Astaxanthin ameliorates serum level and spinal expression of macrophage migration inhibitory factor following spinal cord injury

Astaxanthin (AST) is a lipid-soluble carotenoid with antioxidant and anti-inflammatory properties. Previous reports demonstrated the promising effects of AST on spinal cord injury (SCI)-induced inflammation and sensory-motor dysfunction. Macrophage migration inhibitory factor (MIF), as a cytokine, plays a critical role in the inflammatory phase of SCI. The aim of this study was to evaluate the effects of AST on post-SCI levels of MIF in serum and spinal cord. The possible correlation between MIF and mechanical pain threshold was also assessed. Adult male rats were subjected to a severe compression spinal injury and 30 min later were treated with AST (Intrathecal, 2 nmol) or vehicle. Neuropathic pain was assessed by von Frey filaments before the surgery, and then on days 7, 14, 21, and 28 post-SCI. Western blot and ELISA were used to measure the serum level and spinal expression of MIF following SCI in the same time points. AST treatment significantly attenuated the SCI-induced dysregulations in the serum levels and tissue expression of MIF. A negative correlation was observed between mechanical pain threshold and serum MIF level (r = -0.5463, P < 0.001), as well as mechanical pain threshold and spinal level of MIF (r = -0.9562; P < 0.001). AST ameliorates SCI-induced sensory dysfunction, probably through inhibiting MIF-regulated inflammatory pathways.