A.M. Polimova, G.R. Khakimova, G.K. Vladimirov, T.V. Zhidkova, D.Yu. Izmailov, E.V. Proskurnina, M.V. Ugrumov, Yu.A. Vladimirov

Degeneration of brain neurons in neurodegenerative diseases, including Alzheimer's and Parkinson-s diseases, is generally explained by their damage of the cells under the action of free radicals. Meanwhile, there exist very few methods of a direct detection of radicals in isolated life cells and human and animal tissues. The chemiluminescence (CL) in the presence of the sensitizers can be one of them. The aim of this study was to develop a method of study of the radical-producing ability of brain tissue based on recording of lucigenin-sensitized chemiluminescence (CL). The CL of thin slices (300 µm thick) of two brain areas has been studied in C57BL/6 mice: of substantia nigra (SN), the localization point of the bodies of dopaminergic neurons, and striatum, the area of projection of their axons. In order to determine the possible application of the method to comparative analysis of free radical production in norm and disease, normal mice and those with toxin-induced parkinsonism have been investigated. In a chemiluminescent experiment three slices of a certain brain region were placed together into a cuvette of a chemiluminometer, stirred and aerated by air current. . CL in the presence of luminol, a well-known chemiluminescent probe sensitive to reactive oxygen species, was very weak, while the tissue CL in the presence of С-525, a sensitizer enhancing the ultraweak luminescence in the reactions of chain lipid oxidation, was not detectible at all. The lucigenin-sensitized CL was produced solely by brain sections and not by the washing solution. Not any luminescence appeared without stirring and aeration. A superoxide dismutase (SOD) mimetic and oxidative phosphorylation uncoupler 2,4-dinitrophenol inhibited CL in concentrations of 0.1 to 1.0 mM. In experiments with intact animals, a good reproducibility of results was obtained for both the striatum and SN. The chemiluminescence intensity of these areas was shown to be different. The data of inhibitory analysis have indicated that mitochondria are the major source of SAR in the brain tissue ur preliminary results show that the method could be applied in investigations of free radical production in pathology. As a model, we used an early symptomatic stage of Parkinson's disease. Two pairs of animals (control and MPTP treated) were taken. Not any significant decrease in SAR production was observed in the experiments in spite of the fact that the amount of life neurons was reported to be severely reduced at this stage of parkinsonism. In our opinion, the developed method of of SAR detection in brain slices, where the sensitive photomultiplier is used, has an advantage over a very laborious and expensive method with the use of cooled photomatrix.