Icariin, a flavonoid with anti-cancer effects, alleviated paclitaxel-induced neuropathic pain in a SIRT1-dependent manner

Background: One of the most common side effects of paclitaxel was dosage-dependently painful neuropathy. Various reports indicated that spinal neuroinflammation was involved in paclitaxel-induced neuropathic pain. This study investigated the effect of icariin on paclitaxel-induced neuroinflammation and peripheral neuropathy in rats. Methods: Two parts were included in this study. In part one, the effect of icariin on paclitaxel-induced neuropathic pain was investigated. Mechanical thresholds were measured as primary outcomes. Production of proinflammatory factors (tumor necrosis factor-a, interleukin-1 beta, and interleukin-6), activation of nuclear factor-kappa B (NF-kappa B(p65)) signal, and activation of astrocytes were detected as secondary outcomes. Spinal Sirtuin 1 (SIRT1) expression, H4 acetylation, and NAD(+) content were measured to investigate the effect of icariin on spinal SIRT1 signal pathway. In part two, the role of SIRT1 signal on icariin-induced effect in rats was investigated, and EX527, a SIRT1 inhibitor, was employed. Results: The results showed paclitaxel treatment induced significant decrease in mechanical thresholds. Paclitaxel treatment also induced NF-kappa B(p65) activation and upregulation of proinflammatory factors (TNF-alpha, IL-1 beta, and IL-6). Paclitaxel also induced astrocyte activation in the spinal cord. However, 100mg/kg icariin treatment significantly alleviated paclitaxel-induced mechanical allodynia and spinal neuroinflammation. Furthermore, icariin treatment dosage-dependently reversed paclitaxel-induced SIRT1 downregulation and H4 acetylation. EX527, a selective SIRT1 inhibitor, completely reversed icariin-induced anti-neuroinflammation and anti-allodynia effects in paclitaxel-induced neuropathic pain rats. Conclusions: This meant that spinal SIRT1 activation was involved in icariin-induced effects in paclitaxel-induced neuropathic pain rats. Icariin could be a potential agent for the treatment of paclitaxel-induced neuropathic pain.