Yuan Xiaocui, Guo Yixiao, Yi Huiyuan, Hou Xuemei, Zhao Yulong, Wang Yuying, Jia Hong, Baba Sani Sa'idu, Li Man, Huo Fuquan
Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Institute of Neuroscience, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, China.
Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, China.
Front Pharmacol. 2024 Oct 1;15:1439448. doi: 10.3389/fphar.2024.1439448. eCollection 2024.
Knee osteoarthritis (KOA) is a chronic degenerative bone metabolic disease that primarily affects older adults, leading to chronic pain and disability that affect patients' daily activities. Electroacupuncture (EA) is a commonly used method for the treatment of chronic pain in clinical practice. Previous studies indicate that the endocannabinoid system is involved in EA analgesia, but whether endocannabinopeptide VD-hemopressin (α) and RVD-hemopressin (α) derived from hemoglobin chains are involved in EA analgesia is unclear.
RNA-seq technology was used to screen which genes involved in EA analgesia. The expression of hemoglobin α chain and 26S proteasome were determined by Western blotting. The level of VD-hemopressin (α) and RVD-hemopressin (α) were measured by UPLC-MS/MS. Microinjection VD-Hemopressin (α), RVD-Hemopressin (α) and 26S proteasome inhibitor MG-132 into vlPAG, then observe mechanical and thermal pain thresholds.
Therefore, we used RNA-seq to obtain differentially expressed genes and involved in EA analgesia in the periaqueductal gray (PAG), which were translated into the hemoglobin α chain. EA significantly increased the expression of the hemoglobin α chain and the level of hemopressin (α) and RVD-hemopressin (α). Microinjection of VD-hemopressin (α) and RVD-hemopressin (α) into the ventrolateral periaqueductal gray (vlPAG) mimicked the analgesic effect of EA, while CB1 receptor antagonist AM251 reversed this effect. EA significantly increased the expression of 26S proteasome in KOA mice. Microinjection of 26S proteasome inhibitor MG132 before EA prevented both the anti-allodynic effect and upregulation of the concentration of RVD-hemopressin (α) by EA treatment and upregulated the expression of the hemoglobin α chain.
Our data suggest that EA upregulated the concentration of VD-hemopressin (α) and RVD-hemopressin (α) through enhancement of the hemoglobin α chain degradation by 26S proteasome in the PAG, then activated the CB1 receptor, thereby exerting inhibition of chronic pain in a mouse model of KOA. These results provide new insights into the EA analgesic mechanisms and reveal possible targets for EA treatment of chronic pain.
膝关节骨关节炎（KOA）是一种慢性退行性骨代谢疾病，主要影响老年人，导致慢性疼痛和残疾，影响患者的日常活动。电针（EA）是临床实践中治疗慢性疼痛常用的方法。先前的研究表明，内源性大麻素系统参与电针镇痛，但源自血红蛋白链的内源性大麻素肽VD-血加压素（α）和RVD-血加压素（α）是否参与电针镇痛尚不清楚。
采用RNA测序技术筛选参与电针镇痛的基因。通过蛋白质免疫印迹法测定血红蛋白α链和26S蛋白酶体的表达。采用超高效液相色谱-串联质谱法测定VD-血加压素（α）和RVD-血加压素（α）的水平。向腹外侧导水管周围灰质（vlPAG）微量注射VD-血加压素（α）、RVD-血加压素（α）和26S蛋白酶体抑制剂MG-132，然后观察机械痛阈和热痛阈。
因此，我们利用RNA测序获得了中脑导水管周围灰质（PAG）中参与电针镇痛的差异表达基因，并将其翻译成血红蛋白α链。电针显著增加了血红蛋白α链的表达以及血加压素（α）和RVD-血加压素（α）的水平。向腹外侧导水管周围灰质（vlPAG）微量注射VD-血加压素（α）和RVD-血加压素（α）模拟了电针的镇痛效果，而CB1受体拮抗剂AM251可逆转这种效果。电针显著增加了KOA小鼠中26S蛋白酶体的表达。在电针前微量注射26S蛋白酶体抑制剂MG132可阻止电针治疗的抗痛觉过敏作用和RVD-血加压素（α）浓度的上调，并上调血红蛋白α链的表达。
我们的数据表明，电针通过增强PAG中26S蛋白酶体对血红蛋白α链的降解来上调VD-血加压素（α）和RVD-血加压素（α）的浓度，然后激活CB1受体，从而在KOA小鼠模型中发挥对慢性疼痛的抑制作用。这些结果为电针镇痛机制提供了新的见解，并揭示了电针治疗慢性疼痛的可能靶点。
