scholarly journals Harnessing the Anti-Nociceptive Potential of NK2 and NK3 Ligands in the Design of New Multifunctional μ/δ-Opioid Agonist–Neurokinin Antagonist Peptidomimetics

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5406
Author(s):  
Charlène Gadais ◽  
Justyna Piekielna-Ciesielska ◽  
Jolien De Neve ◽  
Charlotte Martin ◽  
Anna Janecka ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Pain Treatment ◽  
Binding Assays ◽  
Opioid Agonist ◽  
Opioid Binding ◽  
Μ Opioid Receptor ◽  
Multiple Ligands ◽  
Neurokinin 1 ◽  
Covalently Linked ◽  
Δ Opioid Receptor

Opioid agonists are well-established analgesics, widely prescribed for acute but also chronic pain. However, their efficiency comes with the price of drastically impacting side effects that are inherently linked to their prolonged use. To answer these liabilities, designed multiple ligands (DMLs) offer a promising strategy by co-targeting opioid and non-opioid signaling pathways involved in nociception. Despite being intimately linked to the Substance P (SP)/neurokinin 1 (NK1) system, which is broadly examined for pain treatment, the neurokinin receptors NK2 and NK3 have so far been neglected in such DMLs. Herein, a series of newly designed opioid agonist-NK2 or -NK3 antagonists is reported. A selection of reported peptidic, pseudo-peptidic, and non-peptide neurokinin NK2 and NK3 ligands were covalently linked to the peptidic μ-opioid selective pharmacophore Dmt-DALDA (H-Dmt-d-Arg-Phe-Lys-NH2) and the dual μ/δ opioid agonist H-Dmt-d-Arg-Aba-βAla-NH2 (KGOP01). Opioid binding assays unequivocally demonstrated that only hybrids SBL-OPNK-5, SBL-OPNK-7 and SBL-OPNK-9, bearing the KGOP01 scaffold, conserved nanomolar range μ-opioid receptor (MOR) affinity, and slightly reduced affinity for the δ-opioid receptor (DOR). Moreover, NK binding experiments proved that compounds SBL-OPNK-5, SBL-OPNK-7, and SBL-OPNK-9 exhibited (sub)nanomolar binding affinity for NK2 and NK3, opening promising opportunities for the design of next-generation opioid hybrids.

scholarly journals Elucidating the active δ-opioid receptor crystal structure with peptide and small-molecule agonists

2019 ◽  
Vol 5 (11) ◽  
pp. eaax9115 ◽  
Author(s):  
Tobias Claff ◽  
Jing Yu ◽  
Véronique Blais ◽  
Nilkanth Patel ◽  
Charlotte Martin ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Opioid Receptor ◽  
Small Molecule ◽  
Pain Treatment ◽  
Receptor Activation ◽  
Atomic Scale ◽  
Site Directed Mutagenesis ◽  
Opioid Agonist ◽  
Activated State ◽  
Δ Opioid Receptor

Selective activation of the δ-opioid receptor (DOP) has great potential for the treatment of chronic pain, benefitting from ancillary anxiolytic and antidepressant-like effects. Moreover, DOP agonists show reduced adverse effects as compared to μ-opioid receptor (MOP) agonists that are in the spotlight of the current “opioid crisis.” Here, we report the first crystal structures of the DOP in an activated state, in complex with two relevant and structurally diverse agonists: the potent opioid agonist peptide KGCHM07 and the small-molecule agonist DPI-287 at 2.8 and 3.3 Å resolution, respectively. Our study identifies key determinants for agonist recognition, receptor activation, and DOP selectivity, revealing crucial differences between both agonist scaffolds. Our findings provide the first investigation into atomic-scale agonist binding at the DOP, supported by site-directed mutagenesis and pharmacological characterization. These structures will underpin the future structure-based development of DOP agonists for an improved pain treatment with fewer adverse effects.

scholarly journals Proteasome Involvement in Agonist-induced Down-regulation of μ and δ Opioid Receptors

2001 ◽  
Vol 276 (15) ◽  
pp. 12345-12355 ◽  
Author(s):  
Kirti Chaturvedi ◽  
Persis Bandari ◽  
Norihiro Chinen ◽  
Richard D. Howells
Keyword(s):  
Opioid Receptor ◽  
Opioid Receptors ◽  
Proteasome Inhibitors ◽  
Metabolic Labeling ◽  
Down Regulation ◽  
Hek 293 ◽  
293 Cells ◽  
Ubiquitin Proteasome ◽  
Μ Opioid Receptor ◽  
Δ Opioid Receptor

This study investigated the mechanism of agonist-induced opioid receptor down-regulation. Incubation of HEK 293 cells expressing FLAG-tagged δ and μ receptors with agonists caused a time-dependent decrease in opioid receptor levels assayed by immunoblotting. Pulse-chase experiments using [35S]methionine metabolic labeling indicated that the turnover rate of δ receptors was accelerated 5-fold following agonist stimulation. Inactivation of functional Giand Goproteins by pertussis toxin-attenuated down-regulation of the μ opioid receptor, while down-regulation of the δ opioid receptor was unaffected. Pretreatment of cells with inhibitors of lysosomal proteases, calpain, and caspases had little effect on μ and δ opioid receptor down-regulation. In marked contrast, pretreatment with proteasome inhibitors attenuated agonist-induced μ and δ receptor down-regulation. In addition, incubation of cells with proteasome inhibitors in the absence of agonists increased steady-state μ and δ opioid receptor levels. Immunoprecipitation of μ and δ opioid receptors followed by immunoblotting with ubiquitin antibodies suggested that preincubation with proteasome inhibitors promoted accumulation of polyubiquitinated receptors. These data provide evidence that the ubiquitin/proteasome pathway plays a role in agonist-induced down-regulation and basal turnover of opioid receptors.

Inflammation-reactive astrocytes can be restored with a three drug combination

2014 ◽  
Vol 5 (3) ◽  
pp. 209-209
Author(s):  
E. Hansson ◽  
L. Block ◽  
U. Björklund ◽  
B. Biber
Keyword(s):  
Opioid Receptor ◽  
Primary Cultures ◽  
Reactive Astrocytes ◽  
Opioid Antagonist ◽  
Opioid Agonist ◽  
Cell Parameters ◽  
Ultralow Concentrations ◽  
Inflammatory State ◽  
Μ Opioid Receptor

Abstract Aims In inflammation-reactive astrocytes the cell parameters, Ca2+ signalling, Na+ transporters, cytoskeleton, and release of proinflammatory cytokines are affected. We want to re-establish these parameters with agents, which might have a potential to restore the cells back to a normal non-inflammatory level. Methods Astrocytes in primary cultures were incubated with lipopolysaccharide (LPS) (10 ng/ml) for 24 h to become inflammation-reactive. Different parameters were analysed to verify this inflammation: Ca2+ signalling, Na+/K+-ATPase expression, actin filament organization, and interleukin-1beta release (IL-1β). Results We have used an opioid agonist, endomorphin-1, that stimulates the Gi/o protein of the μ-opioid receptor, an opioid antagonist, naloxone, that inhibits the Gs protein of the μ-opioid receptor in ultralow concentrations, and an anti-epileptic agent, levetiracetam, that counteracts the release of IL-1β. The combination of these three agents managed to activate the Gi/o protein and Na+/K+-ATPase activity, inhibit the Gs protein, and decrease the release of IL-1β. The disorganized actin filaments were restored. Conclusions The findings that the important cell parameters in astrocytes were restored back to their normal non-inflammatory state after the cells were treated with the inflammatory agent LPS could be of clinical significance. It may be useful for the treatment of neuroinflammation and also maybe of long-term pain. The astrocyte networks play a significant role and therefore a well-working intercellular Ca2+ signalling is of utmost importance. Significance These findings put new potential drug regimens towards treatment of neuroinflammation and long-term pain into focus.

μ-Opioid receptor agonist effects on medullary respiratory neurons in the cat: evidence for involvement in certain types of ventilatory disturbances

2003 ◽  
Vol 285 (6) ◽  
pp. R1287-R1304 ◽  
Author(s):  
Peter M. Lalley
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Opioid Receptor ◽  
Membrane Properties ◽  
Respiratory Neurons ◽  
Opioid Agonist ◽  
Chest Wall Compliance ◽  
Wall Compliance ◽  
Μ Opioid Receptor ◽  
Synaptic Drive

μ-Opioid receptor agonists depress tidal volume, decrease chest wall compliance, and increase upper airway resistance. In this study, potential neuronal sites and mechanisms responsible for the disturbances were investigated, dose-response relationships were established, and it was determined whether general anesthesia plays a role. Effects of μ-opioid agonists on membrane properties and discharges of respiratory bulbospinal, vagal, and propriobulbar neurons and phrenic nerve activity were measured in pentobarbital-anesthetized and unanesthetized decerebrate cats. In all types of respiratory neurons tested, threshold intravenous doses of the μ-opioid agonist fentanyl slowed discharge frequency and prolonged duration without altering peak discharge intensity. Larger doses postsynaptically depressed discharges of inspiratory bulbospinal and inspiratory propriobulbar neurons that might account for depression of tidal volume. Iontophoresis of the μ-opioid agonist DAMGO also depressed the intensity of inspiratory bulbospinal neuron discharges. Fentanyl given intravenously prolonged discharges leading to tonic firing of bulbospinal expiratory neurons in association with reduced hyperpolarizing synaptic drive potentials, perhaps explaining decreased inspiratory phase chest wall compliance. Lowest effective doses of fentanyl had similar effects on vagal postinspiratory (laryngeal adductor) motoneurons, whereas in vagal laryngeal abductor and pharyngeal constrictor motoneurons, depression of depolarizing synaptic drive potentials led to sparse, very-low-frequency discharges. Such effects on three types of vagal motoneurons might explain tonic vocal fold closure and pharyngeal obstruction of airflow. Measurements of membrane potential and input resistance suggest the effects on bulbospinal Aug-E neurons and vagal motoneurons are mediated presynaptically. Opioid effects on the respiratory neurons were similar in anesthetized and decerebrate preparations.

Sign in / Sign up

Export Citation Format

Share Document