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Medientyp:
E-Artikel
Titel:
Postsynaptic Mechanisms Underlying Responsiveness of Amygdaloid Neurons to Nociceptin/Orphanin FQ
Beteiligte:
Meis, Susanne;
Pape, Hans-Christian
Erschienen:
Society for Neuroscience, 1998
Erschienen in:The Journal of Neuroscience
Sprache:
Englisch
DOI:
10.1523/jneurosci.18-20-08133.1998
ISSN:
0270-6474;
1529-2401
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>Effects of nociceptin/orphanin FQ (N/OFQ), the endogenous ligand of the opioid-like orphan receptor (ORL), were investigated in the rat lateral (AL) and central (ACe) amygdala<jats:italic>in vitro</jats:italic>. Approximately 98% of presumed projection neurons in the AL responded to N/OFQ with an increase in inwardly rectifying potassium conductance, resulting in an impairment in cell excitability. Half-maximal effects were obtained at 30.6 n<jats:sc>m</jats:sc>; the Hill coefficient was 0.63. In the ACe, 31% of the cells displayed responses similar to that in the AL, 44% were nonresponsive, and 25% responded with a small potassium current with a linear current–voltage relationship. Responses to N/OFQ were reduced by 100 μ<jats:sc>m</jats:sc>Ba<jats:sup>2+</jats:sup>, were insensitive to 10 μ<jats:sc>m</jats:sc>naloxone, and were blocked by a selective ORL antagonist, [Phe<jats:sup>1</jats:sup>ψ(CH<jats:sub>2</jats:sub>-NH)Gly<jats:sup>2</jats:sup>]NC(1–13)NH<jats:sub>2</jats:sub>(IC<jats:sub>50</jats:sub>= 760 n<jats:sc>m</jats:sc>). Involvement of G-proteins was indicated by irreversible effects and blockade of action of N/OFQ during intracellular presence of GTP-γ-S (100 μ<jats:sc>m</jats:sc>) and GDP-β-S (2 m<jats:sc>m</jats:sc>), respectively, and prevention of responses after incubation in pertussis toxin (500 ng/ml). These mechanisms may contribute to the role of N/OFQ in the reduction of fear responsiveness and stress that have recently been suggested on the basis of histochemical and behavioral studies.</jats:p>