Potential role of remimazolam in alleviating bone cancer pain in mice via modulation of translocator protein in spinal astrocytes

Bone cancer pain (BCP) is a complex clinical challenge, with current treatments often falling short of providing adequate relief. Remimazolam, a benzodiazepine receptor agonist recognized for its anxiolytic effects, has emerged as a potential agent in managing BCP. This study explores the analgesic properties of remimazolam and its interaction with the translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, in spinal astrocytes. In the context of BCP, previous research has indicated that TSPO expression in spinal astrocytes may serve a protective regulatory function in neuropathic pain models. Building on this, the BCP mice received various doses of remimazolam on the 15th day post-inoculation, and pain behavior was assessed over time. The results showed that BCP induced an upregulation of TSPO and astrocyte activation in the spinal dorsal horn, alongside increased extracellular signal-regulated kinase (ERK) signaling and inflammatory cytokine expression. Remimazolam administration resulted in a dose-dependent reduction of pain behaviors, which corresponded with a decrease in both ERK pathway activation and inflammatory factor expression. This suggests that remimazolam's analgesic effects are mediated through its action as a TSPO agonist, leading to the attenuation of neuroinflammation and pain signaling pathways. Importantly, the analgesic effects of remimazolam were reversed by the TSPO antagonist PK11195, underscoring the pivotal role of TSPO in the drug's mechanism of action. This reversal also reinstated the heightened levels of ERK activity and inflammatory mediators, further confirming the involvement of TSPO in the modulation of these pain-related processes. These findings open new avenues for the therapeutic management of bone cancer pain, positioning remimazolam as a promising candidate for further investigation and development.