engleski

Association of 4-Hydoxynonenal with local and systemic consequences of oxidative stress in experimental ischemia-reperfusion brain injury

Incomplete ischemia of the brain (of the anesthetized rats) was induced by transient occlusion of the carotid arteries, while the vertebral arteries were left open. In some of the rats carotid arteries were reopened after 120 min thus causing reperfusion injury. Control rats were equally operated, but their carotid arteries were left open all the time. Development of lipid peroxidation was analyzed by immunohistochemical evaluation of the presence of 4-hydroxynonenal (HNE) in the brain cells using monoclonal antibodies raised against the aldehyde [1,2]. The same antibodies were used to reveal the presence of HNE-adducts in plasma. Systemic consequences of such brain injury were further studied by analyzing the effects of the plasma samples in vitro on the growth of cultured murine fibroblasts and mononuclear cells (estimated according to the 3H-TdR incorporation). In the controls intensive HNE staining was obtained only in the brain membranes and adjacent blood vessels as well as in ependim and plexus chorioideus. Only some neurons in pons and hippocampus were moderately positive, while there were no HNE positive glial cells at all. Ischemia increased HNE positivity in the mentioned brain structures and caused generation of HNE in blood vessels of frontal part of the brain and in diencephalon and hippocampus. Abundant HNE was detected not only in neurons, but in glial cells, too. However, there was no obvious difference of the HNE-adducts content in plasma of the sham operated rats and animals exposed to brain ischemia. Surprisingly, in animals exposed to ischemia-reperfusion HNE positivity decreased in the blood vessels spreading from the carotid arteries and in ependim and plexus chorioideus. The neurons were also less positive than in rats exposed only to ischemia while HNE ”disappeared” completely from oligodendroglia cells (remaining weak in astrocytes). High HNE content could be seen only in hippocampus, soft membranes and adjacent blood vessels. In spite of observed ”wash” of HNE from the brain of ”reperfused” rats the content of HNE-adducts in plasma could be determined as low as in the other groups (<2 ng/ml). Hence, no particular differences of the HNE content in plasma depending on the type of injury could be seen. On the contrary, there was an obvious difference of the biological activity in vitro of the plasma samples obtained from the differently treated animals. While growth promoting activity plasma of the control rats increased, if taken after two hours of ”sham operation” (in comparison to the initial activity of plasma taken in the beginning of the experiment), ischemia caused a decrease of the in vitro growth promoting activity of plasma. Moreover, after ten minutes of brain reperfusion, ”biological activity” of plasma returned to normal (observed for the plasma taken at the beginning of the experiment) if it was added to the fibroblast cultures, and even above the normal if added to the mononuclear cells. Thus, we conclude that brain ischemia increases HNE synthesis in the brain, while the aldehyde is mainly washed after reperfusion from the brain regions supplied by the blood through the vessels which were occluded during ischemia. Such an event is not associated by the remarkable change of the quantity of HNE-adducts in the blood, but primarily with the changed biological activity of the plasma, indicating modification of some, yet unidentified, humoral factors which have growth factor-like biological activity [3].

brain; oxidative stress; HNE; ischemia; injury; neuropathology

nije evidentirano