RESUMO
The effects of the iron chelator desferrioxamine (DFx) on liver iron accumulation, malondialdehyde (MDA) production, porphyrin accumulation and uroporphyrinogen decarboxylase (URO-D; EC 4.1.1.37) activity were investigated over a period of 14 weeks in C57BL/10 mice, made porphyric by the administration of hexachlorobenzene (HCB) and iron-dextran (Imferon, IMF) or IMF alone. In addition, we measured the amount of low molecular weight (LMW) iron in liver tissue to determine a possible correlation with MDA production. These experiments showed that combined treatment with HCB + IMF, as well as IMF alone, resulted in porphyrin accumulation, increased MDA production and reduced URO-D activity, whereas HCB alone had no effect. DFx caused a reduction in hepatic porphyrins, this reduction being more distinct in the IMF group than in the HCB + IMF group. The effect of DFx on MDA production and URO-D activity was in agreement with the results on porphyrin accumulation. LMW iron pool measurements at 11 weeks correlated well with data on MDA production in all treated groups in that period (r2 = 0.84), suggesting both variables are interdependent. In conclusion, these results suggest an important role for iron in porphyrin accumulation, probably through its catalytic role in the generation of oxygen-related free radicals, resulting in direct damage to URO-D. The effectiveness of DFx in reducing porphyrin accumulation is probably the result of a reduction in LMW iron, thus diminishing the amount of iron available for a catalytic role in the generation of oxygen-related free radicals.
