Effect of dexmedetomidine on expression of hypoxia-inducible factor-1α during endotoxin-caused apoptosis in macrophages of mice

Abstract

Objective To evaluate the effect of dexmedetomidine on expression of hypoxia-inducible factor-1α(HIF-1α)during endotoxin-caused apoptosis in macrophages of mice. Methods Mouse macrophage cell line RAW264.7 cultured in vitro were seeded in 6-well or 96-well plates and divided into 4 groups(n=16 each)when cell confluence reached 60%-70% using a random number table method: control group(group Con), dexmedetomidine group(group Dex), lipopolysaccharide(LPS)group, and LPS plus dexmedetomidine group(group LPS+ Dex). Phosphate buffer solution was added in group Con.Dexmedetomidine 1 μmol/L was added in group Dex.LPS 1 μg/ml was added in LPS and LPS+ Dex groups.Dexmedetomidine 1 μmol/L was added immediately after adding LPS in group LPS+ Dex.Cells were then cultured for 24 h in each group.Cell apoptosis was measured using TUNEL, mitochondrial membrane potential using JC-1, reactive oxygen species(ROS) content by ROS kit, and ATP content by ATP kit.The apoptosis rate was calculated.The expression of HIF-1α, cytochrome C(Cyt-c), caspase-9 and cleaved caspase-3 was detected by Western blot. Results Compared with group Con, the apoptosis rate and ROS content were significantly increased, ATP content and mitochondrial membrane potential were decreased, the expression of HIF-1α, Cyt-c, caspase-9 and cleaved caspase-3 was up-regulated in group LPS(P 0.05). Compared with group LPS, the apoptosis rate and ROS content were significantly decreased, ATP content and mitochondrial membrane potential were increased, the expression of HIF-1α was up-regulated, and the expression of Cyt-c, caspase-9 and cleaved caspase-3 was down-regulated in group LPS + Dex(P<0.05). Conclusion Dexmedetomidine can reduce endotoxin-caused oxidative stress injury to macrophages, improve mitochondrial function and inhibit mitochondrial apoptosis, and the mechanism may be related to up-regulating the expression of HIF-1α in mice. Key words: Dexmedetomidine; Sepsis; Apoptosis; Macrophage; Mitochondria; Apoptosis; Hypoxia-induced factor 1, αlpha subunit