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Sympathoinhibitory Action Of Nociceptin In The Rat Spinal Cord
Author(s) -
Brailoiu GC,
Lai CC,
Chen CT,
Hwang LL,
LIN HH,
Dun NJ
Publication year - 2002
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2002.03635.x
Subject(s) - nociceptin receptor , spinal cord , action (physics) , neuroscience , medicine , anesthesia , pharmacology , psychology , opioid , opioid peptide , receptor , physics , quantum mechanics
SUMMARY 1. Whole‐cell patch recordings were made from antidromically identified sympathetic preganglionic neurons (SPN) of immature rat spinal cord slices. Bath application of nociceptin (0.1–1 μmol/L) suppressed excitatory postsynaptic potentials (EPSP) and hyperpolarized a population of SPN; these effects were naloxone (1 μmol/L) insensitive. 2. Nociceptin suppressed the amplitude of EPSP without causing a concomitant change in glutamate‐induced depolarizations, suggesting a presynaptic inhibitory action. 3. Analysis of current–voltage relationships showed that nociceptin hyperpolarized SPN by increasing an inwardly rectifying K + current. 4. Intrathecal injection of nociceptin (3, 10 and 30 nmol) to urethane‐anaesthetized rats dose‐dependently reduced the mean arterial pressure and heart rate; these effects were not prevented by prior intravenous injection of naloxone (1 mg/kg). 5. Results from our in vitro and in vivo experiments suggest that nociceptin suppresses spinal sympathetic outflow either by attenuating excitatory synaptic responses or hyperpolarizing SPN.