Behavioral and cellular pharmacology characterization of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3′-carboxamido)morphinan (NAQ) as a mu opioid receptor selective ligand

Abstract

Mu opioid receptor (MOR) selective antagonists and partial agonists have been used for the treatment of opioid abuse and addiction. Our recent efforts on the identification of MOR antagonists have provided several novel leads displaying interesting pharmacological profiles. Among them, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-[(3'-isoquinolyl)acetamido]morphinan (NAQ) showed sub-nanomolar binding affinity to the MOR with significant selectivity over the delta opioid receptor (DOR) and the kappa opioid receptor (KOR). Its central nervous system penetration capacity together with marginal agonism in the MOR–GTPγS binding assay made it a very interesting molecule for developing novel opioid abuse and addiction therapeutic agents. Therefore, further pharmacological characterization was conducted to fully understand its biological profile. At the molecular and cellular level, NAQ not only induced no translocation of β-arrestin2 to the MOR, but also efficaciously antagonized the effect of DAMGO in MOR-βarr2eGFP-U2OS cells in the β-arrestin2 recruitment assay. At the in vivo level, NAQ displayed a potent inhibition of the analgesic effect of morphine in the tail-flick assay (ID50 = 1.19 mg/kg). NAQ (10 mg/kg) also significantly decreased the hyper-locomotion induced by acute morphine without inducing any vertical jumps. Meanwhile NAQ precipitated lesser withdrawal symptoms in morphine dependent mice than naloxone. In conclusion, NAQ may represent a new chemical entity for opioid abuse and addiction treatment.

In vitro and in vivo functional profile characterization of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3-carboxamido)morphinan (NAQ) as a low efficacy mu opioid receptor modulator

“…6), which suggests that NAQ may inhibit the development of opioid dependence if co-administered with an opioid agonist. The results observed in this study further supported the data we observed in our previous study where NAQ did not induce β-arrestin2 recruitment and also NAQ pretreatment completely blocked DAMGO induced β-arrestin2 recruitment (Zhang et al, 2016, 2014). To be noted, in our previous study (Zhang et al, 2014), the β-arrestin2 recruitment assay was conducted using live cell confocal imaging, which was a qualitative assay.…”

“…The results observed in this study further supported the data we observed in our previous study where NAQ did not induce β-arrestin2 recruitment and also NAQ pretreatment completely blocked DAMGO induced β-arrestin2 recruitment (Zhang et al, 2016, 2014). To be noted, in our previous study (Zhang et al, 2014), the β-arrestin2 recruitment assay was conducted using live cell confocal imaging, which was a qualitative assay. The β-arrestin2 recruitment assay using the PathHunter assay in CHO-K1 cells is a quantitative assay, and the results obtained using this platform corroborated the findings from our previous study.…”

Application of Receptor Theory to the Design and Use of Fixed-Proportion Mu-Opioid Agonist and Antagonist Mixtures in Rhesus Monkeys

“…A second implication of the present study was that fentanyl/naltrexone mixtures could be used to stratify MOR ligands based on their in vivo antinociceptive efficacy in rhesus monkeys. In the present study, NAQ produced ,10%MPE and these results are consistent with and extend previous findings in mice (Zhang et al, 2014;Yuan et al, 2015) and rats (Siemian et al, 2016). Buprenorphine (Walker et al, 1995;Maguire and France, 2014), nalbuphine (Walker et al, 1993;France and Gerak, 1994;Banks et al, 2010b), morphine (Bowen et al, 2002), oxycodone, and methadone (Stevenson et al, 2003;Banks et al, 2010b) produced dose-dependent and thermal intensity-dependent antinociception in the present study, and these results were generally consistent with the extant literature examining MOR agonists in a warm-water tail-withdrawal procedure in monkeys.…”

17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) Modulating the Mu Opioid Receptor in a Biased Fashion

“…DAMGO-induced β-arrestin2 translocation has been previously reported. 23 The results from NAP confocal microscopy were in good agreement with the PathHunter β-arrestin2 recruitment assay (Figure 4). NAP did not induce visible β-arrestin2 recruitment in MBU cells.…”