Ciprofol alleviates remifentanil-induced hyperalgesia by regulating α2GABAARs, NR2B, and P-CaMKIIα levels in the spinal cord and hippocampus.

OBJECTIVES:Several studies have shown that propofol administration during surgery effectively attenuates remifentanil-induced hyperalgesia (RIH). Ciprofol, a novel intravenous sedative agent analogous to propofol, has not yet been proven efficacious in alleviating RIH. The present study aimed to investigate the effect of ciprofol on RIH and the possible mechanisms involved. METHODS:The RIH model was established by an infusion of remifentanil (1 μg·kg-1·min-1) 60 min in rats with incisional pain. Ciprofol (0.1, 0.25, and 0.4 mg·kg-1·min-1) was simultaneously infused to evaluate its effect on RIH. The antinociception of ciprofol was verified by measured paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). γ-aminobutyric acid type A receptor α2 subunit (α2GABAAR), N-methyl-d-aspartate receptor NR2B subunit (NR2B), calcium/calmodulin-dependent protein kinase II α (CaMKIIα), and phosphorylated CaMKIIα (P-CaMKIIα) in the spinal cord and hippocampus of rats were assessed by western blotting and immunohistochemistry. KEY FINDINGS:The results showed that ciprofol dose-dependently increased PWMT and PWTL values in RIH rats. Moreover, ciprofol upregulated α2GABAAR and downregulated NR2B and P-CaMKIIα in the rat spinal cord and hippocampus. CONCLUSIONS:Ciprofol alleviates RIH effectively, and the anti-hyperalgesic mechanisms may involve increasing α2GABAAR levels and decreasing NR2B and P-CaMKIIα levels in the spinal cord and hippocampus.