Protective effect of hydralazine on a cellular model of Parkinson's disease: a possible role of hypoxia-inducible factor (HIF)-1α

Parkinson's disease (PD) is a neurodegenerative disease accompanied by a low expression level of cerebral hypoxia-inducible factor (HIF-1 alpha). Hence, activating the hypoxia-signaling pathway may be a favorable therapeutic approach for curing PD. This study explored the efficacy of hydralazine, a well-known antihypertensive agent, for restoring the impaired HIF-1 signaling in PD, with the aid of 6-hydroxydopamine (6-OHDA)-exposed SH-SY5Y cells. The cytotoxicity of hydralazine and 6-OHDA on the SH-SY5Y cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and apoptosis detection assays. The activities of malondialdehyde, nitric oxide (NO), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) were also measured. Expression levels of HIF-1 alpha and its downstream genes at the protein level were assessed by Western blotting. Hydralazine showed no toxic effects on SH-SY5Y cells, at the concentration of <= 50 mu mol/L. Hydralazine decreased the levels of apoptosis, malondialdehyde, and NO, and increased the activities of FRAP and SOD in cells exposed to 6-OHDA. Furthermore, hydralazine up-regulated the protein expression levels of HIF-1 alpha, vascular endothelial growth factor, tyrosine hydroxylase, and dopamine transporter in the cells also exposed to 6-OHDA, by comparison with the cells exposed to 6-OHDA alone. In summary, hydralazine priming could attenuate the deleterious effects of 6-OHDA on SH-SY5Y cells by increasing cellular antioxidant capacity, as well as the protein levels of HIF-1 alpha and its downstream target genes.