Effect of irrigation with hypothermic artificial cerebral spinal fluid on aquaporin-4 expression in spinal cord following spinal ischemia-reperfusion in rabbits

Abstract

Objective To investigate the effect of irrigation with hypothermic artificial cerebral-spinal fluid (aCSF)on expression of aquaporin-4(AQP-4) in the spinal cord following spinal ischemia-reperfusion (I/R) in rabbits.Methods Fifty-four adult male New Zealand white rabbits weighing 2.0-2.5 kg were randomly divided into 3 groups (n=18 each):group sham operation(S group); group I/R and group irrigation with hypothermic aCSF (FI group). Spinal I/R was induced by clamping the abdominal aorta below renal artery for 60 min. Hypothermic aCSF(25 X.)was infused at L4,5 interspace at a rate of 30 ml/h and drained from L7,8 interspace during spinal ischemia.Neurological function was evaluated at 4, 24, 48 and 72 h of reperfusion and scored (0=no hind limb activity, 4=hind limb function completely recovered) in 6 animals in each group. Six animals were sacrificed at 4, 24 and 72 h respectively in each group.The lumbar segment (L5-8) was removed for measurement of water content and AQP-4 protein expression (by immuno-histochemistry).Results Neurological function scores were significantly lower,water content was higher and AQP-4 expression smaller in group I/R than in group S. I/R-induced effects were significantly attenuated by irrigation of hypothermic aCSF. Conclusion Irrigation with hypothermic aCSF can ameliorate the spinal cord I/R injuries by up-regulation of AQP-4 expression. Key words: Hypothermia, induced; Cerebrospinal fluid; Reperfusion injury; Spinal cord; Aqua-porin 4