SPINAL NITRIC OXIDE IN CHRONIC INFLAMMATORY PAIN

未经治疗的慢性疼痛导致中枢神经系统（CNS）内神经元回路的重组、中枢致敏和疼痛增强。 慢性疼痛患者常伴有抑郁情绪，发病率较高。 在慢性炎症的动物模型中，爪和关节炎症伴有热和机械痛觉过敏以及血浆和关节滑膜组织中一氧化氮（NO）产生增加。 一氧化氮由精氨酸通过NO合酶（NOS）合成，所述NO合酶存在于至少三种同种型中，即组成型内皮型（ceNOS）和神经型（cnNOS）以及诱导型（iNOS）。 虽然炎症中NO增加的主要来源可能是由于iNOS的活性是参与免疫应答的外周细胞，但在脊髓中也发现NOS活性增加，脊髓是疼痛处理的第一个中继部位。 脊髓iNOS和cnNOS在炎性疼痛中的相对活性及其对痛觉过敏和炎症的贡献尚不清楚。所提出的研究旨在检验脊髓cnNOS活性有助于在慢性炎性疼痛中观察到的炎症和痛觉过敏的假设。 将通过向大鼠施用肽聚糖/多糖（PG/PS）或完全弗氏佐剂（CFA）来诱导慢性炎症，这是产生肢体慢性炎症的治疗。 具体目的是（1）用选择性抑制剂或反义寡脱氧核苷酸（ODN）选择性地抑制脊髓cnNOS的活性，直接施用到脊髓中并测量外周炎症以及热和机械伤害感受。 将通过免疫细胞化学在炎症发展和维持期间的不同时间点测量脊髓切片和背根神经节中脊髓cnNOS蛋白的表达。 还将通过测量精氨酸转化为瓜氨酸来测定脊髓匀浆中的总NOS活性。 将这些结果与脊髓注射错义ODN或载体获得的结果进行比较。 (2)建立了一种用NO敏感微电极对麻醉大鼠脊髓内NO释放进行真实的实时原位测定的技术。 该技术将用于测量在发炎和非发炎后爪的有害机械刺激后的脊髓NO释放。 将测量cnNOS抑制对该释放的影响。 这些研究结果将提供有关脊髓NO在外周慢性炎症和痛觉过敏的发生、发展和维持中的作用的信息。 这些信息可用于开发治疗慢性炎性疼痛或其他类型慢性疼痛的新药。

Untreated chronic pain leads to reorganization of neuronal circuits within the central nervous system (CNS), central sensitization, and enhanced pain. Chronic pain patients are often depressed, with higher morbidity probability. In animal models of chronic inflammation, paw and joint inflammation is accompanied by both thermal and mechanical hyperalgesia as well as increased nitric oxide (NO) production in plasma and joint synovial tissue. Nitric oxide is synthesized from arginine by NO synthase (NOS) which is found in at least three isoforms, constitutive endothelial (ceNOS) and neuronal (cnNOS) and inducible (iNOS). Although a major source of increased NO in inflammation is likely due to activity of iNOS is peripheral cells involved in the immune response, increased NOS activity is also found in spinal cord, the first relay site for pain processing. The relative activities of spinal iNOS and cnNOS in inflammatory pain and their contributions to hyperalgesia and inflammation are not known. The proposed studies are designed to test the hypothesis that spinal cnNOS activity contributes to both the inflammation and the hyperalgesia observed in chronic inflammatory pain. Chronic inflammation will be induced by administration of peptidoglycan/polysaccharide (PG/PS) or complete Freund s adjuvant (CFA) into rats, treatments that produce chronic inflammation of the limbs. Specific aims are to (1) selectively inhibit activity of spinal cnNOS with selective inhibitors or antisense oligodeoxynucleotide (ODN) administered directly into the spinal cord and measuring peripheral inflammation and thermal and mechanical nociception. Expression of spinal cnNOS protein in spinal cord slices and dorsal root ganglia will be measured by immunocytochemistry at various time points during development and maintenance of inflammation. Total NOS activity is spinal cord homogenates will also be determined by measuring conversion of arginine to citrulline. These results will be compared to those obtained with spinal injection of missense ODN or vehicle. (2) develop a technique using a NO-sensitive microelectrode to measure real time in situ release of NO in the spinal cord of anesthetized rats. This technique will be used to measure spinal NO release following noxious mechanical stimulation of both inflamed and non-inflamed hindpaws. Effects of cnNOS inhibition on this release will be measured. Results of these studies will provide information about the role of spinal NO in initiation, development and maintenance or peripheral chronic inflammation and hyperalgesia. This information can be used to develop new drugs to treat chronic inflammatory pain or other types of chronic pain.