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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1999-2-8
pubmed:abstractText
The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is mediated by two main categories of receptors: the GABA(A) and GABA(B) receptor. Recent immunocytochemical and electron microscopical studies revealed the existence of GABA at the efferent olivocochlear innervation of the guinea pig cochlea. In this microiontophoretic study we examined the effect of GABA on spontaneous and glutamate or acetylcholine induced activity of afferent fibres in the dendritic region of inner hair cells. Furthermore, the receptor subtypes being responsible for this GABA action were analysed using specific agonists and antagonists on alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartic acid (NMDA) induced activity. The spike activities of the subsynaptic area were recorded in the third or fourth turn of the cochlea of anaesthetised guinea pigs. Application of GABA had little effect on spontaneous activity whereas the glutamate or acetylcholine induced firing rate could be depressed by GABA. AMPA and NMDA induced activity was reduced by the GABA(A) agonist muscimol but not by the GABA(B) agonist baclofen. The GABA(A) antagonist blocked the inhibition of both GABA and the GABA(A) agonist. In contrast, the GABA(B) antagonist saclofen was without effect. These results reveal that GABA reduces the activated firing rate of inner hair cell afferents mediated by the GABA(A) receptor subtype.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0378-5955
pubmed:author
pubmed:issnType
Print
pubmed:volume
125
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
147-53
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed-meshheading:9833968-Acetylcholine, pubmed-meshheading:9833968-Action Potentials, pubmed-meshheading:9833968-Afferent Pathways, pubmed-meshheading:9833968-Animals, pubmed-meshheading:9833968-Auditory Pathways, pubmed-meshheading:9833968-Baclofen, pubmed-meshheading:9833968-Bicuculline, pubmed-meshheading:9833968-Cochlea, pubmed-meshheading:9833968-Electrophysiology, pubmed-meshheading:9833968-Glutamic Acid, pubmed-meshheading:9833968-Guinea Pigs, pubmed-meshheading:9833968-Hair Cells, Auditory, Inner, pubmed-meshheading:9833968-Iontophoresis, pubmed-meshheading:9833968-Muscimol, pubmed-meshheading:9833968-N-Methylaspartate, pubmed-meshheading:9833968-Receptors, GABA-A, pubmed-meshheading:9833968-alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid, pubmed-meshheading:9833968-gamma-Aminobutyric Acid
pubmed:year
1998
pubmed:articleTitle
GABA(A) receptor modulates the activity of inner hair cell afferents in guinea pig cochlea.
pubmed:affiliation
Division of Neurobiology, University of Berne, Switzerland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't