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.