Yonsei medical journal
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Yonsei Med. J.
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Yonsei medical journal · May 2013
Effects of co-administration of intrathecal nociceptin/orphanin FQ and opioid antagonists on formalin-induced pain in rats.
Nociceptin/orphanin FQ (N/OFQ) as an endogeneous hexadecapeptide is known to exert antinociceptive effects spinally. The aims of this study were to demonstrate the antinociceptive effects of i.t. N/OFQ and to investigate the possible interaction between N/OFQ and endogenous opioid systems using selective opioid receptor antagonists in rat formalin tests. ⋯ I.t. N/OFQ exerted an antinociceptive effect in both phases of the rat-formalin test through the nociceptin opioid peptide receptor. In addition, the results suggested that δ- and μ-opioid receptors, but not κ-opioid receptors, are involved in the antinociceptive effects of N/OFQ in the spinal cord of rats.