PPAR inhibition of spinal pain transmission

糖尿病影响9%的美国人口，其中约三分之一的患者患有糖尿病。 慢性神经性疼痛，通常称为疼痛性糖尿病神经病变（PDN）。PDN很难 止痛治疗仅在PDN患者的一小部分中有效。的发展 与糖尿病，特别是2型糖尿病相关的疼痛的镇痛药，由于我们的不完全 了解PDN的基本机制。一个重要的新线索来自于最近的发现 甲基乙二醛（MG），一种糖酵解的高活性二羰基产物， 高血糖症在PDN患者中特别高。MG引起蛋白质的非酶糖化。的 所产生的蛋白质加合物或晚期糖基化终产物（MG-AGEs）是有毒的，并导致糖尿病性疾病。 包括PDN在内的并发症。我们的中心假设是2型糖尿病患者MG升高会导致疼痛， 这种情况可以通过靶向MG本身、TRPA 1、AC 1、Epac和PPARγ的新型药物来缓解。到 为了检验MG驱动2型糖尿病神经病理性疼痛（PDN）的假设，具体目标1将首先 确定MG及其代谢酶Glycosidase-1是否在疼痛过程中升高 2型遗传性Leprdb/db（db/db）小鼠和Zucker糖尿病脂肪（ZDF）大鼠模型中的组织 糖尿病然后，我们问是否有一个有前途的新一类的MG-清除肽将减轻情感疼痛 和脊椎疼痛的传递我们的初步数据表明基因缺失或药物抑制 TRPA 1（MG的糖基化靶点）可以阻断MG诱导的疼痛。事实上，TRPA 1是一个主要的目标， 开发用于慢性疼痛的新镇痛剂，但尚未在2型PDN模型中进行测试。填补这一 差距，具体目标2将测试TRPA 1拮抗剂减少情感性疼痛和脊髓疼痛的假设 在db/db小鼠和ZDF大鼠中的传递。与TRPA 1通道开放（例如通过MG）相关联， Ca 2+内流进入细胞导致Ca 2+敏感蛋白的激活，其包括腺苷酸环化酶I （AC1）。我们的数据表明，NB 001选择性抑制AC 1阻断2型PDN。AC 1生成 细胞内第二信使cAMP，不仅靶向蛋白激酶A，也靶向交换蛋白 由cAMP（Epac）直接激活。Specific Aim 3将使用新型Epac 1和Epac 2小分子抑制剂， 确定这些目标中的哪个驱动PDN。在33篇原创研究文章、评论和一本书中， 在上一个资助周期（22与PI作为第一或资深作者）发表，我们的进展包括 发现吡格列酮是一种过氧化物酶体增殖物激活受体γ（PPARγ）激动剂，FDA- 被批准用于治疗糖尿病，作用于背角神经元，以抑制与皮肤相关的慢性疼痛。 炎症和创伤性神经损伤。我们的新数据表明，在PDN和MG诱导的 疼痛，在女性中具有令人惊讶的强大镇痛作用。具体目标4建议研究PPARγ db/db和ZDF的作用机制，新的重点是脊髓伤害性传递的性别差异。

Diabetes affects 9% of the United States population and approximately one-third of these patients experience chronic neuropathic pain, commonly referred to as painful diabetic neuropathy (PDN). PDN is difficult to manage as analgesic treatments are only effective in a small subset of PDN patients. The development of analgesics for pain associated with diabetes, in particular type 2 diabetes, is stalled by our incomplete understanding of the underlying mechanisms of PDN. An important new clue comes from the recent finding that methylglyoxal (MG), a highly reactive dicarbonyl product of glycolysis that accumulates with hyperglycemia, is particularly high in patients with PDN. MG causes non-enzymatic glycation of proteins. The resulting protein adducts, or advanced glycation end products (MG-AGEs), are toxic and contribute to diabetic complications including PDN. Our central hypothesis is that elevated MG in type 2 diabetes causes pain and that this can be alleviated with new classes of drugs targeting MG itself, TRPA1, AC1, Epac, and PPARγ. To test the hypothesis that MG drives neuropathic pain (PDN) in type 2 diabetes, Specific Aim 1 will first determine whether elevations in MG and its metabolizing enzyme, Glyoxalase-1, occur in pain processing tissues in the hereditary Leprdb/db (db/db) mouse and Zucker Diabetic Fatty (ZDF) rat models of type 2 diabetes. We then ask whether a promising new class of MG-scavenging peptides will alleviate affective pain and spinal pain transmission. Our preliminary data indicate that genetic deletion or pharmacological inhibition of TRPA1, a glycation target of MG, blocks MG-induced pain. Indeed, TRPA1 is a leading target for the development of new analgesics for chronic pain, but has not been tested in models of type 2 PDN. To fill this gap, Specific Aim 2 will test the hypothesis that TRPA1 antagonists reduce affective pain and spinal pain transmission in db/db mice and ZDF rats. Consequent to TRPA1 channel opening (e.g. by MG), the resulting Ca2+ influx into the cell leads to the activation of Ca2+-sensitive proteins, which includes adenylyl cyclase I (AC1). Our data indicate that selective inhibition of AC1 with NB001 blocks type 2 PDN. AC1 generates the intracellular second messenger, cAMP, which targets not only protein kinase A but also exchange protein directly activated by cAMP (Epac). Specific Aim 3 will use novel Epac1 and Epac2 small molecule inhibitors to determine which of these targets drive PDN. Among the 33 original research articles, reviews, and a book published during the previous funding cycle (22 with the PI as first or senior author), our Progress includes the discovery that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist that is FDA- approved to treat diabetes, acts at dorsal horn neurons to inhibit the chronic pain associated with cutaneous inflammation and traumatic nerve injury. Our new data indicate additional efficacy in PDN and MG-induced pain, with surprisingly robust analgesic effects in females. Specific Aim 4 proposes to study PPARγ mechanism of action in db/db and ZDF, with a new focus on sex differences in spinal nociceptive transmission.