INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
GABA regulates the release of acetylcholine (ACh) at the medial olivocochlear (MOC) efferent-inner hair cell synapse through presynaptic GABAB(1a,2) receptors
Autor/es:
WEDEMEYER , C; ZORRILLA DE SAN MARTÍN, J.; TORBIDONI, AV; BETTLER; B; ELGOYHEN, A.B; KATZ, E.
Lugar:
Huerta Grande - Córdoba
Reunión:
Congreso; Reunion Anual de la Sociedad Argentina de Neurociencias; 2011
Resumen:
Before the onset of hearing, inner hair cells (IHCs) of the mammalian cochlea are innervated by MOC efferent fibers. Although ACh is the main neurotransmitter, GABA is present at MOC synaptic terminals. We have previously shown that GABA modulates the cholinergic input at MOC-IHC synapses by acting on GABA B receptors. To further evaluate the role of GABA B in the modulation of ACh release, synaptic currents evoked by electrically stimulating the efferent fibers were recorded in voltage-clamped IHCs from isolated mouse organs of Corti of GABAB knock-out (KO) mice isoforms. GABAB receptors are formed by the GABAB2 subunit with either the GABAB(1a) or the GABAB(1b) subunit. We compared the effects of the agonist baclofen in GABAB(1a-1b), GABAB(1a) and GABAB(1b) KO mice. Baclofen (1µM), caused a significant reduction in the quantum content (m) of evoked release in both, wild-type (32.3±6.9%, p<0.05) and GABAB(1b) KO mice (26.7±7.7%, p<0.05). Baclofen did not affect m in GABAB(1a-1b) or GABAB(1a) KO mice (p>0.05, n=5). Our results show that ACh release at the MOC-IHC synapse is negatively regulated by GABA acting on presynaptic GABAB(1a,2) receptors.