Effect of valproic acid on acute lung injury in a rodent model of intestinal ischemia reperfusion

Abstract

ObjectivesAcute lung injury (ALI) can develop during the course of many clinical conditions, and is associated with significant morbidity and mortality. Valproic acid (VPA), a well-known anti-epileptic drug, has been shown to have anti-oxidant and anti-inflammatory effects in various ischemia/reperfusion (I/R) models. The purpose of this study was to investigate whether VPA could affect survival and development of ALI in a rat model of intestinal I/R. MethodsTwo experiments were performed. Experiment I: Male Sprague-Dawley rats (250–300g) were subjected to intestinal ischemia (1h) and reperfusion (3h). They were randomized into 2 groups (n=7 per group) 30min after ischemia: Vehicle (Veh) and VPA (300mg/kg, IV). Primary end-point for this study was survival over 4h from the start of ischemia. Experiment II: The histological and biochemical effects of VPA treatment on lungs were examined 3h (1h ischemia+2h reperfusion) after intestinal I/R injury (Veh vs. VPA, n=9 per group). An objective histological score was used to grade the degree of ALI. Enzyme linked immunosorbent assay (ELISA) was performed to measure serum levels of interleukins (IL-6 and 10), and lung tissue of cytokine-induced neutrophil chemoattractant (CINC) and myeloperoxidase (MPO). In addition, the activity of 8-isoprostane was analyzed for pulmonary oxidative damage. ResultsIn Experiment I, 4-h survival rate was significantly higher in VPA treated animals compared to Veh animals (71.4% vs. 14.3%, p=0.006). In Experiment II, ALI was apparent in all of the Veh group animals. Treatment with VPA prevented the development of ALI, with a reduction in the histological score (3.4±0.3 vs. 5.3±0.6, p=0.025). Moreover, compared to the Veh control group the animals from the VPA group displayed decreased serum levels of IL-6 (952±213pg/ml vs. 7709±1990pg/ml, p=0.011), and lung tissue concentrations of CINC (1188±28pg/ml vs. 1298±27pg/ml, p<0.05), MPO activity (368±23ng/ml vs. 490±29ng/ml, p<0.05) and 8-isoprostane levels (1495±221pg/ml vs. 2191±177pg/ml, p<0.05). ConclusionVPA treatment improves survival and attenuates ALI in a rat model of intestinal I/R injury, at least in part, through its anti-oxidant and anti-inflammatory effects.