Effect of Toll-Like Receptor 4/Myeloid Differentiation Factor 88 Inhibition by Salvianolic Acid B on Neuropathic Pain After Spinal Cord Injury in Mice.

Background: Spinal cord injury (SCI) is a common type of injury, and about half of patients affected by SCI will suffer from neuropathic pain within a year after injury. However, the treatment effect of neuropathic pain is far from satisfactory. Our study attempted to reveal whether salvianolic acid B (SalB) could relieve the neuropathic pain caused by SCI in mice by inhibiting the Toll-like receptor 4 (TLR4)/Myeloid differentiation factor 88 (MyD88) pathway.

Methods: The mice were randomly divided into a sham group, model group, high-dose treatment group, and low-dose treatment group. The high- and low-dose groups received varying doses of SalB after modeling.

Results: The increase of pain sensitivity was evaluated by detecting paw withdrawal mechanical threshold and withdrawal thermal latency. Messenger RNA and protein expression levels of TLR4 and myD88 were detected by using quantitative reverse-transcription polymerase chain reaction and western blot, respectively. Compared with the model group, there was a significant reduction in paw withdrawal mechanical threshold and withdrawal thermal latency after SalB treatment.

Conclusions: SalB reduced the release of tumor necrosis factor-α and substance P by inhibiting the TLR4/MyD88 pathway in the SCI mouse model. This not only resulted in lower pain, but also contributed to long-term relief of mechanical hyperalgesia.