TIME COURSE OF CEREBELLAR CATALASE LEVELS AFTER NEONATAL IONIZING RADIATION

DI MEGLIO A; CÁCERES, L; ZIEHER, L. M; GUELMAN, L. R

Pinamar, Bs As, Argentina

Congreso; X Congress of the Panamerican Association for Biochemistry and Molecular Biology (PABMB) , XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB) and the XX Annual Meeting of the Argentine Society for Neurochemistry (SAN; 2005

Panamerican Association for Biochemistry and Molecular Biology , Argentine Society for Biochemistry and Molecular Biology and Argentine Society for Neurochemistry

Reactive oxygen species are physiologically generated as a consequence of aerobic respiration; the generation is increased in response to external stimuli, including ionizing radiation. The central nervous system (SNC) is vulnerable to oxidative stress due to its high oxygen consumption rate, its high level of polyunsaturated fatty acids and a high rate of oxygen free radical generation without appropriate levels of antioxidative defences. An important compound of this defence system is the antioxidant enzyme catalase, a heme protein that removes hydrogen peroxide from the cell by catalyzing its conversion to water. The objective of the present work was to study if catalase is susceptible to oxidative stress generated by ionizing radiation in cerebellum. For that, neonate rats were irradiated and the levels of catalase were measure at 15, 30, 60 and 90 days of age. The results show that at 15 days there is a drop in the activity of catalase in irradiated cerebellum (% respect the control, 65.6 ± 14.8), which continues dropping at 30 days (51.35 ± 5.8 %), and at 60 days the activity descend even more (9.3 ± 0.34 %). However, at 90 days postirradiation, a 50 % increase over control values in catalase activity was observed. This suggest, although at 15 and 30 days catalase proportionally descend with the fall of tissue’s weight due to the radiation, at 60 days there is an additional change that can’t be explained just for the lost of weight in the irradiated cerebellum. It could be suggest that, in long term, the irradiation could be generating the oxidation of the heme group of the enzyme. In conclusion, an antioxidant enzyme, catalase has shown to be susceptible to ionizing radiation.