Sodium aescinate ameliorates chronic neuropathic pain in male mice via suppressing JNK/p38-mediated microglia activation.

Objective: A study confirmed that sodium aescinate (SA) can effectively relieve bone cancer pain, but its role in neuropathic pain (NP) remains confused.

Methods: Eighty male mice were randomly divided into four groups: sham+vehicle, sham+SA (40 μg/L, intrathecal injection), chronic contraction injury (CCI)+vehicle, CCI+SA. Behavioral assessments were used to evaluate the locomotor activity and paw withdrawal threshold (PWT) of mice. At the end of the study, spinal cord tissues were collected for histopathological analysis. The JNK/p38 signaling activation, Iba-1 expression, pro-inflammatory cytokines levels, and microglia subtype were assessed by western blotting, immunohistochemical staining, enzyme-linked immunosorbent assay, and flow cytometry with CD86/CD206, respectively.

Results: Early treatment with SA delayed the development of mechanical allodynia in CCI mice. Repeated SA treatment could prominently increase the reduction of PWT induced by CCI, and improve the locomotor activity of CCI mice. Mechanically, CCI surgery induced significant up-regulation of p-JNK and p-p38 protein levels, increased number and M1/M2 ratio of microglia, as well as pro-inflammatory factors in the spinal cords of mice, which could be blocked after SA administration.

Conclusions: SA might suppress the activation of microglia and neuroinflammation by selectively inhibiting the JNK/p38 signaling pathway, thereby alleviating CCI-induced NP in male mice.