PART I. The N/OFQ-NOP Receptor System.- 1. The History of N/OFQ and the NOP Receptor.- 2. NOP-Targeted Peptide Ligands.- 3. NOP-Targeted Nonpeptide Ligands.- 4. Pharmacological Assays for Investigating the NOP Receptor.- 5. Electrophysiological Actions of N/OFQ.- 6. NOP Receptor Signaling Cascades.- 7.Regulation of the Genes Encoding the ppN/OFQ and NOP Receptor.- PART II. Biological Actions of NOP Ligands.- 8.NOP-Related Mechanisms in Pain and Analgesia.- 9. NOP-Related Mechanisms in Substance Use Disorders.- 10. NOP Receptor Ligands and Parkinson's Disease.- 11. NOP Ligands for the Treatment of Anxiety and Mood Disorders.- 12. The Nociceptin/Orphanin FQ System and the Regulation of Memory.- 13. N/OFQ-NOP System in Food Intake.- 14. N/OFQ-NOP System in Peripheral and Central Immunomodulation.- 15. N/OFQ-NOP System and Airways.- 16. Effects of NOP-Related Ligands in Nonhuman Primates.- PART III. First Clinical Studies with NOP Ligands.- 17. Nociceptin/Orphanin FQ and Urinary Bladder.- 18. Cebranopadol: A Novel First-in-Class Potent Analgesic Acting via NOP and Opioid Receptors.- 19. Therapeutic Approaches for NOP Receptor Antagonists in Neurobehavioral Disorders: Clinical Studies in Major Depressive Disorder and Alcohol Use Disorder with BTRX-246040 (LY2940094).- 20. Correction to: Electrophysiological Actions of N/OFQ.