Study in vitro and in vivo of nociceptin/orphanin FQ(1-13)NH2 analogues substituting N-Me-Gly for Gly2 or Gly3.

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In the present study, two analogues containing N-Me-Gly (Sarcosine, Sar) were synthesized to further investigate the structural-activity relationships of orphanin FQ/nociceptin (OFQ/NC, NC). The replacement of Gly(2) or Gly(3) with Sar increased the flexibility and decreased the hydrophobicity of the N-terminal tetrapeptide. The activity of the analogues was investigated in a series of assays in vivo and in vitro. [Sar(2)]NC(1-13)NH(2) was found to (1) produce dose-dependent inhibition of the electrically induced contraction in MVD assay (pEC(50) = 6.14); (2) produce significant hyperalgesia effects in a dose-dependent manner when intracerebroventricularly (i.c.v.) injected in mice. The inhibitive effects of [Sar(2)]NC(1-13)NH(2) in MVD assay could be significantly antagonized by [Nphe(1)]NC(1-13)NH(2), and partially antagonized by naloxone; the hyperalgesic effect of [Sar(2)]NC(1-13)NH(2) could be significantly antagonized by naloxone, and partially antagonized by [Nphe(1)]NC(1-13)NH(2). On the contrary, [Sar(3)]NC(1-13)NH(2) showed no effects in these assays. All the findings suggest that the flexibility of the peptide bond between Phe(1) and Gly(2) and between Gly(2) and Gly(3) play an important role in NC-OP(4) receptor interaction, and the hydrophobicity of the N-terminal tetrapeptide showed no significant effect on this interaction. The present work also helps to provide a novel method to elucidate structural and conformational requirements of the opioid peptide-receptor interaction.





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Chen, Li-xiang, Quan Fang, Qiang Chen, Jia Guo, Zhuan-zi Wang, Yong Chen and Rui Wang (2004). Study in vitro and in vivo of nociceptin/orphanin FQ(1-13)NH2 analogues substituting N-Me-Gly for Gly2 or Gly3. Peptides, 25(8). pp. 1349–1354. 10.1016/j.peptides.2004.05.012 Retrieved from

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Yong Chen

Associate Professor in Neurology

Dr. Yong Chen is an Associate Professor of Neurology at the Duke University School of Medicine.  He is also affiliated with Duke Anesthesiology-Center for Translational Pain Medicine (CTPM) and Duke-Pathology.

The Chen lab mainly studies sensory neurobiology of pain and itch, with a focus on TRP ion channels and neural circuits. The main objective of our lab is to identify molecular and cellular mechanisms underlying chronic pain and chronic-disease associated itch, using a combination of animal behavioral, genetic, molecular and cellular, advanced imaging, viral, and optogenetic approaches.  There are three major research areas in the lab: craniofacial pain, arthritis pain and joint function, and systemic-disease associated itch.

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