The Effect Of Repeated Amphetamine Stimulation On Synaptic Protein Oxidative Modification In Rat Brain

We explore the effect of repeated amphetamine stimulation on total protein oxidative modification and oxidative modification to synaptic proteins including VMAT2, Snap25 and Syntaxin in the rat brain. This research helps us to further understand the mechanism of addiction and to identify novel targets for the treatment of amphetamine addiction.First, rats were treated with amphetamine at 2 mg/kg daily for 1, 3, 7, 10 or 14 days.Behavioral tests including open field test and elevated plus maze test were performed on rats. The open field test was used to analyze the locomotor activities and the elevated plus maze was used to evaluate the risk-taking behaviors. After behavioural tests, frontal cortex, hippocampus and amygdala were isolated. Total protein oxidative modification such as protein carbonylation, cysteine nitrosylation and cysteine sulfenylation were measured in these brain regions using DNPH method, biotin-switch method and dimedone method respectively. Oxidative modification to synaptic proteins including VMAT2,Snap25 and Syntaxin were also measured in these brain regions.We found that(1) Although chronic treatment with amphetamine for 7 or 14 days has no effects on the total protein carbonylation level in rat hippocampus and amygdala, this treatment significantly increased total protein carbonylation in rat frontal cortex.(2)Treatment with amphetamine for 3 or 7 days also increased the total protein nitrosylation level in rat frontal cortex. In addition, treatment with amphetamine treated for 7 days significantly increased the nitrosylation of Snap25 in rat frontal cortex.(3) Treatment with amphetamine for 7 or 10 days increased total protein sulfenylation level in rat hippocampus but not in in rat frontal cortex and amygdala.In conclusion, repeated amphetamine stimulation can increase oxidative stress,resulting in oxidative modification to proteins in rat brain. These findings suggest that protein oxidative modification may play an important role in the pathological development of amphetamine addiction.