References of "Engel, Dominique"
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See detailInteractions between calcium channels and SK channels in midbrain dopamine neurons and their impact on pacemaker regularity: Contrasting roles of N- and L-type channels.
de Vrind, V.; Scuvée-Moreau, Jacqueline ULg; Drion, Guillaume ULg et al

in European Journal of Pharmacology (2016)

Although small-conductance Ca2+-activated K+ (SK) channels and various types of voltage-gated Ca2+ (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is ... [more ▼]

Although small-conductance Ca2+-activated K+ (SK) channels and various types of voltage-gated Ca2+ (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is unclear. More particularly, the role of various Cav channel types in either promoting irregularity of firing (by generating an inward current during SK channel blockade) or promoting regularity of firing (by providing the source of Ca2+ for the activation of SK channels) has not been systematically explored. We addressed this question using intracellular and extracellular recordings from substantia nigra, pars compacta (SNc), dopaminergic neurons in rat midbrain slices. Neurons were pharmacologically isolated from their differences. When examining the ability of various Cav channel blockers to inhibit the SK-mediated afterhyperpolarization (AHP), we found that only the N-type Cav channel blocker ω-conotoxin-GVIA was able to reduce the apamin-sensitive AHP, but only partially (~40%). Specific blockers of L, P/Q, T or R channels had no effect on this AHP. Combining ω-conotoxin-GVIA and other specific blockers did not yield greater block and even the broad Cav blocker Cd2+ induced a submaximal (~75%) effect. Extracellular recordings examining firing regularity yielded congruent results: none of the specific blockers was able to increase firing irregularity to the extent that the specific SK blocker apamin did. The irregularity of firing observed with apamin could only be reversed by blocking L-type Ca2+ channels. Thus various sources of Ca2+ appear to be required for SK channel activation in SNc neurons (some of them still unidentified), ensuring robustness of pacemaking regularity. [less ▲]

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See detailDifferential somatic Ca2+ channel profile in midbrain dopaminergic neurons
Philippart, Fabian ULg; Destreel, Geoffrey ULg; Merino-Sepulveda, Paulina et al

in Journal of Neuroscience (2016)

Dopaminergic (DA) neurons located in the ventral midbrain continuously generate a slow endogenous pacemaker activity, the mechanism of which is still debated. It has been suggested that, in the substantia ... [more ▼]

Dopaminergic (DA) neurons located in the ventral midbrain continuously generate a slow endogenous pacemaker activity, the mechanism of which is still debated. It has been suggested that, in the substantia nigra pars compacta (SNc), the pacemaking relies more on Ca2+ channels and that the density of L type Ca2+ channels is higher in these DA neurons than in those located in the ventral tegmental area (VTA). This might lead to a higher Ca2+ load in SNc DA neurons, and explain their higher susceptibility to degeneration. However, direct evidence for this hypothesis is lacking. We found that the L-type current and channel density is indeed higher in the somata of rat SNc DA neurons, and that this current undergoes less inactivation in this region. Non stationary fluctuation analysis (NSFA) measurements showed a much higher number of L-type channels in the soma of SNc DA neurons, as well as a smaller single channel conductance, pointing to a possible different molecular identity of L-type channels in DA neurons from the two areas. A major consequence of this is that pacemaking and even more so bursting are associated with a larger Ca2+ entry through L-type channels in SN DA neurons than in their VTA counterparts. Our results establish a molecular and functional difference between two populations of midbrain DA neurons that may contribute to their differential sensitivity to neurodegeneration. [less ▲]

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See detailHigh dendritic expression of Ih in the proximity of the axon origin controls the integrative properties of nigral dopamine neurons.
Engel, Dominique ULg; Seutin, Vincent ULg

in Journal of Physiology (2015), 593(22), 4905-4922

Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The ... [more ▼]

Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The hyperpolarization-activated cation current Ih present in the dendrites of some pyramidal neurons affects their membrane and integration properties, synaptic plasticity and higher functions such as memory. A gradient of increasing h-channel density towards distal dendrites has been found to be responsible for the location independence of excitatory postsynaptic potential (EPSP) waveform and temporal summation in cortical and hippocampal pyramidal cells. However, reports on other cell types revealed that smoother gradients or even linear distributions of Ih can achieve homogeneous temporal summation. Although the existence of a robust, slowly activating Ih current has been repeatedly demonstrated in nigral dopamine neurons, its subcellular distribution and precise role in synaptic integration are unknown. Using cell-attached patch-clamp recordings, we find a higher Ih current density in the axon-bearing dendrite than in the soma or in dendrites without axon in nigral dopamine neurons. Ih is mainly concentrated in the dendritic membrane area surrounding the axon origin and decreases with increasing distances from this site. Single EPSPs and temporal summation are similarly affected by blockade of Ih in axon- and non-axon-bearing dendrites. The presence of Ih close to the axon is pivotal to control the integrative functions and the output signal of dopamine neurons and may consequently influence the downstream coding of movement. [less ▲]

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See detailSodium Channels
Engel, Dominique ULg

in Engel, Dominique (Ed.) Encyclopedia of Computational Neuroscience (2014)

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See detailEndogenous zinc modulates di-synaptic GABAergic transmission in the dentate gyrus
Grauert, A; Engel, Dominique ULg; Ruiz, AJ

Poster (2011)

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See detailTiming and efficacy of transmitter release at mossy fiber synapses in the hippocampal network
Bischofberger, J; Engel, Dominique ULg; Frotscher, M et al

in Pflügers Archiv : European Journal of Physiology (2006), 453(3), 361-72

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See detailPatch-clamp recording from mossy fiber terminals in hippocampal slices
Bischofberger, J; Engel, Dominique ULg; Li, L et al

in Nature Protocols (2006), 1(4), 2075-81

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