Apoptosis and DNA fragmentation as induced by tertiary butylhydroperoxide in the brain

In this study, the effect of intracerebroventricular administration of the free radical generator, tertiary butylhydroperoxide, on DNA, was quantitated. Previous studies had established DNA as a very important site of free radical attack. The purpose of the study was to detect whether DNA was one of the primary targets of the toxin as well as to detect any apoptosis that may have been induced by the toxin. The DNA fragmentation assay clearly showed DNA damage within 20 min of administration of 109.7 mg/kg t-BuOOH almost in all brain regions in both 2-month and 8-month-old C57BL/6 mice. In Situ Apoptosis Detection assay, where brain sections were stained with Apoptag, demonstrated that t-BuOOH induces apoptosis in many brain regions. Electron microscopy was done to show nuclear damage and DNA fragments appearing in the cytoplasm. Cresyl violet staining was done to show that while low dose (21.9 mg/kg) t-BuOOH induces apoptosis, it may also induce necrosis in other cells of the same brain region. Thus, from this study we can conclude that DNA may be one of the primary target sites of free radical attack in the brain, and results in both necrosis and apoptosis. This can have a profound effect on neurodegeneration.