The Edinger-Westphal nucleus of the juvenile rat contains transient- and repetitive-firing neurons
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The Edinger-Westphal nucleus of the juvenile rat contains transient- and repetitive-firing neurons. / Laursen, M; Rekling, J C.
In: Neuroscience, Vol. 141, No. 1, 11.08.2006, p. 191-200.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The Edinger-Westphal nucleus of the juvenile rat contains transient- and repetitive-firing neurons
AU - Laursen, M
AU - Rekling, J C
PY - 2006/8/11
Y1 - 2006/8/11
N2 - Classically, the Edinger-Westphal nucleus is described as containing neurons controlling accommodation and pupillary constriction via projections to the ciliary ganglion. However, in several species including rat, some Edinger-Westphal neurons have ascending or descending CNS projections suggesting that the Edinger-Westphal nucleus might also have non-ocular functions. To further characterize the function of this nucleus we studied the electrophysiological properties of Edinger-Westphal neurons in a slice preparation from juvenile rats. The position of the Edinger-Westphal nucleus was determined using an immunohistochemical procedure directed at the peptide Urocortin, which is expressed in Edinger-Westphal neurons. Passive and active membrane responses were investigated and two different neuron types were identified. One type had a transient firing response to 400 ms depolarizing current pulses and one type had a repetitive firing response. Transient-firing neurons had an outward rectifying response inhibiting firing, possibly due to slowly inactivating I(D)-like potassium channels since low concentrations (200 microM) of the potassium channel blocker 4-aminopyridine elicited repetitive firing. In all neurons, low threshold Ca(2+) spikes were seen and these were blocked by nickel(II) chloride hexahydrate, suggesting that they are mediated via low voltage-activated Ca(2+) channels. Some biocytin-labeled neurons had axons or axonal collaterals projecting laterally or dorsally, suggesting possible non-ocular targets. In conclusion, the rat Edinger-Westphal nucleus contains two separate types of neurons with distinct electrophysiological properties.
AB - Classically, the Edinger-Westphal nucleus is described as containing neurons controlling accommodation and pupillary constriction via projections to the ciliary ganglion. However, in several species including rat, some Edinger-Westphal neurons have ascending or descending CNS projections suggesting that the Edinger-Westphal nucleus might also have non-ocular functions. To further characterize the function of this nucleus we studied the electrophysiological properties of Edinger-Westphal neurons in a slice preparation from juvenile rats. The position of the Edinger-Westphal nucleus was determined using an immunohistochemical procedure directed at the peptide Urocortin, which is expressed in Edinger-Westphal neurons. Passive and active membrane responses were investigated and two different neuron types were identified. One type had a transient firing response to 400 ms depolarizing current pulses and one type had a repetitive firing response. Transient-firing neurons had an outward rectifying response inhibiting firing, possibly due to slowly inactivating I(D)-like potassium channels since low concentrations (200 microM) of the potassium channel blocker 4-aminopyridine elicited repetitive firing. In all neurons, low threshold Ca(2+) spikes were seen and these were blocked by nickel(II) chloride hexahydrate, suggesting that they are mediated via low voltage-activated Ca(2+) channels. Some biocytin-labeled neurons had axons or axonal collaterals projecting laterally or dorsally, suggesting possible non-ocular targets. In conclusion, the rat Edinger-Westphal nucleus contains two separate types of neurons with distinct electrophysiological properties.
KW - 4-Aminopyridine
KW - Action Potentials
KW - Animals
KW - Animals, Newborn
KW - Brain Stem
KW - Corticotropin-Releasing Hormone
KW - Dose-Response Relationship, Radiation
KW - Electric Stimulation
KW - Female
KW - Ganglia, Parasympathetic
KW - Immunohistochemistry
KW - Lysine
KW - Male
KW - Neurons
KW - Nickel
KW - Patch-Clamp Techniques
KW - Potassium Channel Blockers
KW - Rats
KW - Rats, Wistar
KW - Sodium Channel Blockers
KW - Tetrodotoxin
KW - Urocortins
U2 - 10.1016/j.neuroscience.2006.03.062
DO - 10.1016/j.neuroscience.2006.03.062
M3 - Journal article
C2 - 16677766
VL - 141
SP - 191
EP - 200
JO - Neuroscience
JF - Neuroscience
SN - 0306-4522
IS - 1
ER -
ID: 1203630