Department of Pain, The First Hospital of China Medical University, Shenyang 110001, People's Republic of China.
Medical Oncology, Department of Gastrointestinal Cancer, Liaoning Cancer Hospital and Institute, Shenyang 110001, People's Republic of China.
Biomed Pharmacother. 2024 Jan;170:116067. doi: 10.1016/j.biopha.2023.116067. Epub 2023 Dec 26.
Neuropathic pain, a chronic condition with a high incidence, imposes psychological burdens on both patients and society. It is urgent to improve pain management and develop new analgesic drugs. Traditional Chinese medicine has gained popularity as a method for pain relief. Diosmetin (Dio) is mainly found in Chinese herbal medicines with effective antioxidant, anti-cancer, and anti-inflammatory properties. There are few known mechanisms underlying the effectiveness of Dio in treating neuropathic pain. However, the complete understanding of its therapeutic effect is missing.
This study aimed to evaluate Dio's therapeutic effects on neuropathic pain models and determine its possible mechanism of action. We hypothesized that Dio may activate antioxidants and reduce inflammation, inhibit the activation of Kelch-like epichlorohydrin-associated protein 1 (Keap1) and nuclear factor-k-gene binding (NF-κB), promote the metastasis of nuclear factor erythroid 2-related factor 2 (Nrf2) and the expression of heme oxygenase 1 (HO-1), thus alleviating the neuropathic pain caused by spinal nerve ligation.
Chronic nociceptive pain mouse models were established in vivo by L4 spinal nerve ligation (SNL). Different dosages of Dio (10, 50, 100 mg/kg) were intragastrically administered daily from the third day after the establishment of the SNL model. Allodynia, caused by mechanical stimuli, and hyperalgesia, caused by heat, were assessed using the paw withdrawal response frequency (PWF) and paw withdrawal latency (PWL), respectively. Cold allodynia were assessd by acetone test. RT-PCR was used to detect the content of interleukin-(IL)- 1β, IL-6 and tumor necrosis factor (TNF)-a. Immunofluorescence and western blotting were employed to assess the expression levels of Glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule (Iba1), Keap1, Nrf2, HO-1, and NF-κB p-p65 protein.
Dio administration relieved SNL-induced transient mechanical and thermal allodynia in mice. The protective effect of Dio in the SNL model was associated with its anti-inflammatory and anti-glial responses in the spinal cord. Dio inhibited both inflammatory factors and macrophage activation in the DRG. Furthermore, Dio regulated the Keap1/Nrf2/NF-κB signaling pathway. HO-1 and Nrf2 were upregulated following Dio administration, which also decreased the levels of Keap1 and NF-κB p65 protein.
Mice with SNL-induced neuropathic pain were therapeutically treated with Dio. Dio may protect against pain by inhibiting inflammatory responses and improved Keap1/Nrf2/NF-κB pathway. These results highlight the potential therapeutic effect of Dio for the development of new analgesic drugs.
神经病理性疼痛是一种发病率较高的慢性疾病，给患者和社会带来心理负担。改善疼痛管理和开发新的镇痛药物迫在眉睫。中药作为一种缓解疼痛的方法越来越受到关注。地奥司明（Dio）主要存在于具有有效抗氧化、抗癌和抗炎特性的中草药中。Dio 治疗神经病理性疼痛的有效性的作用机制知之甚少。然而，其治疗效果的完整理解是缺失的。
本研究旨在评估地奥司明（Dio）治疗神经病理性疼痛模型的疗效，并确定其可能的作用机制。我们假设地奥司明（Dio）可能通过激活抗氧化剂和减少炎症、抑制 Kelch-like epichlorohydrin-associated protein 1 (Keap1) 和核因子-κB 基因结合 (NF-κB) 的激活、促进核因子红细胞 2 相关因子 2 (Nrf2) 的转移和血红素加氧酶 1 (HO-1) 的表达，从而缓解脊神经结扎引起的神经病理性疼痛。
通过 L4 脊神经结扎（SNL）在体内建立慢性痛觉过敏小鼠模型。从 SNL 模型建立后的第三天开始，每天通过灌胃给予不同剂量的地奥司明（10、50、100mg/kg）。使用足底撤回反应频率（PWF）和足底撤回潜伏期（PWL）分别评估机械刺激引起的痛觉过敏和热刺激引起的痛觉过敏。冷觉过敏通过丙酮试验进行评估。RT-PCR 用于检测白细胞介素-（IL）-1β、IL-6 和肿瘤坏死因子（TNF）-a 的含量。免疫荧光和蛋白质印迹用于评估胶质纤维酸性蛋白（GFAP）、离子钙结合接头分子（Iba1）、Keap1、Nrf2、HO-1 和 NF-κB p-p65 蛋白的表达水平。
地奥司明（Dio）给药缓解了 SNL 诱导的小鼠瞬时机械性和热痛觉过敏。地奥司明（Dio）在 SNL 模型中的保护作用与其在脊髓中的抗炎和抗神经胶质反应有关。地奥司明（Dio）抑制了 DRG 中的炎症因子和巨噬细胞激活。此外，地奥司明（Dio）调节了 Keap1/Nrf2/NF-κB 信号通路。地奥司明（Dio）给药后 HO-1 和 Nrf2 上调，同时降低 Keap1 和 NF-κB p65 蛋白水平。
SNL 诱导的神经病理性疼痛小鼠经地奥司明（Dio）治疗。地奥司明（Dio）可能通过抑制炎症反应和改善 Keap1/Nrf2/NF-κB 通路来保护疼痛。这些结果强调了地奥司明（Dio）作为开发新的镇痛药物的潜在治疗作用。
