Brain mitochondrial oxidative injuries induced by diazepam in mouse

QIU Xiao-zhong; CHEN Yuan; ZHOU Mei; ZHANG Wen-Zhu

doi:10.3321/j.issn:1673-4254.2001.04.012

Abstract：Objective To probe into the molecular mechanisms by which a single dose of diazepam causes side-effect injuries to the brain. Mehtods A single dose of diazepam (10 mg/kg·b.w.) was injected daily into the abdominal cavity of the mice for 3 d. The mice receiving injection with saline served as control. The brain tissues weighing precisely 350 mg were obtained from each of the rats to isolate the mitochondria, and MnSOD and cytochrome C oxidase activities were determined. Assessment of the broken mitochondrial DNA was performed with FADU method. Results A single dose of diazepam caused the mitochondrial protein to decrease from (3.307±0.240) mg/ml to (2.7461±0.451) mg/ml (n=12, t=2.690, 0.01<P<0.05) in the mouse brain, and MnSOD activity from (75.46±6.63) U/mg to (55.30±3.83) U/mg (n=12, t=6.448, P<0.01). A reduction of the absorption coefficient of cytochrome C at 550 nm from 0.112±0.008 to 0.070±0.083 (n=12, t=8.782, P<0.01) was also resulted. Diazepam could disrupt the mitochondrial DNA strands, reducing the percentage of double strand DNA from 92.95%±2.82% to 79.53%±2.33% (t=8.466, P<0.01) at 0 ℃ and from 70.45%±3.49% to 43.15%±6.01% (t=13.817, P<0.01) at 15 ℃. Conclusions A single dose of diazepam may lead to free radical-mediated injuries to the mouse brain, also causing mitochondrial DNA disruption by oxidative stress.