Fig. 8.

a Schematic of the S1P/S1PR3/p38 MAPK signaling pathway involved in neuroinflammation. After LPS stimulation or spinal cord injury, resting microglia underwent M1 polarization and released proinflammatory mediators to induce neuronal apoptosis, which was improved by the specific inhibitors. b One of the Sphk1/S1P signaling pathways. S1P catalyzed by Sphk1 in the cytoplasm are transported outside the cell and bind to membrane receptors (S1PR3), then downstream activation of p38 MAPK phosphorylation and NF-κB nuclear transcription is triggered