Nociceptin/orphanin FQ (N/OFQ) is an antistress neuropeptide transmitter in the brain that counteracts corticotropin-releasing factor (CRF)-mediated stress and anxiety symptoms during drug and alcohol withdrawal. It also inhibits the release of a wide array of neurotransmitters, including dopamine and glutamate, which allows for it to block the rewarding properties of cocaine. Chronic cocaine administration in rodents has been shown to decrease N/OFQ and increase nociceptive opioid peptide (NOP) receptors in the nucleus accumbens. No previous studies have reported on the in vivo status of NOP in chronic cocaine-abusing humans.. Login at top right hand side of page using your MPFT NHS OpenAthens for full text.