Role of the cAMP Pathway in a Chronic Muscle Pain Model

CAMP通路可被细胞外信号、激素和神经递质激活，在疼痛传递中发挥重要作用。CAMP途径激活蛋白激酶A(PKA)。然后，PKA使NMDA受体和cAMP反应元件元件结合蛋白(CREB)磷酸化，使其更有效，导致基因转录。以前的研究都是研究具有显著组织损伤和炎症的短期痛觉过敏。CAMP在慢性肌肉疼痛中的作用尚不清楚。具体目标#1将确定阻断cAMP通路是否逆转慢性肌肉疼痛模型中的机械性痛敏。这将通过鞘内注射1)腺苷环化酶或2)PKA的抑制剂来阻断cAMP途径，然后测量对机械性痛觉过敏的影响来确定。具体目标#2将确定慢性肌肉疼痛时脊髓中的NMDA受体和CREB是否被磷酸化。这将通过进行免疫组织化学染色和蛋白质印迹来确定：1)NMDA受体(NR1)的PKA位点和2)CREB的磷酸化。预计在慢性疼痛中，磷酸化将增加，阻断PKA将减少机械性痛觉过敏，并减少CREB和NMDA受体的磷酸化。

The cAMP pathway, which can be activated by extracellular signals, hormones and neurotransmitters, plays a significant role in pain transmission. The cAMP pathway activates protein kinase A (PKA). PKA then phosphorylates the NMDA receptor, making it more effective, and the cAMP-response-element-element-binding protein (CREB), resulting in gene transcription. Previous studies all investigates short- term hyperalgesia with significant tissue damage and inflammation. The role of cAMP in chronic muscle pain is unknown. Specific aim #1 will determine if blockade of the cAMP pathway reverses mechanical hyperalgesia in a chronic muscle pain model. This will be determined by blocking the cAMP pathway by intrathecally administering inhibitors of 1) adenylate cyclase or 2) PKA and then measuring the effect on mechanical hyperalgesia. Specific aim #2 will determine if the NMDA receptor and CREB are phosphorylated in the spinal cord in chronic muscle pain. This will be determined by conducting immunohistochemical stains and western blots for phosphorylation of 1) the PKA site of the NMDA receptor (NR1) and 2) CREB. It is expected that phosphorylation will increase in the chronic pain and that blocking PKA will decrease mechanical hyperalgesia and the phosphorylation of CREB and the NMDA receptor.