Effect of heme oxygenase-1 on brain edema induced by asphyxial cardiac arrest and resuscitation in rats

Abstract

Objective To investigate the effect of heme oxygenase-1 ( HO-1) on brain edema in a rat model of asphyxial cardiac arrest and resuscitation. Methods Forty male SD rats weighing 250-300 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation; group II cardiac arrest (CA); group Ⅰ Hemin (HO-1 inducer) and group IV SnPP (HO-1 inhibitor). Asphyxial cardiac arrest and resuscitation were performed in CA, Hemin and SnPP groups (group Ⅰ ,Ⅲ, Ⅳ) . Hemin and SnPP groups received hemin 15 mg/kg intraperitoneally (IP) at 12 h before CA and SnPP K 30 μmol/kg IP at 1 h before CA respectively. The animals were sacrificed at 1 and 6 h after recovery of spontaneous circulation (ROSC) . The water content of the cortex, hippocampus and brain stem and the expression of HO-1 and aquaporin-4 (AQP4) mRNA in cortex and hippocampus ( by RT-PCR) were determined. Results Water content of cortex and hippocampus was significantly higher at 1 h after ROSC in CA and SnPP groups than in sham operation group and was significantly lower in Hemin group than in CA group. There was no significant difference in water content of brain stem at 1 and 6 h after ROSC among all 4 groups. The expression of AQP4 mRNA was significantly higher in cortex and hippocampus at 1 h after ROSC in CA and SnPP groups than in sham operation group and was significantly lower in Hemin group than in CA group.Conclusion HO-1 can reduce brain water content at early stage after cardiac arrest and resuscitation by regulating the expression of AQP4. Key words: Heme oxygenase-1; Cardiopulmonary resuscitation; Brain edema; Aquaporin 4