Proapoptotic effects of 2,5-hexanedione on pheochromocytoma cells via oxidative injury

N-hexanes are prominent environmental pollutants that are able to cause neurotoxicity in vivo and in vitro. Central and peripheral neuropathies induced by n-hexane exposure are a major health concern. 2,5-Hexanedione (2,5-HD) is the most significant neurotoxic metabolite of n-hexane; however, little is known regarding the underlying mechanism of its neurotoxicity. Thus, the aim of the present study was to investigate the damaging effects of 2,5-HD on pheochromocytoma PC12 cells, and to explore the underlying mechanism. Cell viability was tested using a Cell Counting Kit-8 method, and the leakage of lactate dehydrogenase (LDH) from cells was measured using an LDH assay kit. Glutathione peroxidase (GSHPx) and superoxide dismutase (SOD) activities, and the level of malondialdehyde (MDA) were determined using corresponding assay kits. Apoptotic cells were detected using an annexin V-fluorescein isothiocyanate/propidium iodide (PI) apoptosis kit, and were subsequently observed by fluorescence microscopy. The relative expression levels of cleaved-caspase-3, Bcl-associated-X protein (Bax) and Bcl-2 were identified by western blotting. The results revealed that 2,5-HD was able to decrease the viability of PC12 cells and promoted the leakage of LDH in a concentrationdependent manner. Further analysis demonstrated that 2,5-HD decreased the activity of the antioxidative enzymes, SOD and GSHPx, and led to an increase in the levels of MDA in the supernatant of cultured PC12 cells. The annexin V/PI staining results revealed that the numbers of apoptotic cells were increased following treatment with 2,5-HD. In addition, 2,5-HD (5 and 10 mmol/l) led to significant increases in the expression levels of caspase-3 and Bax, with the concomitant downregulation of Bcl-2. The antioxidant N-acetylcysteine was identified to antagonize 2,5-HD-stimulated cleaved-caspase-3 and Bax upregulation, and Bcl-2 downregulation. Collectively, the results of the present study suggested that 2,5-HD exerts proapoptotic effects on PC12 cells via oxidative injury. These findings may be applied in the development of novel therapeutic strategies to treat neurological disorders associated with nhexane exposure.