In the present study, we examined whether LDK1258, which produces strong CB₁ receptor allosteric effects in in vitro assays, would elicit in vivo effects consistent with allosteric activity. In initial studies, LDK1258 reduced food consumption and elicited delayed antinociceptive effects in the chronic constrictive injury of the sciatic nerve (CCI) model of neuropathic pain, which unexpectedly emerged 4 h post-injection. UPLC-MS/MS analysis quantified significant levels of LDK1258 in both blood and brain tissue at 30 min post-administration that remained stable up to 4 h. The observation that LDK1258 also produced respective antinociceptive and anorectic effects in rimonabant-treated wild type mice and CB₁ (−/−) mice suggests an off-target mechanism of action. Likewise, LDK1258 produced a partial array of common cannabimimetic effects in the tetrad assay, which were not CB₁ receptor mediated. Additionally, LDK1258 did not substitute for the CB₁ receptor orthosteric agonists CP55,940 or anandamide in the drug discrimination paradigm. In other in vivo assays sensitive to CB₁ receptor allosteric modulators, LDK1258 failed to shift the dose-response curves of either CP55,940 or anandamide in producing thermal antinociception, catalepsy, or hypothermia, and did not alter the generalization curve of either drug in the drug discrimination assay. Thus, this battery of tests yielded results demonstrating that LDK1258 produces antinociceptive effects in the CCI model of neuropathic pain, anorectic effects, and other in vivo pharmacological effects in a manner inconsistent with CB₁ receptor allosterism. More generally, this study offers a straightforward screening assay to determine whether newly synthesized CB₁ receptor allosteric modulators translate to the whole animal.

在本研究中，我们检查了在体外试验中产生强 CB ₁受体变构效应的LDK1258 是否会引发与变构活性一致的体内效应。在最初的研究中，LDK1258 在神经性疼痛的坐骨神经 (CCI) 模型的慢性收缩性损伤中减少了食物消耗并引发了延迟的镇痛作用，这种作用在注射后 4 小时出乎意料地出现。UPLC-MS/MS 分析在给药后 30 分钟量化了血液和脑组织中显着水平的 LDK1258，并在 4 小时内保持稳定。观察到 LDK1258 在利莫那班治疗的野生型小鼠和 CB _{1中也产生了各自的镇痛和厌食作用}(-/-) 小鼠表明脱靶作用机制。同样，LDK1258 在四分体试验中产生了部分常见的大麻素效应，这些效应不是 CB ₁受体介导的。此外，LDK1258 不能替代药物鉴别范式中的 CB ₁受体正构激动剂 CP55,940 或 anandamide。在对 CB ₁敏感的其他体内测定中受体变构调节剂 LDK1258 未能改变 CP55,940 或 anandamide 在产生热镇痛、僵直症或体温过低方面的剂量反应曲线，并且在药物鉴别试验中没有改变这两种药物的泛化曲线。因此，这组测试产生的结果表明，LDK1258 在神经性疼痛的 CCI 模型中以与 CB ₁受体变构不一致的方式产生镇痛作用、厌食作用和其他体内药理作用。更一般地说，这项研究提供了一种简单的筛选试验，以确定新合成的 CB ₁受体变构调节剂是否转化为整个动物。