Effect of dexmedetomidine on cell apoptosis during spinal cord ischemia-reperfusion in rats

Abstract

Objective To evaluate the effect of dexmedetomidine on cell apoptosis during spinal cord ischemia-reperfusion(I/R)in rats. Methods Forty-eight adult male Wister rats, weighing 200-260 g, were divided into 4 groups(n=12 each) using a random number table: sham operation group(Sham group), I/R group, prophylactic dexmedetomidine use group(DPro group)and dexmedetomidine postconditioning group(DPost group). The model of spinal cord I/R was established by temporary occlusion of the abdominal aorta using the modified Zivin′s method.Dexmedetomidine 5 μg·kg-1·h-1 was intravenously infused at 1 h before occlusion of the abdominal aorta in group DPro.Dexmedetomidine 5 μg·kg-1·h-1 was intravenously infused for 1 h starting from the time point immediately after beginning of reperfusion in group DPost.The equal volume of normal saline was given instead in Sham and I/R groups.The motor nerve function of the hindlimb was assessed and scored at 4, 12 and 24 h of reperfusion.The rats were sacrificed at 24 h of reperfusion, and L2-5 segments of the spinal cords were removed for microscopic examination and for determination of Bcl-2 and Bax positive cells(by immuno-histochemistry)and cell apoptosis(by flow cytometry). The apoptosis rate was calculated. Results Compared with group Sham, motor nerve function scores were significantly decreased at 4-12 h of reperfusion, and the apoptosis rate of nerve cells and Bcl-2 and Bax positive cells were increased in group I/R, and motor nerve function scores were significantly decreased at 4 h of reperfusion, and the apoptosis rate of nerve cells and Bcl-2 and Bax positive cells were increased in DPro and DPost groups(P<0.05 or 0.01). Motor nerve function scores were significantly higher, and the apoptosis rate of nerve cells was lower, Bcl-2 positive cells were higher, and Bcl-2 and Bax positive cells were lower in DPro and DPost groups than in group I/R(P<0.05 or 0.01). Conclusion The mechanism by which dexmedetomidine reduces spinal cord I/R injury is related to inhibiting cell apoptosis in rats. Key words: Dexmedetomidine; Reperfusion injury; Spinal cord; Apoptosis