Journal of Pain Research (Sep 2021)
Neuropathic Pain Creates Systemic Ultrastructural Changes in the Nervous System Corrected by Electroacupuncture but Not by Pregabalin
Abstract
Lei Gao,1,2,* Jian-Feng Zhang,3,* John P Williams,4 Yi-Ning Yan,1 Xi-Lai Xiao,1 Wan-Rui Shi,5 Xiao-Yan Qian,1 Jian-Xiong An1– 3,6 1Department of Anesthesiology, Pain and Sleep Medicine, Aviation General Hospital of China Medical University and Beijing Institute of Translational Medicine, Chinese Academy of Sciences, Beijing, People’s Republic of China; 2School of Anesthesiology, Weifang Medical University, Weifang, Shangdong, People’s Republic of China; 3Savaid Medical School, University of Chinese Academy of Sciences, Beijing, People’s Republic of China; 4Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; 5Department of Anesthesiology, Peking University Third Hospital, Beijing, People’s Republic of China; 6School of Medical Science & Engineering, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jian-Xiong AnDepartment of Anesthesiology, Pain and Sleep Medicine, Aviation General Hospital of China Medical University, Beiyuan Road 3#, Beijing, 100012, People’s Republic of ChinaTel +86 13801281750Fax +86 59520233Email [email protected]: It is unclear whether neuropathological structural changes in the peripheral nervous system and central nervous system can occur in the spared nerve injury model. In this study, we investigated the pathological changes in the nervous system in a model of neuropathic pain as well as the effects of electroacupuncture (EA) and pregabalin (PGB) administration as regards pain relief and tissue repair.Patients and Methods: Forty adult male SD rats were equally and randomly divided into 4 groups: spared nerve injury group (SNI, n = 10), SNI with electroacupuncture group (EA, n = 10), SNI with pregabalin group (PGB, n =10) and sham-operated group (Sham, n=10). EA and PGB were given from postoperative day (POD) 14 to 36. EA (2 Hz and 100 Hz alternating frequencies, intensities ranging from 1– 1.5– 2 mA) was applied to the left “zusanli” (ST36) and “Yanglingquan” (GB34) acupoints for 30 minutes. The mechanical withdrawal thresholds (MWTs) were tested with von Frey filaments. Moreover, the organizational and structural alterations of the bilateral prefrontal cortex, hippocampus, sciatic nerves and the thoracic, lumbar spinal cords and dorsal root ganglions (DRGs) were examined via light and electron microscopy.Results: MWTs of left hind paw demonstrated a remarkable decrease in the SNI model (P < 0.05). In the SNI model, ultrastructural changes including demyelination and damaged neurons were observed at all levels of the peripheral nervous system (PNS) and central nervous system (CNS). In addition, EA improved MWTs and restored the normal structure of neurons. However, the effect was not found in the PGB treatment group.Conclusion: Chronic pain can induce extensive damage to the central and peripheral nervous systems. Meanwhile, EA and PGB can both alleviate chronic pain syndromes in rats, but EA also restores the normal cellular structures, while PGB is associated with no improvement.Keywords: neuropathic pain, structural changes, electroacupuncture, pregabalin
