Effect of valproic acid on survival and neurologic outcomes in an asphyxial cardiac arrest model of rats

Aim of the studyValproic acid (VPA) has been known to reduce neuronal injury, has anti-inflammatory and anti-apoptotic effects as a histone deacetylase (HDAC) inhibitor. Thus, this study was performed to investigate the effects of VPA on survival and neurological outcomes in an asphyxial cardiac arrest model of rats.MethodsMale Sprague-Dawley rats were subjected to asphyxial cardiac arrest. For survival study, rats were subjected to 450 s of asphyxial cardiac arrest. Cardiopulmonary resuscitation (CPR) was performed and then rats were blindly allocated to one of two groups (control group, n = 10; VPA group, n = 10). Valproic acid (300 mg kg−1) or vehicle (normal saline) was administered via tail vein immediately after return of spontaneous circulation (ROSC) and observed for 72 h. For neurological outcome study, rats (n = 7 for each group) were subjected to same experimental procedures except duration of cardiac arrest of 360 s. Neurological deficit scale (NDS) score was measured every 24 h after ROSC for 72 h and was ranged from 0 (brain dead) to 80 (normal). Brain tissues were harvested at 72 h for evaluation of apoptotic injury and acetylation status of histone H3.ResultsIn survival study, 2 rats in VPA group were excluded because cardiac arrest was not achieved in predetermined time. Thus, 10 rats were allocated to control group and 8 rats were allocated to VPA group. The survival rates at 72 h after cardiac arrest were significantly higher in VPA group than in control group (6/8 in VPA group, 3/10 rats in control group; log rank test, p < 0.05). In neurological outcome study, all rats survived for 72 h and NDS at 72 h were significantly higher in VPA group than in control group (p < 0.05). In brain tissues, expressions of acetylated histone H3 were not significantly different. However, expressions of cleaved caspase-3 were significantly lower in VPA group than in control group (p < 0.05).ConclusionVPA increased survival rates and improved neurologic outcome in asphyxial cardiac arrest model of rats while decreasing expressions of cleaved caspase-3.