Changes in respiration of the mitochondrial fraction of brain homogenates in rats with stepwise incomplete cerebral ischemia

Abstract

Objective: to conduct a comparative analysis of mitochondrial respiration in brain homogenates of rats with stepwise incomplete cerebral ischemia (SICI) with varying duration between ligations of both common carotid arteries (CCA). Material and methods. The experiments were performed on 24 male mongrel white rats weighing 260±20 g. All rats were distributed among three subgroups. Cerebral ischemia was simulated under intravenous thiopental anesthesia (40-50 mg/kg). The control group (n=6) comprised sham-operated rats of similar gender and weight. To study mitochondrial respiration, the brain was extracted in the cold environment (0-4 °C), dried with filter paper, weighed and homogenized sensu the modified technique in an isolation medium containing 0.32 M sucrose, 10 mM Tris-HCl, 1 mM EDTA, pH of 7.4 (in a ratio of 1:10), using Potter – Elvehjem homogenizer with Teflon pestle. Results. SICI with an interval of 1 and 3 days between ligation of both CCA led to neuronal damage in the parietal cortex and hippocampus of rats, which manifested itself in a reduction of the neuron size, deformation of the perikaryons, an increase in the number of shrunken neurons and shadow cells. The most pronounced changes were observed in the subgroup with one-day interval between ligations. These changes were similar to the changes in incomplete cerebral ischemia (ICI) (p=0.07), except for the absence of cells with pericellular edema in the hippocampus and a smaller number of those in the parietal cortex. ICI with seven-day interval between ССА ligations, on the contrary, was manifested by less pronounced histological changes, especially in the hippocampus. Conclusion. Comparative analysis of mitochondrial respiration in brain homogenates revealed that the severity of brain damage in SSIC depended on the interval between blood flow arrest in both CCA. At the same time, the highest level of energy metabolism disorder was observed during CCA ligation with an interval of one day, which implied insufficient implementation of compensatory mechanisms.