Retro-nociceptin methylester, a peptide with analgesic and memory-enhancing activity
Related Experiment Video
Updated: Oct 10, 2026

Intracranial Pharmacotherapy and Pain Assays in Rodents
Published on: April 9, 2019
Y Jinsmaa1, M Takahashi, H Fukunaga
1Research Institute for Food Science, Kyoto University, Uji, Japan.
Abstract:
Retro-nociceptin methylester (retro-Noc-ME), which has an oppositely directed structure to that of nociceptin, showed weak affinity for nociceptin receptor and antagonized nociceptin-induced inhibition of contraction in a guinea pig ileum (GPI) assay. The peptide induced analgesia after intracerebroventricular (i.c.v.) administration at a dose of 100 nmol per mouse. Analgesia was not blocked by the opioid antagonist naloxone, which suggests that the analgesia is not mediated by opioid receptor. Furthermore, analgesia caused by retro-Noc-ME was not attenuated after repeated administration, that is, there was an absence of tolerance. The peptide improved learning ability after i.c.v. administration in a step-through experiment in mice.
Related Concept Videos
Nociception
Cognitive Enhancers: Cholinesterase Inhibitors and NMDA Receptor Antagonists
Analgesia and Pain Management
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Long-term Potentiation
