Somatostatin released from the capsaicin-sensitive sensory nerves mediates analgesic and anti-inflammatory effects via the somatostatin sst4 receptor without endocrine actions. Therefore, sst4 is considered to be a novel target for drug development in pain including chronic neuropathy, which is an emerging unmet medical need. Here, we examined the in silico binding, the sst4-linked G-protein activation on stable receptor expressing cells (1 nM to 10 μM), and the effects of our novel pyrrolo-pyrimidine molecules in mouse inflammatory and neuropathic pain models. All four of the tested compounds (C1–C4) bind to the same binding site of the sst4 receptor with similar interaction energy to high-affinity reference sst4 agonists, and they all induce G-protein activation. C1 is the more efficacious (γ-GTP-binding: 218.2% ± 36.5%) and most potent (EC50: 37 nM) ligand. In vivo testing of the actions of orally administered C1 and C2 (500 µg/kg) showed that only C1 decreased the resiniferatoxin-induced acute neurogenic inflammatory thermal allodynia and mechanical hyperalgesia significantly. Meanwhile, both of them remarkably reduced partial sciatic nerve ligation-induced chronic neuropathic mechanical hyperalgesia after a single oral administration of the 500 µg/kg dose. These orally active novel sst4 agonists exert potent anti-hyperalgesic effect in a chronic neuropathy model, and therefore, they can open promising drug developmental perspectives.
来自对辣椒素敏感的感觉神经释放的生长抑素通过生长抑素sst4受体介导镇痛和抗炎作用,而无内分泌作用。因此,sst4被认为是包括慢性神经病变在内的疼痛药物开发的新靶点,这是一种新兴的未满足的医疗需求。在这里,我们检查了在稳定表达细胞上的sst4结合,sst4相关的G蛋白激活(1 nM至10 μM),以及我们的新型吡咯并嘧啶分子在小鼠炎症和神经痛模型中的作用。所有四种经过测试的化合物(C1-C4)与sst4受体的相同结合位点结合,与高亲和力参考sst4激动剂有类似的相互作用能量,并且它们都诱导G蛋白激活。C1是效力更高(γ-GTP结合:218.2% ± 36.5%)和最有效(EC50:37 nM)的配体。口服给予C1和C2(500 µg/kg)的作用的体内测试显示,只有C1显著降低了树脂花生素诱导的急性神经源性炎症热性触觉痛和机械性过敏。同时,它们两者在单次口服500 µg/kg剂量后明显减轻了部分坐骨神经结扎诱导的慢性神经病性机械性过敏。这些口服活性新型sst4激动剂在慢性神经病模型中表现出强效的抗过敏作用,因此,它们可以开启有希望的药物开发前景。