Abstract
Nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are involved in various biological functions including pain. High density of NOP receptor has been found in the ventrolateral periaqueductal gray (vlPAG), the main output pathway involved in descending pain-control system. The aim of our work was to evaluate the involvement of the N/OFQ/NOP system in the modulation of MOP analgesia in the rat vlPAG using UFP-101, a selective NOP antagonist. N/OFQ significantly blocked DAMGO (a selective MOP agonist) analgesia, while UFP-101 enhanced the effect of the opioid given at a subanalgesic dose. These results confirm our hypothesis of an antiopioid role for N/OFQ in the vlPAG.
MeSH terms
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Analgesics, Opioid / administration & dosage
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Analgesics, Opioid / pharmacology*
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Animals
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Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / administration & dosage
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Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / pharmacology*
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Male
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Narcotic Antagonists*
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Nociceptin
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Nociceptin Receptor
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Opioid Peptides / administration & dosage
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Opioid Peptides / antagonists & inhibitors*
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Opioid Peptides / metabolism
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Opioid Peptides / pharmacology
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Pain Measurement
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Periaqueductal Gray / drug effects*
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Periaqueductal Gray / metabolism
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Rats
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Rats, Sprague-Dawley
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Receptors, Opioid / metabolism
Substances
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(Nphe(1),Arg(14),Lys(15))N-OFQ NH(2)
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Analgesics, Opioid
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Narcotic Antagonists
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Opioid Peptides
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Receptors, Opioid
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Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
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Nociceptin Receptor
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Oprl protein, rat