Effect of short-term lead exposure on PTZ-induced seizure threshold in mice

This study was designed to determine the effect of different concentrations of lead acetate on seizure threshold. Balb\c male mice were randomly divided into one control group provided with tap water and four experimental groups received lead acetate in drinking water for 30 days at concentrations of 50, 100, 200 and 400 ppm. Intravenous infusion of pentylenetetrazole (PTZ) was used to induce seizure signs and elapsed time was recorded to calculate the threshold dose. At the end of the experiments blood samples were taken to measure the blood lead level. Threshold doses of PTZ were significantly lower in 100, 200 and 400 ppm lead exposed groups for the induction of all seizure stages. Blood lead level increased in all experimental groups compared to control dose-dependently. Considering the lack of any response induced by 50 ppm concentration of lead, it may be concluded that 100 ppm of lead was the minimal effective dose. Therefore, lead acetate at a concentration of 100 ppm that produces similar blood level in human populations approves the enhancement of convulsive attack risk. Considering the effect of low levels of lead in the reduction of seizure threshold, more investigations should be carried out to clarify the exact mechanisms.