Reference : Effect of dopamine and baclofen on N-methyl-D-aspartate-induced burst firing in rat vent...
Scientific journals : Article
Human health sciences : Pharmacy, pharmacology & toxicology
http://hdl.handle.net/2268/34047
Effect of dopamine and baclofen on N-methyl-D-aspartate-induced burst firing in rat ventral tegmental neurons.
English
Seutin, Vincent mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Pharmacologie >]
Johnson, S. W. [> > > >]
North, R. A. [> > > >]
1994
Neuroscience
Elsevier Science
58
1
201-6
Yes (verified by ORBi)
International
0306-4522
New York
NY
[en] Action Potentials/drug effects ; Animals ; Baclofen/pharmacology ; Barium/pharmacology ; Dendrites/drug effects/physiology ; Dopamine/pharmacology ; Male ; Membrane Potentials/drug effects ; N-Methylaspartate/antagonists & inhibitors/pharmacology ; Potassium/physiology ; Rats ; Rats, Sprague-Dawley ; Substantia Nigra/drug effects/physiology ; Synaptic Transmission/drug effects ; Tegmentum Mesencephali/drug effects/physiology
[en] Intracellular microelectrode recordings were made from dopamine-containing neurons of the ventral tegmental area or substantia nigra zona compacta in rat brain slices in vitro. The firing pattern of the neurons was switched from a tonic, single-spike pattern to a burst firing mode by adding N-methyl-D-aspartate (20 microM) to the superfusing solution; after adding tetrodotoxin the membrane potential underwent rhythmical oscillations of 20-40 mV at 0.5-2 Hz. Baclofen (1 microM) and dopamine (30 microM) hyperpolarized the neurons; when the potential was restored to its original level, the oscillations of potential and/or burst firing were not observed, but the tonic firing pattern was restored. These effects of baclofen and dopamine were prevented by barium (1 mM), which also prevented the membrane hyperpolarization. Oscillations of membrane current of a similar frequency were observed when the somatic membrane was voltage-clamped at -60 mV; these were also blocked by barium (1 mM). It is concluded that the oscillations in membrane potential observed with N-methyl-D-aspartate are generated predominantly at a dendritic location which is not voltage-clamped with an electrode at the soma. Baclofen and dopamine inhibit the oscillations by increasing the potassium conductance and hyperpolarizing the dendrites.
http://hdl.handle.net/2268/34047

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