The opioid receptor positive allosteric modulator BMS‐986187 enhances some, but not all, delta‐opioid receptor mediated behaviors

Activation of the delta opioid receptor (DOR) by orthosteric agonists produces antinociception, antihyperalgesia, antidepressant‐like effects, and convulsions in animal models. Positive allosteric modulators (PAMs) bind to a receptor site distinct from the orthosteric binding site and can augment the activity of the endogenous system. Therefore, a DOR PAM could be an effective strategy for eliciting potential therapeutic effects without convulsions. To evaluate this hypothesis, we investigated the ability of the opioid receptor PAM BMS‐986187 to elicit DOR‐mediated behaviors in mice alone or in combination with the DOR orthosteric agonist SNC80 and evaluated the potential contribution of multiple opioid receptor subtypes to the observed behavioral effects. Antidepressant‐like effects were evaluated in the mouse forced swim test and convulsions were evaluated by continuous observation. The contribution of DORs and mu‐opioid receptors (MORs) was evaluated through pharmacological and genetic manipulation of the receptor subtypes. BMS‐986187 alone produced antidepressant‐like effects without convulsions. These antidepressant‐like effects were blocked by the DOR antagonist naltrindole and absent in DOR knockout mice, indicating a DOR‐mediated effect. The antidepressant‐like effects of BMS‐986187 were enhanced in MOR knockout mice and following betaFNA pretreatment, suggesting that activation of MORs functionally inhibited DOR‐mediated antidepressant‐like effects. BMS‐986187 increased the potency of the orthosteric DOR agonist SNC80 to decrease immobility in the forced swim test but not to elicit convulsions. In addition, SNC80, but not BMS‐986187, enhanced the convulsive effects of pentylenetetrazol. Overall, these findings suggest that BMS‐986187 has activity at DORs and MORs in vivo and enhances some, but not all, behavioral effects of DOR agonists. Support or Funding Information This work was funded in part by a Research Starter Grant from the PhRMA Foundation. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .