GABAAReceptor-Mediated Tonic Inhibition in Thalamic Neurons

• DOI: 10.1523/jneurosci.3362-05.2005
• Publication Date: 2005-12-14T23:03:18Z
• Authors: David W. Cope; Stuart W. Hughes; Vincenzo Crunelli
• Keywords: Tonic (physiology); GABAB receptor

Tonic GABA A receptor-mediated inhibition is typically generated byδ subunit-containing extrasynaptic receptors. Because the δ subunit highly expressed in thalamus, we tested whether thalamocortical (TC) neurons of dorsal lateral geniculate nucleus (dLGN) and ventrobasal complex exhibit tonic inhibition. Focal application gabazine (GBZ) (50 μ m ) revealed presence a 20 pA current 75 63% TC from both nuclei, respectively. No was observed GABAergic reticularis thalami (NRT). Bath 1μ increased amplitude to ∼70 100% neurons, but it still not NRT neurons. In dLGN sensitive low concentrations subunit-specific receptor agonists allotetrahydrodeoxycorticosterone (100 n 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol (THIP) insensitive benzodiazepine flurazepam (5 ). GBZ (25–200 preferentially blocked current, whereas phasic synaptic primarily maintained. Under intracellular current-clamp conditions, preferential block with led small depolarization increase input resistance. Using extracellular single-unit recordings, caused cessation low-threshold burst firing promoted firing. Enhancement by THIP hyperpolarized Thus, generates an inhibitory tone. Its modulation contributes shift between different modes, promotes transition behavioral states, predisposes absence seizures.