Cellular neurophysiological actions of nociceptin/orphanin FQ.
Cellular actions of nociceptin/orphanin FQ (N/OFQ) resemble those of micro-, delta-, and kappa-opioids, i.e. activation of inwardly rectifying K(+) conductance, inhibition of high-voltage-activated Ca(2+) channel currents, and impediment of neurotransmitter release. Differences in ORL(1) and micro-receptor distribution lead to: 1) more widespread actions of N/OFQ on periaqueductal gray neurons than opioids and 2) differential effects of N/OFQ and opioids in the brainstem. Also, unlike opioids, N/OFQ inhibits T-type Ca(2+) channel current in sensory neurons. Opioids and N/OFQ may modulate glutamate responses in different ways, and certain actions of N/OFQ are potentiated following nerve injury whereas those of micro-opioids are attenuated. Agonists at ORL(1) receptors may therefore be of clinical interest in the management of neuropathic pain.
Moran
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Division of Neuroscience and Department of Pharmacology, 9-75 Medical Sciences Building, University of Alberta, T6G 2H7, Edmonton, AB, Canada.
Abdulla
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FA
Smith
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PA
D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D004594:Electrophysiology; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism; D009294:Narcotics / Q000819:agonists; D009474:Neurons / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D018847:Opioid Peptides / Q000378:metabolism* / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism; D014665:Vasodilator Agents / Q000378:metabolism; D014981:Xenopus; D000097629:Nociceptin
D002118:Calcium; D009294:Narcotics; D018377:Neurotransmitter Agents; D018847:Opioid Peptides; D011188:Potassium; D014665:Vasodilator Agents; D000097629:Nociceptin