Harnessing ectonucleotidases to treat chronic pain

描述（由申请人提供）：患有慢性疼痛的美国人比心脏病、糖尿病和癌症加起来还要多。不幸的是，现有的镇痛药并不是对所有的疼痛都完全有效，而且有严重的副作用。这些事实突出了现代生物医学研究无疑面临的一个关键挑战——需要在没有严重副作用的情况下缓解疼痛。我们将通过利用在背根神经节（DRG）和脊髓的痛觉（痛觉）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——一种在啮齿类动物和人类中具有镇痛特性的化合物。腺苷通过a1 -腺苷受体抑制疼痛。为了充分利用外核苷酶治疗疼痛，我们将确定所有在痛觉回路中将核苷酸代谢为腺苷的外核苷酶，然后确定这些酶是否可以单独或联合使用来治疗急性和慢性疼痛。我们将利用缺失这些酶的转基因小鼠，重组外核苷酸酶蛋白，行为分析和膜片钳电生理学来进行这些实验。此外，我们将利用药物化学合成腺苷前药，这些前药可以通过外核苷酶转化为强效的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，并使用行为和生理试验来评估镇痛效果和副作用。我们还将在慢性炎症和神经性疼痛的动物模型中测试外核苷酸酶和前药的疗效。

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.