[en] Spontaneous apamin-sensitive hyperpolarizations in dopaminergic neurons of neonatal rats. J. Neurophysiol. 80: 3361-3364, 1998. Intracellular recordings from substantia nigra slices revealed the existence of spontaneous hyperpolarizations (amplitude 2-8 mV, duration 100-400 ms) at -60 mV in most dopaminergic neurons of neonatal (9-15 days) but not adult rats. These events were blocked by apamin (300 nM) and bicuculline methochloride (100-300 microM), which blocks apamin-sensitive currents. They were unaffected by the selective gamma-aminobutyric acid-A (GABAA) antagonists SR95531 (100 microM) and picrotoxin (30-50 microM), the GABAB antagonist CGP35348 (300 microM), the D2 antagonist haloperidol (1 microM), and the metabotropic antagonist MCPG (1 mM). The hyperpolarizations were strongly attenuated or abolished when recording electrodes contained 200 mM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. They were resistant to tetrodotoxin in the majority of the cells. They had some voltage dependency and were in some cases transiently potentiated when cells were briefly depolarized by current injection. We conclude that dopaminergic neurons have developmentally regulated physiological properties. These spontaneous hyperpolarizations might affect the firing rate of these cells, which was found to be lower in neonates than in adults.
Disciplines :
Pharmacy, pharmacology & toxicology
Author, co-author :
Seutin, Vincent ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Pharmacologie
Massotte, Laurent ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Département des sciences biomédicales et précliniques
Scuvée-Moreau, Jacqueline ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Pharmacologie - Département des sciences biomédicales et précliniques
Dresse, Albert ; Université de Liège - ULiège > Services généraux (Faculté de médecine) > Relations académiques et scientifiques (Médecine)
Language :
English
Title :
Spontaneous Apamin-Sensitive Hyperpolarizations in Dopaminergic Neurons of Neonatal Rats
Publication date :
December 1998
Journal title :
Journal of Neurophysiology
ISSN :
0022-3077
eISSN :
1522-1598
Publisher :
American Physiological Society, United States - Maryland
CARMIGNOTO, G. AND VICINI, S. Activity-dependent decrease in NMDA receptor responses during development of the visual cortex. Science 258: 1007-1011, 1992.
FIORILLO, C. D. AND WILLIAMS, J. T. Glutamate mediates an inhibitory postsynaptic potential in dopamine neurons. Nature 394: 78-82, 1998.
JOHNSON, S. W. AND NORTH, R. A. Two types of neurone in the rat ventral tegmental area and their synaptic inputs. J. Physiol. (Lond.) 450: 455-468, 1992.
JOHNSON, S. W. AND SEUTIN, V. Bicuculline methiodide potentiates NMDA-dependent burst firing in rat dopamine neurons by blocking apamin-sensitive Ca2+-activated K+ currents. Neurosci. Lett. 231: 13-16, 1997.
LANCASTER, B. AND NICOLL, R. A. Properties of two calcium-activated hyperpolarizations in rat hippocampal neurones. J. Physiol. (Lond.) 389: 187-203, 1987.
LEINEKUGEL, X., MEDINA, I., KUALILOV, I., BEN-ARI, Y., AND KHAZIPOV, R. Ca2+ oscillations mediated by the synergistic actions of GABAA and NMDA receptors in the neonatal hippocampus. Neuron 18: 243-255, 1997.
MERCURI, N. B., BONCI, A., CALABRESI, P., STEFANI, A., AND BERNARDI, G. Properties of the hyperpolarization-activated cation current Ih in rat midbrain dopaminergic neurons. Eur. J. Neurosci. 7: 462-469, 1995.
SATIN, L. S. AND ADAMS, P. R. Spontaneous miniature outward currents in cultured bullfrog neurons. Brain Res. 401: 331-339, 1987.
SEUTIN, V., SCUVÉE-MOREAU, J., AND DRESSE, A. Evidence for a non-GABAergic action of quaternary salts of bicuculline on dopaminergic neurones. Neuropharmacology 36: 1653-1657, 1997.
TEPPER, J. M., TRENT, F., AND NAKAMURA, S. Postnatal development of the electrical activity of rat nigrostriatal dopaminergic neurons. Dev. Brain Res. 54: 21-33, 1990.
YUNG, W. H., HAUSSER, M. A., AND JACK, J. J. B. Electrophysiology of dopaminergic and non-dopaminergic neurones of the guinea-pig substantia nigra pars compacta in vitro. J. Physiol. (Lond.) 436: 643-667, 1991.