Nonoreceptor/orphenkephalin FQ (N /OFQ) is a 17-amino acid neuropeptide that is an endogenous ligand of nonoreceptor (ORL-1). Nociceptive peptide, as an effective antianalgesic drug, can effectively counteract the effect of painkillers. Its activation has been linked to brain functions such as pain perception and fear learning. The genetic code for prepronociceptin is located on human Ch8p21. Pain sensitive peptides are derived from propain sensitive peptide proteins, along with two other peptides, nocistatin and NocII, both of which inhibit N/OFQ receptor function. Nociceptin was the first example of reverse pharmacology; The NOP receptor was discovered prior to the discovery of endogenous ligands by two different groups in 1995 In animal studies, the N/OFQ-NOP receptor pathway has also been found to play both positive and negative roles in learning and memory. For example, breakdowns in this pathway have been linked to alterations in fear learning in brain disorders such as post-traumatic stress disorder (PTSD). Thus, receptor pathways maintain homeostasis responses to fear and stressful situations. Nociceptor can also play an inhibitory role in memory function, as some studies have shown that it impairs spatial learning in vivo while inhibiting long-term enhancement and synaptic transmission in vitro