Direct Actions of Carbenoxolone on Synaptic Transmission and Neuronal Membrane Properties
AUTOR(ES)
Tovar, Kenneth R.
FONTE
American Physiological Society
RESUMO
The increased appreciation of electrical coupling between neurons has led to many studies examining the role of gap junctions in synaptic and network activity. Although the gap junctional blocker carbenoxolone (CBX) is effective in reducing electrical coupling, it may have other actions as well. To study the non–gap junctional effects of CBX on synaptic transmission, we recorded from mouse hippocampal neurons cultured on glial micro-islands. This recording configuration allowed us to stimulate and record excitatory postsynaptic currents (EPSCs) or inhibitory postsynaptic currents (IPSCs) in the same neuron or pairs of neurons. CBX irreversibly reduced evoked α-amino-3-hydroxy-5-methyl-4-isoxazole-proprionic acid (AMPA) receptor–mediated EPSCs. Consistent with a presynaptic site of action, CBX had no effect on glutamate-evoked whole cell currents and increased the paired-pulse ratio of AMPA and N-methyl-d-aspartate (NMDA) receptor–mediated EPSCs. CBX also reversibly reduced GABAA receptor–mediated IPSCs, increased the action potential width, and reduced the action potential firing rate. Our results indicate CBX broadly affects several neuronal membrane conductances independent of its effects on gap junctions. Thus effects of carbenoxolone on network activity cannot be interpreted as resulting from specific block of gap junctions.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2724329Documentos Relacionados
- The action of zinc on synaptic transmission and neuronal excitability in cultures of mouse hippocampus.
- Analysis of adenosine actions on Ca2+ currents and synaptic transmission in cultured rat hippocampal pyramidal neurones.
- The actions of baclofen on neurones and synaptic transmission in the nucleus tractus solitarii of the rat in vitro.
- Neuronal synchronization without calcium-dependent synaptic transmission in the hypothalamus.
- Neurotrophin 3 potentiates neuronal activity and inhibits gamma-aminobutyratergic synaptic transmission in cortical neurons.