Effect of dexmedetomidine on platelet activating factor levels in plasma and hippocampus of mice with postoperative cognitive dysfunction

Abstract

Objective To investigate the effect of dexmedetomidine (DEX) on platelet activating factor (PAF) levels in the plasma and hippocampus of mice with postoperative cognitive dysfunction (POCD). Methods A total of 30 specific pathogen free C57BL/6J mice were randomly divided into three groups (n=10): sham-operated group, POCD group and DEX intervention group. Mice in sham-operated group only received anesthesia but not partial hepatectomy surgery; the POCD models of POCD group and DEX intervention group were established by partial hepatectomy surgery under anesthesia; DEX (25 μg/kg) was given to mice from the DEX intervention group by intraperitoneal injection 30 min prior to partial hepatectomy surgery; normal saline of the same volume was injected intraperitoneally prior to partial hepatectomy surgery in sham-operated group and POCD group. Behavioral test was performed via fear conditioning tests (FCS), and the percentage of freezing time was recorded on the 3rd d of POCD modeling. The PAF levels in the blood and hippocampus were measured by enzyme-linked immunosorbent assay (ELISA). Results (1) As compared with the sham-operated group, POCD group had significantly lower percentage of freezing time in audible alerts on FCS (57.3%±9.1% vs. 30.0%±5.4%, P<0.05); as compared with the POCD group, DEX intervention group had significantly higher percentage of freezing time in audible alerts on FCS (30.0%±5.4% vs. 46.5%±6.6%, P<0.05). (2) The PAF levels in the plasma and hippocampus of POCD group were significantly increased as compared with those in the sham-operated group ([0.5±0.3] ng/mL vs. [22.5±2.2] ng/mL; [5.7±1.0] ng/mL vs. [9.8±1.4] ng/mL], P<0.05); the PAF levels in the plasma and hippocampus of DEX intervention group were significantly increased as compared with those in the POCD group ([22.5±2.2] ng/mL vs. [14.6±1.6] ng/mL; [9.8±1.4] ng/mL vs. [7.4±1.2] ng/mL, P<0.05). Conclusion DEX can improve early POCD in mice after partial hepatectomy surgery by reducing PAF levels in the plasma and hippocampus. Key words: Dexmedetomidine; Postoperative cognitive dysfunction; Platelet activating factor; Fear conditioning test