In Vivo Properties of KNT-127, a Novel δ Opioid Receptor Agonist: Receptor Internalization, Antihyperalgesia and Antidepressant Effects in Mice
Overview
Affiliations
Background And Purpose: Activation of δ opioid (DOP) receptors regulates pain and emotional responses, and also displays ligand-biased agonism. KNT-127 (1,2,3,4,4a,5,12,12a-octahydro-2-methyl-4aβ,1β-([1,2]benzenomethano)-2,6-diazanaphthacene-12aβ,17-diol) is a novel DOP receptor agonist inducing analgesia and antidepressant effects in mice. Here, we have assessed KNT-127 for (i) analgesia against chronic inflammatory pain; (ii) effects on depression, locomotion and DOP receptor internalization; and (iii) for cross-tolerance to analgesic and antidepressant effects of acute treatment by other DOP receptor agonists.
Experimental Approach: Inflammatory pain was induced by complete Freund's adjuvant injection into tail or hindpaw, and thermal and mechanical sensitivities were determined in mice. Locomotor and antidepressant-like effects were measured using actimetry and forced swim test respectively. In vivo KNT-127 selectivity and internalization were assessed using DOP receptor knockout mice and knock-in mice expressing fluorescent-tagged DOP receptors. KNT-127 was injected acutely at 0.1-10.0 mg·kg(-1) or administered chronically at 5 mg·kg(-1) daily over 5 days.
Key Results: Acute treatment with KNT-127 reversed inflammatory hyperalgesia, produced an antidepressant-like effect but induced neither hyperlocomotion nor receptor sequestration. Chronic treatment with KNT-127 induced tolerance and cross-tolerance to SNC80-induced analgesia, but no tolerance to SNC80-evoked hyperlocomotor or antidepressant-like effects.
Conclusions And Implications: The DOP receptor agonist KNT-127 induced agonist-specific acute and chronic responses, at both behavioural and cellular levels. It displays activities similar to the other recently reported DOP agonists, AR-M1000390, ADL5747 and ADL5859, and differs from SNC80. SNC80 differs from the other DOP receptor agonists including KNT-127, by exhibiting ligand-biased tolerance at this receptor.
Yoshioka T, Yamada D, Hagiwara A, Kajino K, Iio K, Saitoh T Mol Psychiatry. 2024; .
PMID: 39643691 DOI: 10.1038/s41380-024-02814-z.
Knock-In Mouse Models to Investigate the Functions of Opioid Receptors .
Degrandmaison J, Rochon-Hache S, Parent J, Gendron L Front Cell Neurosci. 2022; 16:807549.
PMID: 35173584 PMC: 8841419. DOI: 10.3389/fncel.2022.807549.
Neve J, Barlow T, Tourwe D, Bihel F, Simonin F, Ballet S RSC Med Chem. 2021; 12(6):828-870.
PMID: 34223156 PMC: 8221262. DOI: 10.1039/d1md00041a.
Bertels Z, Witkowski W, Asif S, Siegersma K, van Rijn R, Pradhan A Headache. 2020; 61(1):170-178.
PMID: 33326598 PMC: 8082730. DOI: 10.1111/head.14019.
Faouzi A, Varga B, Majumdar S Molecules. 2020; 25(18).
PMID: 32948048 PMC: 7570672. DOI: 10.3390/molecules25184257.