Protective effects of selenium and zinc on the brain acetyl cholinesterase activity in lead intoxified rat

Lead is a common toxic agent which impairs various organs functions of the body. The basis of this toxicity is believed to be the negative influence on enzymatic system of cells. In the past few years, increasing consideration has been given to interactions occurring between lead and some essential metals including Se and Zn. Based on the finding that some trace elements could reverse the toxicity of lead on tissue functions this work was performed to study the protective effects of Zn and Se against lead toxicity. Thus changes in acetyl cholinesterase (AchE) activity in brain regions were investigated in different conditions. Four groups of rats were chosen. In acute study, i.p. administration of Pb (13.5 mg/kg) for 2 weeks reduced the activity of AchE in the cortex by 28.7% but Pb in presence of Zn (0.5 mg/kg) and Se (0.4 mg/kg) inhibited AchE activity only by 11.5% and 25%, respectively, such inhibition in mid-brain were 44.7%, 18.2%, 32% and in the cerebellum 48.2%, 38.4% and 12.0%. In chronic study, animals were administered Pb alone (4 mg/kg) or in the presence of Se or Zn for 60 days. Following these treatments, AchE activities in the cortex were reduced by 41.5%, 22.0% and 39.6%, respectively. These inhibitions in mid-brain were 56.0%, 37.6%, 54.5% and in cerebellum 46.0%, 45.0%, 32.6%. It is concluded that lead had toxic effect on AchE activity in different brain regions and Zn and Se could reverse this inhibition to some extent.