Ventura Laura, do Espírito-Santo Renan F, Keaser Michael, Zhang Youping, Ro Jin Y, Da Silva Joyce T
Center to Advance Chronic Pain Research, Department of Neural and Pain Sciences, University of Maryland Baltimore School of Dentistry, Baltimore, MD 21201, USA.
Program in Neuroscience, University of Maryland Baltimore School of Medicine, Baltimore, MD 21201, USA.
Biomedicines. 2024 Sep 3;12(9):2005. doi: 10.3390/biomedicines12092005.
Knee osteoarthritis (OA) often causes chronic pain that disproportionately affects females. Proinflammatory cytokines TNF-α, IL-1β, and IL-6 are key effectors of OA pathological changes. Green light shows potential as an alternative intervention for various pain conditions. However, no studies have investigated green light's analgesic effects in both sexes in chronic knee OA. We induced unilateral knee OA with intra-articular injection of monoiodoacetate (MIA) in male and female Sprague-Dawley rats. Two days post-injection, the rats were exposed to green-light-emitting diodes (GLED) or ambient room light eight hours daily for 24 days. Knee mechanical sensitivity was assessed using a small animal algometer. Blood serum concentrations of TNF-α, IL-1β, IL-6, and IL-10 were quantified at baseline and 23 days post-injection. MIA injection decreased the knee mechanical thresholds of the male and female rats. GLED exposure attenuated mechanical hypersensitivity in both sexes compared to the controls; however, GLED-induced analgesia occurred sooner and with greater magnitude in males than in females. In both sexes, the analgesic effects of green light lasted 5 days after the final GLED session. Finally, GLED exposure reversed the elevation of serum proinflammatory cytokines. These findings suggest that GLED exposure reduces primary hyperalgesia in OA, potentially by lowering proinflammatory cytokines, and indicate sex differences in GLED-induced analgesia.
膝关节骨关节炎（OA）常引发慢性疼痛，对女性的影响尤为严重。促炎细胞因子肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）和白细胞介素-6（IL-6）是OA病理变化的关键效应因子。绿光显示出作为各种疼痛病症替代干预手段的潜力。然而，尚无研究调查绿光对慢性膝关节OA患者两性的镇痛效果。我们通过向雄性和雌性Sprague-Dawley大鼠关节腔内注射单碘乙酸盐（MIA）诱导单侧膝关节OA。注射后两天，大鼠每天接受8小时的绿光发光二极管（GLED）照射或室内环境光照射，持续24天。使用小动物痛觉测定仪评估膝关节机械敏感性。在基线和注射后23天对血清中TNF-α、IL-1β、IL-6和IL-10的浓度进行定量分析。MIA注射降低了雄性和雌性大鼠的膝关节机械阈值。与对照组相比，GLED照射减轻了两性的机械性超敏反应；然而，GLED诱导的镇痛在雄性中比在雌性中出现得更早且程度更大。在两性中，绿光的镇痛效果在最后一次GLED照射后持续5天。最后，GLED照射逆转了血清促炎细胞因子的升高。这些发现表明，GLED照射可能通过降低促炎细胞因子来减轻OA中的原发性痛觉过敏，并表明GLED诱导的镇痛存在性别差异。
