Linked Life Data

9636097

Source:http://linkedlifedata.com/resource/pubmed/id/9636097

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1998-7-17
pubmed:abstractText
The thalamic reticular nucleus (RTN) is the major source of inhibitory contacts in the thalamus and thus plays an important role in regulating the excitability of the thalamocortical network. Inhibition occurs through GABAergic synapses on relay cells as well as through GABAergic synapses between reticularis neurons themselves. Here we report that the role and mechanisms of this inhibition, which frequently have been studied using N-methyl derivatives of the gamma-aminobutyric acid-A (GABAA) receptor antagonist bicuculline, should be revisited. Using the whole cell patch-clamp technique in thalamic slices from young rats, we observed an enhancement by bicuculline methiodide, methobromide, and methochloride (collectively referred to as bicuculline-M; 5-60 microM) of the low-threshold calcium spike burst in RTN neurons that persisted in the presence of tetrodotoxin (1 microM) and was not reproduced in picrotoxin (100-300 microM). The effect did not involve activation of any GABA receptor subtype. Voltage-clamp recordings showed that bicuculline-M blocked the current underlying the low-threshold spike burst afterhyperpolarization (AHP), an effect that was mimicked by apamin (100 nM). Recordings from nucleated patches extracted from reticularis neurons demonstrated that this effect was not mediated by modulation of the release of an unidentified neurotransmitter but that bicuculline-M directly blocks small conductance (SK) channels. The AHP-blocking effect also was observed in other brain regions, demonstrating that although bicuculline-M is a potent GABAA receptor antagonist, it is of limited value in assessing GABAergic network interactions, which should be studied using picrotoxin or bicuculline-free base. However, bicuculline-M may provide a useful tool for developing nonpeptide antagonists of SK channels.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-3077
pubmed:author
pubmed:issnType
Print
pubmed:volume
79
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2911-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Effect of bicuculline on thalamic activity: a direct blockade of IAHP in reticularis neurons.
pubmed:affiliation
Laboratoire de Physiologie, Ecole Supérieure de Physique et Chimie Industrielles de la Ville de Paris, Unité Mixte de Recherche 7637, 75005 Paris, France.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't