Rashvand Mina, Danyali Samira, Manaheji Homa
Department of Physiology, School of Medicine, Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Basic Clin Neurosci. 2020 Jan-Feb;11(1):15-30. doi: 10.32598/bcn.11.1.1. Epub 2020 Jan 1.
Glycogen Synthase Kinase-3β (GSK-3β) participates in several signaling pathways and plays a crucial role in neurodegenerative diseases, inflammation, and neuropathic pain. The ratio of phosphorylated GSK-3β over total GSK-3β (p-GSK-3β/t-GSK-3β) is reduced following nerve injury. Apoptosis is a hallmark of many neuronal dysfunctions in the context of neuropathic pain. Thus, this study aimed to evaluate the contribution of p-GSK-3β/t-GSK-3β ratio in spinal dorsal horn apoptosis following peripheral nerve injury.
In this study, adult male Wistar rats (220-250 g) underwent Spinal Nerve Ligation (SNL) surgery. Mechanical allodynia and thermal hyperalgesia were assessed before the surgery (day 0); then, every other day up to day 8. GSK-3β selective inhibitor, AR-014418 [0.3 mg/kg, Intraperitoneal (IP)] was administrated 1 h prior to SNL on day 0, then daily up to the day 8. The GSK-3β activity and apoptosis in the lumbar section (L4, L5, or L6) of the study rat's spinal cord were assessed by immunohistochemical and Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling (TUNEL) staining, respectively on day 8 post-SNL.
Following the SNL, the mechanical allodynia and thermal hyperalgesia increased on day 2 up to day 8 post-SNL. The ratio of p-GSK-3β/t-GSK-3β decreased, and the number of apoptotic cells increased in the spinal dorsal horn on day 8. However, AR-A014418 administration could increase the p-GSK-3β/t-GSK-3β ratio and decreased apoptosis in the SNL rats. In addition, AR-A014418 decreased the mechanical allodynia from day 4 up to day 8; however, it did not affect thermal hyperalgesia.
The study findings suggested that increasing the p-GSK-3β/t-GSK-3β ratio might be a helpful strategy for reducing the apoptotic cells and subsequent neuropathic pain during peripheral nerve injury.
糖原合酶激酶-3β（GSK-3β）参与多种信号通路，在神经退行性疾病、炎症和神经性疼痛中起关键作用。神经损伤后，磷酸化GSK-3β与总GSK-3β的比值（p-GSK-3β/t-GSK-3β）会降低。细胞凋亡是神经性疼痛背景下许多神经元功能障碍的一个标志。因此，本研究旨在评估p-GSK-3β/t-GSK-3β比值在周围神经损伤后脊髓背角细胞凋亡中的作用。
在本研究中，成年雄性Wistar大鼠（220-250克）接受脊髓神经结扎（SNL）手术。在手术前（第0天）评估机械性异常性疼痛和热痛觉过敏；然后，每隔一天评估一次，直至第8天。在第0天SNL前1小时腹腔注射（IP）GSK-3β选择性抑制剂AR-014418[0.3毫克/千克]，然后每天注射，直至第8天。在SNL后第8天，分别通过免疫组织化学和末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）染色评估研究大鼠脊髓腰段（L4、L5或L6）的GSK-3β活性和细胞凋亡情况。
SNL后，在SNL后第2天至第8天，机械性异常性疼痛和热痛觉过敏增加。第8天，脊髓背角p-GSK-3β/t-GSK-3β比值降低，凋亡细胞数量增加。然而，给予AR-A014418可增加SNL大鼠的p-GSK-3β/t-GSK-3β比值并减少细胞凋亡。此外，AR-A014418从第4天至第8天减轻了机械性异常性疼痛；然而，它对热痛觉过敏没有影响。
研究结果表明，提高p-GSK-3β/t-GSK-3β比值可能是减少周围神经损伤期间凋亡细胞和后续神经性疼痛的一种有效策略。
