Pain Management Center, Second Hospital of Tianjin Medical University, Tianjin 300211, China.
Central Laboratory, Tianjin Research Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, China.
Biomed Res Int. 2018 May 17;2018:4670834. doi: 10.1155/2018/4670834. eCollection 2018.
Neuropathic pain is a chronic and intractable pain, with very few effective analgesics. It involves an impaired cell autophagy process. Hydrogen-rich saline (HRS) reportedly reduces allodynia and hyperalgesia in a neuropathic pain model; however, it is unknown whether these effects involve autophagy induction.
We investigated the relationship between HRS and cell autophagy in a neuropathic pain model generated by chronic constriction injury (CCI) in Sprague-Dawley rats. Rats received an intraperitoneal injection of HRS (10 mL/kg daily, from 1 day before until 14 days after CCI), 3MA (autophagy inhibitor), 2ME2 (HIF-1 inhibitor), or EDHB (HIF-1 agonist). The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested 1 day before and 1, 3, 7, 10, and 14 days after the operation. HIF-1 and cell autophagy markers in the spinal cord were evaluated by western blotting and real-time PCR assays at 14 days after CCI. Autophagosomes with double membranes were identified by transmission electron microscopy.
CCI caused behavioral hypersensitivity to mechanical and thermal stimulation in the hind-paw of the injured side. HRS improved MWT and TWL, activated autophagy, and increased autophagosomes and autolysosomes in CCI rats. 3-MA aggravated hyperalgesia and allodynia and suppressed autophagy, while EDHB attenuated hyperalgesia and activated the autophagy procedure and the HIF-1 downstream target gene BNIP3. HIF-1 inhibitors reversed the regulatory effects of HRS on autophagy in CCI rats at 14 days after spinal cord injury.
HRS reduced mechanical hyperalgesia and activation of cell autophagy in neuropathic pain through a HIF1-dependent pathway.
神经病理性疼痛是一种慢性且难治的疼痛，有效的镇痛药物非常有限。它涉及细胞自噬过程受损。富氢生理盐水（HRS）据报道可减轻神经病理性疼痛模型中的痛觉过敏和痛觉超敏；然而，尚不清楚这些作用是否涉及自噬诱导。
我们在慢性缩窄性损伤（CCI）所致神经病理性疼痛模型中研究了 HRS 与细胞自噬之间的关系。CCI 前 1 天至 CCI 后 14 天，大鼠腹腔内注射 HRS（10mL/kg，每天 1 次）、3MA（自噬抑制剂）、2ME2（HIF-1 抑制剂）或 EDHB（HIF-1 激动剂）。CCI 前 1 天和术后第 1、3、7、10 和 14 天，测试机械性缩足反射阈值（MWT）和热缩足潜伏期（TWL）。CCI 后 14 天，通过 Western blot 和实时 PCR 检测脊髓中 HIF-1 和细胞自噬标志物。用透射电镜鉴定双层膜自噬体。
CCI 导致受伤侧后足对机械和热刺激的行为敏感性增加。HRS 改善 MWT 和 TWL，激活自噬，增加 CCI 大鼠的自噬体和自噬溶酶体。3MA 加重痛觉过敏和痛觉超敏，抑制自噬，而 EDHB 减轻痛觉过敏并激活自噬程序和 HIF-1 下游靶基因 BNIP3。CCI 后 14 天，HIF-1 抑制剂逆转了 HRS 对脊髓损伤大鼠自噬的调节作用。
HRS 通过 HIF1 依赖性途径减轻神经病理性疼痛中的机械性痛觉过敏和细胞自噬激活。
