O'Brien Melissa S, Richter Emily, Woodward Taylor, Bradshaw Heather B, McDougall Jason J
Departments of Pharmacology and Anaesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada.
Department of Psychological and Brain Sciences, Program in Neuroscience, Indiana University, Bloomington, IN, United States.
Pain. 2025 Jun 1;166(6):1274-1284. doi: 10.1097/j.pain.0000000000003458. Epub 2024 Oct 18.
Visual exposure to dim, green, light has been found to reduce pain levels in patients living with migraine, low back pain, and fibromyalgia. Preclinical studies discovered that the analgesic effect of green light was due to the central release of endogenous opioids and a reduction in inflammatory cytokines in the cerebrospinal fluid. The present study assessed the effect of green light therapy (GLT) on joint pain in a rat model of osteoarthritis (OA) and investigated the role of endolipids. Male and female Wistar rats (207-318 g) received an intra-articular injection of sodium monoiodoacetate (3 mg in 50 μL saline) into the knee to induce OA. On day 9, animals were placed in a room illuminated by either white (neutral-white 4000K; 20 lux) or green (wavelength: 525 nm; luminance: 20 lux) light for 5 days (8 hours per day). Joint nociception was assessed by von Frey hair algesiometry, dynamic weight bearing, and in vivo single unit extracellular recordings from knee joint mechanonociceptors. Compared to white light, GLT significantly reduced secondary mechanical hypersensitivity in both sexes and improved hindlimb weight bearing in females only. There was no effect of GLT on joint nociceptor activity in either sex. Serum lipidomics indicated an increase in circulating analgesic endolipids in response to GLT, particularly the N -acyl-glycines. Partial blockade of the endocannabinoid system with the G protein receptor-18/cannabinoid-1 receptor antagonist AM281 (500 μg/kg i.p.) attenuated GLT-induced analgesia. These data show for the first time that GLT acts to reduce OA pain by upregulating circulating analgesic endolipids, which then engage the endocannabinoid system.
研究发现，视觉暴露于昏暗的绿光下可降低偏头痛、下背痛和纤维肌痛患者的疼痛程度。临床前研究发现，绿光的镇痛作用归因于内源性阿片类物质的中枢释放以及脑脊液中炎性细胞因子的减少。本研究评估了绿光疗法（GLT）对骨关节炎（OA）大鼠模型关节疼痛的影响，并研究了内脂质的作用。将雄性和雌性Wistar大鼠（207 - 318克）膝关节内注射一碘乙酸钠（3毫克溶于50微升盐水中）以诱导OA。在第9天，将动物置于白色（中性白4000K；20勒克斯）或绿色（波长：５２５纳米；亮度：20勒克斯）光照的房间中5天（每天8小时）。通过von Frey毛发痛觉测定法、动态负重以及膝关节机械性伤害感受器的体内单单位细胞外记录来评估关节伤害感受。与白光相比，GLT显著降低了两性的继发性机械性超敏反应，并且仅改善了雌性的后肢负重。GLT对两性的关节伤害感受器活性均无影响。血清脂质组学表明，响应GLT，循环镇痛内脂质增加，尤其是N-酰基甘氨酸。用G蛋白受体-18/大麻素-1受体拮抗剂AM281（500微克/千克腹腔注射）部分阻断内源性大麻素系统可减弱GLT诱导的镇痛作用。这些数据首次表明，GLT通过上调循环镇痛内脂质来减轻OA疼痛，然后这些内脂质作用于内源性大麻素系统。
