INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ascorbic acid is a positive modulator of a9a10 nicotinic cholinergic receptors
Autor/es:
BOFFI JC; WEDEMEYER C; CALVO DJ; KATZ E; ELGOYHEN AB
Lugar:
Huerta Grande, Córdoba, Argentina
Reunión:
Congreso; Segunda Reunión Conjunta de la Sociedad Argentina de Neurociencias (SAN) y el Taller Argentino de Neurociencias (TAN); 2010
Resumen:
Activity of inhibitory efferent cholinergic neurons projecting from the brainstem
and synapsing cochlear hair cells containing á9á10 nicotinic receptors, can ame-
liorate acoustic trauma. Consequently, compounds that increase á9á10-mediated
responses have a potential therapeutic use in noise-induced hearing loss. We have
analyzed the effect of ascorbic acid (ASC) in á9á10 injected X. laevis oocytes by
two-electrode voltage-clamp recordings. Responses to 10µM acetylcholine (ACh)
were potentiated by ASC in a concentration-dependent manner (0.1-30mM ASC).
At 3mM ASC, an 81±6% (n=7) potentiation was observed. Potentiation was more
pronounced at lower (305±40%, 3µM ACh, n=8) than at higher (138±35%, 1mM
ACh, n=8) ACh concentrations. No significant changes in the half maximal con-
centration of ACh and Hill coefficients were observed at 3mM ASC (EC50 = 18±1,
nHill = 0.8±0.1, n=5-9). The ASC oxidized form, dihidroascorbate, had no effect
on ACh-evoked responses at a 3mM concentration, suggesting that the reduced
form of ASC is the active compound. Altogether, our results show that ASC po-
tentiates á9á10-mediated responses and thus has a potential therapeutic use in
noise-induced hearing loss.