Harnessing ectonucleotidases to treat chronic pain

描述（由申请人提供）：更多的美国人患有慢性疼痛比心脏病，糖尿病和癌症的总和。不幸的是，现有的镇痛药并不是对所有疼痛状况都完全有效，并且具有严重的副作用。这些事实突出了现代生物医学研究所面临的一个毫无疑问的关键挑战--提供无严重副作用的止痛药的需求。我们将通过利用在背根神经节（DRG）和脊髓的伤害感受（疼痛感应）回路中内源性发现的外核苷酸酶来直接解决这一挑战。外核苷酸酶将引起疼痛的嘌呤核苷酸（如ATP和ADP）降解为腺苷--一种在啮齿动物和人类中具有止痛特性的化合物。腺苷通过A1-腺苷受体抑制疼痛。为了充分利用外核苷酸酶来治疗疼痛，我们将鉴定在伤害感受回路中将核苷酸代谢为腺苷的所有外核苷酸酶，然后确定这些酶是否可以单独使用或组合使用来治疗急性和慢性疼痛。我们将利用遗传修饰的小鼠，这些酶，重组外核苷酸酶蛋白，行为测定和膜片钳电生理学这些实验。此外，我们将使用药物化学合成腺苷前药，可以通过外核苷酸酶转化为有效的A1-腺苷受体激动剂。我们将测量这些前药在血清中的稳定性，并使用行为和生理学测定来评估镇痛功效和副作用。我们还将测试外核苷酸酶和前药在慢性炎症和神经性疼痛动物模型中的疗效。 公共卫生相关性：这些研究将使我们能够开发新的蛋白质和小分子，靶向外核苷酸酶治疗急性和慢性疼痛。此外，这些研究有可能改变我们治疗数百万患者疼痛的方式，同时减少副作用。

DESCRIPTION (provided by applicant): More Americans suffer from chronic pain than heart disease, diabetes and cancer combined. Unfortunately, existing analgesics are not completely effective for all pain conditions and have serious side effects. These facts highlight what is undoubtedly a critical challenge for modern biomedical research-the need to provide pain relief without serious side effects. We will directly address this challenge by harnessing ectonucleotidases that are found endogenously in nociceptive (pain-sensing) circuits in dorsal root ganglia (DRG) and spinal cord. Ectonucleotidases degrade purine nucleotides (like ATP and ADP) that cause pain into adenosine-a compound that has analgesic properties in rodents and humans. Adenosine suppresses pain by acting through A1-adenosine receptors. To fully harness ectonucleotidases for the treatment of pain, we will identify all of the ectonucleotidases that metabolize nucleotides to adenosine in nociceptive circuits and then determine if these enzymes can be used alone or in combination to treat acute and chronic pain. We will utilize genetically modified mice that are missing these enzymes, recombinant ectonucleotidase proteins, behavioral assays and patch clamp electrophysiology for these experiments. In addition, we will use medicinal chemistry to synthesize adenosine prodrugs that can be converted into potent A1-adenosine receptor agonists by ectonucleotidases. We will measure the stability of these prodrugs in serum and use behavioral and physiological assays to assess analgesic efficacy and side effects. We will also test ectonucleotidases and prodrugs for efficacy in animal models of chronic inflammatory and neuropathic pain. PUBLIC HEALTH RELEVANCE: These studies will allow us to develop new proteins and small molecules that target ectonucleotidases for the treatment of acute and chronic pain. In addition, these studies have the potential to transform how we treat pain in millions of patients with fewer side effects.