Quantification of superoxide radical in the brain of rats with experimentally induced obstructive jaundice.

The study aimed to directly measure in vivo superoxide radical (O2) a direct indicator of oxidative stress, in the brain of rats with experimentally induced obstructive jaundice by employing a new quantitative ultrasensitive fluorescent assay requiring minimum sample. O2 anion is specific for dihydroethidine (DHE) and upon reaction gives a characteristic product, namely 2-OH-ethidium. Ten male rats underwent laparotomy and were divided into two groups: I, sham operated and II bile duct ligation. Ten days later, following injection with DHE (a O2 trap), all animals were killed and samples from cerebral cortex, midbrain and cerebellum were removed for analysis. It was shown that compared to group I, in group II the O2 was increased by 67% in the cerebral cortex and by 37% in the midbrain as a consequence of experimental obstructive jaundice, while its levels were unaffected in the cerebellum. The data in this experimental obstructive jaundice model imply a region-specific increase of O*2 formation rate, being higher in cerebral cortex, less so in the midbrain and not at all in cerebellum.