Changes in lipid peroxidation, Cu/Zn-superoxide dismutase and its mRNA following an intracerebroventricular injection of 6-hydroxydopamine in mice

A single i.c.v. injection of 6-hydroxydopamine (6-OHDA) in mice resulted in a biphasic increase in lipid peroxidation as assayed by the level of thiobarbituric acid-reacting substances (TBARS). An increase in Cu/Zn-superoxide dismutase (SOD) activity was temporally related with the first peak of TBARS but remained unchanged during the second TBARS peak. This suggests that a free radical species other than O₂^- may be involved in the late onset increase in TBARS. The level of Cu/Zn-SOD mRNA did not immediately reflect the change in Cu/Zn-SOD activity but rather increased gradually reaching significantly higher levels only 8 weeks after i.c.v. an injection of 6-OHDA. This increase in Cu/Zn-SOD mRNA likely occurs in response to a consumption of intrinsic SOD. Thus, short- and long-term increases in lipid peroxidation likely occur by different mechanisms and studies of both are needed to elucidate the neurodegenerative process.