Structure-Based Optimization of Multifunctional Agonists for Opioid and Neuropeptide FF Receptors with Potent Nontolerance Forming Analgesic Activities

Abstract

The opioid and neuropeptide FF pharmacophore-containing chimeric peptide 0 (BN-9) was recently developed and produced potent nontolerance forming analgesia. In this study, 11 analogues of 0 were designed and synthesized. An in vitro cAMP assay demonstrated that these analogues behaved as multifunctional agonists at both opioid and NPFF receptors. In mouse tail-flick test, most of the analogues produced potent nontolerance forming antinociception. Notably, 11 (DN-9) was 33-fold more potent than 0 at analgesic effects, which was mediated by μ- and κ-opioid receptors. In addition, 11 also produced powerful analgesic effects in the formalin pain and CFA-induced chronic inflammatory pain models. Strikingly, following its repeated administration for 6 days, 11 did not produce antinociceptive tolerance in the tail-flick test and CFA-induced pain model. The present work indicates that it is reasonable to design multifunctional peptide ligands for opioid and NPFF receptors in a single molecule producing effective nontolerance forming antinociception.

GpTx‐1 and [Ala5, Phe6, Leu26, Arg28]GpTx‐1, two peptide NaV1.7 inhibitors: analgesic and tolerance properties at the spinal level

“…The motor coordination and equilibrium of mice were measured following the procedures of our previous study (Wang et al ., ). Prior to the injection, the mice were trained on a rotarod apparatus (ZB‐200, Chengdu Technology & Market Co., Ltd.) at a speed of 16 rpm for two consecutive days, and each day they were trained for three sessions at 5 min intervals.…”

Central and peripheral modulation of gastrointestinal transit in mice by DN‐9, a multifunctional opioid/NPFF receptor agonist

“…The in vitro cAMP assay was performed as previously reported. 18 HEK-293A cells stably expressing the MOP, DOP, KOP, NPFF 1 , or NPFF 2 receptors were seeded 24 hours before the cAMP assay. The cells were incubated in serum-free medium with 1 mmolL -1 IBMX,…”

“…The previous study demonstrated that DN-9 functions as a multifunctional agonist against opioid and NPFF receptors. 18 To evaluate whether the NPFF agonism of DN-9 was involved in DN-9-induced GI transit modulation, the NPFF receptor antagonist RF9 was used in the present study. As shown in Figure 6B or activation.…”

“…Phe-Gly-Pro-Gln-Arg-Phe-NH 2 ) that behaves as an agonist to opioid (MOP, DOP, and KOP) and neuropeptide FF (NPFF 1 and NPFF 2 ) receptors in vitro cAMP functional assay. 18 In addition, DN-9 exhibits potent non-tolerance-forming antinociception in different pain models. 18,19 Compared with morphine, DN-9 exhibits weaker constipating effects at antinociceptive doses.…”

“…18 In addition, DN-9 exhibits potent non-tolerance-forming antinociception in different pain models. 18,19 Compared with morphine, DN-9 exhibits weaker constipating effects at antinociceptive doses. It is notable that high doses of DN-9 significantly slow GI transit in mice.…”