:
Congreso; XLII Reunion Anual de la Sociedad Argentina de Bioquimica y Biologia Molecular; 2006
Resumen:
The aim of this work was to
study the effects of neramexane, an uncompetitive NMDA receptor antagonist, on
the a9a10 nicotinic receptor (nAChR). cDNAs coding for the rat a9 and a10 subunits were expressed in Xenopus laevis oocytes and agonist-evoked
currents were measured under two-electrode voltage-clamp. Electrophysiological
recordings in inner hair cells (IHCs) were performed by patch-clamp in acutely
excised apical turns of the organ of Corti. The effects of neramexane were
compared with those of memantine, a well-studied pore blocker of NMDA
receptors. Our results indicate that, in oocytes, both compounds block
ACh-evoked responses at micromolar concentrations with similar apparent
affinities (neramexane IC50: 0.39 ± 0.03 mM;
memantine IC50: 1.2 ± 0.4 mM). Blockage of rat a9a10 by neramexane was voltage-independent while blockage by memantine was
slightly voltage-dependent. Neramexane inhibited ACh currents in a mixed
competitive and noncompetitive manner. In IHCs, neramexane blocked ACh-evoked
responses with an IC50 value (0.3 ± 0.08 mM)
similar to that found for recombinant a9a10 receptors. In addition, neramexane blocked
responses to synaptically released ACh. Since memantine and neramexane are effective when administered to animal
models for various disease states, our findings suggest that the actions of
these compounds at nAChRs may be of therapeutic relevance