Relationships between silicon content and glutathione peroxidase activity in tissues of rats receiving lithium in drinking water

Lithium salts are widely used in psychiatry, but their presence in organism can result in both beneficial and adverse effects. Silicon, the third most abundant trace element in humans as well as antioxidant enzyme glutathione peroxidase (GPx) play important roles in organism. The disturbance of their level can cause severe disorders. The aim of our work was to evaluate the influence of Li₂CO₃ administration in drinking water for a period of 4 weeks on Si content and GPx activity in the tissues of liver, kidney, brain and femoral muscle in rats. The concentrations of provided solutions were 0.7, 1.4, 2.6, 3.6, 7.1 and 10.7 mmol Li⁺·dm⁻³. GPx activity was decreased versus control as a consequence of Li treatment, particularly in kidney and brain. This effect could be suggested to contribute to renal abnormalities which could occur during Li therapy. Si tissue level was significantly enhanced versus control in liver and femoral muscle in groups receiving high Li doses. In brain no well-marked changes were observed, whereas in kidney we observed the depletion in low-Li-groups, restoration of Si level in higher-Li-groups and unexpected decrease in the highest-Li-group. Positive correlations between Si content and GPx activity in the tissues of kidney (r = 0.677) and brain (r = 0.790) as well as negative correlation (r = −0.819) in femoral muscle were found. We consider that our results give some reason for suggesting that monitoring of silicon level in patients undergoing Li therapy could be recommended. However, more investigations should be performed, particularly regarding the relationships between Si and GPx in blood and urine Si excretion during lithium administration.