Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States of America.
BlackThorn Therapeutics, San Francisco, CA, United States of America.
PLoS One. 2020 Dec 29;15(12):e0232864. doi: 10.1371/journal.pone.0232864. eCollection 2020.
Activation of the kappa opioid receptor (KOR) contributes to the aversive properties of stress, and modulates key neuronal circuits underlying many neurobehavioral disorders. KOR agonists directly inhibit ventral tegmental area (VTA) dopaminergic neurons, contributing to aversive responses (Margolis et al. 2003, 2006); therefore, selective KOR antagonists represent a novel therapeutic approach to restore circuit function. We used whole cell electrophysiology in acute rat midbrain slices to evaluate pharmacological properties of four novel KOR antagonists: BTRX-335140, BTRX-395750, PF-04455242, and JNJ-67953964. Each compound concentration-dependently reduced the outward current induced by the KOR selective agonist U-69,593. BTRX-335140 and BTRX-395750 fully blocked U-69,593 currents (IC50 = 1.2 ± 0.9 and 1.2 ± 1.3 nM, respectively). JNJ-67953964 showed an IC50 of 3.0 ± 4.6 nM. PF-04455242 exhibited partial antagonist activity asymptoting at 55% blockade (IC50 = 6.7 ± 15.1 nM). In 3/8 of neurons, 1 μM PF-04455242 generated an outward current independent of KOR activation. BTRX-335140 (10 nM) did not affect responses to saturating concentrations of the mu opioid receptor (MOR) agonist DAMGO or the delta opioid receptor (DOR) agonist DPDPE, while JNJ-67953964 (10 nM) partially blocked DAMGO and DPDPE responses. Importantly, BTRX-335140 (10 nM) rapidly washed out with complete recovery of U-69,593 responses within 10 min. Collectively, we show electrophysiological evidence of key differences amongst KOR antagonists that could impact their therapeutic potential and have not been observed using recombinant systems. The results of this study demonstrate the value of characterizing compounds in native neuronal tissue and within circuits implicated in the neurobehavioral disorders of interest.
κ 阿片受体（KOR）的激活有助于应激的厌恶特性，并调节许多神经行为障碍相关的关键神经元回路。KOR 激动剂直接抑制腹侧被盖区（VTA）多巴胺能神经元，导致厌恶反应（Margolis 等人，2003 年，2006 年）；因此，选择性 KOR 拮抗剂代表了一种恢复回路功能的新型治疗方法。我们使用急性大鼠中脑切片的全细胞膜片钳电生理学技术，评估了四种新型 KOR 拮抗剂：BTRX-335140、BTRX-395750、PF-04455242 和 JNJ-67953964 的药理学特性。每种化合物均浓度依赖性地降低了 KOR 选择性激动剂 U-69,593 诱导的外向电流。BTRX-335140 和 BTRX-395750 完全阻断 U-69,593 电流（IC50=1.2±0.9 和 1.2±1.3 nM，分别）。JNJ-67953964 的 IC50 为 3.0±4.6 nM。PF-04455242 表现出部分拮抗剂活性，在 55%阻断时达到渐近线（IC50=6.7±15.1 nM）。在 8 个神经元中有 3 个，1 μM PF-04455242 在不依赖 KOR 激活的情况下产生外向电流。BTRX-335140（10 nM）对饱和浓度的μ阿片受体（MOR）激动剂 DAMGO 或 δ阿片受体（DOR）激动剂 DPDPE 的反应没有影响，而 JNJ-67953964（10 nM）部分阻断了 DAMGO 和 DPDPE 的反应。重要的是，BTRX-335140（10 nM）快速洗脱，在 10 分钟内 U-69,593 的反应完全恢复。综上所述，我们通过电生理学证据表明，KOR 拮抗剂之间存在关键差异，这可能会影响它们的治疗潜力，而在重组系统中观察不到这些差异。这项研究的结果表明，在与神经行为障碍相关的天然神经元组织和回路中对化合物进行特征描述的价值。
