Esketamine inhibits the c-Jun N-terminal kinase pathway in the spinal dorsal horn to relieve bone cancer pain in rats.

Cancer-induced bone pain (CIBP) is one of the most common and feared symptoms in patients with advanced tumors. The X-C motif chemokine ligand 12 (CXCL12) and the CXCR4 receptor have been associated with glial cell activation in bone cancer pain. Moreover, mitogen-activated protein kinases (MAPKs), as downstream CXCL12/CXCR4 signals, and c-Jun, as activator protein AP-1 components, contribute to the development of various types of pain. However, the specific CIBP mechanisms remain unknown. Esketamine is a non-selective N-methyl-d-aspartic acid receptor (NMDA) inhibitor commonly used as an analgesic in the clinic, but its analgesic mechanism in bone cancer pain remains unclear. We used a tumor cell implantation (TCI) model and explored that CXCL12/CXCR4, p-MAPKs, and p-c-Jun were stably up-regulated in the spinal cord. Immunofluorescence images showed activated microglia in the spinal cord on day 14 after TCI and co-expression of CXCL12/CXCR4, p-MAPKs (p-JNK, p-ERK, p-p38 MAPK), and p-c-Jun in microglia. Intrathecal injection of the CXCR4 inhibitor AMD3100 reduced JNK and c-Jun phosphorylations, and intrathecal injection of the JNK inhibitor SP600125 and esketamine also alleviated TCI-induced pain and reduced the expression of p-JNK and p-c-Jun in microglia. Overall, our data suggest that the CXCL12/CXCR4-JNK-c-Jun signaling pathway of microglia in the spinal cord mediates neuronal sensitization and pain hypersensitivity in cancer-induced bone pain and that esketamine exerts its analgesic effect by inhibiting the JNK-c-Jun pathway.

The protective effect and mechanism of sevoflurane on LPS-induced acute lung injury in mice.

Acute lung injury (ALI) is a disturbance caused by infectious or non-infectious inflammation and lipopolysaccharide (LPS) could induce an artificial pathological ALI process. Sevoflurane has been demonstrated to be an inhaled anesthetic having anti-inflammatory and protective effects on inflammatory injury. To study the protective effects and mechanisms of sevoflurane on LPS-induced acute lung injury in mice. By assessing W/D ratio, sevofluranecan counteract the edema induced by LPS. The ELISA results showed that sevoflurane reduced IFN-γ production and increased IL-10 level. Elevation of PGE2 induced by sevofluraneand LPS in peritoneal macrophages was inhibited by NS-398, an inhibitor of the PGE2 regulator COX-2, indicating that NS-398 blocked COX-2 mediated PGE2 synthesis. NS-398 itself did not cause lung inflammation and mitigated the protective effect of sevoflurane on LPS-induced ALI in mice. LPS changes immune homeostasis, resulting in acute lung inflammatory injury. Inhaled sevoflurane regulates immune homeostasis, thereby playing a protective role in alleviating LPS-induced ALI.