Antinociceptive effects of spinally administered nociceptin/orphanin FQ and its N-terminal fragments on capsaicin-induced nociception

► Intrathecal injection of N/OFQ caused a dose-dependent antinociceptive effect. ► The N-terminal fragments of N/OFQ were antinociceptive with a potency lower than N/OFQ. ► Antinociceptive effect of N/OFQ (1-13) and (1-11) lasted longer than that of N/OFQ. ► N/OFQ (1-13)-induced antinociception is mediated through spinal NOP receptors.