Silicon Reverses Lipid Peroxidation but not Acetylcholinesterase Activity Induced by Long-Term Exposure to Low Aluminum Levels in Rat Brain Regions.

Abstract

Aluminum (Al) is the most widely distributed metal in the environment and is extensively used in daily life leading to easy exposure to human beings. Besides not having a recognized physiological role, Al may produce adverse effects through the interaction with the cholinergic system contributing to oxidative stress. The present study evaluated, in similar conditions of parenteral nutrition, whether the reaction of silicon (SiO2) with Al(3+) to form hydroxyaluminosilicates (HAS) reduces its bioavailability and toxicity through intraperitoneal administrations of 0.5mg Al/kg/day and/or 2mg Si/kg/day in Wistar rats. Al and Si concentrations were determined in rat brain tissue and serum. Acetylcholinesterase (AChE) activity and lipid peroxidation (LPO) were analyzed in the cerebellum, cortex, hippocampus, striatum, hypothalamus, and blood. An increase in the Al concentration was verified in the Al+Si group in the brain. All the groups demonstrated enhanced Si compared to the control animals. Al(3+) increased LPO measured by thiobarbituric acid reactive substances (TBARS) in cerebellum and hippocampus, whereas SiO2 reduced it when compared with the control group. An increase of AChE activity was observed in the Al-treated group in the cerebellum whereas a decrease of this enzyme activity was observed in the cortex and hippocampus in the Al and Al+Si groups. Al and Si concentrations increased in rat serum; however, no effect was observed in blood TBARS levels and AChE activity. SiO2 showed a protective effect in the hippocampus and cerebellum against cellular damage caused by Al(3+)-induced lipid peroxidation. Thus, SiO2 may be considered an important protector in LPO induced by Al(3+).